Amino Groups Of Chitosan Research Articles

Fabrication and reversible disulfide functionalization of PEGylated chitosan-based hydrogels: Platforms for selective immobilization and release of thiol-containing molecules

In this study, we report on the fabrication of chitosan based hydrogel scaffolds incorporating reactive disulfide functionalities towards the reversible thiol immobilization and release endeavor. Native chitosan chemically modified with polyethylene glycol (PEG) groups was exploited in hydrogel synthesis together with an acryloyl group containing benzothiazole disulfide compound. The chemical crosslinking and incorporation of the reactive disulfide groups into the gel network was maintained by Michael addition of chitosan amino groups onto acrylic benzothiazole compound and bisacryloyl modified polyethylene glycol crosslinker. A series of hydrogels with different amounts of thiol reactive benzothiazole disulfide groups was obtained with moderately high gel conversions. The characterization of the hydrogels was performed by equilibrium swelling, structural morphology and rheology studies. The amount of reactive disulfide groups in the hydrogels were determined using UV–vis spectroscopy. Facile conjugation of a thiol-containing methyl red dye via thiol-disulfide exchange was demonstrated. The on demand cleavage of the attached thiol probe from the scaffold was achieved in the presence of a disulfide reducing agent, namely dithiothreitol (DTT). The efficient and simple fabrication of these hydrogels, as well as benign and reversible immobilization of thiol containing molecules onto the network could make these scaffolds as attractive platforms for biomedical applications such as bioconjugation/bioimmobilization, controlled drug/protein release and tissue engineering.

Designing, preparation and evaluation of the antimicrobial activity of biomaterials based on chitosan modified with silver nanoparticles

Chitosan was chemically modified through a four-step procedure. First, the amino groups of chitosan have reacted with benzaldehyde (Derivative 1); second, hydroxyl groups on C6 of Derivative 1 have reacted with epichlorohydrin (Derivative 2); third, the epoxy groups of Derivative 2 have reacted with 4-aminosalicylic acid (Derivative 3); and fourth, benzaldehyde moieties of Derivative 3 have been removed to retrieve the amino groups (Derivative 4). For further modification, three nano-biocomposites were synthesized via impregnating three different concentrations of silver nanoparticles inside Derivative 4. These derivatives and Derivative 4/AgNP composites were structurally identified using elemental analysis, FTIR, XPS, 1H NMR, XRD, SEM, EDS and TEM techniques. These derivatives and Derivative 4/AgNP composites have superior antimicrobial activities than virgin chitosan. Some of them have inhibition zone analogous or superior than the utilized reference drugs. Cytotoxic activity of Derivative 4 and Derivative 4/AgNPs-5 composite indicated that these materials are safe on normal human cells. Accordingly, combinations between chitosan and functional groups derived from the different modifiers in addition to AgNPs within a single structure have extraordinarily enhanced the efficiency of chitosan. It might be deemed as a path to attain promising frameworks which are taken as proper competitors for antimicrobial materials in biomedical fields.

Formation of Polyelectrolyte Complexes from Chitosan and Alkaline Gelatin

The interaction of chitosan and alkaline gelatin biopolymers in formation of polyelectrolyte complexes has been studied by the Fourier IR spectroscopy and scanning electron microscopy. Also the influence of chitosan on the morphology of gelatin hydrogels has been observed. It has been shown that in the range of chitosan (C)/gelatin (G) (w/w) ratio Z = g= gC/gG from 0.1 to 1.5, chitosan–gelatin complexes are formed due to electrostatic interactions of charges amino-groups of chitosan and carboxylic groups of gelatin as well as due to intermolecular hydrogen bonds. In this case, the share of collagen-like triple helices in the spatial network of hydrogel decreases. The formation of chitosan–gelatin complexes leads to the qualitative changes in the hydrogel morphology even at low ratios of biopolymer (at Z = 0.025 gC/gG). The fiber-like structure of gelatin gels transforms and less structured but denser zones appear in the gel network.

Analysis of the Adsorption of Toxic Chromium (VI) by Untreated and Chitosan Treated Banana and Areca Fiber

This paper work involves bunch experiments to investigate the effect of contact time, pH, and adsorbent dose on the extent of adsorption by bio-composites. Adsorption capacity of Chromium (VI) onto chitosan coated with banana and areca fiber was investigated in a batch system by considering the effects of various parameters like contact time, initial concentration, pH and adsorbent dose. The chitosan and fibers (banana and areca) were then cross-linked with glutaraldehyde to remove chromium [Cr (VI)] from water via static adsorption. It was found that optimum chromium absorption capacity of chitosan was assessed at pH of 2.5 to 4.5 and contact time of 30 to 180 minutes for raw banana and areca fiber and for chitosan treated banana & areca fiber. Though optimum adsorption of chromium of chitosan was measured 34.17 ppm (85.42%) from a 100 ml solution containing 40 parts per million (ppm) of Cr (VI) at 120 minutes, pH of 3.0 and 120 milligram (mg) adsorbent dose size, use of composite will be more favorable in the point of environmental concern as well as low cost because chitosan preparation is comparatively costly then banana and areca fiber. On the other hand, untreated banana and areca fiber optimum adsorption of chromium measured 3.65 ppm (9.1%) at 180 min and, pH of 4.5 and 140 mg adsorbent dose size and 3.76 ppm (9.4%) at 180 min, pH of 4.5 and 160 mg adsorbent dose size respectively. In case of chitosan treated banana fiber, it was observed that adsorption was increased from 17.664 to 30.057 (75.14%). On the other hand, for areca fiber with chitosan, it was observed that adsorption was increased from 21.664 to 30.156 (75.39%) ppm. The Langmuir and Freundlich adsorption models were used for the mathematical description of the adsorption of chromium ion onto composites and it was found that the Langmuir adsorption isotherm was more fitted models which mean that a monolayer adsorption surface was created. After analyzing from IBM SPSS 25 software, we got the standard deviation value of adsorbed Cr by raw chitosan, untreated banana and areca of pH test results were 9.399, 1.072, 0.728 ppm, time test results were 2.163, 0.859, 0.896 ppm and adsorbent dose test results were 6.588, 0.966, 1.211 ppm correspondingly. The standard deviation results of pH, time and amount of treated banana fiber test results were 1.831, 2.693 and 5.469 ppm congruently. On the other hand, the standard deviation results of pH, time and amount of treated areca fiber test results were 3.293, 2.673 and 4.152 ppm individually. Fourier transform infrared (FT-IR) spectroscopy analysis indicated that both amino and hydroxyl groups of chitosan, banana and areca fiber were engaged in the adsorption.

Antioxidant Activity Improvement of Apples Juice Supplemented with Chitosan-Galactose Maillard Reaction Products.

Chitosan-galactose Maillard reaction (CG) were prepared by heating at 100 °C for 3 hrs in a model system containing chitosan (CH) and 1%, 1.5% and 2% (w/v) of galactose. The results showed that the absorbance at 294 and 420 nm, the fluorescence intensity and the color differences of CG Maillard reaction products (MRPs) increased significantly with the increase of galactose concentration, which indicated the development of MRPs. In addition, FT-IR analysis showed that the degree of deacetylation of CG-MRPs was reduced with the increasing galactose ratio by the schiff base (–C=N) formation, indicating that the galactose has been attached to the amino group of chitosan. Likewise, the antioxidant activities (DPPH, chelating ability and reducing power) of CG-MRPs were investigated. Notably, the effect of galactose concentration in CG-MRPs was found to enhance the antioxidant activity, indicating that CG-2% exhibited the highest antioxidant activity in the range of 0.25–2.0 mg/mL. Furthermore, the apple juice supplemented with CG-MRPs could significantly improve the antioxidant activities, and CG-2% in apple juice showed the better antioxidant capacity at the concentration of 1.0 mg/mL. Thus, we conclude that CG-MRPs addition may greatly improve the antioxidant quality of apple juice.

Synthesis of Chitosan-Ignosulfonate Composite as an Adsorbent for Dyes and Metal Ions Removal from Wastewater.

Sodium lignosulfonate is a polymer with extensive sources and abundant functional groups. Therefore, it has potential value for research and wide utilization. In this study, the adsorption material was prepared by blending sodium lignosulfonate and chitosan, which could adsorb anionic and cationic dyes and metal ions. The composite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetry (TG). The results showed that the composite was cross-linked mainly by the strong electrostatic interaction between the protonated amino group in chitosan and the sulfonate group in sodium lignosulfonate. Moreover, the effects of initial concentration, adsorption time, initial pH, and mass ratio of chitosan to sodium lignosulfonate on the adsorption performance of the composite were investigated. Meanwhile, the adsorption processes were agreed well with the pseudo-second-order kinetic model and Langmuir isotherm model. The adsorption mechanism was that the electrostatic interaction between the protonated amino and hydroxyl groups of the composite with anionic (SO3–) and HCrO4– groups of Congo red and Cr(VI), respectively. In addition, the electrostatic interaction between SO3– of the composite and positively charged group of Rhodamine B played an important role in the adsorption of Rhodamine B.

Self-assembled nano-vesicles based on mPEG-NH2 modified carboxymethyl chitosan-graft-eleostearic acid conjugates for delivery of spinosad for Helicoverpa armigera

In this work, carboxymethyl chitosan-graft-eleostearic acid (CMCS-g-EA) was synthesized via the amide reaction between the amino groups of carboxymethyl chitosan and the carboxyl group of eleostearic acid, and then mPEG-NH2 was grafted to CMCS-g-EA to prepare amphiphilic polymers (mPEG-CMCS-g-EA). The chemical structures of the above conjugates were characterized by FT-IR and 1H NMR. Both CMCS-g-EA and mPEG-CMCS-g-EA based nano-vesicles were prepared by ultrasonic self-assembly method and they exhibited a low critical aggregation concentration (CAC) of 14.97 μg/mL, 16.82 μg/mL, respectively. The spinosad-loaded mPEG-CMCS-g-EA nano-vesicles (SSD@mPEG-CMCS-g-EA NVs) were spherical in shape with an average diameter of 502.8 nm and the zeta potential of −25.60 mV. The encapsulation efficiency (EE) and drug loading content (LC) of SSD@mPEG-CMCS-g-EA nano-vesicles were 42.00%, 23.07%, respectively. In vitro release revealed that the SSD@mPEG-CMCS-g-EA nano-vesicles exhibited a sustained and pH-responsive drug release property, and could significantly enhance the photostability of spinosad. Furthermore, the toxicological tests demonstrated that the SSD@mPEG-CMCS-g-EA nano-vesicles could efficiently inhibit the growth and development of Helicoverpa armigera. These results indicated that the SSD@mPEG-CMCS-g-EA nano-vesicles were highly potential for the treatment of Helicoverpa armigera.

Microencapsulation of Garlic Extract by Complex Coacervation Using Whey Protein Isolate/Chitosan and Gum Arabic/Chitosan as Wall Materials: Influence of Anionic Biopolymers on the Physicochemical and Structural Properties of Microparticles

The aim of this study was to encapsulate garlic extract by complex coacervation method using whey protein isolate (WPI)/chitosan (CH) and gum Arabic (GA)/CH as wall materials. Two anionic biopolymers (GA and WPI) were used to find the most suitable wall materials to interact electrostatically with cationic CH. The complex coacervates were freeze-dried to obtain microparticles powders. The microparticles were examined for the nitrogen adsorption/desorption, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), sorption isotherms, zeta potential, antioxidant activity, total phenolic content, solubility, moisture content, hygroscopicity, size distribution, and water activity. X-ray diffractograms evidenced microparticles with amorphous structure. WPI/CH and GA/CH microparticles showed surface area of 2.23 and 2.40 m2 g−1 and mean pore diameter of 5.20 and 5.37 nm, respectively. The nitrogen adsorption/desorption assay showed that microparticles presented mesopores and macropores that resulted in quick completion of microparticles surface monolayer with nitrogen. The sorption characteristics of microparticles followed the type II isotherm and Guggenheim-Anderson-de Boer (GAB) model was the best model to fit the experimental data. FTIR spectrum of microparticles reveals physical interactions between garlic compounds and functional groups of wall materials, indicating that garlic compounds were intact and encapsulated. TGA results indicated that the wall materials were effective in protecting the garlic sensitive compounds. The negative carboxyl groups (–COO−) of GA were better than WPI for coacervation with positive amino groups (NH3+) of chitosan in terms of less hygroscopicity, smaller particle size, and higher retention of garlic phenolic compounds.

Charge tunable chitosan/PLA microspheres for potential biomedical application

In this study, we synthesized charge-tunable Chitosan/Poly (lactic acid) (PLA) microspheres for potential biomedical application. Microspheres were prepared in emulsion followed by ultrasonic solvent evaporation, and characterized by Scanning Electron Microscopy (SEM), Infrared Spectroscopy with Fourier Transform (FTIR), Dynamic Light Scattering (DLS), Zeta Potential measurements and Thermogravimetry (TG). The resulted suspension presented good colloidal stability. FTIR spectra of microspheres showed the displacement of characteristic peaks of both chitosan and PLA, confirming the interaction between both components. By SEM, particle agglomeration was observed after drying process. Zeta potential data showed positive charges at acidic pH due to the protonation of chitosan amino groups. Nevertheless, PLA carboxylates and hydroxyl groups from both polymers were responsible for the negative charges found at physiological pH. TG analysis showed thermal stability at physiological conditions, indicating the potential application of the microspheres as controlled drug delivery systems, among other biomedical applications.

Chitosan Film as Eco-Friendly and Recyclable Bio-Adsorbent to Remove/Recover Diclofenac, Ketoprofen, and their Mixture from Wastewater.

This paper reported the first example on the use of chitosan films, without further modification, to remove and recover, through bio-sorption processes, the emerging pollutant Diclofenac from water. The latter was adopted as a model, among non-steroidal anti-inflammatory drugs, by obtaining a maximum adsorption capacity, qmax, on chitosan of about 10 mg/g, under the applied experimental conditions of work. The literature gap about the use of chitosan films, which was already used for dyes and heavy metals removal, to adsorb emerging pollutants from water was covered, claiming the wide range application of chitosan films to remove a different class of pollutants. Several parameters affecting the Diclofenac adsorption process, such as the pH and ionic strength of solutions containing Diclofenac, the amount of the bio-sorbent and pollutant, and the temperature values, were investigated. The kinetics and the adsorption isotherms, along with the thermodynamic parameters (ΔG°, ΔH°, and ΔS°) were also evaluated. The process occurred very efficiently, and Chitosan/Diclofenac amounts dependent, remove about the 90% of the pollutant, in 2 h, from the tested solutions, through electrostatic interaction involving the carboxylic moiety of Diclofenac and Chitosan amino groups. This finding was confirmed by the pH and salt effects on the bio-sorption process, including swelling measurements of Chitosan films and by FTIR-ATR analysis. In detail, the maximum adsorption was observed at pH 5, when pollutant and Chitosan were negatively and positively charged, respectively. By reducing or increasing the pH around this value, a reduced affinity was observed. Accordingly, the presence of salts retarded the Diclofenac removal screening its charges, which hinders the interaction with Chitosan. The sorption was spontaneous (ΔG° < 0) and endothermic (ΔH° > 0) following the pseudo-second order kinetic model. The process was Diclofenac and Chitosan amount dependent. In addition, the Freundlich and Temkin isotherms well described the process, which showed the heterogeneous character of the process. Experiments of the complete desorption were also performed by using NaCl solutions 0.25 M (like sea water salt concentration) proposing the reuse of the pollutant and the recycling of the bio-sorbent lowering the associated costs. The versatility of the adsorbent was reported by exploring the possibility to induce the Diclofenac light-induced degradation after the adsorption and by-products adsorption onto chitosan films. To emphasize the chitosan capacity of treating water, the removal of another pollutant such as Ketoprofen and the mixture of Diclofenac and Ketoprofen were investigated. In this way, a green and eco-friendly production-pollution prevention technology for removing emerging pollutants from water was presented, which reduced the overall environmental impact. This illustrated experiments both in static and dynamic conditions for potential industrial applications.

Green synthesis of chitosan-cinnamaldehyde cross-linked nanoparticles: Characterization and antibacterial activity

Traditional method of chitosan (naturally available abundant biopolymer) nanoparticles synthesis is the ionic cross-linking between chitosan and say, sodium tri-polyphosphate (TPP). These nanoparticles are structurally less stable and are basically obtained viaconversion of chitosan, a pure bio-based material, into a hybrid structure of biopolymer and a synthetic chemical. The present work reports a novel attempt to synthesize antimicrobial chitosan nanoparticles by chemical cross-linking with cinnamaldehyde, another eco-friendly bactericidal agent. The synthesized nanoparticles (size range, 80–150 nm) were analysed for their surface morphology. X-ray diffraction pattern denoted the amorphous characteristics of the formed nanoparticles. The FTIR analysis revealed formulation of chitosan nanoparticles to be based on Schiff reaction between amino group of chitosan and aldehyde group of cinnamaldehyde. NMR analysis also confirmed the formulation of cinnamaldehyde cross-linked chitosan nanoparticles. TGA and DSC were performed to analyse thermal characteristics and stability of prepared nanoparticles. Subsequently, the study successfully indicated that the synthesized nanoparticles exhibit synergistic antibacterial activity (98%) against Staphylococcus aureus (Gram-positive) and (96%) Escherichia coli (Gram-negative) bacteria. The MIC and MBC values were found to be 5 mg/mL and 10 mg/mL, respectively, for both types of bacteria.

Interaction pattern and in vitro, in vivo release behavior of simvastatin-loaded chitosan nanoformulation

Objective and methods: This study predicted the nature of chitosan interactions and effects of this interaction on drug release mechanism in simvastatin-loaded chitosan nanoformulation using molecular docking, spectroscopic and thermal analysis.Significance: This work explains in depth the molecular mechanism of simvastatin and chitosan bond formation in nanoformulation.Results: The effective encapsulation and sustain release properties of chitosan were indicated by increase in melting endotherm of simvastatin. Intermolecular hydrogen bond between third hydroxyl group pyranone ring of simvastatin and amino group of chitosan represented the stability of active lactone moiety that was not cleaved during formulation which is prerequisite for biological activity. UV–vis spectroscopic characterization, shift in infrared vibration wavenumber of simvastatin and chitosan, ligand titration, 1HNMR and 13C-NMR analyses confirmed this interaction pattern. The pharmacokinetic evaluation in mouse model revealed the sustain release property of nanoformulation.Conclusion: Thus formation of intermolecular hydrogen bond in nanoformulation contributed to modified physicochemical properties and improved in vivo performance of simvastatin.

Original antifouling strategy: Polypropylene films modified with chitosan‐coated silver nanoparticles

ABSTRACTA new coating strategy of polypropylene (PP) films with silver nanoparticles (AgNPs) is proposed to obtain surfaces with antifouling properties. As a first step, the photograft polymerization is used to produce polyacrylic acid‐grafted PP (PAA‐grafted PP) films. A green AgNP synthesis is used by thermal reduction of AgNO3 with amino groups of chitosan (CS), which controls ion diffusion and stabilizes nanoparticles. AgNP/CS complexes are adsorbed on PAA‐grafted PP by electrostatic interactions, yielding AgNP/CS‐coated PP films. These films show an excellent antimicrobial activity, even for AgNP contents as low as 0.08 wt %, reducing more than 4 log units in the viable Staphylococcus aureus concentration or inducing Escherichia coli death. This trend is consistent with an adequate amount of small AgNP adsorbed in an organized manner within a thin surface layer. Therefore, the antimicrobial activity of this film seems to be more than promising, used as an active surface for a wide range of applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48448.

Redox-initiated diffusion-limited aggregation in biopolymer

Fractal patterns have been obtained in a polysaccharide (chitosan biopolymer) containing salt and an active metal wire. The amino groups in chitosan chelate with silver ions and form a cationic complex with the silver nitrate (AgNO3). Presence of the copper wire in the chitosan–AgNO3 system leads to an exothermic redox reaction which creates an anisotropy in the system affecting the growth mechanism. Initial movement of the ions is governed by the potential difference between the redox species/couple (Cu and Ag) and the energy released in terms of heat enhances the mobility of the mobile fractal forming species. This release in energy is reflected in the rise in temperature of the system by 4° to 5 °C. Initially, dense patterns form around the corners of the metal wire, which in time change to diffusion-limited aggregates as the redox reaction rate changes due to the depletion of the active metal wire’s ions. The fractal forming species (Ag) has been confirmed by x-ray diffraction, energy dispersive x-ray analysis and scanning electron microscopy. The fractal dimension determined by the box-counting method confirms the formation of a dense branched morphology at the corners of the metal wire and diffusion-limited aggregation away from the corners. The aggregation process and resulting pattern in the present experimental system evolves due to the varying spatial and temporal anisotropy existing within the system.

Electrostatic Effects of Metronidazole Loaded in Chitosan-Pectin Polyelectrolyte Complexes

Electrostatic interactions of polymeric charges become one of the important factors to form the polyelectrolyte complexes (PECs). In this work, PECs has successfully created through the interaction between positive charges of chitosan (CS) and negative charges of pectin (PE) based on the effect of pH and pKa of the polymers. The formation of PECs provides small particle size, positive surface charge, and high %entrapment efficiency (%EE) after loaded metronidazole (MTZ). Dropwise addition of PE solution into CS solution was carried out to form PECs. A certain concentration of chitosan and pectin fixed at ratio 3:1 while the pH of both polymers varied as pH 1, 3, 5, and 9. The alterations after forming PECs observed particle size, zeta potential, and turbidity of the solution along with FTIR, DSC, and TAG. Precipitation of PECs solution was found in the fixed pH 5 of PE solution dropwise into pH 7 and 9 CS solution, which referred to the unstable of the PECs system. The pH 1 and 9 of PE and CS obtained the large size which about 600-1200 nm, while zeta potential found a low positive charge of 5.54-11.90 mV. Thus, only the fixed pH 5 of CS solution and pH 3, 5, or 7 of PE solution to form PECs were used to load MTZ. After loaded MTZ, the particle size of the PECs was about 400-500 nm and the zeta potential was about 20-50 mV. Electrostatic interactions resulted from FTIR detected the changes in amino groups of CS and carboxyl groups of PE. Thermal analysis on DSC for determinations of melting points or transition temperatures and TGA to monitor weight loss by heat were confirmed the PECs and MTZ-PECs formation. The pH 5 of PE interacts with pH 5 of CS offered the smallest particle size as 438 nm, zeta potential about 23.5 mV, and the highest percentage of EE as about 50% of the drug-loaded. The pH 5 of PE and CS were the pH-responsive to the pKa, thus, the acidity of the polymers may provide a suitable condition to form the appropriate polyelectrolyte complexes. Keywords: Polyelectrolyte complex, polycation, polyanion, charge density

Formaldehyde Detection by a Combination of Formaldehyde Dehydrogenase and Chitosan on a Sensor Based on an Organic Field-Effect Transistor

Formaldehyde is utilized for the preservation of materials due to its strong bactericidal effects. As formaldehyde is also a harmful substance that causes health hazards, the quantitative monitoring of formaldehyde in natural and living environments is desirable. For the rapid and easy detection of formaldehyde, in this study we applied an organic field-effect transistor (OFET)-based sensor that can function as a potentiometric device for electrochemical measurements. A polyion-complex gel of formaldehyde dehydrogenase (FDH) and chitosan (CT) was constructed on a gold electrode. When the FDH/CT gel-coated electrode was connected to an OFET device it could detect formaldehyde in an aqueous solution, in which the amino groups of chitosan would protonate during the enzymatic reaction. The limit of detection was calculated to be 3.1 µM (93 ppb), demonstrating the applicability of the film-type OFET sensor to environmental monitoring.

A novel adsorbent of core-shell construction of chitosan-cellulose magnetic carbon foam: Synthesis, characterization and application to remove copper in wastewater

Developing a environmental and cost-effective adsorbents for removal of Cu(II) from industrial wastewater is a quite serious problem. This study prepared a novel adsorbent of chitosan-cellulose enwrapped magnetic carbon foam (CCMF) to remove Cu(II) from industrial sewage. Magnetic core-shell construction facilitated the solid-liquid separation after adsorption. Groups of adsorption experiments for the adsorbability of CCMF were systematically studied at various conditions, such as pH (3.0–6.0), adsorbent dosage (1.0–4.0 g/L), initial concentration of Cu(II) (25–600 mg/L), temperature (20–30 °C) and adsorption time (10–1800 min). Fourier-transform infrared (FTIR) spectroscopy indicated that the amino and hydroxyl groups of chitosan were involved in the adsorption reaction and that N and O atoms were the adsorption sites. X-ray photoelectron spectroscopy (XPS) further confirmed that the N atom was the main adsorption site. The adsorption isotherm of Cu(II) on the CCMF was well correlated with the Langmuir isotherm model, the adsorption processes were a monolayer reaction and controlled by homogeneous adsorption sites on the surface, and the maximum adsorption capacity was 115.65 mg/g at pH 6.0 and 30 °C. The adsorption process of Cu(II) on the CCMF followed the pseudo-first-order kinetic equation within the initial 120 min. Meanwhile, the entire process fitted well with the pseudo-second-order kinetic model. Results have demonstrated that CCMF is a potential environmental adsorbent for the removal of Cu(II) in industry wastewater.

Chitosan Modified with Reduced Graphene Oxide Binder for Lithium-Sulfur Battery

The lithium-sulfur battery is a great promising candidate for next generation high energy density batteries. However, the poor conductivity of sulfur and the dissolution of soluble molecular intermediates (lithium polysulfide) interrupt practical application. To address this issue, the chitosan modified with reduced graphene oxide (Chitosan/rGO) was prepared as a binder in order to improve the electrical conductivity of sulfur and suppress the dissolution of lithium polysulfide into the electrolyte. The positively charged amino group in chitosan readily binds with negatively charged surface of rGO. The high conductivity of rGO provided facile pathway for electron and ion transport and the polar functional groups in chitosan could trap the lithium polysulfide due to their high affinity which was carefully confirmed by cyclic voltammetry. The chitosan/rGO binder with optimized composition showed enhanced initial discharge capacity, 1342 mAh g-1 at 0.05 C and the reversible specific capacity after 100 cycles was 856 mAh g-1 at 0.2 C. These are attributed to synergistic effect between chitosan and rGO. This work offers a simple and effective ways for improving the capacitive performance of Li-S batteries for practical applications.

Analysis of pH and salt concentration on structural and model-drug delivery properties of polysaccharide-based multilayered films

This paper explores the influence of pH and ionic strength of polyelectrolyte solutions as a simple and chemically amenable strategy for tuning the structure and drug delivery properties of polyelectrolyte multilayers produced via layer-by-layer technique. Carboxymethylcellulose/chitosan films were buildup under different pH (4.0 and 6.0) and salt concentrations (0 or 0.2 M NaCl) conditions. Systematic data analyses using Design of Experiments indicate that high ionic strength favors the formation of thinner and rougher films. Higher pH led to the formation of thinner and rougher films, attributed to the substantial decrease in the degree of ionization of carboxymethylcellulose and the random coil conformation of chitosan at the outermost layer, respectively. The random coiled conformation of chitosan near to neutral pH also seems to be the major factor to increase the surface film roughness under wet conditions. Drug delivery tests performed with Rose Bengal (model drug) indicate a predominant non-Fickian release mechanism for most of the buildup conditions tested. Densely packed multilayered films obtained at pH 6.0 and 0.2 M NaCl resulted in a faster, Fickian release mechanism, with minimal changes in surface morphology under wet conditions. The total amount of drug released shows a significative influence of only the polyelectrolyte solution pH, associated with the higher amount of free amino groups of chitosan at the film surface at higher pH conditions. These findings shed light on a strategy to develop functional coatings with tailored structural and drug delivery properties by simply controlling film depositions conditions.

FABRICATION AND CHARACTERIZATIONS OF GELATIN/CHITOSAN WITH ALOE VERA AND ACHATINA FULICA SP MUCUS AS SCAFFOLD FOR SKIN TISSUE ENGINEERING

Scaffold is a biomaterial widely used in tissue engineering. Scaffold is temporary porous structure which contain extracellular matrix. It serves as scaffolding which is required for cells infiltration and physical support to guide the cell proliferation and differentiation into the targeted functional tissues. Scaffold must be biocompatible, small pore size, flexible and support regenerative application. Aloe vera as natural resource, it has capability in accelerating wound healing, facilitating the inflammation, increasing wound contraction and epithelialization, and increasing organization of the regenerated tissue. Snail mucus (SM) has capability in inhibiting bacterial growth. This study aims to synthesize and characterize a scaffold made of gelatin-chitosan-Aloe vera (AV) - Achatina fulica sp mucus. The method is to synthesize scaffold with its compositions, gelatin-chitosan (1: 1 ratio) which is dissolved into 0.05 M acetic acid, then a variation of Aloe vera (AV) and snail mucus (SM) at 0% AV; 0% SM; 0.07 AV; 0.07 SM; 0.15 AV; 0.15 SM; 0.07 AV; 0.15 SM; 0.15 AV; 0.007 SM were mixed with the chitosan-gelatin solution, then used freeze dry method to obtain porous scaffold. Characterization which performed in this research including Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), porosity test, tensile strength test, swelling test, and degradation test. Based on FTIR test, Aloe vera and snail mucus interacted with free amino and hydroxyl groups of chitosan and gelatin, characterized by absorption bands at 2937.59 cm-1 wave numbers which are symmetrical and asymmetrical stretching of (-CH) .SEM test results obtained pore size of 70 - 235 μm. Porosity test results showed that five scaffolds have porosity value of 87-96%; thus, allowing the process of cell proliferation to occur well. The result of physical characteristic test yielded tensile strength of 1.425 MPa on gelatin-chitosan as control sample and 0.732 MPa for sample with 0.15% AV and 0.15% SM. Swelling test showed a variation of scaffold composition with Aloe vera with Achatina fulica sp’s mucus having a swelling percentage of 200-520%. The degradation test results showed that the whole sample was not depleted for 21 days; thus, giving time for cell regeneration. Sample with 0.15% Aloe vera and 0.07% snail mucus has some potentials as scaffolds for skin tissue in case of burns wound, due to its morfology, porosity, and degradation.