9 results found
Diba M, Garcia-Gallastegui A, Taylor RNK, et al., 2014, Quantitative evaluation of electrophoretic deposition kinetics of graphene oxide, CARBON, Vol: 67, Pages: 656-661, ISSN: 0008-6223
The electrophoretic deposition (EPD) technique is an attractive approach for development of graphene and graphene oxide (GO) films for a variety of applications. However, in order to establish the influence of the EPD parameters on the properties of the deposited films, a deeper investigation of the fundamental GO-EPD kinetics is required. Previous studies have reported a simultaneous anodic reduction of GO flakes during EPD, complicating the kinetics and process control. Therefore, in this study, low voltages were used to prevent significant GO reduction during EPD, as confirmed by XPS and FTIR. Accordingly, the GO-EPD kinetics was established as a function of deposition time and voltage, accompanied by microscopic characterization of the deposited films. The experimental results show that the deposition follows a linear growth law, in good agreement with the predictions of Hamaker's law. Comparisons of optical absorbance and profilometry provide estimates of (reduced) GO deposition rate, extinction coefficient, and density. © 2013 Elsevier Ltd. All rights reserved.
Pishbin F, Mourino V, Flor S, et al., 2014, Electrophoretic Deposition of Gentamicin-Loaded Bioactive Glass/Chitosan Composite Coatings for Orthopaedic Implants, ACS APPLIED MATERIALS & INTERFACES, Vol: 6, Pages: 8796-8806, ISSN: 1944-8244
Despite their widespread application, metallic orthopaedic prosthesis failure still occurs because of lack of adequate bone-bonding and the incidence of post-surgery infections. The goal of this research was to develop multifunctional composite chitosan/Bioglass coatings loaded with gentamicin antibiotic as a suitable strategy to improve the surface properties of metallic implants. Electrophoretic deposition (EPD) was applied as a single-step technology to simultaneously deposit the biopolymer, bioactive glass particles, and the antibiotic on stainless steel substrate. The microstructure and composition of the coatings were characterized using SEM/EDX, XRD, FTIR, and TGA/DSC, respectively. The in vitro bioactivity of the coatings was demonstrated by formation of hydroxyapatite after immersion in simulated body fluid (SBF) in a short period of 2 days. High-performance liquid chromatography (HPLC) measurements indicated the release of 40% of the loaded gentamicin in phosphate buffered saline (PBS) within the first 5 days. The developed composite coating supported attachment and proliferation of MG-63 cells up to 10 days. Moreover, disc diffusion test showed improved bactericidal effect of gentamicin-loaded composite coatings against S. aureus compared to control non-gentamicin-loaded coatings.
Pishbin F, Mourino V, Gilchrist JB, et al., 2013, Single-step electrochemical deposition of antimicrobial orthopaedic coatings based on a bioactive glass/chitosan/nano-silver composite system, ACTA BIOMATERIALIA, Vol: 9, Pages: 7469-7479, ISSN: 1742-7061
Composite orthopaedic coatings with antibacterial capability containing chitosan, Bioglass® particles (9.8μm) and silver nanoparticles (Ag-np) were fabricated using a single-step electrophoretic deposition (EPD) technique, and their structural and preliminary in vitro bactericidal and cellular properties were investigated. Stainless steel 316 was used as a standard metallic orthopaedic substrate. The coatings were compared with EPD coatings of chitosan and chitosan/Bioglass®. The ability of chitosan as both a complexing and stabilizing agent was utilized to form uniformly deposited Ag-np. Due to the presence of Bioglass® particles, the coatings were bioactive in terms of forming carbonated hydroxyapatite in simulated body fluid (SBF). Less than 7wt.% of the incorporated silver was released over the course of 28days in SBF and the possibility of manipulating the release rate by varying the deposition order of coating layers was shown. The low released concentration of Ag ions (<2.5ppm) was efficiently antibacterial against Staphyloccocus aureus up to 10days. Although chitosan and chitosan/Bioglass® coating supported proliferation of MG-63 osteoblast-like cells up to 7days of culture, chitosan/Bioglass®/Ag-np coatings containing 342 μg of Ag-np showed cytotoxic effects. This was attributed to the relatively high concentration of Ag-np incorporated in the coatings.
Basnett P, Knowles JC, Pishbin F, et al., 2012, Novel Biodegradable and Biocompatible Poly(3-hydroxyoctanoate)/Bacterial Cellulose Composites, ADVANCED ENGINEERING MATERIALS, Vol: 14, Pages: B330-B343, ISSN: 1438-1656
Novel poly(3-hydroxyoctanoate), P(3HO), and bacterial cellulose composites have been developed. P(3HO) is hydrophobic in nature whereas bacterial cellulose is extremely hydrophilic in nature. Therefore, homogenized bacterial cellulose has been che mically modified in order to achieve compatibility with the P(3HO) matrix. Modified bacterial cellulose microcrystals and P(3HO) have been physically blended and solvent casted into two-dimensional composite films. Mechanical characterization shows that the Young's modulus of the P(3HO)/bacterial cellulose composites is significantly higher in comparison to the neat P(3HO) film. The melting temperature (T m ) of the composites is lower while the glass transition temperature (T g ) is higher than the neat P(3HO) film. Also, the composite film has a rougher surface topography as compared to the neat P(3HO) film. A month's in vitro degradation study has been carried out in Dulbeccos modified eagle medium and in phosphate buffer saline. The incorporation of modified bacterial cellulose microcrystal in the P(3HO) film has increased the degradability of the composite film. Finally, in vitro biocompatibility studies using human microvascular endothelial cells established the biocompatibility of the P(3HO)/bacterial cellulose microcrystal films. The cell proliferation was 50-110% higher on the P(3HO)/bacterial cellulose composites as compared to the neat P(3HO) film. Hence, in this study, for the first time, P(3HO)/bacterial cellulose composites have been developed. The addition of bacterial cellulose has resulted in properties that are highly desirable for medical applications including the development of biodegradable stents. Novel P(3HO)/bacterial cellulose composites have been developed to be used as a potential material for a range of medical applications including the development of biodegradable stents. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Mourino V, Newby P, Pishbin F, et al., 2011, Physicochemical, biological and drug-release properties of gallium crosslinked alginate/nanoparticulate bioactive glass composite films, SOFT MATTER, Vol: 7, Pages: 6705-6712, ISSN: 1744-683X
The aim of this work was to develop biodegradable and bioactive materials with sufficient structural integrity and prophylaxis effect against infection based on alginate-bioactive glass composite. The incorporation of bioactive glass nanoparticles (NBG) into Ga-crosslinked alginate films significantly improved their mechanical properties when compared with films fabricated with micron-sized bioactive glass particles. In addition, Ga-alginate films containing NBG induced a bacteriostatic effect in vitro towards S. aureus due to the presence of Ga ions (Ga 3+ ), whose release is controlled solely by crosslinking the ion with alginate. Biomineralization studies in simulated body fluid suggested the deposition of hydroxyapatite on the surface of the films indicating their bioactive nature. In addition, the films were shown to feature biocompatibility toward osteoblast-like cells. Thus, it was shown that Ga-crosslinked composite films possessed relevant physicochemical, biological and controlled bacteriostatic effects which make these materials promising candidates for bone tissue engineering applications. © 2011 The Royal Society of Chemistry.
Pishbin F, Simchi A, Ryan MP, et al., 2011, Electrophoretic deposition of chitosan/45S5 Bioglass (R) composite coatings for orthopaedic applications, SURFACE & COATINGS TECHNOLOGY, Vol: 205, Pages: 5260-5268, ISSN: 0257-8972
This article presents experimental results on the electrophoretic deposition (EPD) of bioresorbable chitosan/45S5 Bioglass ® composite coatings for orthopaedic implants based on the Taguchi design of experiments (DOE) approach. The influence of EPD parameters including Bioglass ® concentration, electric voltage and deposition time on deposition yield was studied by an orthogonal Taguchi array of L 18 type. Multivariate analysis of variance (MANOVA) and regression analysis based on the partial least-square method were used to identify the significant factors affecting the deposition yield and its stability during constant-voltage EPD. The coatings were characterised by high resolution scanning electron microscope (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). It is shown that the co-deposition of polymer/Bioglass ® system is very sensitive to the concentration of Bioglass ® particles. The addition of Bioglass ® to the chitosan suspension alters the deposition rate due to variation of pH, suspension conductivity, and zeta potential. For low Bioglass ® concentrations, co-deposition of the chitosan and the bioactive glass particles occurs while at the higher concentrations massive deposition of the bioactive glass particles controls the deposition yield. The optimum condition for a high deposition rate with low standard deviation and homogeneous microstructure is achieved when an almost equal concentrations of chitosan and Bioglass ® is utilized. The validity of the approach is shown by confirmation experiments at the predicted optimal condition, and the mechanism of electrophoretic co-deposition of the polymer/glass system is discussed. © 2011 Elsevier B.V.
Simchi A, Tamjid E, Pishbin F, et al., 2011, Recent progress in inorganic and composite coatings with bactericidal capability for orthopaedic applications, NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE, Vol: 7, Pages: 22-39, ISSN: 1549-9634
UNLABELLED: This review covers the most recent developments of inorganic and organic-inorganic composite coatings for orthopedic implants, providing the interface with living tissue and with potential for drug delivery to combat infections. Conventional systemic delivery of drugs is an inefficient procedure that may cause toxicity and may require a patient's hospitalization for monitoring. Local delivery of antibiotics and other bioactive molecules maximizes their effect where they are required, reduces potential systemic toxicity and increases timeliness and cost efficiency. In addition, local delivery has broad applications in combating infection-related diseases. Polymeric coatings may present some disadvantages. These disadvantages include limited chemical stability, local inflammatory reactions, uncontrolled drug-release kinetics, late thrombosis and restenosis. As a result, embedding of bioactive compounds and biomolecules within inorganic coatings (bioceramics, bioactive glasses) is attracting significant attention. Recently nanoceramics have attracted interest because surface nanostructuring allows for improved cellular adhesion, enhances osteoblast proliferation and differentiation, and increases biomineralization. Organic-inorganic composite coatings, which combine biopolymers and bioactive ceramics that mimick bone structure to induce biomineralization, with the addition of biomolecules, represent alternative systems and ideal materials for "smart" implants. In this review, emphasis is placed on materials and processing techniques developed to advance the therapeutic use of biomolecules-eluting coatings, based on nanostructured ceramics. One part of this report is dedicated to inorganic and composite coatings with antibacterial functionality. FROM THE CLINICAL EDITOR: Inorganic and composite nanotechnology-based coating methods have recently been developed for orthopedic applications, with the main goal to provide bactericide and other enhanced
Pishbin F, Simchi A, Ryan MP, et al., 2010, A study of the electrophoretic deposition of Bioglass (R) suspensions using the Taguchi experimental design approach, 4th International Conference on Shaping of Advanced Ceramics, Publisher: ELSEVIER SCI LTD, Pages: 2963-2970, ISSN: 0955-2219
This paper presents a study of the Taguchi design method to optimise the rate of electrophoretic deposition (EPD) of Bioglass ® particles from aqueous suspensions. The effect of Bioglass ® concentration, pH and electric field was investigated. An orthogonal array of L 16 type with mixed levels of the control factors was utilized. Multivariate analysis of variance (MANOVA) and regression analysis based on the partial least-square method were used to identify the significant factors affecting the deposition rate and its stability during constant-voltage EPD. It was found that the pH of the suspension significantly influences the deposition rate whereas the applied electric field has the smallest effect on the deposition rate. In addition, the interaction between the Bioglass ® concentration and pH, which are key processing parameters influencing the deposition rate, was found to be significant. Although a high deposition rate was obtained at low electric field (5V/cm) and pH 7, the instability of the suspension in particular at high Bioglass ® concentrations resulted in an increase in the variability of the deposition rate. The optimal EPD condition predicted was verified by experiments and good qualitative agreement was obtained. The experimental results and statistical analyses are discussed based on the current knowledge of the EPD of ceramic materials. © 2010 Elsevier Ltd.
The electrophoretic deposition (EPD) of chitosan on metallic substrates was investigated. The electrophoretic mobility of the natural biopolymer in aqueous solution as a function of pH was studied. Because the protonation/deporotonation of chitosan is pH-dependent, the electrophoretic mobility and deposition rate is shown to increase with increasing pH from 2.9 to 4.1. The film growth rate is estimated to vary in the range 0.02-0.08 μm/s depending on the pH value. At high growth rates ( > 0.05 μm/s), a porous film is obtained due to hydrogen entrapment. The EPD method developed here is applicable for the surface modification of metal implants by chitosan to develop novel bioactive coatings. © 2009 Elsevier B.V. All rights reserved.
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