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Bound water in collagen. Evidence from Fourier Transform Infrared and Fourier transform infrared photoacoustic spectroscopic study
Abstract
In this study, FTIR photoacoustic spectroscopy is utilized to investigate collagen in the solid state. A resolution enhancement of the amide I band in collagen The presence of bound water, probably hydrogen bonded, in chick skin type I collagen has been shown from resolution enhancement of the amide I region of FTIR spectrum of collagen. However, as noted earlier, in the case of collagen, 20,35 the principle molecular vibrations of the polypeptide backbone are confined by stereochemical constraints to certain narrow regions in the spectra, viz., amide I, 1636-1661 cm-1, amide II, 1549-1558 cm-1 which differ from the characteristic vibrations for α-helical and β-sheet structures.
... FTIR analysis was carried out to show that collagen had formed. This is indicated by the absorption of wave numbers 1636-1661 cm-1 amide A marker, 1600-1700 cm-1 amide I marker, 1650-1580 cm-1 amide II marker (Renugopalakrishnan et al, 1989) and 1200-1300 cm-1 amide III marker (Friess and Lee, 1996) ...
... The FTIR spectra data show the peak wave number of amide II. These wave numbers prove stretching C-N (1335-1250 cm -1 ) and N-H deformation (1650-1580 cm-1) of the peptide group (Renugopalakrishnan et al, 1989). Amide III region (1200-1300 cm -1 ) of red snapper has been shown in the FTIR spectra results. ...
... For instance, by monitoring the intensity ratio between Amide I and Amide II signals and between the Amide III and the signal located at about 1450 cm −1 , the denaturation can be controlled. [131,132] In our previous works, [9,10] we proposed a method to calculate the amount of triple helices in a collagen samples by deconvoluting the Amide I signal, since this is due to the contribute of the CO stretching modes, which could vary depending on the secondary and, sometimes, on the tertiary arrangement [133,134] This means that each Amide I band is a multicomponent band and these components can be separated and observed, by utilizing our approach. The asymmetrical collagen Amide I band was deconvoluted in order to separate the contributions Macromol. ...
Collagen represents one of the most widely used biomaterial for scaffolds fabrication in tissue engineering as it represents the mechanical support of natural tissues. It also provides physical scaffolding for cells and it influences their attachment, growth, and tissue regeneration. Among all fibrillary col- lagens, type I is considered one of the gold standard for scaffolds fabrication, thanks to its high biocompatibility, biodegradability, and hemostatic proper- ties. It can be extracted by chemical and enzymatic protocols from several collagen-rich tissues, such as tendon and skin, of different animal species. Both the extraction processes and the manufacturing protocols for scaffolds fabrication provide structural and mechanical changes that can be tuned in order to deeply impact the properties of the final biomaterial. The aim of this review is to discuss the role of X-rays to study structural changes of type I col- lagen from fresh collagen-rich tissues (bovine, equine, fish) to the final scaf- folds, with the aim to screen across available collagen sources and scaffolds fabrication protocols to be used in tissue regeneration.
... Ker je slednji bolj občutljiv v primerjavi s prvim (Anastassopoulou et al. 2015, 93), se njuno razmerje s tafonomskimi procesi niža (Leskovar 2016, 77). Odvajanje traku amida I (tabela 2) in III raz-Uporaba FTIR spektroskopije za analizo kosti iz arheoloških okolij Tabela 2. Posamezne komponente traku amida I. (Payne, Veis 1988;Renugopalakrishnan et al. 1989;Prystupa, Donald 1996;Chang, Tanaka 2002;Habermehl et al. 2005;Barth 2007;Chadefaux et al. 2009) (tabela 2). Pri tafonomskih procesih običajno pride do denaturacije kolagena, ki jo je mogoče opaziti v razmerju med komponento ~ 1660 in ~ 1630 cm -1 (60/30) znotraj amida I ter komponento ~ 1237 in 1270 cm -1 (37/70) znotraj amida III (Habermehl et al. 2015, 825-826;Leskovar 2016, 78). ...
... Ker je slednji bolj občutljiv v primerjavi s prvim (Anastassopoulou et al. 2015, 93), se njuno razmerje s tafonomskimi procesi niža (Leskovar 2016, 77). Odvajanje traku amida I (tabela 2) in III raz-Uporaba FTIR spektroskopije za analizo kosti iz arheoloških okolij Tabela 2. Posamezne komponente traku amida I. (Payne, Veis 1988;Renugopalakrishnan et al. 1989;Prystupa, Donald 1996;Chang, Tanaka 2002;Habermehl et al. 2005;Barth 2007;Chadefaux et al. 2009) (tabela 2). Pri tafonomskih procesih običajno pride do denaturacije kolagena, ki jo je mogoče opaziti v razmerju med komponento ~ 1660 in ~ 1630 cm -1 (60/30) znotraj amida I ter komponento ~ 1237 in 1270 cm -1 (37/70) znotraj amida III (Habermehl et al. 2015, 825-826;Leskovar 2016, 78). ...
FTIR-ATR spectroscopy enables fast and accurate chemical analyses of different materials. Small sample requirements and a potentially non-destructive nature render the technique a highly useful tool in (osteo)archaeological analyses. Offering an insight into the chemical composition, it can be employed in the study of the state of sample preservation or the influence of environment on the sample’s chemical structure. The contribution brings a brief presentation of the technique, the chemical structure of the bone, the changes in bone structure after death and the different possibilities for FTIR-ATR data manipulation and interpretation.
... The FTIR spectra of MO CCLW Fig.(2) suggest that the protein structure of the leather is maintained after the chromium based extraction. The protein structure is evidenced by the signal at 1627.81 cm⁻¹ due to carbonyl group C=O and at 1542.95 cm⁻¹ due to N-H [22] . ...
... 44,40 The two spectra are even characterized by the usual C−O stretching vibration absorption bands at about 1079 and 1032 cm −1 , arising specifically from ν(C−O−C) and ν(C− O). 42 It is worth highlighting that the 1237/1450 cm −1 absorption ratios for CG and for FACG are both in the range from 0.8 and 1, confirming that the secondary structure of the protein triple helix is not affected. 45,46 The FTIR spectrum of NPsCG (black line in Figure 1a), even if preserving the principal features of the triple helix protein gel, presents some important differences if compared with the two other spectra. In fact, the 1237/1450 cm −1 absorption ratio is in the usual range. ...
A porous collagen-based hydrogel scaffold was prepared in presence of iron oxide nanoparticles (NPs) and was characterized by means of infrared spectroscopy and scanning electron microscopy. The hybrid scaffold was then loaded with fluorescein sodium salt as a model compound. The release of the hydrosoluble species was triggered and accurately controlled by the application of an external magnetic field, as monitored by fluorescence spectroscopy. The biocompatibility of the proposed matrix was also tested by the MTT assay performed on 3T3 cells. Cell viability was only slightly reduced when the cells were incubated in presence of the collagen-MNPs hydrogel, compared to controls.
... Peaks around 1653 and 1535 cm −1 in the FTIR spectra of native LF were attributed to CO stretching vibrations of amide I band 60,61 and N−H bending vibrations and C−N stretching vibrations of amide II band, 62−65 respectively. Both the CO bonds and the C−N bonds were involved in the hydrogen bonds which took place between the different elements of secondary structure of proteins. ...
The interactions between native, thermally modified lactoferrin (LF) and (-)-epigallocatechin-3-gallate (EGCG) at pH 3.5, 5.0, and 6.5 were investigated. Turbidity, particle size, and charge of LF-EGCG complexes were mainly dominated by pH value and secondary structure of protein. At pH 3.5 and 5.0, LF-EGCG complexes were nanoparticles which had high ?-potential, small size, and soluble state. At pH 6.5, they were submicrometer particles which exhibited low ?-potential, large size, and insoluble state. The infrared spectra of freeze-dried LF-EGCG complexes showed that they were different from LF and EGCG alone. Far-UV CD results indicated that heat denaturation might irreversibly alter the secondary structure of LF and EGCG induced a progressive increase in the proportion of alpha-helix structure at the cost of beta-sheet and unordered coil structure of LF at pH 3.5, 5.0, and 6.5. EGCG exhibited a strong affinity for native LF but a weak affinity for thermally modified LF at pH 5.0 and 6.5. An inverse result was observed at pH 3.5. These results could have potential for the development of food formulations based on LF as a carrier of bioactive compounds.
... Thus, the second and third states of bound water in collagen and at mineral surfaces in bone respectively are not removed even with the highest vacuum conditions of the SEM. The SEM high vacuum conditions must also be less invasive than the application of the high temperatures (reported in the range of 60-140 • C) used to remove water during complete collagen dehydration (Renugopalakrishnan et al., 1989). ...
The lamellar unit is a critical component in defining the overall mechanical properties of bone. In this paper, micro-beams of bone with dimensions comparable to the lamellar unit were fabricated using focused ion beam (FIB) microscopy and mechanically tested in bending to failure using atomic force microscopy (AFM). A variation in the mechanical properties, including elastic modulus, strength and work to fracture of the micro-beams was observed and related to the collagen fibril orientation inferred from back-scattered scanning electron microscopy (SEM) imaging. Established mechanical models were further applied to describe the relationship between collagen fibril orientation and mechanical behaviour of the lamellar unit. Our results highlight the ability to measure mechanical properties of discrete bone volumes directly and correlate with structural orientation of collagen fibrils.
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... Stretching vibrations of the CO bond of the amide together with the weakly coupled in-plane N−H bending and C−N stretching contribute to the amide I absorption. 44 Because both CO and NH bonds were involved in the hydrogen bonding between different elements contributing to secondary structure, amide I bond was an ideal wavenumber range for secondary structure analysis of protein. Previous studies have systematically correlated proteins of known secondary structure with the shape of the amide I band, and the following secondary structure in this band has been suggested: 45,46 β-turn, 1678− 1682 cm −1 ; α-helix, 1648−1659 cm −1 ; random coil, 1638−1640 cm −1 ; and β-sheet, 1625−1635 cm −1 . ...
Prolamins from grains have attracted intensive attentions in recent years due to their potential in satisfying the demand of environmental friendly (biodegradable), abundantly available (sustainable) and cost effective biomaterials. However, for kafirin, the prolamin from sorghum, its composition, structure, morphology and self-assembly behaviors have not been fully characterized. In this paper, kafirin was extracted from the whole sorghum grain and found to contain 68%, 14%, 6% and 12% of α -, β -, γ - fractions and cross-linked kafirin. Freeze-dried kafirin contained ~49%α-helix in the solid state. When dissolved in 65% isopropanol, 60% tert-butanol and 85% ethanol aqueous solvents, the relative α-helix content in kafirin increased with the decrease of solvent polarity. Structural analysis using small-angle x-ray scattering (SAXS) indicated that kafirin took stretched and extended conformations with dimensions of 118×15×15 Å and 100×11×11 Å in 60% tert-butanol and 65% isopropanol, respectively. More elongated conformation of individual kafirin with high-order assembly was observed in 85% ethanol. The morphology of kafirin assemblies captured by atomic force microscopy (AFM) confirmed the transition from uniform particles at low kafirin concentration to disk-like or rod-like particles at high kafirin concentration. These results suggest that both protein concentration and solvent polarity can effectively regulate kafirin assemblies from thick rod-like to slim rod-like structures, a convenient way to tune the fibrillation of prolamin based biomaterials.
... The FTIR spectrumofthe nHAC appeared asasuperposition of the spectraof the collagen fibrilsand the calciump hosphate. The FTIR spectrumo fthe nHAC shows typicalp eaksof phos-phateat563 (assignment: m 4),602 (assignment: m 4),962 (assignment: m 1),a nd 1034( assignment: m 3)cm -1 .The weakbandsat1419 and 874cm -1 arederived from carbonatei ons,whichi ndicatest hatPO 4 3sitesin the nHAC werereplaced partiallybycarbonatei ons [22].Thisw as possible becauseCO 3 2could beincorporated intothe solution from the airduring mineralprecipitation [5].The FTIR spectrumofthe nHAC hadthe characteristicbandsat1655, 1554 and 1238cm -1 ,whichrepresented amide I, II and III bandsof collagen [23,24].Amide Ia bsorptionarised predominantlyfrom protein amide C=Ostretchingvibrations, amide II absorptionarised from amide N-Hbending vibrationsand C-Nstretching vibrations(60 %and 40%contribution tothe peak,respectively),and the amide III peakwas complex,consisting of the components from C-Nstretching and N-Hin plane bending from amide linkages,aswell ast he absorptionsarising from wagging vibrationsfrom CH 2 groupsin the glycine backboneand proline side-chains [25].The FTIRspectrumo fH0depicted characteristicab-sorptionbandsat1664and 978cm -1 ,whichrepresented the presenceof-C=Ogroupand -C-Ostretchingofprimary alcoholicgrouprespectively. ...
Mineralized collagen fibrils are the basis for various connective tissues such as bone and cartilage. Injectable biomaterials incorporating mineralized collagen fibrils are applicable to a wide variety of implant types for bone regeneration. A mineralized collagen fibrils/chitosan thermo-sensitive and injectable scaffold for bone regeneration was prepared successfully. The thermo-sensitive properties of the mineralized collagen fibrils/chitosan system depended on the concentrations of mineralized collagen fibrils. 0.02 g mL(-1) of mineralized collagen fibrils filler was appropriate for application since it allowed lower gelation temperature and more rapid gelation following injection, due to the increased hydrogen bonds between the collagen in mineralized collagen fibrils and chitosan.
... Peaks around 1653 and 1535 cm −1 in the FTIR spectra of native LF were attributed to CO stretching vibrations of amide I band 60,61 and N−H bending vibrations and C−N stretching vibrations of amide II band, 62−65 respectively. Both the CO bonds and the C−N bonds were involved in the hydrogen bonds which took place between the different elements of secondary structure of proteins. ...
The interactions between native, thermally modified lactoferrin (LF) and (-)-epigallocatechin-3-gallate (EGCG) at pH 3.5, 5.0 and 6.5 were investigated. Turbidity, particle size and charge of LF-EGCG complexes were mainly dominated by pH value and secondary structure of protein. At pH 3.5 and 5.0, LF-EGCG complexes were nano-particles which had the high ζ-potential, the small size and soluble state. At pH 6.5, they were sub-micrometer particles which exhibited the low ζ-potential, the large size and insoluble state. The infrared spectra of freeze-dried LF-EGCG complexes showed that they were different from LF and EGCG alone. Far-UV CD results indicated that the heat denaturation might irreversibly alter the secondary structure of LF and EGCG induced a progressive increase in the proportion of α-helix structure at the cost of β-sheet and unordered coil structure of LF at pH 3.5, 5.0 and 6.5. EGCG exhibited a strong affinity for native LF but weak one for thermally modified LF at pH 5.0 and 6.5. An inverse result was observed at pH 3.5. These results could be potential for the development of food formulations based on LF as a carrier of bioactive compounds.
... Highly intensive peaks were observed at a wavelength of 1160 cm -1 reflecting the anti-symmetrical stretching vibrations of C-O-C bonds. Wavelengths of 1032 and 1086 cm -1 show the presence of symmetrical stretching vibrations of C-O bonds, which are characteristic to sugars[32 -34], while the peaks at 2600 and 3566 and 3700 cm-1 highlight the stretching vibrations of the -OH group in chitosan.The peaks of collagen confirm the presence of the functional groups C=O, amide I (1658 cm -1 ), N-H amide II bending vibrations and C-N stretching vibrations (1554 cm -1 ), C-N and N-H amide III (1240 cm -1 )[35,36].The FTIR analysis of Chit/Col indicates amide bonds I, and stretching vibrations indicate C=O (1600 -1690 cm -1 ) at a wavelength of 1652 cm -1 , which correlate with the nitrogen content in the fibres. The presence of amide bonds II, stretching vibrations for CN=O and bending vibrations for NH (1480 -1575 cm -1 ) ...
A method is presented for the preparation of collagen-modified chitosan fibres (Chit/Col) from chitosan-collagen solutions. The fibres may be used in the construction of scaffolds. Chitosan solutions with a concentration of 5.21% in an aqueous 3.0% acetic acid solution with the addition of glycerol were mixed with aqueous solutions of collagen. The applied chitosan was derived from the northern shrimps (Pandalus borealis) and the collagen from calf hide. The usability of chitosan and collagen was determined for the preparation of spinning solutions and Chit/Col fibres. Rheological properties are discussed for the chitosan-collagen solutions used in the spinning of Chit/Col fibres with linear density in the range of 3.30-8.36 dtex. The fibres are featured by increased nitrogen content and tenacity when compared to pure chitosan fibres. The performance of the spinning process was good.
... The amide III corresponds to vibrations in plane of C-N and N-H of bound amide, and vibrations of CH 2 groups of glycine. [20][21][22] The amide II peak presented visible changes in its position, as a function of water content, as depicted in Figure 6, which seems to follow a given trend. The changes were found to be more prominent in the films without glycerol, mainly in the region of low water content. ...
In this work, it was investigated the effect of different moisture contents on PVA-gelatin films by means of dielectric properties, infrared spectroscopy, microwave response and gravimetric method. The films were elaborated from a blend of gelatin and PVA, with 0 and 25 % glycerol. The sorption isotherms were determined by gravimetric methods, at 25 °C. A capacimeter was used for dielectric measurements, and a device called SOLFAN setup was used for microwave measurements. The sorption isotherms were markedly affected by the glycerol content and relative humidity, due to the hygroscopic nature of the films. The dielectric constant and the microwave response signal were also strongly affected by the moisture and glycerol content in the films. Finally, Infrared spectra showed some changes in the amide peak positions, attributed to the modifications in the interactions between the macromolecules. The behaviors obtained in this work were explained on the basis the way the water enters in the film matrix.
... The IR spectrum (Fig. 2) shows characteristic peaks corresponding to the organic components of the fish scales (1662, 1560 and 1242 cm − 1 ), namely amide I, II and III bands of collagen [1,[7][8][9][10]. The absorption peak at 1662 cm − 1 is associated with the C = O stretching vibrations of the amide I protein, the amide II absorption (1560 cm − 1 ) is due to the N-H bending vibration and the C-N stretching vibrations; the amide III peak (1242 cm − 1 ) have components of C-N stretching and N-H in plane bending, as well as absorptions arising from CH 2 groups from the glycine back bone and proline side-chains [11,12]. ...
In the present paper, the nanocomposite laminate structure of scales from the Amazonian fish Arapaima Gigas is investigated. The structure and composition of the scales were assessed by means of X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR). The theory of Fickian diffusion is used and discussed in order to rationalize the water absorption and desorption behavior of the scales. Morphology studies and fracture analysis of the native scales were carried out using Transmission Electron Microscopy (TEM), Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM). A fibrous layer of collagen and a plywood-like structure were observed. In order to study the mineral phase, the native scales were burned at 600 °C until all the organic components were degraded. The remaining ashes were then observed under the microscope and weighed to determine ratio of organic and inorganic components. The mechanical behavior of dry and wet scales was assessed by tensile tests and the effect of water in mechanical properties is also discussed.
... The characteristic peaks of Col (Fig. 10), appears at 3312 cm À1 (amide II, N-H bending and C-N stretching) and 1240 cm À1 (amide III, CN stretching and N-H bending) [39][40][41]. PVA/Col NFs spectrum shows that the amide A band shifted to lower frequencies than in collagen and the amide B band disappeared, because of amide B band was observed only for Col/PVA blend weight ratio (99:1) [42]. The spectra of PVA/Col/n-HAp NCNFs, has a small decrement for amide A compared with pure Col, accompanied by absence of amide B (due to the high amount of PVA) [42]. ...
Polyvinyl alcohol (PVA) nanofibers, PVA/Type I Collagen (Col) and their composites with hydroxyapatite nanoparticles (nano-HAp) were prepared by electrospinning techniques. The composite nanofibrous membranes were subjected to detailed analysis. Morphological investigations show that the generated nanofibers (NFs) have uniform morphology with an average diameter of ∼160 nm for pure PVA, ∼176 nm for PVA/n-HAp, ∼245 nm for PVA/Col and ∼320 nm for PVA/Col/n-HAp. It is of interest to observe that large numbers of HAp nanorods are preferentially oriented parallel to the longitudinal direction of the electrospun PVA and/or PVA/Col NFs. FTIR and thermal analysis demonstrated that there was strong intermolecular hydrogen bonding between the molecules of PVA/Col/n-HAp. Furthermore, the obtained PVA/Col/nHAp NFs scaffold (7 cm × 11 cm) has a porous structure with adjustable pore size and shape. The pore size is in the range of 650 μm with a porosity of 49.5%. On the other hand, mechanical characterizations revealed that the incorporating of 5 wt% n-HAp into the matrix of PVA/Col nanofibers could significantly improve the rigidity of the resultant biocomposite nanofibrous scaffold. These results strongly suggest a huge potential of the prepared scaffold for bone tissue engineering.
... These bands were hardly detected in the composite. There were two bands that did show a red shift when comparing their position in the composite respect the collagen spectra, which were those corresponding to amide II and the amide I. Regarding the amide II band [22], the wavenumber shifted from 1,558 cm -1 for collagen, to 1,551 cm -1 in the composite. The amide I band [23] also showed a shift from 1,653 to 1,647 cm -1 . ...
A bone inspired material was obtained by incorporating collagen in the liquid phase of an α-tricalcium phosphate cement, either in solubilized or in fibrilized form. This material was able to set in situ, giving rise to a calcium deficient hydroxyapatite (CDHA)/collagen composite. The morphology and distribution of collagen in the composite was shown to be strongly affected by the collagen pre-treatment. The interactions between collagen and the inorganic phase were assessed by FTIR. A red shift of the amide I band was indicative of calcium chelation by the collagen carbonyl groups. The rate of CDHA formation was not affected when diluted collagen solutions (1 mg/ml) were used, whereas injectability improved. The presence of solubilized collagen, even in low amount (1 %), increased cell adhesion and proliferation on the composites. Still in the absence of osteogenic medium, significant ALP activity was detected both in the inorganic and the collagen-containing cements. The maximum ALP activity was advanced in the collagen-containing cement as compared to the inorganic cement.
... It can provide valuable information on their conformational changes in aqueous solution [37]. The spectrum of free BSA displays two characteristic peaks at 1653 and 1541 cm −1 [38]. The former is principally ascribed to the amide C=O stretching vibrations (amide I) and the latter to the amide N–H bending vibrations and C–N stretching vibrations (amide II). ...
The interaction between trans-resveratrol (TR) with bovine serum albumin (BSA) in aqueous solution was investigated by means of fluorescence, synchronous
fluorescence and infrared spectroscopy. The fluorescence of BSA can be quenched remarkably by TR in aqueous solution. A notable
red-shift of the maximum emission of BSA from 340 to 353nm together with appearance of an isoemissive point at 395 nm were
observed. The results indicate that TR binds to BSA, forming a TR–BSA complex. The TR–BSA binding distance was determined
to be less than 7 nm, suggesting that energy transfer from BSA to TR may occur. The interaction process is spontaneous. Based
on the obtained thermodynamic parameters, electrostatic forces may play a major role in this process. Both synchronous fluorescence
and FT-IR spectra confirmed the interaction, and indicate the conformational changes of BSA.
The effect of pH on interactions of soybean glycinin (11S) and β-conglycinin (7S) with (−)-epigallocatechin- 3-gallate (EGCG) were determined by turbidity. Results confirmed that the protein structure and interactions of 11S and 7S with EGCG depended largely on the pH. The binding affinity between 11S, 7S proteins and EGCG was strongest at pH 7.0 among the three pH levels and 7S showed a greater affinity to EGCG compared to 11S. The interaction mechanisms and structures of 11S-EGCG and 7S-EGCG complexes were further determined by multiple spectroscopic technique and molecular docking. Results showed that EGCG induced changes in the microenvironment of tryptophan, tyrosine, and C–H bending vibration at different pH levels. Binding to EGCG altered the secondary structures of the 11S and 7S proteins, inducing an increase in β-sheet at the cost of α-helix at pH7.0 and α-helix at pH5.0, respectively. The 11S and 7S presented more compact microstructure with the addition of EGCG. Electrostatic interaction, hydrogen bonding and hydrophobic interaction were all involved in the formation of complexes, where the hydrogen bond was the dominant one. These results might be helpful for the development of 11S-EGCG and 7S-EGCG as a bioactive food additive in the food industry.
Cellulose produced by some bacteria (bacterial cellulose, BC) represents an interesting emerging biocompatible nanomaterial. It has been widely used in tissue engineering. BC possesses unique properties, such as high mechanical properties, high purity, excellent microstructure, high water‐holding capacity, and high crystallinity. Despite the intensive research, application of BC has been limited, due to its biological activity and pore structure. This study summarized the modifications of structure and composition. Several biomaterials could be associated with BC, for example gelatin, chitosan, heparin, collagen, and hydroxyapatite, and several methods were used to control the microstructure of BC, namely, laser‐patterning technique and freeze‐drying technology. The results confirmed BC as a promising biomaterial with the potential to be an effective biopolymer in biomedical fields. These approaches will help researchers to develop new ideas in tissue engineering field.
Inspired by delicate structures and intelligent functions of natural multiple enzyme systems, combining nanotechnology developments such as nanomaterials, self-assembly, and enzyme mimics is fascinating in the development of next-generation high-performance enzyme cascade bioplatform. In our novel design, the dual-functional protein/inorganic hybrid acted as both a nanozyme with outstanding peroxidase-like activity as well as a scaffold to immobilize and stabilize nature oxidase with retained activity, resulting in high-performance enzyme cascade bioplatform in one-pot assembling process. Due to the special physical-chemical surface properties, the multipoint attachment of various interactions between nature enzyme and protein/inorganic hybrid result in an efficient immobilization of enzyme with retained activity. As a result, the proposed cascade bioplatform exhibited excellent sensitivity with a wide linear range of 0.1 to 400 μM and a detection limit of 0.05 μM for cholesterol. Therefore, the highly rational designed protein/inorganic hybrid and the dual-functional strategy in this study would provide a facile one-pot and effective means for the high-performance enzyme cascade bioplatform, which has potential applications in biosensing, biotransformation, decontamination and biofuel.
Casein was modified by ultrasound treatment (160W, 400 W)and the structural characteristics of casein (control), USC-1 (160W of ultrasound treated casein) and USC-2 (400W of ultrasound treated casein) were investigated. Ultrasound treatment resulted in increase in the numbers of protein bands of casein in region of low molecular weight according to SDS-PAGE pattern. The relative percentage of the proteins with molecular mass (MM) of over 30 kD in USC-1 and USC-2 significantly decreased compared with control sample. Coupled with this is the relative percentage of the proteins with MM of region 20 kD-30 kD for the ultrasonic-treated caseins increased. Contents of α-helix, β-sheet and random coil of casein for USC-1 and USC-2 decreased compared with control. While, β-turn content for USC-1 and USC-2 increased. Ratio of α-helix to β-sheet in USC-1 and USC-2 significantly decreased (from 0.70 to 0.47 and 0.46). Ultrasound treatment had a strong crushing action of surface of the casein micelle and resulted in its structural disruption. Particle size distribution range of casein was approximately 0.5-70 μm, Particle size of USC-1 and USC-2 was less than 30μm. D (50), D (4, 3) as well as D (3, 2) for USC-1 and USC-2 reduced compared with the control. The ratio of D (4, 3) to D (3, 2) also decreased with increase of ultrasonic intensity. This study demonstrated that ultrasound treatment could be an effective method for modification of casein structure. This modification is the basis on improvement in functional properties.
The poor flexibility, low toughness and thermal stability have restricted the applications of degradable poly(lactic acid) bioplastic. The introduction of deoxyribonucleic acid, whey protein or collagen with helical structures, which include numerous intermolecular hydrogen bonds, can produce changes in mechanical and thermal properties of poly(lactic acid) materials. Due to the presence of more –C = O and –NH groups with strong hydratability, different composites exhibited a higher heat resistance compared with the neat poly(l-lactic acid). Moreover, for collagen/poly(l-lactic acid) composites, the tensile strength and elongation at break were increased by 88.6 and 154.9% compared with the neat poly(l-lactic acid), respectively. The results provide a basis for the design of novel poly(lactic acid)-based composites and can expand the application areas of materials, including plastic films, taker-bags, textiles and so on.
Potassium cobalt hexacyanoferrate was modified on alkali-hydrolyzed leather scrap (AHLS/KCoFC) to prepare a novel adsorbent for cesium (Cs⁺) adsorption. AHLS/KCoFC was characterized with SEM, FT-IR, XRD, and XPS to affirm the correct modification. Batch experiments were performed to investigate the adsorption performance of AHLS/KCoFC for Cs⁺ under various conditions, including pH, initial concentration, contact time and temperature. The equilibrium data was fitted well with Langmuir model and the maximum adsorption capacity was 36.75 mg g⁻¹ at pH 6.0, 298.15 K and concentration 100 mg L⁻¹. Thermodynamic and kinetic studies showed that the adsorption process was spontaneous and endothermic, the pseudo-second-order kinetic model fitted accurately the data, and the adsorption process was controlled by intraparticle diffusion, but it was not the only rate-limiting step. Moreover, selective adsorption was investigated systematically. It was found that AHLS/KCoFC exhibited high selectivity for Cs⁺ in presence of coexisting ions. At the optimum conditions, AHLS/KCoFC could be employed to the recovery of Cs⁺ from saline lake brine, and the adsorption efficiency was achieved 97.33%, suggesting AHLS/KCoFC is potential application advantage as an efficient adsorbent.
Collagen membranes possess ideal biological properties and can be served as a barrier for supporting infiltration and proliferation of osteoblasts in guided bone regeneration (GBR). However, pure collagen lacks desirable mechanical properties and also leads to inflammation, resulting in progressive bone resorption. In our previous study, EGCG cross-linked collagen membranes exhibit better mechanical properties and anti-inflammatory effect. However, higher concentration of EGCG may not improve cell viability. Herein, we present an enhanced EGCG cross-linked collagen membranes with surface modification of PEG to improve cell viability and cell adhesion, considering the better biocompatibility of PEG. Scanning electron microscope images showed that PEG-EGCG-collagen membrane exhibited smoother surface fiber aggregates. Fourier transform infrared spectroscopy demonstrated that the structure characteristics were maintained after addition of EGCG and PEG. Cell viability was significantly increased after modification of PEG, as determined by the Cell Counting Kit-8 (CCK-8) and live/dead assay. Better shapes of cytoskeleton were observed in immunostaining images. Additionally, enzyme-linked immunosorbent assay showed PEG-EGCG-collagen membrane significantly decreased the level of inflammatory factors secreted by MG63 cells. Collectively, with respect to all the aspects including intact structure, cell viability promotion and mediation of pro-inflammatory cytokine secretion, our results indicate that PEG-EGCG-collagen membrane might be used in GBR applications.
The mechanical properties of collagen fibrils depend on the amount and the distribution of water molecules within the fibrils. Here, we use atomic force microscopy (AFM) to study the effect of hydration on the viscoelastic properties of reconstituted type I collagen fibrils in air with controlled relative humidity. With the same AFM tip, we investigate the same area of a collagen fibril with two different force spectroscopy methods: force-distance (FD) and amplitude-phase-distance (APD) measurements. This allows us to separate the contributions of the fibril's viscoelastic response and the capillary force to the tip-sample interaction. A water bridge forms between the tip apex and the surface, causing an attractive capillary force, which is the main contribution to the energy dissipated from the tip to the specimen in dynamic AFM. The force hysteresis in the FD measurements and the tip indentation of only 2 nm in the APD measurements show that the hydrated collagen fibril is a viscoelastic solid. The mechanical properties of the gap regions and the overlap regions in the fibril's D-band pattern differ only in the top 2 nm but not in the fibril's bulk. We attribute this to the reduced number of intermolecular crosslinks in the reconstituted collagen fibril. The presented methodology allows the mechanical surface properties of hydrated collagenous tissues and biomaterials to be studied with unprecedented detail on the nanometer scale.
In recent years, nanoparticles (NPs) based on biopolymers or peptides are gaining popularity for the encapsulation and release of drug molecules, especially for cancer therapy, due to their ability for targeted and controlled release. The use of collagen peptide (CP) for the preparation of chitosan (CN) NPs is especially interesting as it results in NPs that are stable under physiological conditions. In this work, mono-dispersed pH responsive CPCN NPs of about 100 nm were prepared via ionic gelation method by simple and mild co-precipitation of CN and CP. Investigation of NPs with Fourier transform infra-red (FTIR) spectroscopyand dynamic light scattering (DLS) measurements reveals that hydrogen bonding and electrostatic interactions are believed to be major driving forces for NP formation and drug encapsulation, respectively. Scanning electron microscopic (SEM) investigations show that hard and fine CPCN NPs transform to soft and bigger gel like particles as a function of collagen concentration. The unique “polymeric gel” structure of NPs showed high encapsulation efficiency towards doxorubicin hydrochloride (DOX) as well as pH controlled release. Anti-proliferative and cell viability analysis revealed that DOX loaded NPs showed excellent anti-proliferative characteristics against HeLa cells with favorable biocompatibility against normal cells. Such NPs have high potential for use as smart drug delivery carriers in advanced cancer therapy.
Collagen membranes have ideal biological and mechanical properties for supporting infiltration and proliferation of osteoblasts and play a vital role in guided bone regeneration (GBR). However, pure collagen can lead to inflammation, resulting in progressive bone resorption. Therefore, a method for regulating the level of inflammatory cytokines at surgical sites is paramount for the healing process. Epigallocatechin-3-gallate (EGCG) is a component extracted from green tea with numerous biological activities including an anti-inflammatory effect. Herein, we present a novel cross-linked collagen membrane containing different concentrations of EGCG (0.0064%, 0.064%, and 0.64%) to regulate the level of inflammatory factors secreted by pre-osteoblast cells; improve cell proliferation; and increase the tensile strength, wettability, and thermal stability of collagen membranes. Scanning electron microscope images show that the surfaces of collagen membranes became smoother and the collagen fiber diameters became larger with EGCG treatment. Measurement of the water contact angle demonstrated that introducing EGCG improved membrane wettability. Fourier transform infrared spectroscopy analyses indicated that the backbone of collagen was intact, and the thermal stability was significant improved in differential scanning calorimetry. The mechanical properties of 0.064% and 0.64% EGCG-treated collagen membranes were 1.5-fold greater than those of the control. The extent of cross-linking was significantly increased, as determined by a 2,4,6-trinitrobenzenesulfonic acid solution assay. The Cell Counting Kit-8 (CCK-8) and live/dead assays revealed that collagen membrane cross-linked by 0.0064% EGCG induced greater cell proliferation than pure collagen membranes. Additionally, real-time polymerase chain reaction and enzyme-linked immunosorbent assay results showed that EGCG significantly affected the production of inflammatory factors secreted by MC3T3-E1 cells. Taken together, our results indicate that treatment of collagen membranes with appropriate concentrations of EGCG has an anti-inflammatory effect and shows promise for GBR applications.
Circular dichroism (CD) spectra are used extensively for studying the conformation of proteins and polypeptides. The correlation of certain spectral features with well-defined peptide conformations has been used to develop computational procedures for conformational analysis (Perczel et al., 1992; Johnson, 1992; Venyaminov et al., 1993). While these procedures yield reasonable estimates of the fractions of a helix, 13 strand and sheet as well as various types of bends present in a test polypeptide, significant fractions are often ascribed “random” or “other” conformations. In these computations, conformations related to structures rich in imino peptide bonds are seldom taken into account. The imino-rich scleroprotein type I collagen and other members of the collagen gene family account for over one-third of the total protein content in the vertebrate body. The conformation of collagen is related to the polyproline II helix. There is growing evidence that many globular proteins may contain small domains with collagenlike structure (Ananthanarayanan et al., 1987; Adzhubei and Sternberg, 1993, 1994). Collagen, polyproline II, and related synthetic polypeptides exhibit CD spectra that appear to be similar to the spectra of many globular proteins in the so-called random coil conformation arising from the collapse of stabilizing interactions.
The effect of Zn2+ on the interactions between Quercetin (Que), Myricetin (Myr), two typical naturally occurring biologically-active molecules, and bovine serum albumin (BSA) was investigated by means of fluorescence, infrared and ultraviolet spectroscopic methods. The fluorescence intensity of BSA decreased remarkably upon addition of both Que and Myr, respectively, exhibiting that each compound binds to BSA in aqueous solution. When appropriate amount of Zn2+ was added to the mixture of BSA and Que or Myr, the fluorescence of BSA decreased again accompanied by appreciable blue-shift of its maximum emission wavelength, among which the changes resulted by Myr are more noticeable than Que. The results indicate that Zn2+ can exert some effects on the interactions of both Myr and Que with BSA, and the effects are related to the number of the hydroxyl in B ring of the molecule. The quantitative calculation shows that the binding constant and the number of binding sites of both compounds decreases in the presence of Zn2+. The infrared spectrum and ultraviolet spectra indicate that Zn2+ binds to both Que and Myr, forming Zn2+ complex, respectively. The effect of Zn2+ on the interactions of Que, Myr with BSA in aqueous solution may be ascribed to the zinc complex formation. Increasing number of hydroxyl in B ring of the flavones-type compounds such as Que and Myr may increase their affinity to BSA. However, the presence of Zn2+ may decrease their binding ability.
A short overview of recent advances in studies of the interactions between natural polymers and application of polymers from natural sources as components of the blends for biomedical and cosmetic applications is presented. This work is focused on the blends of collagen, chitosan, silk fibroin and keratin. These bioinspired and biobased materials can be good alternative for materials based on synthetic polymers. The case study of the blends made of collagen and keratin hydrolysate is presented.
The cyclic dechroming process for chrome shavings by method of coordination substitution reaction and photocatalysis was investigated. Using EDTA (ethylene diamine tetraacetic acid) as dechroming agent and NaOH as recovery agent, the process conditions were optimized through the orthogonal tests. The removal efficiency of chrome from chrome shavings was 98.88% when dechroming was undertaken in 0.03 mol/L EDTA solution at 50°C and pH 6.0 for 14 days with stirring and then treated in the same solution under ultraviolet (145 W, 254 nm) for 8 days, and the loss of collagen was 5.31%. The chrome was separated from the dechroming solution as Cr(OH)3 precipitate by adding NaOH into the dechroming solution (cone, of NaOH = 1.00 mol/L) and stirring at 70°C for 1 d. The solution containing EDTA was reused for dechroming again after filtering and adjusting pH to 6.0 by sulfuric acid and the removal efficiencies of chrome were all more than 97% in triplicate trials. The structure of collagen after chrome extraction was characterized by SEM and FT-IR. The results indicated that the triple helix structure of collagen was well preserved. The thermal stability of collagen after chrome extraction was characterized by DSC; the results indicating that it was in conformity with rawhide. The dechroming process without strong acid and alkali can prevent collagen from hydrolysis. A certain amount of Cr(VI) appeared by adding alkali in precipitating Cr and recovering EDTA. However, Cr(VI) was reduced to Cr(III) when pH of the recovered EDTA solution was adjusted to 6.0 by adding sulfuric acid. This kind of closed recycling dechroming technology can reuse dechroming agent, and thus avoid the elution of wastewater during dechroming process.
As the three-dimensional (3D) architecture of porcine acellular dermal matrix (pADM) mimics the biological characteristics of the native extracellular matrix (ECM), then it has been extensively utilized as a tissue scaffold. In this study, a novel pADM-derived micro-and nano electrospun collagen membrane (PDEC) was sucessfully prepared by the electrospinning technique using porcine acellular dermal matrix (pADM) as raw material and 1,1,1,3,3,3-hexafluoro-2-propanol (HIFP) as solvent， which was by scanning electron microscopy (SEM) analysis. Meanwhile, in contrast, another collagen-derived electrospun collagen (CDEC) was also fabricated by using pure porcine collagen as raw material. The structure and composition of the PDEC and CDEC were measured by fourier transform infrared (FTIR) spectroscopy, SDS–PAGE gel electrophoresis, specific intrinsic viscosity and atomic force microscope (AFM). Results indicate that the structure integrity of the PDEC is almost maintained and just only a small amount of the PDEC is destroyed into gelatin, while almost all the CDEC is degraded. Moreover, the result of circular dichroism (CD) analysis also demonstrates that the PDEC possesses a higher content of α-helix structure but a less β-turn structure. Additionally, the results of the ultrasensitive differential scanning calorimetry (US-DSC) and XRD analysis also suggest that the thermal stability and crystallization of the PDEC have little differences from collagen. Moreover, the mechanical properties of PDEC are significantly enhanced compared to that of CDEC. Above all, the results obtained in the MTT study also indicate that the cytotoxicity of the PDEC has almost the same good biological activity as natural porcine collagen, which is superior than that of CDEC obviously. In conclusion, our study provides a new pADM-derived electrospun collagen of which its triple helical structure has seldom been damaged and thus it can be applied as a novel electrospun collagen scaffold for tissue engineering materials.
Parchments are interesting archeological objects. A wide variety of modern analytical techniques have been applied in order to get better insight on parchment preservation stage as well as to contribute to their conservation and restoration. However, no practical method to help the museum workers and laboratory experts in these routine jobs exists. Several requirements have to be satisfied to obtain an appropriate procedure capable of parchment characterization as an entire analytical object. Due to the unique character of common archeological objects, non-destructive techniques or those requiring no (or only minimal) sampling, are preferred. The second problem in this method development deals with the nature of objects under the study. Archeological objects (and parchment particularly) regularly have complex shapes and structures and their origin is rarely known, and they can be found in various states of conservation. Their degree of deterioration can modify the che mical and the physical composition mainly of the surface layers, which are directly accessible to analysis. However, the information obtainable from deeper layers can sometimes be more helpful. Therefore, an application of a single analytical technique to describe parchment conditions often is not advantageous and a special experimental approach, which combines several examination techniques and chemical analysis should be favored. In this context, an assortment of five analytical techniques (synchronous fluorescence, laser induced breakdown spectroscopy, visual color imaging, characterization using high voltage application and near infrared analysis) as well as every technique alone represents one of the best choices, since it combines simplicity, good analytical performance and robustness, non- destructiveness and non-invasiveness. The aim of this work was to develop a guide procedure for characterizing archeological objects using complex nondestructive analytical methodology. Using this guide, the entire parchment analysis can be performed very fast in situ and archeological items can be identified in real time during an on-line data collection. Furthermore, it allows several constituents of interest to be measured simultaneously leading to accurate and objective identification of authentic items.
Introdução O colágeno, devido a várias de suas proprieda-des, dentre elas sua baixa alergenicidade mesmo quan-do extraído de fontes heterólogas, vem sendo amplamente utilizado como matéria prima para a fa-bricação de biomateriais para usos em medicina e odontologia sob as mais variadas formas 1 . Na forma de géis injetáveis, estes biomateriais são utilizados como suportes para a reconstrução de tecidos moles em defeitos de natureza traumática ou estética 2 , na correção da incontinência urinária 3 , no aumento de Resumo: Este trabalho descreve o efeito da ransana, um polissacarídeo bacteriano, sobre géis de colágeno aniônico. A interação colágeno:ransana ocorreu independentemente do pH, mesmo com baixas concentra-ções de ransana, e os materiais obtidos no estado sólido foram caracterizados por serem mais estáveis térmicamente à medida em que se aumenta a concentração do polissacarídeo. Nenhuma alteração na estrutu-ra secundária em tripla hélice do tropocolágeno foi observada. O efeito mais significativo da ransana sobre os géis aniônicos de colágeno foi um aumento significativo da viscosidade, e as variações observadas em função de pH e temperatura sugerem que nesta interação, não estão envolvidas forças de natureza eletrostática ou hidrofóbica. Micrografias de colágeno aniônico e colágeno aniônico:ransana mostraram a presença de estru-turas vesiculares, diferente do padrão fibrilar característico de colágeno nativo. Um modelo de interação baseado na ação da ransana sobre a água estruturada, associada à organização macromolecular do colágeno em solução é proposto. Mais importante, géis de colágeno aniônico:ransana mostraram uma estabilidade térmica compatível com aquelas desejáveis para um biomaterial injetável de colágeno, evitando o uso do glutaraldeído como agente de estabilização. Palavras-chave: Colágeno aniônico, ransana, géis, biomateriais, caracterização.
We propose that the acupuncture system and the DC body field detected by western scientists both inhere in the continuum of liquid crystalline collagen fibers that make up the bulk of the connective tissues. Bound water layers on the collagen fibers provide proton conduction pathways for rapid intercommunication throughout the body, enabling the organism to function as a coherent whole. This liquid crystalline continuum mediates hyperreactivity to allergens and the body's responsiveness to different forms of subtle energy medicine. It constitutes a "body consciousness" working in tandem with the "brain consciousness" of the nervous system. We review supporting evidence from biochemistry, cell biology, biophysics and neurophysiology, and suggest experiments to test our hypothesis.
Conventional collagen-based heart valves eventually fail because of insufficient replacement of graft material by host tissue. In the present study, type I collagen was blended with silk fibroin and the synthetic elastic polymer poly (glycerol-sebacate) (PGS) in varying proportions to create multi-functional electrospun nanofibrous materials tailored for use as endovascular scaffolds such as heart valve replacement. Depending on the blended material the elastic moduli ranged from 2.3 to 5.0 Mpa; tensile stresses ranged from 0.8 to 1.5 Mpa; and strains ranged from 30% to 70%. Electrospun materials with a weight ratio of 4.5:4.5:1 (collagen, fibroin, and PGS) (termed PFC mats) were the most similar to native heart valves. In vitro degradation of PFC mats was 0.01% per week. Endothelial cells adhered to, proliferated, and formed cell-cell junctions on PFC mats. Compared to collagen hydrogels and electrospun collagen mats respectively 220 – 290% less platelet adhesion was observed for PFC mats. The study demonstrates that PFC material has superior mechanical properties, low degradation, and reduced thrombogenic potential and suggests that further investigation of this biomaterial for cardiovascular applications is warranted.
Some physical and structural properties of gelatin films were studied as a function of glycerol content, focusing on the interactions between the glycerol, film structure and the moisture content. Fourier transform infrared spectroscopy was used to study the changes of the main functional groups of the film. The displacement in the amide's position occurred with lower plasticizer content, possible due to the predominance of bound water in the film matrix. The glycerol increased the flexibility of the films, as determined by the measurements of tensile strength, elongation and elastic modulus. Finally, microwave reflected signal measurements and dielectric constant measurements were also found to be sensitive to glycerol content, presumably due to its hydrophilic nature.
Bacterial cellulose is considered to be a potential material for tissue engineering. However, the absence of enough activity restricts its practical application as tissue engineering scaffold. This paper describes the synthesis of a novel bacterial cellulose/gelatin composite via crosslinking by procyanidin (PA). The morphology of the bacterial cellulose/gelatin composite was observed by field emission scanning electron microscopy (FE-SEM) and transmission electronic microscope (TEM). The composites were further characterized by fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD). It was found that the 0.25 wt.% Gel solution was the appropriate concentration for the BC/Gel composite. Furthermore, the proliferation, infiltration and adhesion of NIH3T3 cells on the BC/Gel-025 composite were evaluated. The results showed that the composite had better bioactivity than pure bacterial cellulose, and the composite supported cell growth.
The effect of glycerol content on the physical properties of gelatin-based edible films was studied in this work, on the basis of the interactions between the plasticizer and polymeric matrix. In this work, some non-usual techniques were used to characterize edible films. For dielectric measurements and infrared spectroscopy, these films were conditioned in silica gel in order to minimize the water effect. For other analysis, the films were conditioned in NaBr. Infrared spectroscopy showed no apparent changes in the position peaks, suggesting an absence of new interactions between the plasticizer and film matrix. It seems that the plasticizers only occupy some specific regions between the polymeric matrix, increasing their distance, and thus, affecting their mobility, which results in more flexible films. Dielectric constant of the films increased with plasticizer content, and decreased over silica gel conditioning. The polarizability was found to arise mainly from water molecules present in the film. Microwave response was found to be also sensitive to water content in the films, due to plasticizer hydrophilic nature. According to the diffractograms, gelatin films presented essentially an amorphous nature, independently of the glycerol content. The results suggest, therefore, that the glycerol induces no chemical modifications in the films.
This work is a continuation of the study of the interactions which can occur when chitosan is in contact with bovine anticollagen. The major result of the first part was that under classical conditions, there exists a competition between collagen gelation and the formation of a pure polyanion-polycation complex with chitosan. In the present study, we have attempted to reach the 1:1 stoichiometry by two different methods. When collagen is denatured, the polyanion-polycation complex is improved, but the theoretical stoichiometry is not achieved. The presence of a large excess of chitosan gives rise to a second mechanism of interaction. Contrary to the case of the polyanion-polycation interaction, the latter seems to induce the denaturation of collagen. This behaviour is confirmed by infrared and circular dichroism spectrometries, as well as differential scanning calorimetry.
The objective of this paper was to study the behaviour of a collagen membrane when diffusing surfactants through it. The tests were performed using sodium dodecyl sulphate, alkyl dimethyl amine oxides and alkyl dimethyl betaines. Results showed that, when using mixtures of these compounds, the total amount of diffused surfactant has a minimum which corresponds to the range of compositions with a minimum skin irritation potential according to standard irritability values. Fourier transform infrared spectroscopy was applied to evaluate the water content of diffusion collagen membranes. Collagen membranes proved to be useful for studying both the diffusion phenomena of surfactants and their mixtures, and the variation of the water contents.
Normal mode studies are reported for l‐proline l‐hdroxyproline, a fragment of collagen. A comparision of amide I mode in peptide with that in collagen shows the presence of such sequences in collagen. Other possible sequences show appreciable differences, and hence they are not likely to be present in large numbers.
This paper reports the structural, electrical and optical properties of Yttrium doped zinc oxide (YZO) thin films deposited on Corning (7059) glass substrates by spin coating technique. A precursor solution of ZnO, 0.2M in concentration was prepared from zinc acetate dissolved in anhydrous ethanol with diethanolamine as a sol gel stabilizer. Yttrium nitrate hexahydrate (Y2NO3·6H2O) was used as the dopant (3wt%) in the present study. The films of different thickness in the range (200–500nm) were prepared. The films were annealed in air at 450°C for 1h. It was observed that the c-axis orientation improves and the grain size increases as is indicated by an increase in intensity of the (002) peak and the decrease in the FWHM with the increase of film thickness. The resistivity decreased sharply from 2.8×10−2 to 5.8×10−3Ω-cm as the thickness increased from 200 to 500nm. However, the average transmittance decreased from 87% to 82.6% as the film thickness increased to 500nm. The lowest sheet resistance of ∼120Ω/□ was obtained for the 500nm thick film.
A new material which is collagen/ poly (ethylene oxide) (PEO) blend was developed to determine its possibility as a promising material for tissue scaffold. PEO with average molecular weight of 600,000 and collagen originated from calf skin were dispersed in 0.1 M acetic acid to prepare a concentration of 1 wt% for PEO and 0.15 wt% for collagen. The collagen-PEO600K blend film was then obtained by solution casting method. SEM results shown that by having certain ratio of collagen and PEO, the membrane began to developed porous structures which are possible to assist tissue attachment on the scaffold. The X-ray diffractograms demonstrate PEO 600K influences on the blend thus enhancing crystallinity of collagen. The Infra red spectrum shows intermolecular interactions of collagen and PEO which alter the collagen structure thus explained the membrane morphological changes. Therefore, we concluded that the phase structure and also the molecular structure of the blend are crucial to produce desirable morphological structure of the membrane which is required for a reliable tissue scaffold.
Thermal processing is required for a variety of products and remains a problem for whey proteins that undergo denaturation and aggregation above the denaturation temperature. This causes challenges to maintain clarity and dispersibility of protein dispersions, particularly at acidity near the isoelectric point of the protein and increased ionic strength. This work reports for the first time that glycation of whey protein with a sufficient number of maltodextrins prevented protein aggregation before and after heating at 88 °C for 2 min at pH 3.0-7.0 and 0-150 mM NaCl or CaCl(2). The mechanism of maintaining protein dispersion clarity during heating was illustrated by several complementary analytical techniques that elucidated primary, secondary, and tertiary structures, as well as thermal denaturation and surface charge properties of glycated whey proteins. Steric hindrance was concluded to be the major mechanism responsible for transparent dispersions with protein structures smaller than 12 nm after heating.
The thermal properties of amorphous gelatin films and gelatin films with renatured structural order were measured by using conventional and temperature modulated differential scanning calorimetry (DSC). Different amounts of gelatin structural order associated with a melting enthalpic change in the DSC measurement were prepared based on different gelatin drying conditions. Two consecutive heating and cooling DSC measurements on the gelatin films showed that there was no change in the glass-transition temperature (Tg) for the amorphous gelatin but there was a decrease in the Tg for the structural gelatin on the second DSC scan. This decrease was attributed to the plasticizing effect from the release of originally hydrogen-bonded water associated with the structural gelatin. In addition, a reversing endotherm observed upon melting of the structural gelatin during a temperature modulated DSC measurement indicated that the transition of bound water to free water occurred as the partial triple-helix gelatin melted. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1795–1801, 2006
The increasing use of plastics and their nonbiodegradability have raised environmental awareness and hence there is a need for the development of environmentally friendly degradable materials. One of the ways to reach this goal is via the modification of the synthetic polymer, modified polyethylene (MPE), with protein, collagen hydrolyzate (CH). CH is a biopolymer isolated from hide/skin fleshing of untanned solid waste from the leather industry after enzymatic hydrolysis. An investigation on the blending of MPE with CH using polymer melt technique is reported. The resulting thermoplastic films were evaluated using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTA), and scanning electron microscope (SEM), in addition to simulated soil burial respirometric testing. It is interesting to note that CH easily blends with MPE, but like other biopolymers, it also has effects on the original mechanical properties of the MPE. The CH addition in the blend significantly increases the biodegradation rate. The effect of CH on MPE biodegradability has been investigated. About 53% biodegradation is observed, after 24 days, when the polymer is blended with 5% CH and about 63% biodegradation is found in the case of polymer blended with 20% CH. Although MPE/CH thermoplastic film with 40% CH have shown better performance in biodegradation, the mechanical strength properties were rather poor in this case. The optimum thermoplastic film composition for blending of CH with MPE is about 10–20 wt % CH, which retains an acceptable range of compatibility, mechanical strength, and biodegradability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
This paper describes the biosynthesis of a novel collagen-bacterial cellulose (COL/BC) composite by adding collagen to the culture medium of Acetobacter xylinum. The morphology of COL/BC composite was observed by SEM and TEM and compared with pristine BC. The composite was further characterized by FTIR and XRD. It is found that the structure of BC network changes when collagen is present in the nutrient medium. Further work is underway to gain insights into the mechanisms governing the experimental phenomena.
Collagen is a multifunctional protein which enters into highly specific interactions with many proteins including cell surface
receptors. The physiological solid state of collagen complicates explanations of its behavior as a bioactive material, since
conformational parameters for collagen molecules are deduced either from X-ray diffraction of fibers, or derived from properties
of individual molecules in solution. Physiological interactions of collagen involve molecules on the fiber surface. The anisotropic
environment of these molecules can be expected to induce local conformational fluctuations relevant to intermolecular recognition
and allosteric binding. We have examined conformational heterogeneity within the triple helix using stereochemical mapping,
synthetic polypeptide models, and cryogenic atomic force microscopy. We have identified a 15-residue domain inα1(I) chain residues766GTPGPQGIAGQRGVV780 which shows equal preference for a strand-bend-strand conformation and for the collagen fold. A synthetic peptide analogous
to this sequence generates aβ-rich structure in mixed solvents with the central —IA— residues forming the core of aβ-bend. This peptide is a potent force-conducting ligand for collagen receptors, serving as an anchorage for cells for tissue
engineering. Our studies provide a rational mechanism for intermolecular recognition based on local conformational tautomerism
of a helix-domain sequence.
The development of mesoporous materials offers new possibilities for incorporating biological agents into silica structures and controlling the release kinetics from the matrix due to its well-arranged pore architecture. Indeed, the introduction of appropriate organic compounds into these ceramics has presented excellent results regarding drug release control. In this paper, two types of materials were used to evaluate drug delivery: SBA-15 and a hybrid SBA-15-collagen. The samples were charged with atenolol as a model drug and in vitro release assays were carried out. Significant differences were observed between the release patterns of the different materials, and the release rate was influenced by the presence of collagen in the mesopores.
A calculation of the normal modes of vibration and their dispersion for the helical conformation of polyglycine II chain is carried out using Wilson's GF matrix method as modified by Higgs for an infinite system. A potential field which provides best fit to the observed frequencies in I.R. and inelastic neutron scattering is obtained. Conformational dependence of results in relation to polyglycine I with planar structure and various amide bands is discussed.
A quantitative comparison is attempted between the diffraction pattern calculated for collagen II and the observed high-angle X-ray diffraction pattern for wet collagen. The effect of bound water molecules is considered. The diffraction results are found to be in moderate agreement. The changes of the infra-red absorption spectra of oriented films of collagen extracted from rat-skin on variation of the relative humidities of the specimens (using both H2O and D2O) have been examined. The spectra clearly indicate the presence of two mechanisms of hydrogen bonding; the relative numbers of NH groups involved in the two systems and the orientations of the transition moments associated with the amide group vibrations are in good agreement with those calculated for collagen II. The characteristic NH absorption frequency of collagen (3330 cm-1) is associated with intra-molecular hydrogen bonding. The infra-red absorption spectra of films of denatured collagen and hot-cast gelatin are consistent with the presence of randomly coiled single chains resulting from the breakdown of the native collagen triple chain structure. The intra- and intermolecular order in collagen and gelatin films is examined on the basis of observed rates of deuteration.
The general theory of Fourier self-deconvolution, i.e., spectral deconvolution using Fourier transforms and the intrinsic line-shape, is developed. The method provides a way of computationally resolving overlapped lines that can not be instrumentally resolved due to their intrinsic
linewidth. Examples of the application of the technique to synthetic and experimental infrared spectra are presented, and potential applications are discussed. It is shown that lines in spectra having moderate signal/noise ratios (∼1000) can readily be reduced in width by a factor of 3.
The method is applicable to a variety of spectroscopic techniques.
A new photoacoustic cell for use with Fourier transform infrared spectrometers is detailed. Photoacoustic infrared spectra showing high sensitivity on a variety of chemical systems are presented. Comparison of the photoacoustic infrared spectra with transmission and attenuated total internal reflectance spectra show that saturation effects can play a prominent role in the photoacoustic spectra. Spectral subtractions and study of the situ chemical reactions are possible using the photoacoustic technique. The photoacoustic and diffuse reflectance techniques yield very similar spectra.
Variations between mull and pellet spectra of organic compounds are due either to an induced physical isomerization or to the samples' having been rendered amorphous in the alkali halide pellet. Factors which influence these changes are: (1) crystal energy of the organic phase; (2) energy of grinding sample and matrix; (3) lattice energy of matrix; (4) particle size of matrix; (5) ability of sample to recrystallize in the pellet (related to crystal energy); and (6) relative stability of polymorphic forms. Relative merits of mull and pellet techniques are presented and it is shown how these can supplement each other. From the frequency of occurrence of polymorphism, it is concluded that this is a general rather than a rare problem facing the organic chemist.
ABS>In the preparation of potassium bromide pressed windows for use in ; the infrared analysis of solids, severe grinding of the potassium bromide powder ; may produce strong absorptton bands that could interfere seriously with the ; spectra of the sample. These absorption bands appear to be due to some crystal ; alteration of the potassium bromide as a result of the grinding process. They ; were less apt to occur when the coarser powder, which had received a relatively ; gentle grinding, was used. Window blanks prepared from the coarser powders ; showed smaller adsorbed water peaks and generally higher over-all transmittance ; readings than windows pressed from the very fine powders. (auth);
Infrared spectra of liquid H2O, D2O, and HDO from 0.7 to 10 μm have been obtained. The H2O spectrum is based on that of natural water, the D2O spectrum on that of heavy water containing approximately 99.6 weight per cent D2O. The HDO spectrum has been deduced from spectra of H2O-HDO-D2O mixtures by application of Beer's law. The spectra are presented in terms of logarithms of both an extinction length, L, the sample thickness that has unit optical density, and the molecular extinction coefficient, ϵ, plotted against logarithms of both wavelegnth and wave number. Vibration mode assignments have been made for most of the absorption bands observed. The spectral data obtained have been useful in the development of infrared monitoring instrumentation and methods of analysis for H2O-HDO-D2O mixtures in connection with the heavy water reactor research programs at the Chalk River Nuclear Laboratories.
The Raman Spectrum of Collagen is presented from feline corneas which were fresh and intact, heat denatured, and incubated in 2H20. Two bands in the amide I region at approx. 1630 cm-1 and approx. 1660 cm-1 and two bands at ca. 1270 cm-1 and 1247 cm-1 in the amide III region appear in the Raman spectrum of fresh and heat denatured corneal collagen. The two amide III bands have been assigned to amide III vibrations in the polar and non-polar regions of the protein. Only one small amide I band at approx. 1650 cm-1 appears when corneas are treated with 2H2O suggesting that some portion of the Raman peaks in the amide I region for corneas in water is associated with water vibrations. Feline corneal collagen fibrils do not appear to dissociate appreciably upon heating to 70 degrees C. In fact, heated corneas appear structurally similar to corneas aged 30 h at 50 degrees C. We suggest that the swelling induced by heating and aging is predominantly caused by water being absorbed and remaining between the collagen fibrils, causing a slightly more disordered collagen matrix.
The set of synthetic polytripeptides and polyhexapeptides which can adopt a triple-helical form constitute a good model system for investigating collagen structure. Here we consider previous and new infrared spectroscopic studies on collagen and present the infrared spectra of a number of polymers with collagen-like features.
The amide A band position for all triple-helical polypeptides is higher than that observed for most proteins and polypeptides, and this high frequency appears to be related to the degree of supercoiling of the triple helix. It is possible that with increased supercoiling of the three chains the angles between the groups involved in the intramolecular hydrogen bonds become less favorable, or these bonds may become unusually long.
The frequency of the amide I band varies considerably for triple-helical polypeptides with different amino acid sequences, and often minor bands are observed. This finding contrasts with the observations for polypeptides in a pleated sheet or α-helical form, where the same amide I frequency is observed regardless of the amino acid composition. An explanation for this variation is proposed in terms of the hydrogen bonding properties of imino acids.
Significant spectral changes in the amide I region are observed on hydration in the spectra of some triple-helical polypeptides, but corresponding changes have not been found in the collagens examined.
The secondary structures of two phosphoproteins from chicken bone matrix of Mr approximately 15kDa and approximately 28kDa, rich in Asx, Glx, and Ser, and containing Ser(P) and Thr(P) residues, have been investigated in solution by Circular Dichroism (CD) and Fourier Transform-Infrared Spectroscopy (FT-IR). CD spectroscopy, which yields useful information on the backbone conformation of polypeptides and proteins, suggests a predominantly beta-sheet structure for the two phosphoproteins. The FT-IR spectra of the approximately 15kDa protein, which is sensitive to secondary structure and hence provides complimentary information to CD spectroscopy, are consistent with the results obtained by CD studies.
The infrared amide I band of collagens (rat and cod skin) and related compounds (polyproline, polyglycine, and polytripeptides) was studied. Assignment of amide I-band components for polyproline II and polytripeptides (Gly-Pro-Pro)n and (Gly-Pro-Gly)n in the solid state and water solution was made. Three amide I components observed in the polypeptide spectra were attributed to three different peptide CO groups in each triplet. On the basis of this assignment, the interpretation of the amide I multicomponent structure in collagen and isomorphous oligo- and polypeptides was attempted. The ordering of intra- and intermolecular hydrogen bonds involving peptide CO groups in collagen and related compounds was discussed.
The possibility of hydroxyproline residues stabilizing the collagen triple-helical structure by the formation of additional hydrogen bonds through their γ-hydroxyl group has been studied from structural considerations. It is not possible for this hydroxyl group to form a direct hydrogen bond with a suitable group in a neighbouring chain of the triple-helical protofibril. However, in the modified one-bonded structure, which is stabilized by additional hydrogen bonds being formed through water molecules as intermediaries (put forward in 1968 by Ramachandran, G. N. and Chandrasekharan, R.), it is found that the γ-hydroxyl group of hydroxyproline can form a good hydrogen bond with the water oxygen as acceptor, the hydrogen bond length being 2.82 Å. It is proposed that, in addition to stabilizing the collagen triple-helical structure due to the stereochemical properties of the pyrrolidine ring, hydroxyproline gives added stability by the formation of an extra hydrogen bond. Experimental studies on the determination of shrinkage and denaturation temperatures of native collagen and its synthetic analogues, as a function of their hydroxyproline content, are being undertaken to test this hypothesis.
A valence force field has been refined for single-chain polyglycine II using the known structure and four isotopic derivatives. The calculated frequencies are in good agreement with the observed. The force field is compared with that derived from polyglycine I and for the nylons. Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/37832/1/360110906_ftp.pdf
If the collagen triple helix is so built as to have one set of NH ⃛ O hydrogen bonds of the type N3H3(A) ⃛ O2(B), then it is possible to have a linkage between N1H1(B) and O1(A) through the intermediary of a water molecule with an oxygen O leading to the formation of the hydrogen bonds N1(B) ⃛ O and O (A). In the same configuration, another water molecule with an oxygen O can link two earbonyl oxygens of chains A and B forming the hydrogen bonds O O1(A) and O O0 (B). The two water oxygens also become receptors at the same time for CH ⃛ O hydrogen bonds. Thus, the neighboring chains in the triple helix are held together by secondary valence bond linkages occurring regularly sit intervals of about 3 Å along the length of the protofibril. The additional water molecules occur on the periphery of the proto-fibril and will contribute their full share towards stabilizing the structure in the solid state. In solution, they will be disturbed by the medium unless they are protected by long side groups. It appears that this type of two-bonded structure, in which one NH ⃛ O bond is to a water molecule, can explain several observations on the stability and hydrogen exchange properties of collagen itself and related synthetic polypeptides. The nature of the water bonds and their strength are found to be better in the one-bonded structure proposed from Madras than in the one having the coordinates of Rich and Crick.
When a solution of collagen molecules, at neutral pH and moderate ionic strength, is warmed from 4 degrees to 30 degrees C, a spontaneous self-assembly process takes place in which native-type collagen fibers are produced. Events occurring during thermally induced fibrillogenesis process can be monitored, in aqueous media and in real time, by Fourier transform infrared spectroscopic techniques. Tentative assignments of observed spectral bands are given.
Cesium iodide, a simple ionic salt at low pressures, undergoes a second-order transformation at 40 gigapascals (400 kilobars) from the cubic B2 (cesium chloride-type) structure to the body-centered tetragonal structure. Also, the energy gap between valence and conduction bands decreases from 6.4 electron volts at zero pressure to about 1.7 electron volts at 60 gigapascals, transforming cesium iodide from a highly ionic compound to a semiconductor. The structural transition increases the rate at which the band gap closes, and an extrapolation suggests that cesium iodide becomes metallic near (or somewhat above) 100 gigapascals. Similar changes in bonding character are likely to occur in other alkali halides at pressures above 100 gigapascals.