Biocomposite Membranes Research Articles

Electroactive bio-composite actuators based on cellulose acetate nanofibers with specially chopped polyaniline nanoparticles through electrospinning

A dry type electro-active biopolymer actuator was newly developed with electrospun cellulose–polyaniline bio-composite membranes. Through electrospinning with the mixture of cellulose acetate and polyaniline solutions, well-defined cellulose acetate nanofibers reinforced with chopped polyaniline nanoparticles were obtained and extracellular nano-porous bio-composite membranes with a good biocompatibility were fabricated. The electro-active bio-composite actuator based on cellulose acetate nanofibers with specially chopped polyaniline nanoparticles through electrospinning shows much larger electromechanical deformations than a pure cellulose acetate actuator.

Synthesis of poly(vinyl alcohol) — hydroxyapatite composites and characterization of their bioactivity

Abstract Abstract A series of poly(vinyl alcohol) membranes reinforced with hydroxyapatite in various weight percent — 0%, 10%, 20%, 30%, 40% and 50% were prepared. Hydroxyapatite was prepared by a sol-gel procedure using diammonium hydrogen phosphate and calcium nitrate tetrahydrate as starting materials in an alkaline aqueous environment and then mixed with a solution of poly(vinyl alcohol), which was prepared by dissolving it in water at 85°C. The different mixtures were cast in a mould and evaporated for 7 days at a temperature of 30°C to obtain 1 mm thin membranes. FTIR spectroscopy was used to identify the different functional groups in the composites. The surface morphology was examined using a scanning electron microscope. In vitro bioactivity tests in Simulated Blood Fluid were performed for up to 28 days, especially for the membrane containing 50 wt.% HA. SEM was used to characterise the surface microstructure of biocomposite membranes before and after soaking in SBF. It was observed that the formation of clusters in membranes increases with increasing amount of HA. The clusters are formed due to agglomeration and crystal growth of HA particles during drying of the membranes. The in vitro bioactivity was found to increase with soaking time of biocomposite materials in simulated blood fluid. Graphical abstract

Biocomposite membranes of sodium alginate and silk fibroin fibers for biomedical applications

ABSTRACTBiocomposite membranes from biodegradable and biocompatible natural polymers were prepared from sodium alginate solution reinforced with silk fibroin fibers in several fiber content by casting and solvent evaporation. The properties of these biocomposites were investigated by scanning electron microscopy, swelling test, water vapor transmission, mechanical and thermal analyses, and cytotoxicity test. A biocomposite with uniform fiber dispersion and good fiber–matrix interaction was obtained through the incorporation of fibroin fibers in the alginate membrane, even though the fibers were used without any surface treatment to enhance the interfacial adhesion. The incorporation of fibroin fibers improved the tensile strength and also provided a new property to the alginate, that is, the resistance to tear. Moreover, the use of silk fibroin fibers in polymeric composites can result in a material with adequate characteristics for application in the biomaterial field, especially as wound dressings, because of its nontoxic effect to cells, flexibility, and resistance to tear. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3451–3457, 2013

Preparation, characterization and in vitro bioactivity of polyvinyl alcohol-hydroxyapatite biphasique membranes

Abstract Six membranes of polyvinyl alcohol (PVA) with various weight percent - 0 %, 10 %, 20 %, 30 %, 40 % and 50 % of hydroxyapatite (HA) were prepared. Fourier Transform Infrared (FTIR) spectroscopy was used to identify the different functional groups in membrane composites. The surface morphology was examined through scanning electron microscope. The in vitro bioactivity tests in Simulated Blood Fluid (SBF) have been performed up to 28 days, especially for membrane containing 50 wt. % HA. SEM was used to characterize surface microstructure of biocomposite membranes before and after immersion in SBF. It was observed the formation of clusters within membranes with increasing amount of HA particles due to hydrogen bond and also the agglomeration and crystal growth of HA particles during drying of membranes. The bioactivity was found increasing with time immersion of biocomposite materials in SBF solution.

An Interference‐Free Glucose Biosensor Based on an Anionic Redox Polymer‐Mediated Enzymatic Oxidation of Glucose

Herein a novel strategy for the construction of an amperometric biosensor for highly sensitive and selective determination of glucose is described. The biosensor is made of a biocomposite membrane of glucose oxidase (GOx) and an Os(bpy)2 (bpy=2,2'-bipyridine)-based anionic redox polymer (Os-RP) mediator. The biosensor is fabricated through the co-immobilization of GOx and the Os-RP on the surface of a glassy carbon electrode by a simple one-step chemical crosslinking process. The crosslinked Os-RP/GOx composite membrane shows excellent catalytic activity toward the oxidation of glucose. Under optimal experimental conditions, a linear correlation between the oxidation current of glucose in amperometry at 0.25 V (vs. Ag/AgCl) and glucose concentration up to 10 mM with a sensitivity of 16.5 μA mM(-1) cm(-2) and a response time <5 s. Due to the presence of anionic sulfonic acid groups in the backbone of the redox polymer, the biosensor exhibits excellent selectivity to glucose in the presence of ascorbic acid and uric acid. The low hydrophobicity of the composite membrane also effectively retards the transport of molecular oxygen within the membrane.

Amperometric determination of tyramine in sauce and beer by epoxy resin biocomposite membrane bound tyramine oxidase

A method is described for construction of an amperometric biosensor for specific determination of tyramine, using black gram tyramine oxidase immobilized covalently on an epoxy resin membrane. The biosensor had optimum response within 10 s at pH 8.5 and 35 °C. A linear relationship was observed between tyramine concentrations and current (mA) in the range of 0.24 to 3.47 mg/dL. The biosensor was employed for determination of tyramine in beer and sauce. The detection limit of sensor was 0.24 mg/dL. The mean analytical recovery of added tyramine (0.5 and 1.0 mg/dL) was 97.3 ± 2.3 and 95.9 ± 3.4%. Within and between batch coefficient of variation were 5.1 and 5.34%, respectively. Enzyme electrode showed 35% loss in its initial activity after its regular use over a period of 2 months. The biosensor has the advantage that it does not suffer from leaching of enzyme and measures tyramine specifically.

Elaboration, Stability and Enzymatic Degradation of Hydroxypropylcellulose/Polysiloxane Biocomposite Membranes

Biopolymers are promising alternatives to synthetic macromolecules for the design of composite materials complying with Green Chemistry principles. In this context, the conditions to associate hydroxypropyl-cellulose and polymethylhydrosiloxane within homogeneous membranes were studied. The stability of these membranes in water and in the presence of a cellulase enzyme were investigated by Thermogravimetric Analysis, Scanning Electron Microscopy and Fourier-Transform Infra-Red Spectroscopy. These investigations reveal that the biopolymer is still accessible to a solubilisation/degradation process without inducing the breaking down of the composite materials, opening the route to the design of novel membranes for environmental applications.

Bio-Composite Membrane Electrolytes for Direct Methanol Fuel Cells

A new class of bio-composite polymer electrolyte membranes comprising chitosan (CS) and certain biomolecules in particular, plant hormones such as 3-indole acetic acid (IAA), 4-chlorophenoxy acetic acid (CAA) and 1-naphthalene acetic acid (NAA) are explored to realize proton-conducting bio-composite membranes for application in direct methanol fuel cells (DMFCs). The sorption capability, proton conductivity and ion-exchange capacity of the membranes are characterized in conjunction with their thermal and mechanical behaviour. A novel approach to measure the permeability of the membranes to both water and methanol is also reported, employing NMR imaging and volume localized NMR spectroscopy, using a two compartment permeability cell. A DMFC using CS-IAA composite membrane, operating with 2M aqueous methanol and air at 70°C delivers a peak power density of 25 mW/cm2 at a load current density of 150 mA/cm2. The study opens up the use of bio-compatible membranes in polymer-electrolyte-membrane fuel cells.

Layered double hydroxide/eggshell membrane: An inorganic biocomposite membrane as an efficient adsorbent for Cr(VI) removal

Hexavalent chromium, Cr(VI), is carcinogenic and mutagenic to the living organisms, and hence more hazardous than other heavy metals. The choice of Cr(VI) removal adsorbents has always been a hot issue in environmental protection. Here we report a novel inorganic biocomposite membrane, layered double hydroxide/eggshell membrane (LDH/ESM) as adsorbent for Cr(VI) removal, in which ESM serves as the substrate and template to immobilize the LDH formed by an in situ hydrothermal crystallization method. X-ray diffraction (XRD) and scanning electron microscope (SEM) images showed that MgAl–CO 3 2−–LDH grown on the fibers of ESM, and the final LDH/ESM composite membrane both maintained the network structure of the ESM substrate. After being treated with an NaCl/HCl mixed solution, the interlayer CO 3 2− anions in the LDH portion of the composite membrane were exchanged for Cl −. The ESM, MgAl–CO 3 2−–LDH/ESM and MgAl–Cl −–LDH/ESM composite membrane were evaluated as adsorbent to remove Cr(VI), respectively, and the effect of the pH values on the adsorption was mainly investigated. It showed that the MgAl–Cl −–LDH/ESM composite membrane had a higher adsorption capacity than ESM and MgAl–CO 3 2−–LDH/ESM—even when the pH value of the Cr(VI) solution was not further adjusted by addition of acid, which is of practical significance in a wastewater treatment plant. The adsorption isotherm of the MgAl–Cl −–LDH/ESM composite membrane showed a good fit with the Langmuir isotherm model.

Synthesis and characterization of nanoporous SiO2/pHEMA biocomposites

Porous SiO(2)/pHEMA biocomposites were synthesized in situ by incorporating silica nanoparticles with a hydroxyethyl methacrylate (HEMA) monomer, following a UV-induced photopolymerization. The nanostructure of the composites was characterized and the resulting physical properties were examined. The release kinetics of the model molecule-vitamin B12-and the hemocompatibility of the porous SiO(2)/pHEMA composites were investigated. Heterogeneous reaction kinetics is proposed to be the formation mechanism of the nanoporosity in the pHEMA matrix as a result of incorporating silica nanoparticles following photopolymerization. Experimental results also demonstrated that the incorporation of the silica nanoparticles into the pHEMA matrix not only enhanced the mechanical property but also maintained a good hemocompatibility of the resulting biocomposites. In addition, it was observed that the drug release profile of the composites (in the form of a membrane) can be precisely regulated from a two-stage pattern to one-stage pattern by varying the concentration of both the SiO(2) nanoparticles and HEMA monomer during synthesis. The permeability of the model drug was enhanced by two orders of magnitude from 4.22 x 10(-7 )cm(2)/h to 3.92 x 10(-5 )cm(2)/h by controlling the micro-to-nanostructure of the composites. The platelet adhesion experiment demonstrated low aggregation of the platelets on the surface of the biocomposite membranes, indicating a promising antithrombotic property.

Carbon nanotube/polysulfone composite screen-printed electrochemical enzyme biosensors

The fabrication, evaluation and attractive performance of multiwall carbon nanotube(MWCNT)/polysulfone biocomposite membrane modified thick-film screen-printed electrochemical biosensors are reported. The fabricated carbon nanotube/polysulfone (CNT/PS) strips combine the attractive advantages of carbon nanotube materials, polysulfone matrix and disposable screen-printed electrodes. Such thick-film carbon nanotubes/polysulfone sensors have a well defined performance, are mechanically stable, and exhibit high electrochemical activity. Furthermore, biocompatibility of CNT/PS composite allows easy incorporation of biological functional moiety of horseradish peroxidase by phase inversion technique. The comparison of graphite with MWCNT as conductor material is described in this paper. The proposed H(2)O(2) biosensor exhibited a linear range (applied potential, -0.2 V) from 0.02 to 0.5 mM and a K(M)(app) of 0.71 mM.

A co-cultured skin model based on cell support membranes

Tissue engineering of skin based on collagen:PCL biocomposites using a designed co-culture system is reported. The collagen:PCL biocomposites having collagen:PCL (w/w) ratios of 1:4, 1:8, and 1:20 have been proven to be biocompatible materials to support both adult normal human epidermal Keratinocyte (NHEK) and mouse 3T3 fibroblast growth in cell culture, respectively, by Dai, Coombes, et al. in 2004. Films of collagen:PCL biocomposites were prepared using non-crosslinking method by impregnation of lyophilized collagen mats with PCL/dichloromethane solutions followed by solvent evaporation. To mimic the dermal/epidermal structure of skin, the 1:20 collagen:PCL biocomposites were selected for a feasibility study of a designed co-culture technique that would subsequently be used for preparing fibroblast/biocomposite/keratinocyte skin models. A 55.3% increase in cell number was measured in the designed co-culture system when fibroblasts were seeded on both sides of a biocomposite film compared with cell culture on one surface of the biocomposite in the feasibility study. The co-culture of human keratinocytes and 3T3 fibroblasts on each side of the membrane was therefore studied using the same co-culture system by growing keratinocytes on the top surface of membrane for 3 days and 3T3 fibroblasts underneath the membrane for 6 days. Scanning electron microscopy (SEM) and immunohistochemistry assay revealed good cell attachment and proliferation of both human keratinocytes and 3T3 fibroblasts with these two types of cells isolated well on each side of the membrane. Using a modified co-culture technique, a co-cultured skin model presenting a confluent epidermal sheet on one side of the biocomposite film and fibroblasts populated on the other side of the film was developed successfully in co-culture system for 28 days under investigations by SEM and immunohistochemistry assay. Thus, the design of a co-culture system based on 1:20 (w/w) collagen:PCL biocomposite membranes for preparation of a bi-layered skin model with differentiated epidermal sheet was proven in principle. The approach to skin modeling reported here may find application in tissue engineering and screening of new pharmaceuticals.

Consolidated biocomposite membrane technology for production of potentiometric biosensors

Consolidated membrane technology, consisting of a simple compression of dry components, is proposed for production of potentiometric biosensor membranes. In order to present this concept, two different kinds of conventional potentiometric biosensors have been designed both based on this novel biocomposite membrane technology. In the first case, a d-amygdalin biosensor based on β-glucosidase incorporated in an iodide-selective membrane has been prepared. In the second case, two enzymes, glucose oxidase (GOD) and peroxidase (POD) are incorporated in the iodide-selective membrane to form a biocomposite for glucose sensing. Some of the main characteristics of the developed potentiometric biosensors are discussed. This involves both the manufacturing technology and the analytical evaluation of biosensors. Results obtained, indicate that this pressing technology is suitable for mass production of potentiometric biosensing devices. For the biosensor based on β-glucosidase, the recommended pressure was 2.3·10 4 kg/cm 2. At this pressure, it was observed that the immobilisation of enzymes in the bulk of the electroactive salts was efficient. The d-amygdalin biosensor had a linear response in the range of 3.9·10 −3 to 10 −2 M and a practical lower detection limit of 2.5·10 −3 M. For the biosensor based on GOD and POD the optimal consolidation pressure was 2.0·10 4 kg/cm 2. In batch measurements, this biosensor has a response time of approximately 2 min. The linear range was between 0.3 and 1.1 mM glucose.

A potentiometric biosensor for d-amygdalin based on a consolidated biocomposite membrane

A new potentiometric biosensor for d-amygdalin based on a consolidated biocomposite membrane has been designed. The manufacturing technique involved a simple compression of dry components presenting an ideal technology for the mass production of potentiometric biosensor devices. The effect of high pressures applied during the preparation of a d-amygdalin biosensor membrane was studied. The immobilisation of β-glucosidase was improved by increasing this pressure. The optimal biocomposite membrane composition was 100 mg electroactive salts (AgI, Ag 2S) and 10 mg enzyme (50 U). Characteristics such as linear range, response times and degree of enzyme immobilisation were studied for each of the pressures used in the production of the membranes.