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The cross-linking density influences the physicochemical properties of cyclodextrin-based nanosponges (CD-NSs). Although the effect of the cross-linker type and content on the NSs performance has been investigated, a detailed study of the cross-linking density has never been performed. In this contribution, nine ester-bridged NSs based on β-cyclode...
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... are chemically or physically three-dimensional nanoporous polymeric networks [1] ( Figure S1, Supplementary Material). They contain cross-links that avoid the dissolution of the hydrophilic polymer chains into the aqueous phase [2]. ...
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... the NSs were air-dried, milled, and utilized for characterization as white homogeneous powders. Figure 1 presents the polymerization reaction. A schematic representation of the NSs synthesis is provided in the Supplementary Material ( Figure S2). ...
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... results in a decreased degree of swelling of gel. The driving force, in the swelling of cross-linked polymers, is due to the contribution of normal entropy and enthalpy changes associated with the mixing of solvent and solute molecules ( Figure S1 in Supplementary Material). Further, changes in configurational entropy result from the dilution of flexible chain molecules. ...
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... is observed a decrease of ʋe by further increasing the molar ratio, and the errors are higher at 1 mm gap size than at 2 mm gap size. The trend of an increase in the ʋe with increasing the cross-linker content at a certain amount (1:6 molar ratio) is observed in Figure S10 (Supplementary Material). It presents the ʋe calculated from rheological measurements carried out in the presence of overfilling and solvent trap. ...
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... presents the ʋe calculated from rheological measurements carried out in the presence of overfilling and solvent trap. Therefore, the values of ʋe, compare to abovementioned, in these conditions are higher ( Figure S11 in Supplementary Material), adding errors to the data. This can be rationalized with what is already investigated in literature [83] that overfilling and gap size cause data errors. ...
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... findings have a huge impact on a wide variety of practical uses, especially for pharmaceutical ( Figure S12 in Supplementary Material) and biomedical purposes. Understanding the correlation between the structural features of PMDA βCD-based NSs and their physicochemical properties will allow one day to identify rapidly and effectively the right synthesis method, in terms of monomers formulation and reaction condition, to fulfill the requirements of the desired specific applications. ...
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... S6: Sample loading in a rheometer, 2 mm gap size, removal of the extra sample outside the geometry and of the solvent trap; Figure S7: Sample loading in a rheometer, 1 mm gap size. Non-removal of the extra sample outside the geometry and of the solvent trap; Figure S8: Storage (G') and loss (G'') modulus versus angular frequency for β-CD:PMDA molar ratio of 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10. 1 mm gap size without removing the extra sample outside the geometry and with solvent trap; Figure S9: Storage (G') and loss (G'') modulus versus molar ratio of β-CD:PMDA (1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10) at an angular frequency (ω) of 1 rad/s; 1 mm gap size without removing the extra sample outside the geometry and with solvent trap; Figure S10: Effective sub-chain density (moles of effective subchains per unit volume) as a function of added cross-linker content; Figure S11: Effective sub-chain density (moles of effective sub-chains per unit volume, ʋe, mol/cm 3 ) as a function of added crosslinker content, for different rheological procedures as previously described (1mm a), 1mm b), 2mm); Figure S12: β-CD: PMDA NSs as delivery systems: acetyl salicylic acid, imiquimod, lansoprazole, insulin, curcumin, resveratrol, meloxicam, rosuvastatin, rilpivrine; Table S1: The varying amounts of PMDA as a cross-linker in the synthesis of β-CD NSs; Table S2: Calculated densities of both, the gel and powder of β-CD: PMDA NSs having the various amount of PMDA. Mean Values ± SD; Table S3: a.) WAC experimental values of β-CD:PMDA NSs; b.), c.) Water absorption capacity (WAC) as the function of the swelling time to monomer ratio of β-CD:PMDA NSs; Table S4: Calculated physicochemical terms (Mc, ʋ, ʋ2m) of β-CD:PMDA NSs having the various amount of PMDA. ...
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... S6: Sample loading in a rheometer, 2 mm gap size, removal of the extra sample outside the geometry and of the solvent trap; Figure S7: Sample loading in a rheometer, 1 mm gap size. Non-removal of the extra sample outside the geometry and of the solvent trap; Figure S8: Storage (G') and loss (G'') modulus versus angular frequency for β-CD:PMDA molar ratio of 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10. 1 mm gap size without removing the extra sample outside the geometry and with solvent trap; Figure S9: Storage (G') and loss (G'') modulus versus molar ratio of β-CD:PMDA (1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10) at an angular frequency (ω) of 1 rad/s; 1 mm gap size without removing the extra sample outside the geometry and with solvent trap; Figure S10: Effective sub-chain density (moles of effective subchains per unit volume) as a function of added cross-linker content; Figure S11: Effective sub-chain density (moles of effective sub-chains per unit volume, ʋe, mol/cm 3 ) as a function of added crosslinker content, for different rheological procedures as previously described (1mm a), 1mm b), 2mm); Figure S12: β-CD: PMDA NSs as delivery systems: acetyl salicylic acid, imiquimod, lansoprazole, insulin, curcumin, resveratrol, meloxicam, rosuvastatin, rilpivrine; Table S1: The varying amounts of PMDA as a cross-linker in the synthesis of β-CD NSs; Table S2: Calculated densities of both, the gel and powder of β-CD: PMDA NSs having the various amount of PMDA. Mean Values ± SD; Table S3: a.) WAC experimental values of β-CD:PMDA NSs; b.), c.) Water absorption capacity (WAC) as the function of the swelling time to monomer ratio of β-CD:PMDA NSs; Table S4: Calculated physicochemical terms (Mc, ʋ, ʋ2m) of β-CD:PMDA NSs having the various amount of PMDA. ...
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... S6: Sample loading in a rheometer, 2 mm gap size, removal of the extra sample outside the geometry and of the solvent trap; Figure S7: Sample loading in a rheometer, 1 mm gap size. Non-removal of the extra sample outside the geometry and of the solvent trap; Figure S8: Storage (G') and loss (G'') modulus versus angular frequency for β-CD:PMDA molar ratio of 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10. 1 mm gap size without removing the extra sample outside the geometry and with solvent trap; Figure S9: Storage (G') and loss (G'') modulus versus molar ratio of β-CD:PMDA (1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10) at an angular frequency (ω) of 1 rad/s; 1 mm gap size without removing the extra sample outside the geometry and with solvent trap; Figure S10: Effective sub-chain density (moles of effective subchains per unit volume) as a function of added cross-linker content; Figure S11: Effective sub-chain density (moles of effective sub-chains per unit volume, ʋe, mol/cm 3 ) as a function of added crosslinker content, for different rheological procedures as previously described (1mm a), 1mm b), 2mm); Figure S12: β-CD: PMDA NSs as delivery systems: acetyl salicylic acid, imiquimod, lansoprazole, insulin, curcumin, resveratrol, meloxicam, rosuvastatin, rilpivrine; Table S1: The varying amounts of PMDA as a cross-linker in the synthesis of β-CD NSs; Table S2: Calculated densities of both, the gel and powder of β-CD: PMDA NSs having the various amount of PMDA. Mean Values ± SD; Table S3: a.) WAC experimental values of β-CD:PMDA NSs; b.), c.) Water absorption capacity (WAC) as the function of the swelling time to monomer ratio of β-CD:PMDA NSs; Table S4: Calculated physicochemical terms (Mc, ʋ, ʋ2m) of β-CD:PMDA NSs having the various amount of PMDA. ...
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Citations
... CDs have been studied for over a century and widely used as a pharmaceutical excipient or being capable of incorporating therapeutic molecules into their central cavity (Hoti et al., 2021;Kawano et al., 2015). Currently, CDs are widely used in food products, textiles, toiletry, and various cosmetics as well as in certain medical products (Liu et al., 2022;Sharma & Baldi, 2016). ...
... During the crosslinking reaction, PMDA undergoes ring opening of the anhydride, followed by the formation of the carboxyl and ester groups, resulting in an ester-bridged CD-based nanosponges. [18][19][20] CD-based nanosponges are known to enhance drug delivery by improving drug solubility, permeability, and release control. This is attributed to their increased number of interaction sites and higher encapsulation efficiency when compared to natural CDs. ...
... Several studies have reported the effect of molar ratio on CDPs synthesis. Hoti et al. [19] investigated the impact of PMDA amount on the network chain and stiffness of crosslinked CDPs. The authors found that increasing the amount of PMDA resulted in a shorter network chain between crosslinks, leading to a more strongly interconnected polymer. ...
... Conversely, decreasing the amount of PMDA resulted in lower stiffness due to the loosely bound polymer chains held together by weak van der Waals forces. Additionally, Hoti et al. [19] observed that higher molar ratios of PMDA led to higher yields of CDPs compared to lower molar ratios. In their study, Trotta et al. [25] reported the optimal b-CD/PMDA molar ratio to be 1/6. ...
https://www.tandfonline.com/eprint/9KKX8BU59W2QYH3H9Z2J/full?target=10.1080/24701556.2024.2355514
... This change in swelling behavior corresponds to the Flory-Rehner swelling equilibrium equation, which states that networks with higher cross-linking density exhibit reduced swelling capacity. [37,38] Control over the swelling ratio was also demonstrated by changing the monomer content in the original ink ( Figure S5, Supporting Information). This shows the importance of the solvent-to-monomer weight ratio in the printing ink being at least 20:80. ...
Organogels are polymer networks extended by a liquid organic phase, offering a wide range of properties due to the many combinations of polymer networks, solvents, and shapes achievable through 3D printing. However, current printing methods limit solvent choice and composition, which in turn limits organogels' properties, applications, and potential for innovation. As a solution, a method for solvent‐independent printing of 3D organogel structures is presented. In this method, the printing step is decoupled from the choice of solvent, allowing access to the full spectrum of solvent diversity, thereby significantly expanding the range of achievable properties in organogel structures. With no changes to the polymer network, the 3D geometry, or the printing methodology itself, the choice of solvent alone is shown to have an enormous impact on organogel properties. As demonstrated, it can modulate the thermo‐mechanical properties of the organogels, both shifting and extending their thermal stability range to span from ‐30 to over 100 °C. The choice of solvent can also transition the organogels from highly adhesive to extremely slippery. Finally, the method also improves the surface smoothness of prints. Such advances have potential applications in soft robotics, actuators, and sensors, and represent a versatile approach to expanding the functionality of 3D‐printed organogels.
... The water absorption capacity measurements were performed by adding 500 mg of dry powders (GLU_BDE and GLU_TTE) in a 15 mL test tube of deionized water, following a procedure described in a previous work [53]. The test tubes were sealed and kept at room temperature. ...
... The density of the polymer is precisely determined using a calibrated pycnometer. Cross-linking determination was performed according to the procedure previously described by our research group [53]. All the measurements were performed in triplicate. ...
... Rheological measurements were performed with a Rheometer TA Instruments Discovery HR 1 device by following the procedure described in our previous work [53]. The instrument was equipped with 20 mm diameter stainless steel plate geometry and Peltier plate temperature control. ...
The development of polymers obtained from renewable sources such as polysaccharides has gained scientific and industrial attention. Cross-linked bio-derived cationic polymers were synthesized via a sustainable approach exploiting a commercial maltodextrin product, namely, Glucidex 2®, as the building block, while diglycidyl ethers and triglycidyl ethers were used as the cross-linking agents. The polymer products were characterized via FTIR-ATR, TGA, DSC, XRD, SEM, elemental analysis, and zeta-potential measurements, to investigate their composition, structure, and properties. Polydispersed amorphous granules displaying thermal stabilities higher than 250 °C, nitrogen contents ranging from 0.8 wt % and 1.1 wt %, and zeta potential values between 10 mV and 15 mV were observed. Subsequently, water absorption capacity measurements ranging from 800% to 1500%, cross-linking density determination, and rheological evaluations demonstrated the promising gel-forming properties of the studied systems. Finally, nitrate, sulfate, and phosphate removal tests were performed to assess the possibility of employing the studied polymer products as suitable sorbents for water remediation. The results obtained from the ion chromatography technique showed high sorption rates, with 80% of nitrates, over 90% of sulfates, and total phosphates removal.
... The degree of swelling specifies an interaction between the scaffolds and the aqueous medium, and it is the consequence of solvent trying to dilute the scaffolds polymeric network by penetration [68]. Scaffolds were placed in water and PBS as aqueous solvents that were absorbed by the polymeric network subsequently causing swelling of the scaffolds, which is directly proportional to the degree of crosslinking, as swelling decreases with the degree of crosslinking ( Figure 9C), in agreement with the literature [69]. Between 85 and 90% swelling was observed in both water and PBS. ...
Innovative materials are needed to produce scaffolds for various tissue engineering and regenerative medicine (TERM) applications, including tissue models. Materials derived from natural sources that offer low production costs, easy availability, and high bioactivity are highly preferred. Chicken egg white (EW) is an overlooked protein-based material. Whilst its combination with the biopolymer gelatin has been investigated in the food technology industry, mixed hydrocolloids of EW and gelatin have not been reported in TERM. This paper investigates these hydrocolloids as a suitable platform for hydrogel-based tissue engineering, including 2D coating films, miniaturized 3D hydrogels in microfluidic devices, and 3D hydrogel scaffolds. Rheological assessment of the hydrocolloid solutions suggested that temperature and EW concentration can be used to fine-tune the viscosity of the ensuing gels. Fabricated thin 2D hydrocolloid films presented globular nano-topography and in vitro cell work showed that the mixed hydrocolloids had increased cell growth compared with EW films. Results showed that hydrocolloids of EW and gelatin can be used for creating a 3D hydrogel environment for cell studies inside microfluidic devices. Finally, 3D hydrogel scaffolds were fabricated by sequential temperature-dependent gelation followed by chemical cross-linking of the polymeric network of the hydrogel for added mechanical strength and stability. These 3D hydrogel scaffolds displayed pores, lamellae, globular nano-topography, tunable mechanical properties, high affinity for water, and cell proliferation and penetration properties. In conclusion, the large range of properties and characteristics of these materials provide a strong potential for a large variety of TERM applications, including cancer models, organoid growth, compatibility with bioprinting, or implantable devices.
... The use of dianhydrides requires the addition of triethylamine (Et3N) as a catalyst. Et3N is a nucleophile and helps to reorganize the cross-linker structure to obtain free ester and carboxyl groups that can react with the hydroxyl groups of CDs [69][70][71]. Since CDI might react with only one CD, fresh CDI-based nanosponges still contain slight amounts of active imidazolyl carbonyl groups, resulting in the formation of dead ends in the polymer structure. This can be avoided by treating CDNSs with water, which enables an almost full elimination of imidazolyl carbonyl groups in 8 h [72]. ...
Cyclodextrin-based nanosponges (CDNSs) are complex macromolecular structures composed of individual cyclodextrins (CDs) and nanochannels created between cross-linked CD units and cross-linkers. Due to their unique structural and physicochemical properties, CDNSs can possess even more beneficial pharmaceutical features than single CDs. In this comprehensive review, various aspects related to CDNSs are summarized. Particular attention was paid to overviewing structural properties, methods of synthesis, and physicochemical analysis of CDNSs using various analytical methods, such as DLS, PXRD, TGA, DSC, FT-IR, NMR, and phase solubility studies. Also, due to the significant role of CDNSs in pharmaceutical research and industry, aspects such as drug loading, drug release studies, and kinetics profile evaluation of drug–CDNS complexes were carefully reviewed. The aim of this paper is to find the relationships between the physicochemical features and to identify crucial characteristics that are influential for using CDNSs as convenient drug delivery systems.
... However, the most important factor is the crosslinking density of the hydrogel network, which is determined by the distance between two crosslinks in the same polymer chain. The shorter their distance, the higher the crosslinking density [45]. SW% data are shown in Figure 4b. ...
In recent decades, hydrogels have emerged as innovative soft materials with widespread applications in the medical and biomedical fields, including drug delivery, tissue engineering, and gel dosimetry. In this work, a comprehensive study of the macroscopic and microscopic properties of hydrogel matrices based on Poly(vinyl-alcohol) (PVA) chemically crosslinked with Glutaraldehyde (GTA) was reported. Five different kinds of PVAs differing in molecular weight and degree of hydrolysis were considered. The local microscopic organization of the hydrogels was studied through the use of the 1H nuclear magnetic resonance relaxometry technique. Various macroscopic properties (gel fraction, water loss, contact angle, swelling degree, viscosity, and Young’s Modulus) were investigated with the aim of finding a correlation between them and the features of the hydrogel matrix. Additionally, an optical characterization was performed on all the hydrogels loaded with Fricke solution to assess their dosimetric behavior. The results obtained indicate that the degree of PVA hydrolysis is a crucial parameter influencing the structure of the hydrogel matrix. This factor should be considered for ensuring stability over time, a vital property in the context of potential biomedical applications where hydrogels act as radiological tissue-equivalent materials.
... The backbone of NS is an elongated polyester thread which is mixed in solution with small molecules termed as crosslinkers that can act similar to the little grappling hooks so that distinct parts of the polymer can be fastened together [14] . Upon reaction between cyclic oligosaccharides known as Cyclodextrins (CDs) and suitable cross-linking reagents, a novel nanomaterial comprising of hyper-cross-linked CDs can be obtained which are popularly known as CD based NSs [15,16] . The polyesters should be biodegradable in nature for which NS can be sufficiently disrupted in the body. ...
... The hydrogel swelling ratio can also determine the hydrogels cross-linking density (CLD) since the swelling ratio increases at higher cross-linking density of gel (37). The CLD represents to the amount of interconnected polymer chains per unit volume of hydrogel (polymer network) that is responsible for the formation and maintenance of the hydrogel structure (38). Furthermore, the improvement in crosslinking density reflects that the hydrogel is composed of a high number of functional groups (39). ...
The aim of this study was to prepare and characterize a small intestine submucosa (SIS) hydrogel as a bio-scaffold. In this study, SIS from five calves, aged 8-12 months and weighing 250-300 kg, was obtained from a slaughterhouse immediately after slaughtering. The SIS was then decellularized, powdered, and subsequently transformed into a hydrogel. This transformation was achieved by dissolving the decellularized SIS powder in phosphate-buffered saline (PBS) at a concentration of 50% w/v, and allowing it to form a hydrogel over a 12-hour period at 37 °C. Characterization of the SIS hydrogel was conducted using various techniques. Fourier Transform Infrared Spectroscopy (FTIR) was employed to identify the chemical structure of the hydrogel, revealing three primary peaks at 1639 cm-1, 1571 cm-1, and 1338 cm-1, corresponding to amide I, II, and III bands, respectively. Additionally, a broad signal at 3440 cm-1 was observed, indicative of the hydroxyproline side chain. The hydrogel's swelling capacity was evaluated, showing an expansion of 437% after a 12-hour immersion in PBS at a pH of 7.4. Scanning Electron Microscopy (SEM) analysis of the lyophilized hydrogel revealed a highly porous and interconnected architecture, resembling a honeycomb structure. Moreover, the hydrogel's antibacterial efficacy was assessed against Staphylococcus aureus using an agar diffusion test, which demonstrated a zone of inhibition measuring 16.11 mm. The combined chemical, morphological, and antibacterial properties of the SIS hydrogel developed in this study suggest its potential as a promising bio-scaffold for inducing tissue regeneration and restoring tissue function.
... The presented work focuses on the research on chemical hydrogels [42] resulting from the combination and photo-induced reaction of two hydrophilic polymers, poly(ethyleneglycol) methyl ether methacrylate (PEGMEMA) and poly(ethyleneglycol) dimethacrylate (PEGDMA) together with a hydrophobic molecule (tert-butyl acrylate (tBA)). The combination of a bifunctional PEG, with either a hydrophilic or/and a hydrophobic molecule, allows for large freedom in the selection of combinations, enabling not only the tuning of the hydrophilic behavior but also having a direct impact on the expected thermo-mechanical properties. ...
... Water Uptake/Swelling Behavior PEG-based materials possess the ability to absorb and retain large amounts of water, which consequently should be considered as an essential component. For this reason, all the specimens were first tested to evaluate the water uptake and swelling behavior in order to assess the range of nominal compositions of the materials approaching the desired performances [17,42]. Figure 1 shows the appearance of the samples after 1 week of swelling, and the water content and swelling ratio, which were calculated by Equations (2) and (3) respectively (Section 4.3). ...
Damages to the intervertebral disc (IVD) due to improper loading or degeneration result in back pain, which is a common disease affecting an increasing number of patients. Different strategies for IVD remediation have been developed, from surgical treatment to disc replacement, by using both metallic and non-metallic materials. Hydrogels are very attractive materials due to their ability to simulate the properties of many soft tissues; moreover, their chemical composition can be varied in order to assure performances similar to the natural disc. In particular, for the replacement of the IVD outer ring, namely, the anulus fibrosus, the shear properties are of paramount importance. In this work, we produced hydrogels through the photo-induced crosslinking of different mixtures composed of two hydrophilic monofunctional and difunctional polymers, namely, poly(ethyleneglycol) methyl ether methacrylate (PEGMEMA) and poly(ethyleneglycol) dimethacrylate (PEGDMA), together with a hydrophobic molecule, i.e., tert-butyl acrylate (tBA). By changing the ratio among the precursors, we demonstrated the tunability of both the shear properties and hydrophilicity. The structural properties of hydrogels were studied by solid-state nuclear magnetic resonance (NMR). These experiments provided insights on both the structure and molecular dynamics of polymeric networks and, together with information obtained by differential scanning calorimetry (DSC), allowed for correlating the physical properties of the hydrogels with their chemical composition.
