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Publications (94)
In the quest for advancing the performance of metallic implants, surface modification emerges as a pivotal strategy to mitigate ion depletion, enhance the host's biological response, and exhibit anti-microbial behavior with reduced cytotoxicity. In this study, we developed a non-traditional electrophoretic deposition (EPD) hybrid coating for medica...
Electrical and piezoresistive properties of hybrid nanocomposite films and tubes made of a segmented aliphatic polyurethane modified with multilayer graphene sheets (MLGSs), multiwall carbon nanotubes (MWCNTs), and hybrid mixtures of both, were investigated. Hybrid nanocomposites were fabricated at a total weight concentration ( Φ T ) of 5 wt.%, wi...
Organoclays were prepared by means of cation-exchange reactions using different concentrations of chlorhexidine diacetate and two different types of clays: montmorillonite and palygorskite. The antibacterial activity against Escherichia coli was evaluated by means of disk diffusion tests as well as through bacterial growth inhibition (monitored by...
Electrospinning has proven to be a suitable technique for the production of small diameter tubes, with diverse applications, in the field of tissue engineering. In this work, tubular scaffolds were prepared by electrospinning a polycaprolactone/polylactic-co-glycolic acid (PLGA) blend and then treated with polypyrrole plasma for a possible applicat...
Two main problems limit the success of titanium implants: bacterial infection, which restricts their osseointegration capacity; and the sti_ness mismatch between the implant and the host cortical bone, which promotes bone resorption and risk of fracture. Porosity incorporation may reduce this di_erence in sti_ness but compromise biomechanical behav...
Chemical and physical crosslinking methods using glutaraldehyde (GA) and ammonium hydroxide (AH), respectively, were utilized to prepare chitosan (CS) and chitosan/collagen (CS-Co) hydrogels; these materials were then subjected to freeze-drying process to obtain 3D porous scaffolds. The effect of crosslinking methods on the physicochemical and biol...
Segmented polyurethanes were prepared with polycaprolactone diol as soft segment and various amounts of 4,4´-Methylenebis(cyclohexyl isocyanate) and atorvastatin, a statin used for lowering cholesterol, in order to obtain SPU with different content of rigid segments. Polyurethanes with 35% or 50% of rigid segment content were physicochemically char...
RAW264.7 macrophages polarized toward an M2 phenotype using a collagen‐based membrane crosslinked with tri‐functionalized oligourethanes and coated with silica: a material with enhanced mechanics, swelling and degradation resistance. This is reported by Pedro U. Muñoz‐González, Olivia Rivera‐Debernardi, Birzabith Mendoza‐Novelo, Jesús A. Claudio‐Ri...
Thermal degradation of three biodegradable polyesters: poly(caprolactone), poly(lactic acid), and poly(hydroxybutyrate), was studied by thermogravimetry coupled to Fourier Transform Infrared Spectroscopy TGA/FTIR before and after they were partially degraded. TGA curves and Gram–Schmidt plots showed only one decomposition stage for both poly(caprol...
Back Cover: RAW264.7 macrophages polarized toward an M2 phenotype using a collagen‐based membrane crosslinked with tri‐functionalized oligourethanes and coated with silica: a material with enhanced mechanics, swelling and degradation resistance. This is reported by Pedro U. Muñoz‐González, Olivia Rivera‐Debernardi, Birzabith Mendoza‐Novelo, Jesús A...
Characterization of clay-drug hybrid materials for antibacterial applications using montmorillonite (MMT) and chlorhexidine diacetate (CA) has been reported; however, antibacterial clays based on palygorskite (PLG) have not been explored. Organoclays based on MMT (a laminar clay) and palygorskite (a microfibrous clay), are expected to differ in the...
The polarization of macrophages M0 to M1 or M2 using molecules embedded in matrices and hydrogels is an active field of study. The design of biomaterials capable of promoting polarization has become a paramount need nowadays, since in the healing process macrophages M1 and M2 modulate the inflammatory response. In this work, several immunocytochemi...
The circumferential compliance and burst strength of vascular grafts are predicted through the conically modified von Mises and elasticity theories, providing an analytical closed form solution for both parameters. Besides the graft's radii, the model for circumferential compliance depends solely on the elastic modulus and Poisson's ratio of the po...
Polydimethylsiloxane (PDMS) films were treated with either oxygen (O2), nitrogen (N2) or argon (Ar) plasma between 40 W and 120 W for 5 to 15 min and their surface properties studied by contact angle measurements, infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Lower contact angles and increases i...
Electrospun polycaprolactone (PCL)/chitosan (CH) blend scaffolds with different CH weight ratios were prepared to study the effect of scaffold composition on its physicochemical and biological properties. Scanning electron microscopy showed bead-free homogeneous randomly arranged nanofibers whose average diameter decreased from 240 to 110 nm with i...
Polycaprolactone (PCL) is a biocompatible polymer approved by the FDA for using in medical devices but it is generally considered as hydrophobic material. In order to improve this drawback, electrospun PCL microfibers were superficially modified by air plasma treatments at three power levels (10, 20, 30 W) and three discharge times (1, 3, 5 min). T...
The aim of this study was to obtain composites foams made of CO based PU and Ti powder and to perform a physical-chemical and mechanical characterization to determine their suitability for bone regeneration purposes
Tensile piezoresistive properties of multiwall carbon nanotube (MWCNT)/segmented polyurethane (SPU) composites comprising 15, 30, and 50 wt % rigid segment (RS) contents and 2, 4, and 6 wt % MWCNT contents are investigated. The physicochemical properties of such composites are used to better understand their mechanical and piezoresistive behavior....
The influence of iron oxide nanoparticles decorating the external surface of multiwall carbon nanotubes (MWCNTs) on the amperometric sensing of glucose in solution is investigated. Oxidized nanotubes are decorated with iron oxide nanoparticles and then glucose oxidase is chemically bound to the MWCNTs for glucose sensing within physiological levels...
Analysis of acoustic emission signals generated during the fatigue testing of core–shell nanoparticles filled acrylic bone cements is reported. Core–shell nanoparticles composed of a poly(butyl acrylate) rubbery core and a poly(methyl methacrylate-co-styrene) (P(MMA-co-St)) outer glassy shell with varying compositions (20/80, 30/70, 40/60, and 50/5...
Composites of glutamine-based segmented polyurethanes with 5 to 25 wt.% bioactive glass nanoparticles were prepared, characterized, and their mineralization potential was evaluated in simulated body fluid. Biocompatibility with dental pulp stem cells was assessed by MTS to an extended range of compositions (1 to 25 wt.% of bioactive glass nanoparti...
Conventional approaches to bone regeneration rarely use multiwall carbon nanotubes (MWCNTs) but instead use polymeric matrices filled with hydroxyapatite, calcium phosphates and bioactive glasses. In this study, we prepared composites of MWCNTs/polycaprolactone (PCL) for bone regeneration as follows: (a) MWCNTs randomly dispersed on PCL, (b) MWCNTs...
The development of elastomeric, bioresorbable and biocompatible segmented polyurethanes (SPUs) for use in tissue-engineering applications has attracted considerable interest because of the existing need of mechanically tunable scaffolds for regeneration of different tissues, but the incorporation of osteoinductive molecules into SPUs has been limit...
In this work, the effect of the incorporation of core-shell particles on the fracture mechanisms of the acrylic bone cements by using acoustic emission (AE) technique during the quasi-static compression mechanical test was investigated. Core-shell particles were composed of a poly(butyl acrylate) (PBA) rubbery core and a methyl methacrylate/styrene...
Chemically oxidized multiwall carbon nanotubes (MWCNTs) were deposited onto commercial E-glass fibers using a dipping procedure assisted by ultrasonic dispersion. In order to investigate the role of the fiber coating (known as “sizing”), MWCNTs were deposited on the surface of as-received E-glass fibers preserving the proprietary coating as well as...
Deposition of acid oxidized multiwall carbon nanotubes (MWCNTs) onto commercial glass fibers (GFs) is achieved by a simple dipping deposition procedure. Given the interaction between the chemical groups of the fiber coating (sizing) and those of the oxidized MWCNTs, a homogenous deposition of MWCNTs onto GFs is achieved only when the fiber coating...
The aim of this work was to provide some fundamental information for optimization of silanization of hydroxyapatite intended for bone cement formulations. The effect of 3-(trimethoxysilyl) propyl methacrylate (MPS) concentration and solvent system (acetone/water or methanol/water mixtures) during HA silanization was monitored by X-ray diffraction (...
The development of elastomeric, bioresorbable, and biocompatible segmented polyurethanes (SPUs) for use in tissue-engineering applications has attracted considerable interest in recent years because of the existing need for mechanically tunable scaffolds for regeneration of different tissues. In this study segmented polyurethanes were synthesized f...
This paper describes the preparation and characterization of water-soluble urethane oligomers bearing protected isocyanate groups. It also points out its ability to crosslink decellularized pericardium, as a model collagen scaffold, and to adjust their structural characteristics. A library of oligourethanes was synthesized by varying the molecular...
Bone cements are materials, either acrylic polymers or calcium phosphate based, which are used in joint replacement surgeries (hip and knee mainly) and recently in other clinical practices like vertebroplasty and kyphoplasty, and even for repairing bone defects (cranial or maxillofacial). Although bone cements have been used clinically with encoura...
Two types of commercial multiwall carbon nanotubes (MWCNTs) with different diameters and physicochemical properties were decorated with iron oxide nanoparticles obtained by hydrolysis at high temperature in the presence of triethylene glycol and iron(III) chloride as metal precursor. A homogeneous distribution of 2–9 nm diameter particles decoratin...
Multiwall carbon nanotube (MWCNT)/elastomeric composite films were fabricated using two segmented polyurethanes: an in-house synthesized one (SPU) and a commercial medical grade one (Tecoflex®, TF). Electrical, mechanical, and electromechanical (piezoresistive) properties of both composites were evaluated as a function of the MWCNT weight concentra...
Nanocomposites were prepared with segmented polyurethanes and Cloisite 30B by either solution mixing or in situ polymerization and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. Cytotoxicity and genotoxicity were assessed with lymphocytes while cell viab...
Polyurethanes are very often used in the cardiovascular field due to their tunable physicochemical properties and acceptable hemocompatibility although they suffer from poor endothelialization. With this in mind, we proposed the synthesis of a family of degradable segmented poly(urea)urethanes (SPUUs) using amino acids (L-arginine, glycine and L-as...
Novel biodegradable segmented polyurethanes (SPUs) were synthesized with polycaprolactone diol, 4,4'-methylen bis (cyclohexyl isocyanate) (HMDI), and either L-glutathione or its constituent amino acids (L-glutamic acid, L-cysteine and glycine) as chain extenders. Fourier transform infrared spectroscopy analysis revealed the feasibility of obtaining...
Core-shell nanoparticles consisting of polybutyl acrylate (PBA) rubbery core and a polymethyl methacrylate (PMMA) shell, with different core-shell ratios, were synthesized in order to enhance the fracture toughness of the acrylic bone cements prepared with them. It was observed by TEM and SEM that the core-shell nanoparticles exhibited a spherical...
Polyurethanes are a family of polymers used in a variety of biomedical applications but mainly in the cardiovascular field due to their good physicochemical and mechanical properties in addition to a good biocompatibility. Traditionally, segmented polyurethanes (SPUs), have been used in cardiovascular applications (Kuan et al., 2011) as permanent d...
In this work, we report the preparation of bone cements by using methyl methacrylate (MMA) as a base monomer and either hydroxyapatite (HA), alpha tricalcium phosphate (α-TCP) or bovine bone particles as bioactive fillers. In general, it was observed that curing times increased by the addition of any of these fillers (from 4 to 6.7 min). Maximum te...
In this work, we report the preparation of bone cements by using methyl methacrylate (MMA) as a base monomer and either hydroxyapatite (HA), alpha tricalcium phosphate (α-TCP) or bovine bone particles as bioactive fillers. In general, it was observed that curing times increased by the addition of any of these fillers (from 4 to 6.7 min). Maximum te...
This paper describes rapid, simple, and cost-effective treatments for producing biocompatible and long-term hydrophilic polydimethylsiloxane (PDMS) surfaces identified in an experimental study investigating 39 treatments in all. The wetting of the surfaces was monitored during six months. Changes in surface morphology and chemical composition were...
Biodegradable segmented polyurethanes were prepared with poly(caprolactone) diol as a soft segment, 4,4'-methylene bis(cyclohexyl isocyanate) (HMDI) and either butanediol or dithioerythritol as chain extenders. Platelet adhesion was similar in all segmented polyurethanes studied and not different from Tecoflex® although an early stage of activation...
Raman spectroscopy, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy, and transmission electron microscopy are used to assess structural changes generated on the surface of multi-walled (MWCNTs) and single-walled (SWCNTs) carbon nanotubes. Different levels of structural modifications are generated by the use of acidic oxida...
In this work, the effect of the incorporation of comonomers containing amine groups on the mechanical and fracture properties of acrylic bone cements was studied. Cements were prepared with either diethyl amino ethyl acrylate (DEAEA), dimethyl amino ethyl methacrylate (DMAEM) or diethyl amino ethyl methacrylate (DEAEM) as comonomer in the liquid ph...
A detailed transmission electron microscopy (TEM) examination of the surface of multi-walled carbon nanotubes (MWCNTs) oxidized using mild experimental conditions shows evidence of nanotube length shortening after acid treatments and important modifications at the nanostructural level, such as damage to the graphitic structure and stripping of the...
The aim of this study was to gain some fundamental knowledge on the thermal degradation pathways of poly(N-vinyl pyrrolidone) using Thermogravimetry coupled with Fourier Transform Infrared Spectroscopy (TG–FTIR) in addition to IR
and 1H NMR spectroscopic studies of the partially degraded samples. It was found that the vinyl pyrrolidone is the main...
Interpenetrated polymer networks of chitosan (CHI), polyacrylic acid (PAA) and polyacrylamide (PAM) were prepared by free radical polymerization. These hydrogels were either washed with double distilled water (CHI/PAA/PAM) A or hydrolyzed with 1M sodium hydroxide (NaOH), (CHI/PAA/PAM) S. Both types of hydrogels were characterized by in-frared spect...
In this paper, we characterize polypyrrole–DBS–ClO4/tape bilayers with prevalent interchange of cations, while acting as macroscopic bending artificial muscles in aqueous solution. The electrochemical origin of their movement is described by linear equations deduced from the driving Faraday's laws. We demonstrate that the engineering parameters for...
Bovine pericardium is a collagenous tissue commonly used as a natural biomaterial in the fabrication of cardiovascular devices. For tissue engineering purposes, this xenogeneic biomaterial must be decellularized to remove cellular antigens. With this in mind, three decellularization protocols were compared in terms of their effectiveness to extract...
In this work, the combined influence of barium sulfate content and co-monomer concentration on the properties of acrylic bone cement for percutaneous vertebroplasty (PVP) was investigated using a response surface methodology. Cements were prepared with methyl methacrylate (MMA) and either diethyl amino ethyl methacrylate (DEAEM) or dimethyl amino e...
Films of conducting polymers can be oxidized and reduced in a reversible way. Any intermediate oxidation state determines an electrochemical equilibrium. Chemical or physical variables acting on the film may modify the equilibrium potential, so that the film acts as a sensor of the variable. The working potential of polypyrrole/DBSA (Dodecylbenzene...
The electrochemical activity of self‐supported thick (70 µm) polypyrrole films electrogenerated in a mixed electrolyte of dodecylbenzenesulfonic acid and LiClO4 was studied in aqueous solutions of LiClO4. This material inhibits hydrogen evolution up to cathodic potentials of −3.0 V versus Ag/AgCl. During oxidation or reduction reactions under galva...
Biodegradable segmented polyurethanes (BSPUs) were prepared with poly(caprolactone) as a soft segment, 4,4'-methylene bis (cyclohexyl isocyanate) and either butanediol (BSPU1) or dithioerythritol (BSPU2) as a chain extender. BSPU samples were characterized in terms of their physicochemical properties and their hemocompatibility. Polymers were then...
Acidic oxidation methods have been widely reported as an effective method to purify and functionalize the surface of carbon nanotubes (CNTs). Although effective, the strong acids typically employed and the high sonication power used to disperse the nanotubes in the solution frequently cause nanotube damage, limiting their great potential as mechani...
Aim:
Bovine pericardium (BP) is a collagenous tissue commonly used in cardiovascular applications. However, it suffers from thrombus formation and calcification, the latter generally being related to cell debris and the use of glutaraldehyde (GA). With this in mind, BP was decellularized, crosslinked and grafted with L-cysteine in order to improve...
Nanocomposites prepared with segmented polyurethane (SPU) and commercially available nanoclays (Cloisite™ Na+, Cloisite™ 15A, Cloisite™ 30B) were studied using thermogravimetric analysis coupled with Fourier Transform Infrared Spectroscopy (TGA/FTIR). The results showed that the thermal degradation of unfilled SPU and the 4, 6 and 10 wt% hand mixed...
Polymeric bone cements are viscoelastic materials. Dynamic mechanical analysis (DMA) is a powerful technique for the characterisation of polymers. Viscoelastic parameters of storage and loss moduli, mechanical loss factors (tan δ) as well as important thermal transition temperature and polymer relaxation processes are easily quantified as a functio...
The thermal degradation behavior of polymethacrylates containing amine groups such as poly(N,N-diethyl aminoethyl methacrylate), PDEAEM, and poly(N-ethyl-m-tolyl-aminoethyl methacrylate), PMEET, has been studied using thermogravimetry coupled with infrared spectroscopy (TGA/FTIR). PDEAEM showed two degradation stages whereas PMEET displayed only on...
Thermogravimetry coupled to Fourier transform infrared spectroscopy (TGA/FTIR) has been used to study the thermal decomposition products evolved during the degradation of several commercially available organoclays (Cloisites™ Na+, 10A, 15A, 20A, 25A, 93A and 30B). It was found that the decomposition pattern of the organoclays was different for each...
For short-term cardiovascular application, segmented polyurethanes (SPUs) based on 4,4-methylenebis(cyclohexyl isocyanate) (HMDI), polytetramethylenglycol (PTMG) and 1,4-butanediol (BD) were synthesized and characterized by spectroscopy (FT-IR, (1)H-NMR) and thermal (TGA, DMA, DSC) and mechanical techniques. The segmented nature of the SPUs was not...
New aromatic methacrylates were prepared by substitution of a methylene group from diethylaminoethyl methacrylate (DEAEM) by an aromatic ring at two different positions. Diethylamino benzyl methacrylate (DEABM) and N-methacryloyloxyethyl)-N-ethyl-m-toluidine (MEET) were polymerized and incorporated as co-monomers in bone cement formulations. Cement...
In this work, the thermal degradation of polymethacrylates containing carboxylic groups namely poly(methacryloyloxy butanoic acid), PMBA; poly(methacryloyloxy hexanoic acid), PMHA; and poly(p-methacryloyloxy benzoic acid), PMBeA was investigated by TGA/FTIR. Moreover, in order to shed more light on the reaction pathways during the thermal decomposi...
This study reports the relationship between the biocompatibility and surface properties of experimental bone cements. The effect of hydroxyapatite (HA) or alpha-tri-calcium phosphate (alpha-TCP) incorporated into bone cements prepared with methyl methacrylate as base monomer and either methacrylic acid or diethyl amino ethyl methacrylate (DEAEMA) a...
Bone cements prepared with methacrylic acid (MAA) and diethyl amino ethyl methacrylate (DEAEM) were compared with formulations employing 4-methacryloyloxybenzoic acid (MBA) and 4-diethyaminobenzyl methacrylate (DEABM) as comonomer. The influence of these new aromatic monomers on various physicochemical, setting and mechanical properties was assesse...
Calcium phosphate bone cements are injectable biomaterials that are being used in dental and orthopaedic applications through minimally invasive surgery techniques. Nowadays, apatitic bone cements based on alpha-tricalcium phosphate (alpha-TCP) are of special interest due to their self-setting behaviour when mixed with an aqueous liquid phase. In t...
Bone cements prepared with methyl methacrylate (MMA) as a base monomer and either methacrylic acid (MAA) or diethyl amino ethyl methacrylate (DEAEMA) as comonomers were characterized in terms of curing behavior, mechanical properties, and their in vitro biocompatibility.
The curing time and setting temperature were found to be composition dependent...
Bone cements prepared with either tetrahydrofurfuryl methacrylate (THFMA) or butyl methacrylate (BMA) and poly(ethyl methacrylate) (PEMA) were characterized after being stored in a dessicator at 30 °C for 1 year by thermal, spectroscopic and mechanical techniques. Differential scanning calorimetry (DSC) revealed evidence of annealing during storage...
The properties of bone cements prepared with both hydroxyapatite (HA) and alpha-tricalcium phosphate (alpha-TCP) and methacrylates containing acidic or basic groups are the main interest of this article. The presence of methacrylic acid or diethyl amino ethyl methacrylate as comonomers in the bone cement and both ceramic types as filler were found...
Hydrogels made of polyvinyl alcohol–vinyl acetate and its blends with water soluble polymer were studied in terms of swelling behavior, microstructure, and dynamic mechanical properties. Hydrogels prepared by blending polyvinyl alcohol–vinyl acetate with either polyacrylic acid or poly(4-vinyl pyridine) exhibited a strong pH dependency. When poly(v...
Bone cements prepared with methyl methacrylate and either methacrylic acid or diethyl amino ethyl methacrylate as comonomers were characterized by infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, dynamic mechanical thermal analysis, and mechanical testing. Selected formulations containing these functionalized methac...
Los cementos óseos son materiales poliméricos que se utilizan con el objeto de fijar prótesis metálicas. Han estado en el mercado por casi 40 años desde que Sir John Charnley propuso su uso en ortopedia. Los cementos óseos convencionales exhiben altos calores de reacción, alta contracción y un elevado contenido de monómero residual; estas propiedad...
A range of hydrogels were prepared by blending aqueous solutions of poly(vinyl alcohol-vinyl acetate) with poly(acrylic acid) in various proportions. The effects of two cross-linking agents (glyoxal and glutaraldehyde) and subsequent thermal treatment on the properties of the blends are discussed. Dynamic mechanical analysis (DMA) of the xerogels i...
Hydrogel blends were prepared from water-soluble polymers of poly(vinyl alcohol-vinyl acetate) and poly(vinyl pyrrolidone). The method of preparation was optimized and different compositions of blends were characterized. The effect of thermal treatment and the introduction of an aldehydic crosslinking agent in the blend was also studied. The swelli...
Transparent hydrogels were prepared by blending solutions of poly(vinyl alcohol-vinyl acetate) with either poly(acrylic acid) or poly(vinyl pyrrolidone) in the presence of glutaraldehyde as a crosslinking agent. The network obtained from the poly(vinyl pyrrolidone) system was subjected to various thermal treatments, the effects of which have been s...
A calorimetric study for estimating crosslinking densities of polydimethylsiloxane (PDMS) networks is presented. It involves the experimental determination of the heat capacities of the polymer with (C) and without (C) crosslinking. The theoretical basis of the method is described as well as the procedure used for the determination of the Cps. The...
Binary blends of poly(vinyl alcohol) (PVA) with poly(acrylic acid) (PAA) and polyacrylamide (PAAm) were characterized by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and infrared spectroscopy (IR). Molecular weight, blend composition, and heating time at 150°C were the variables used. Results obtained by DSC indicate...
