Chitosan Thin Films Research Articles

TiO2 - chitosan thin film induced solar photocatalytic deflocculation of sludge for profitable bacterial pretreatment and biofuel production

The proposed research intended to acquire the perception of proficient biomethane generation enhanced by TiO2 embedded chitosan thin film (TCTF) mediated enzyme secreting bacterial pretreatment of sludge. Impregnates 0.05 g/g SS TiO2 dosage on chitosan solid matrix effectively disperse sludge flocs and induces deflocculation of 99.35%. This TCTF enhances the enzyme secreting bacterial disintegration by increasing the hydrolytic activity. A higher solubilisation of 16% achieved in TCTF mediated bacterial disintegration while related to enzyme secreting bacterial disintegration alone. The high specific growth rate of 0.2 h−1 for enzyme secreting bacterial growth rate is attained at 42 h. Deflocculation and enzyme secreting bacterial pretreatment has a major impact on methane potential assay. The sludge sample TCTF mediated bacterial disintegration yields 140.40 mL/g COD higher methane than the other samples. The energetic and cost analysis of the proposed work confirms the feasibility of this sludge management process having profitable net cost of 89.92 USD/Ton of sludge.

Drug Release from Polymer Thin Films and Gel Pellets: Insights from Programmed Microplate Electroanalysis.

Robotic electroanalysis in 24-well microplates was used to determine Paracetamol (PCT) release from thin films of chitosan and two pH-sensitive synthetic polymers as well as blends of the polymers with each other and with agarose. Square-wave voltammograms were recorded automatically in a potential window of 0.35 V-0.85 V vs. Ag/AgCl/0.1 M KCl and their evaluation revealed time-dependent PCT release into acidic and basic media. Comparison of the release profiles showed that pure chitosan layers released PCT quickly in a single-phase process while liberation from synthetic polymer thin films was slower with a sigmoidal shape at pH 1.2 and pH 8.0 with a maximum release of PCT after approximately 150 and 140 min, respectively. The release profile from thicker agarose films was between those of the thin films. Agarose blended with chitosan or synthetic polymers formed films with biphasic release behavior. Chitosan linearized the initial section of the release profile in chitosan/polymer blends. The automated procedure for release testing offers the advantage of low-cost, labor-effective and error-free data acquisition. The procedure has been validated as a useful microplate assay option for release profile testing.

Beneficial Effects of Nanocurcumin Loaded Chitosan Biofilm on Healing of Full Thickness Excisional Wounds in Diabetic Rats

Objective- In diabetes impaired wound healing and other tissue abnormalities are considered as major concerns. The novel therapeutic options for treatment of wound in diabetic patients are urgently needed. The aim of the present study was to assess beneficial effects of chitosan nanocurcumin biofilm on healing of full thickness excisional wounds in diabetic rats.Design- Experimental StudyAnimals- Forty male diabetic Wistar ratsProcedures- The animals were randomized into four groups of ten animals each. Induction of diabetes was achieved using 60 mg/kg streptozotocin. In group I, 0.1 mL sterile saline 0.9% solution was added to the wounds with no dressing. In group II, the wounds were dressed with chitosan thin-film membranes. In group III, the wounds were treated with curcumin nanoparticles. In group IV, animals with were dressed with chitosan nanocurcumin biofilm. Results- Planimetric, histological and quantitative morphometric studies and determination of hydroxyproline levels showed that there was significant difference between animals in group IV compared to other groups (p = 0.001). Conclusion and clinical relevance- Chitosan nanocurcumin biofilm improved healing of diabetic wound in rats

Silver-chitosan nanocomposite as a plasmonic platform for SERS sensing of polyaromatic sulfur heterocycles in oil fuel

Herein, a silver-chitosan nanocomposite for application in surface enhanced Raman spectroscopy (SERS) sensing was proposed. It was shown that optically transparent chitosan coatings with 0.8 μm thickness allow penetration of target analytes to silver nanoparticles and the analysis in both polar and nonpolar solvents. Under the chosen conditions, chitosan formed continuously smooth films and coatings stabilizing rough nanostructured metallic surfaces and served as a suitable matrix for immobilization, uniform spreading, and preconcentration of the analytes. Polycyclic aromatic sulfur heterocycles were chosen as target analytes being one of the most important fuel quality markers, hazardous components, and the hardest-to-remove impurities. For the most effective immobilization and even distribution of the analytes onto a nanostructured metallic surface, an additional polymer layer of chitosan was found to be needed. The presence of thin films of chitosan resulted in higher reproducibility of SERS spectra as compared to bare nanostructured silver substrates. Additionally, the developed nanocomposite SERS sensors provided the rapid determination of dibenzothiophene and its derivatives in isooctane with the threshold of detection better than 0.1 μM. This approach was successfully applied in the analysis of real fuel samples and the results agreed well with independently measured FTIR and GC-MS data.

Hybrid Plasma – Prospects for Application in Medicine and Biology

Different schemes and designs of generators of low-temperature hybrid plasma produced by simultaneous ionization of plasma-generating medium by an electron beam with electron energy of 30 keV and an RF discharge (13.56 MHz) are considered. A plasma-chemical reactor designed for hybrid plasma generation is described, and results of spectrometric measurements of its reaction volume are presented. The reactor has been used to prepare biocompartible thin chitosan films. Experiments showed that modification of chitosan films in hybrid oxygen plasma improves their hydrophilic properties and has advantages over modification in RF-discharge or electron beam plasma when they are used separately. The bactericidal effect of the hybrid plasma was found in tests Escherichia coli cultures. Prospects for practical hybrid plasma applications in biology and medicine are discussed.

Multifunctional electrochromic energy storage devices by chemical cross-linking: impact of a WO3\xb7H2O nanoparticle-embedded chitosan thin film on amorphous WO3 films

With the advent of multifunctional devices with electrochromic (EC) behavior and electrochemical energy storage, complementary design of film structures using inorganic–organic materials has shown great potential for developing EC energy storage devices. Herein, hybrid films consisting of WO3·H2O nanoparticle (WHNP)-embedded chitosan thin films on amorphous WO3 (a-WO3) films were designed. By exploiting the hybrid effect of chitosan and WHNPs to generate unique chemical cross-linking between them, the designed films exhibited attractive EC behaviors compared to bare a-WO3 films. These included fast switching speeds (4.0 s for coloration and 0.8 s for bleaching) due to enhanced electrical conductivity and Li-ion diffusivity, high coloration efficiency (62.4 cm2/C) as a result of increased electrochemical activity, and superb long-cycling retention (91.5%) after 1000 cycles due to improved electrochemical stability. In addition, hybrid films exhibited a noticeable energy storage performance with a high specific capacitance (154.0 F/g at a current density of 2 A/g) and a stable rate capability as a result of improved electrochemical activity and fast electrical conductivity, respectively. This resulted in brighter illumination intensity for the 1.5-V white-light-emitting diode due to improved energy density compared to a bare a-WO3 film. Therefore, the results suggest a new design strategy for materials to realize the coincident application of multifunctional devices with EC energy storage performance.

Influence of top electrode on resistive switching effect of chitosan thin films

Abstract

Chitosan films for regenerative medicine: fabrication methods and mechanical characterization of nanostructured chitosan films.

Regenerative medicine is continuously facing new challenges and it is searching for new biocompatible, green/natural polymer materials, possibly biodegradable and non-immunogenic. Moreover, the critical importance of the nano/microstructuring of surfaces is overall accepted for their full biocompatibility and in vitro/in vivo performances. Chitosan is emerging as a promising biopolymer for tissue engineering and its application can be further improved by exploiting its nano/microstructuration. Here, we report the state of the art of chitosan films and scaffolds nano/micro-structuration. We show that it is possible to obtain, by solvent casting, chitosan thin films with good mechanical properties and to structure them at the microscale and even nanoscale level, with resolutions down to 100nm.

The electrochemical performance of electrodeposited chitosan bio-nanopolymer in non-aqueous electrolyte: a new anodic material for supercapacitor

The polymeric film electrodes of chitosan are deposited by electrochemical deposition method on the stainless steel substrates. The prepared film electrodes are characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, contact angle techniques and evaluated for the supercapacitor application by studying electrochemical properties through cyclic voltammetry. The XRD study depicts nanocrystalline nature of deposited chitosan with 36 nm crystallite size. The uniform, compact and spongy chitosan thin film covers the utmost substrate surface and has hydrophilic nature with mean water contact angle 57.9°. The chitosan electrode exhibits 13 kW kg−1 power density from the galvanostatic charge discharge study. The chitosan electrode shows the maximum electrochemical capacitance of 36 F g−1 in non-aqueous KCl electrolyte, which presents a new anodic material for supercapacitor application.

Utilization of chitosan/Ag bionanocomposites as eco-friendly photocatalytic reactor for Bactericidal effect and heavy metals removal

Chitosan is a nontoxic, eco-friendly, and biocompatible natural polymer which could be used in an extensive range of applications for example in the areas of membranes, biomedicine, hydrogels, wastewater treatment, food packaging. Moreover, chitosan based nanomaterials had high sorption capacities, chelating activities, stability, and versatility, that would be potentially applied as green reactants in various scientific and engineering applications. The current study involved the preparation of silver nanoparticles incorporated into chitosan thin films and used for various purposes including photo-oxidation of organic pollutants, heavy metal removal (Cd, Pb, Cr, and Fe) and antibacterial activity. The fabricated chitosan/silver (CS/Ag) bionanocomposites thin films were characterized by the ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and Fourier transforms infrared (FT-IR) spectroscopy. Furthermore, the prepared CS/Ag bionanocomposites had revealed good photodegradation rate, heavy metals removal and antimicrobial activity against gram-negative bacteria like E. coli, and gram-positive bacteria like G. bacillus, with increasing the loading of different concentrations of chitosan and silver nanoparticles incorporated into the prepared bionanocomposite thin films. Consequently, the prepared CS/Ag bionanocomposites are considered good candidates for wastewater treatment through photo-oxidation of organic pollutants, heavy metal removal as well as respectable antibacterial materials.

Natural Shape-Retaining Microcapsules With Shells Made of Chitosan-Coated Colloidal Lignin Particles.

Thin film coating of charged nanoparticles with oppositely charged polymers is an efficient and straightforward way for surface modification, but synthetic polyelectrolytes should be replaced by abundant biopolymers. In this study a thin film of chitosan was adsorbed onto colloidal lignin particles (CLPs) that were then systematically studied for olive oil stabilization with an objective to develop shape-retaining microcapsules that comprised of only renewable biomaterials. Full surface coverage was achieved with merely 5 wt% of chitosan relative to the dry weight of CLPs, reversing their surface charge from negative to positive. Such modification rendered the chitosan-coated particles excellent stabilizers for forming Pickering emulsions with olive oil. The emulsion droplets could be further stabilized by sodium triphosphate that provided ionic intra- and inter-particle cross-linking of the chitosan corona on the CLPs. Following the optimum conditions, the non-cross-linked microcapsules exhibited a strong stability against coalescence and the electrostatically stabilized ones additionally retained their shape upon drying and rewetting. Non-cross-linked microcapsules were used to demonstrate encapsulation and rapid release of ciprofloxacin as a model lipophilic drug in aqueous media. Overall, the combination of antimicrobial chitosan and antioxidative lignin nanoparticles hold unprecedented opportunities as biocompatible and biodegradable materials for controlled drug delivery.

Insulating Polymer‐Hydrogel Nanocomposite Thin Film ‐ Based Catalytic Electrode for Efficient Oxygen Evolution Reaction

AbstractThe counter‐intuitive choice of an insulating polymer for embedding electrocatalysts is shown to facilitate a simple and general strategy to fabricate catalytic electrodes for efficient oxygen evolution reaction (OER) during water splitting. The hydrogel characteristics and appreciable swelling of the polymer in aqueous medium are the key enabling factors; electrolyte absorbed in the polymer matrix is likely to be involved in the electrocatalytic process. Nanocomposite thin films of chitosan spin‐cast on common conducting substrates, with an optimal content of NiO and [Ni,Fe]O nanoplates generated through a facile and simple in situ protocol, are shown to effect OER with excellent overpotentials (down to 240 mV at 10 mA/cm2), low Tafel slope, high Faradaic efficiency, appreciable turn‐over frequency, and extended stability with high current density. Preliminary investigations with a range of catalyst‐polymer combinations illustrate the general applicability of the approach.

Electrodeposition of thin chitosan membrane in freestanding SU-8 microfluidic channel for molecular addressing by capillary effect

The electrodeposition of thin chitosan membrane in freestanding microfluidic channel with capillary effect for biomolecule assembly of biosensor is investigated. A dry SU-8 sheet is used to fabricate freestanding fluidic microchannel by microelectromechanical systems (MEMS) technology. The hydrophobic surface of SU-8 microchannel transformed to hydrophilic surface by plasma treatment. The thin chitosan membrane is deposited on hydrophilic SU-8 microchannel by capillary effect, and miniaturization of sensor device is obtained. Membrane thickness of chitosan in freestanding channel can be controlled by concentration of chitosan solution and deposition time. The results show that thin chitosan membrane can be deposited by capillary effect in freestanding channel, and the deposited chitosan thin film shows great potential for immobilizing enzyme on the surface for compact biosensor device.

Perspectives of chitosan nanofiber/film scaffolds with bone marrow stromal cells in tissue engineering and wound dressing

Objective (s): Several methods have been proposed for repairing defects and damages, one of which is cell therapy. Bone marrow stromal cells seem to be suitable for this purpose. On the other hand, many biometric materials are used to improve and correct the defects in the body. Nanofibers are widely used in the medical industry, especially in tissue engineering, as scaffolds in wound healing and wound dressing. Chitosan/polyethylene oxide nanofibers can be a suitable replacement for routine wound coverages. Hence, this study was conducted to present a combination of these methods.Materials and Methods: Chitosan/polyethylene oxide nanofibers and thin films of chitosan were produced and optimized by electron microscopy, on which the bone marrow stromal cells were then cultivated. Interactions between the cells and these biomaterials were investigated through viability, morphology, immunocytochemistry and electron microscopy of cells after 6 days. All data were analyzed using Student’s t-test and one-way ANOVA tests in SPSS version 16. PResults: It seems that the high viscosity of chitosan prevents the formation of nanofibers, while chitosan/polyethylene oxide solutions with 80/20 and 90/10 ratios produce perfect, regular, bead free and non-toxic nanofibers with average diameter of 240±10 and 220±10 nm, respectively. The results of immunocytochemistry and viability showed that the cells had relatively high proliferation on the thin chitosan membranes, while the results of the electron microscopy showed that the morphology of cells was better on the nanofibers than on the thin membrane of chitosan.Conclusion: Since bone marrow stromal cells were grown well on chitosan-nanofibers, each of them alone was used in the therapeutic methods. It is better to consider a combination of two methods as the treatment method, especially in tissue engineering and cell therapy.

Pre-treatment of glass substrates and post treatment of the surface of single and multiple Chitosan film by heated as wettability

In this approach, chitosan thin films have been prepared using single and multiple dip coating method. The glass substrates was heated 100 °C as a pre-treatment and the fabricated thin film were post heated in various temperature: 100 °C, 210 °C, 220 °C and the effect of pre and post heat treatment on their wetting, structural and morphological properties has been investigated. Scanning electron microscopy (SEM and contact angle measurement have been applied for the characterization and study of thin film surfaces. The results of SEM exhibit the aggregation and formation of chitosan films on the surface of substrate changed through applying heat pre-treatment substrates and increasing of heat post temperature to the chitosan surface.Wettability studies showed that the contact angle of prepared thin films was influenced by various parameters such as heat pre-treatment on glass substrates, variation of heat post-treatment and surface morphology.

Antimicrobial coatings prepared from Dhvar-5-click-grafted chitosan powders

Antimicrobial peptides (AMP) are powerful components of the innate immune system, as they display wide activity spectrum and low tendency to induce pathogen resistance. Hence, the development of AMP-based coatings is a very promising strategy to prevent biomaterials-associated infections. This work aims to investigate if Dhvar-5-chitosan conjugates, previously synthesized by us via azide-alkyne “click” reaction, can be applied as antimicrobial coatings. Ultrathin coatings were prepared by spin coater after dissolving Dhvar-5-chitosan conjugate powder in aqueous acetic acid. Peptide orientation and exposure from the surface was confirmed by ellipsometry and contact angle measurements. Bactericidal activity was evaluated against Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, the most prevalent pathogens in implant-associated infections. Results showed that Dhvar-5-chitosan coatings displayed bactericidal effect. Moreover, since Dhvar-5 has head-to-tail amphipathicity, it was clear that the bactericidal potency was dependent on which domain of the peptide (cationic or hydrophobic) was exposed. In this context, Dhvar-5 immobilized through its C-terminus (exposing its hydrophobic end) presented higher antimicrobial activity against Gram-positive bacteria and reduced adhesion of Gram-negative bacteria. This orientation-dependent antimicrobial activity was further corroborated by the anti-biofilm assay, as covalent immobilization of Dhvar-5 through its C-terminus provided anti-biofilm properties to the chitosan thin film. Immobilization of Dhvar-5 showed no cytotoxic effect against HFF-1 cells, as both metabolic activity and cell morphology were similar to control. In conclusion, Dhvar-5-chitosan coatings are promising antimicrobial surfaces without cytotoxic effects against human cells. Statement of SignificanceAMP-tethering onto ground biomaterial is still a poorly explored strategy in research. In this work, AMP-tethered ground chitosan is used to produce highly antibacterial ultrathin films. Powdered AMP-tethered chitosan appears as an alternative solution for antimicrobial devices production, as it is suitable for large scale production, being easier to handle for fabrication of different coatings and materials with antimicrobial properties and without inducing toxicity.

Milk powder quality degradation detection using chitosan film based sensor

Chitosan based milk powder quality degradation sensors have been successfully fabricated by combining electrochemical deposition and photolithography techniques. The aim of this paper is to discuss the potential of chitosan thin film sensors for detecting milk powder quality degradation. The milk powder quality may be decreased upon storage. Milk powder surface composition changes during storage due to increasing in moisture content. Electrical testing of chitosan thin film properties to fresh milk powder and milk powder exposed to air for 1, 2, 3 and 4 weeks has been done at room temperature. The results show that the chitosan-based milk powder quality degradation sensors have good performance demonstrated by very good response, stability, recovery, repeatability and selectivity. The simple, easy and inexpensive technique is required to monitor the milk powder quality degradation.

Investigation of Chitosan Embedded with Silver Vanadate Nanorods and their Optical Properties

Chitosan is a natural polysaccharide polymer which is non-toxic, biodegradable, cationic and biocompatible. Present work study physical and chemical characteristics of pure chitosan thin film and other samples that modified through embedding different concentration of silver vanadate nanorods prepared via solution casting route. Casting route was employed for preparation of chitosan thin films and other sample containing gradient increase of synthesized silver vanadate nanorods.The optical properties have been investigated through ultraviolet–visible (UV/Vis) optical absorption spectroscopy. Experimental data reveals an observable decrease in the values of optical energy gap with increasing content of silver vanadate nanorods which result in enhancement of the sensitivity for all prepared thin films.

A self-targeting and controllable drug delivery system constituting mesoporous silica nanoparticles fabricated with a multi-stimuli responsive chitosan-based thin film layer

Surface modification and functionalization of nanomaterials have been adopted widely in devising smart drug delivery systems. This work examines the fabrication of multi-stimuli responsive surfaces on mesoporous silica nanoparticles (MSN) for environmentally sensitive site specific drug delivery with reduced risk of premature drug leakage. Chitosan cross-linked via disulfide bonds was applied to form a thin film on drug-loaded MSN, realizing a capsulation and stimuli-sensitive regulating gate membrane; that was further conjugated with folate for site specific targeting toward cancer cells. The chitosan thin film was very stable under neutral conditions and could effectively prevent drug leakage, but was sensitive to both pH and GSH stimulations to reach rapid drug release. Thus, drug release could be triggered by changes in such factors that are common to cancer cells. However, complete and accelerated release could only be realized when triggered simultaneously by both acidic pH and GSH. Moreover, tests with HepG-2 cells confirmed that folate-receptor mediated endocytosis successfully enhanced the cellular uptake of the nanoparticle and antitumor activity toward cancer cells. It is expected that this surface chemical modification strategy promises a powerful approach constructing smart drug delivery systems for efficient and safe chemotherapy.

Chitosan-Ag-TiO2 films: An effective photocatalyst under visible light

Aiming the degradation of harmful molecules under visible light, new photocatalytic systems were created. For this purpose, the surface of chitosan thin films was modified in heterogeneous phase via a simple and straightforward mild chemical process: chemisorption of silver ions followed by the synthesis in situ of TiO2 at low temperature (100 °C). A high photocatalytic activity under visible light was observed, leading to the degradation and/or mineralization of different organic products such as o-toluidine, salicylic acid and 4-aminomethyl benzoic acid. This efficiency is partly attributed to the formation of Ag NPs and also to the unexpected appearance of AgCl NPs, likely formed from the residual chlorine contained in the chitosan. The resulting TiO2/Ag/AgCl/Chitosan system is easy to prepare under mild conditions, avoiding calcination treatments and opens new perspectives for the production of visible light-driven photocatalysts. Samples were analysed by different techniques: XRD, Raman, FE-SEM, XPS, TGA, GSDR, LIF and LIP.