Chitosan Thin Films Research Articles

ChemInform Abstract: State‐of‐the‐Art in Electrophilic Trifluoromethylthiolation Reagents

AbstractReview: 102 refs.

Temperature-Responsive PNIPAM-Grafted-Alginate Core Wrapped with LbL Assembled Chitosan/DNA Membranes for Development of Controlled Drug Release System

While considerable consumers experience a more-than-recommended-dose usage of commercially available scar cream for scar therapy treatment, we report here a novel and smart thermally controlled drug delivery gel patch system for scar therapy purpose. The gel patch contains a core of amine-terminated-poly(N-isopropylacrylamide) (NH2-PNIPAM) grafted alginate wrapped with outer membranes consisting of layer-by-layer (LbL) assembled Chitosan and DNA thin films. NH2-PNIPAM cross-linked onto side chain of alginate exhibits contraction and expansion above and below its Lower Critical Solution Temperature (LCST: 32℃) and therefore serves as a switch turning “on and off” the release of drug entrapped in the core. The difference in the release of Texas-Red conjugated Epidermal Growth Factor (EGF-TR) at 33℃ and 22℃ were monitored with fluorescence microscopy and the system showed higher release of EGF-TR at 33℃ than at 22 ◦C. Below LCST (at 22℃), the expanded NH2-PNIPAM resembles stretched arms that close the release of EGF-TR, while above LCST (at 33℃), the NH2-PNIPAM arms coil and allow the release of EGF-TR. The outer membranes consisting of optimized seven oppositely charged Chitosan and DNA layers via LbL assembly controlled the rate and profile of EGF-TR release, as well as dramatically reduced the burst effect in the delivery process. A diffusion controlled behavior was observed for the proposed system and a mathematic model to predict the diffusion efficient of EGF from such gel patch system was further established.

Improved Biodegradable Radiation Cured Polymeric Film Prepared from Chitosan-Gelatin Blend

The mechanical, thermal, swelling, and release properties of chitosan-gelatin (CG) films have been investigated in order to verify the influence of UV and gamma radiation on the stability of the films. Thin films of chitosan and gelatin (1 : 3, w/w) that were radiated with 100 krad of gamma dose showed the best performance and the TS values reached 25, 45, and 49 MPa, respectively, for chitosan, gelatin, and blend. The corresponding highest TS values were 23, 42, and 45 MPa, respectively, for 10 passes of UV radiation. The effect of radiation over gelatin, chitosan, and CG blend caused modification in the arrangement of molecules in the crystal lattice that is significant by XRD analysis. Surfaces of the films were also investigated by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) studies further revealed structural changes of the films. These changes were attributed to understanding the behavior of the irradiated chitosan, gelatin, and CG blend on application of thermal energy using DSC and TGA studies, water uptake of the films in aqueous medium, and soil degradation properties to observe the best possibility for its application.

Surface Morphology of Vapor-Deposited Chitosan: Evidence of Solid-State Dewetting during the Formation of Biopolymer Films.

Chitosan is a useful and versatile biopolymer with several industrial and biological applications. Whereas its physical and physicochemical bulk properties have been explored quite intensively in the past, there is a lack of studies regarding the morphology and growth mechanisms of thin films of this biopolymer. Of particular interest for applications in bionanotechnology are ultrathin films with thicknesses under 500 Å. Here, we present a study of thin chitosan films prepared in a dry process using physical vapor deposition and in situ ellipsometric monitoring. The prepared films were analyzed with atomic force microscopy in order to correlate surface morphology with evaporation parameters. We find that the surface morphology of our final thin films depends on both the optical thickness, i.e., measured with ellipsometry, and the deposition rate. Our work shows that ultrathin biopolymer films can undergo dewetting during film formation, even in the absence of solvents and thermal annealing.

Membranes combining chitosan and natural-origin nanoliposomes for tissue engineering

Chitosan thin films, elaborated by solvent casting, were functionalized by incorporating nanoliposomes based on natural vegetable (soy based) and marine (salmon derived) lecithin.

Controllable layer-by-layer assembly of PVA and phenylboronic acid-derivatized chitosan

Phenylboronic acid-derivatized chitosan (chitosan–PBA) were prepared by grafting small molecules bearing phenylboronic acid groups onto chitosan with N-hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) as a coupling reagent pair. Self-assembly multilayer thin films of chitosan–PBA and poly(vinyl alcohol) were subsequently produced under pH control on supporting surfaces, either a silicon wafer or polystyrene latex particles. The driving force of the self-assembly was the ester formation of phenylboronic acid containing polymers with PVA, which can be “turned off” by simple pH control.

THERMAL STABILITY OF CHITOSAN NANOCOMPOSITES CONTAINING TIO2 AND ORGANO-MODIFIED MONTMORILLONITE

The aim of this work was to investigate the effect of different nanoparticles (TiO2 and organically modified montmorillonite MMT) on thermal stability of chitosan thin films (obtained by casting) and to compare with previously studied- CuO and Ag effect. Thermal degradation was carried out in air atmosphere at 140°C up to 100 hours. Various functional groups of chitosan have a different susceptibility to degradation. The influence of nanoparticles amount on degradation of selected structural groups of chitosan was calculated. It was proved, that elongation at break of chitosan sample and its nanocomposites with TiO2 and organically modified montmorillonite decrease rapidly after 20h of thermal degradation. Moreover, as is clear from FTIR studies, that TiO2 nanoparticles enhance the resistant of the -C-O-C- bond responsible for chain scission of chitosan due to thermal degradation. An opposite effect is observed in a case of MMT, where the chain scission of -C-O-C- bond is higher than for pure chitosan. Another effect of nanoparticles are observed in destruction of unstable amine group (-NH3 band at 1560 cm -1 ) and formation of the amide group (band at 1650 cm -1 ). In this case both nanoadditives accelerate the decomposition of amine group and the formation of amide group in higher extent in comparison to pure chitosan.

In vitro short-time stability of a bioactive glass-chitosan composite coating evaluated by using electrochemical methods

A composite coating consisting from a chitosan (Chit) thin film containing a new bioactive glass SiO2-CaO-P2O5 (BG) was investigated by cyclic voltammetry. The bioactive glass–biopolymer coating has certain porosity and is a good insulator comparing with the biopolymer film.The in vitro short-time stability of Chit and BG-Chit coatings on glassy carbon (GC) electrode is studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), during about 1 day of contact with a protein-free and acellular simulated body fluid (SBF) having an ion concentration nearly equal to that of human blood plasma. The EIS data indicated that after 5hours of immersion in SBF the Chit dissolution and the adsorption of SBF ions on BG matrix were initiated causing the formation of a new outer biomimetic and biologically active hydroxyapatite protective layer. The CV and EIS measurements results recommend the use of composite BG–Chit coatings for in vivo devices (implants, prostheses and tissue engineering scaffolds).

Preparation, characterization and optical properties of ionophore doped chitosan biopolymer thin film and its potential application for sensing metal ion

In this study, the preparation of ionophore doped chitosan biopolymer solution using chitosan, glutaraldehyde and p-tert-butylcalix[4]arene-tetrakis(N,N-dimethylacetamide) in acetic acid under mild condition has been described. After the reaction, the ionophore doped chitosan biopolymer thin film was prepared using spin coating technique. The obtained chitosan derivative was confirmed and characterized by Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible near infra-red (UV–Vis–NIR) spectroscopy. Surface morphology, evaluated by atomic force microscopy (AFM), indicates the biopolymer thin film is relatively smooth and homogeneous. Absorption of the thin film is high with optical band gap of 3.177eV. The incorporation of this derivative thin film with an optical spectroscopy can produce positive responses towards metal ion. This ionophore doped chitosan thin film can be considered as a novel optical material for practical application especially in the field of metal ion sensing.

Potential Antibacterial Activity of Polystyrene Nanoparticles/Chitosan Coated on Cotton Fabrics

SummaryThis research is to study the potential of using polystyrene nanoparticles and chitosan solution to increase the anti‐bacterial activity on cotton fabrics prepared by a conventional pad‐dry‐cure method. Firstly, cotton fabrics were coated with chitosan solutions at the concentrations of 0.1, 0.5, and 1.0 (%w/v) and tested for the antibacterial property which was determined by clear zone measurement and viable count assay using Escherichia coli (ATCC 25922) as a tested microorganism. The results showed that, the percentage bacterial reductions were 87.2, 86.3, and 48.5%, respectively, when the cotton fabrics was coated only with chitosan solution. When polystyrene nanoparticle solution was coated onto cotton fabrics prior to coating with chitosan solutions at the concentrations of 0.1, 0.5, and 1.0 (%w/v), the percentage bacterial reductions were 90.3, 90.8, and 65.5%, respectively. This indicated that coating the cotton fabrics with polystyrene nanoparticles prior to chitosan coating would remarkably increase the antibacterial activity. The scanning electron micrographs showed that polystyrene nanoparticles were aggregated and inserted in between the interfiber spacings. The thin film of chitosan was also observed on the surface of cotton fabrics and hydrophobic property of the fabrics was tested via contact angle measurement.

Chitosan Thin Films on Glass and Silicon Substrates.

Chitosan Thin Films on Glass and Silicon Substrates.

State of the Art Detection System for Curcumin Analog.

In spite of the need for sensing bisdemethoxycurcumin analog (BDMCA), there is no detection system available so far. For the first time, we have demonstrated a sensing system for detecting BDMCA. Initially, chitosan thin films of three different molecular weights (low, average, high) were tested for the conductivity. The high molecular weight chitosan film was found to produce higher conductance and hence, used as the substrate. Addition of BDMCA to this substrate induced a significant conductance change (as revealed by impedance analyzer), making the detection system qualitative. Addition of increasing concentrations of BDMCA produced significantly concomitant increase in the conductivity (observed as decrease in current density as revealed by cyclic voltammetry) making the sensor quantitative. Our results show that this chitosan based electrochemical sensing system can be used for the rapid quantitative detection of BDMCA. As there is no BDMCA sensor available so far, this type of detection is very essential to monitor the pharmacokinetic behavior, the therapeutic dosage, bioavailability and related toxicity of BDMCA in different formulations and samples.

Skin wound healing with chitosan thin films containing supported silver nanospheres

Dermal wound healing involves complex histo-molecular events aimed to repair the discontinuity of the epithelium. Employing nanometric silver particles provides an efficient antimicrobial effect for several dermal infections. The aim is to elucidate imminent advantages of silver nanoparticles, such as the possibility of modulating the epithelial cell repair process. Through the nanostructural implementation of chitosan thin films supporting silver nanoparticles, it was feasible to evaluate in vivo the efficacy and evolution of dermal recuperation after surgical damage. The characterization of chitosan silver nanoparticle films was performed by UV–visible spectra and Fourier transform infrared spectroscopy, X-ray diffraction, and high-resolution electron microscopy. An important dermal healing was accomplished in animals that were treated with chitosan films supporting silver nanoparticles, as confirmed by a histopathological analysis of the skin after 12 days of treatment. The developed chitosan thin film supporting an optimized amount of silver nanoparticles could be employed to treat diseases related to wound healing.

Biopolymer-Based Thin Film for Sensor Application

Chitosan is one of the most available biopolymers in nature, which is non-toxic, biocompatible and biodegradable. The crosslinked chitosan solution was synthesized by homogeneous reaction of medium molecular weight chitosan in aqueous acetic acid with glutaraldehyde as crosslinking agent. Then the solution was deposited on glass cover slip by spin coater to form a thin film. The functional group and chemical binding of crosslinked chitosan thin film has been confirmed by X-ray photoelectron spectroscopy (XPS). The chemical interaction between copper ion and the crosslinked chitosan thin film has also been analyzed by XPS. XPS revealed that copper ion adsorbed to the crosslinked chitosan thin film and the functional groups involved in the adsorption mechanisms of copper ion on the thin film were determined. This biopolymer thin film can be incorporated with surface plasmon resonance technique to produce a high potential optical sensor for detection of Cu (II) ion in solution.

Vacuum deposition of chitosan thin films by electron beam sputtering

Vacuum deposition of chitosan thin films by electron beam sputtering

Preparation and Characterization of Chitosan Thin Films on Mixed-Matrix Membranes for Complete Removal of Chromium.

Herein we present a new approach for the complete removal of CrVI species, through reduction of CrVI to CrIII, followed by adsorption of CrIII. Reduction of chromium from water is an important challenge, as CrIV is one of the most toxic substances emitted from industrial processes. Chitosan (CS) thin films were developed on plain polysulfone (PSf) and PSf/TiO2 membrane substrates by a temperature-induced technique using polyvinyl alcohol as a binder. Structure property elucidation was carried out by X-ray diffraction, microscopy, spectroscopy, contact angle measurement, and water uptake studies. The increase in hydrophilicity followed the order: PSf < PSf/TiO2 < PSf/TiO2/CS membranes. Use of this thin-film composite membrane for chromium removal was investigated with regards to the effects of light and pH. The observations reveal 100 % reduction of CrVI to CrIII through electrons and protons donated from OH and NH2 groups of the CS layer; the reduced CrIII species are adsorbed onto the CS layer via complexation to give chromium-free water.

High Resolution X-Ray Photoelectron Spectroscopy Study of the Interaction of Copper Ion with Chitosan Thin Film

In this study, high-resolution X-ray photoelectron spectroscopy (XPS) has been used to study the chemical interaction between copper ion and chitosan thin film. The chitosan solution was synthesized by homogeneous reaction of medium molecular weight chitosan in aqueous acetic acid with glutaraldehyde as crosslinking agent. Then the solution was deposited on glass cover slip by spin coater to form a thin film. The functional group and chemical binding of crosslinked chitosan thin film has been confirmed by XPS. XPS revealed that copper ion adsorbed to the crosslinked chitosan thin film and the functional groups involved in the adsorption mechanisms of copper ion on the thin film were determined.

Structural and morphology of silver-crosslinked chitosan thin films for SPR sensor

Purpose – This purpose of this study is to investigate the structural and morphology of hybrid silver-crosslinked chitosan thin films potentially for surface plasmon resonance (SPR) sensor application. Silver, silver-chitosan and silver-crosslinked chitosan (annealed) thin films also were prepared as controls for this study. Design/methodology/approach – Silver was firstly coated on top of the glass substrate by magnetron sputtering method. Different chitosan solutions (with and without glutaraldehyde) were coated on top of the substrate by spin coating method. Annealing treatment was carried out for one of silver-crosslink chitosan sample. The structural and morphology of all the thin films were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The SPR curves also were measured by the SPR sensor with air and deionised (DI) water as analytes. Findings – The structure of silver-crosslinked chitosan thin film presented a monoclinic structure with high crystallinity of 131.71 nm at the prominent peak by XRD analysis. The FESEM and AFM analyses revealed the morphology to be rough in surface attributed to enhanced contact with analytes in SPR measurement compared to other thin films. Research limitations/implications – In the present study, the glutaraldehyde used to crosslink the thin film increased hydrophobicity and allows for more binding capacity. Originality/value – The proposed silver-crosslinked chitosan thin film may prove beneficial for biosensing such as in environmental applications by SPR sensor.

Noncovalent functionalization of graphene by CdS nanohybrids for electrochemical applications

Graphene–CdS (GR–CdS) nanocomposites were synthesized via a noncovalent functionalization process. To retain the intrinsic electronic and mechanical properties of graphene, the pristine graphene was firstly modified with 1-aminopyrene based on a strong π–π bond between the pyrenyl groups and the carbon rings of the graphene. Then the CdS nanocrystals were uniformly grown on the amino-graphene. The GR–CdS nanocomposites were characterized by UV–vis spectroscopy and scanning electron microscopy. A glucose biosensor was then fabricated based on the as-prepared GR–CdS nanocomposite by immobilizing glucose oxidase (GOD) in a chitosan thin film on a glassy carbon electrode. Direct electron transfer between GOD and the electrode was achieved and the biosensor showed good electrocatalytic activity with glucose ranging from 0.5 to 7.5mM and a sensitivity of 45.4μAmM−1cm−2. This work provided a simple and nondestructive functionalization strategy to fabricate graphene-based hybrid nanomaterials and it is expected that this composite film may find more potential applications in biosensors and biocatalysis.

Fabrication and Thermo-Mechanical Characterization of HEMA Treated UV Photo-Cured Biodegradable Chitosan Film

Chitosan was extracted from dried prawn shell via chitin and was characterized by Fourier Transformed Infrared (FTIR) Spectroscopy. Thin film of chitosan was prepared by solution casting using a 2% chitosan solution. Chitosan was dissolved in 2% acetic acid. Mechanical properties like tensile strength (TS) and elongation at break (Eb%) of chitosan film were studied. Eight formulations (M1: 5% HEMA to M8: 40% HEMA) were developed with 2-hydroxyethyl methacrylate (HEMA) monomer in methanol (MeOH) along with photoinitiator Darocur-4043 (2%). The film was soaked in those formulations for 1 min and cured under UV radiation at different radiation intensities for the improvement of physico-mechanical properties of the film. The cured films were then subjected to various characterization tests like TS, Eb%, water absorption, FTIR spectroscopy, polymer loading (PL), differential thermal analysis (DTA), and thermo gravimetric analysis (TGA). The M6 formulation containing 30% HEMA in MeOH solution showed the best performance at 20th UV pass. The highest TS, Eb% and PL were found to be 31 MPa, 71.25% and 26.38%, respectively, for the same formulation at 20th UV pass. The DTA/TGA study showed that the film with M6 formulation at 20th UV pass was thermally more stable than non-radiated chitosan film. The FTIR analysis revealed the crosslinking between HEMA and chitosan.