Papers by Keyword: Chitosan (CS)

Abstract: Chitosan grafting acrylic copolymer (CTS-g-AA) supported Nano palladium catalyst was obtained in this paper. Chitosan grafting acrylic copolymer (CTS-g-AA) was prepared firstly and palladium was supported on CTS-g-AA; then nano fibrous catalyst was gained via electrospinning technique. The title catalysts were characterized by TEM, SEM and IR, the diameter of nanofiber was about 70~200 nm, the size of metal particles were in a range of 10~40 nm, and palladium particles dispersed on nanofibers homogeneously. The catalyst was applied to catalyze α-octene hydrogenation in normal temperature and pressure. The results showed that the conversion of α-octene was 99%, and the yield of octane was 65% by double-metal catalyst.

Abstract: Characterization of chitosan / layered silicate nanocomposites obtained by solution-mixing technique, having different compositions including treated and untreated montmorilonite (MMT) has been performed. The optimum amount of MMT and also the effect of nanoparticles type on nanocomposite properties by DSC, X-ray diffraction and TG measurements have been established. The chitosan chains were inserted into silicate layers to form the intercalated nanocomposites. The interlayer distance of the silicates in the nanocomposites enlarged as their amount increased. The stiffness and thermal stability enhanced.

Abstract: A broad range of II-VI materials has been investigated in order to produce light in the full visible range for optoelectronic applications. The present investigation was carried out for the spectroscopic analysis and synthesis of wide band gap cadmium sulfide nanoparticles. Large-band gap semiconductors have the added advantage in that; they can support higher electric field before breaking down, which means that they can be used for high-power electronic devices.Synthesis has been carried out using colloidal synthesis technique at low temperature. The size, stabilization and optical properties were studied using UV-vis Spectrophotometer and Spectroflourometer. Further, the structural studies of synthesized powder were carried out using X-ray diffraction technique; which also confirms the formation of desired product. The capping ligand and the impurities present in the sample were characterized by Fourier transform infra red spectroscopy. Synthesized CdS powder dispersed in aqueous media gave the value of 193 nm for the onset wavelength using UV-vis spectrophotometer, which is significantly blue-shifted compared to bulk CdS and shows the quantum confinement effect. From the onset wavelength the radius of CdS quantum dot calculated using the Brus equation was found to be ca. 0.7 nm.

Abstract: A microfluidic chip with in-situ prepared chitosan membrane immobilized with Glucose Oxidase was developed as glucose oxidase reactor to detect human serum. The chitosan was prepared in-situ in the micro-channel as the immobilization material.Then,GOD was immobilized in the chitosan membrane, in which factors, such as the glutaraldehyde concentration, time of crosslinking and immobilization, buffer pH, were optimized with orthogonal experiments. The concentration of glutaraldehyde was finally chosen as 0.15%, time of crosslinking as 60 min, immobilization time as 15 h, and buffer PH as 8.0. The immobilization efficiency could reach up to 5U•cm2. The homemade microchip could be applied for rapid determination of glucose in serum, combining with the Luminol-K3Fe(SCN)3 Chemiluminescence reaction system. Under optimized conditions of sample velocity of 500uL•min-1, the concentration of K3Fe(SCN)3 of 1×10-2mol•L-1 and the concentration of luminol of 5×10-4 mol•L-1, the detection limit could achieved 1ug•mL-1.

Abstract: Chitosan membranes were prepared by solvent cast method. In order to increase cell adhesion of the chitosan membranes, oxygen plasma treatment was applied to improve the hydrophilicity of the surface of chitosan membranes. The surface properties were characterized by scanning electron microscopy (SEM), contact angle analyzer, X-ray photoelectron spectroscopy (XPS). The effects of exposure time, plasma generating power, and chamber pressure on water contact angle of the chitosan membranes were investigated. The water contact angle of chitosan membranes decreased from 94.1° to 49.2° after plasma treatment. Which suggested the surfaces became more hydrophilic. XPS analysis showed that the oxygen content and the ratio of O/C increased markedly after oxygen plasma treatment. Furthermore, it was found that C-H bonds were broken with oxygen plasma treatment. C-OH group had been increased after plasma irradiation.

Abstract: Owing to the unique characters of the hybrid scaffold components, a novel biodegradable porous composite scaffold was prepared. The nano hydroxyapatite (HAP) (73~136 nm) was crystallized in situ on the organic polyelectrolyte complex matrix through a biomimetic method. The polyelectrolyte complex composed of chitosan and hyaluronic acid had strong impacts on the formation of the nano HAP and directed in situ crystallization of the nano HAP as template. The in situ nano HAP reduced the interfacial energy and presented nano intensifier to the nano hybrid scaffold. Meanwhile, the scaffold kept high porosity.

Abstract: Skin wounds, burns and scars represent a major burden upon world healthcare costs. The successful creation in vitro of skin substitutes has been the focus of a concentrated research activity for the last 30 or more years, culminating in some success for its translation into the clinical setting. In this paper, a novel artificial skin of bacterial cellulose has been biosynthesized by Acetobacter xylinum and modified by chitosan. BC is thought as an optimal substrate material of artificial skin. It is thought to be an interesting material for using as a substratum of artificial skin because it could provide moist environment to a wound resulting in a better wound healing. But BC has no antimicrobial activity to reduce the probability of wound infection. To achieve antimicrobial activity of BC, it was modified by chitosan due to its antibiotic activity. The structure and components were characterized by FTIR and ESEM. The results indicated the nano-composites of BC and chitosan are promising and potential for wound dressings.

Abstract: The treatment for wound is a common issue in nursing procedure. Especially in serious wound, the treatment for wound usually spends many costs and time. Generally, wound dressing is used to protect the wound from bacterial infection in the intervening period between hospitalization and grafting. The pectin and chitosan are natural polymers that have biocompatibility and biodegradability, and pectin and chitosan can be easy obtainment and low cost. Tencel is a regenerated fiber. The Tencel fibers are biodegradable and hydrophilic, and have stable capability of dimension. Therefore, if the pectin and chitosan can be properly developed and combine with the tencel fabric for dressing use, the cost and time for wound treatment could be effective reduction. The absorbent cotton fibers were blended with the tencel fibers to create the cotton/Tencel nonwoven substance using nonwoven manufacturing technique. Chitosan will be electrospun on the Tencel nonwoven substance to create chitosan/Tencel composite nonwoven fabric. Furthermore, the surface structure of chitosan/Tencel composite nonwoven was observed by using scanning electron microscopy (SEM) to examine spinning ability of chitosan. Additionally, the pectin solution was blended with calcium chloride solution. Then pectin blended solution was coated on the optimal chitosan/Tencel composite nonwoven fabric by using mesh printing technique to prepare composite dressing. The result shown the Tencel/chitosan/pectin composite dressing has good capabilities of water absorbency and evaporative water loss. This study showed that a novel process for medical dressing was useful, and the composite dressing had an advantage property on wound healing and protection.

Abstract: This paper investigates the rheological behaviour of chitosan solutions crosslinked with different concentrations of genipin at body temperature and physiological pH. The effect of the crosslinker concentration on the rheological properties of hydrogels was evaluated. The oscillatory time sweep was used to analyze the dynamics of G’ during in situ gelation experiments enabling the determination of the gelation time. Additionally, the stress and frequency sweeps were employed to measure G’ of cured hydrogels. The solutions of chitosan crosslinked with genipin at physiological conditions were found to form relatively strong elastic gels for all the concentrations, when compared to pure chitosan. A significant reduction on gelation time was achieved. This behaviour shows that these formulations are able to be produced in situ and thus constitute promising matrices for cells and bioactive molecules encapsulation.

Abstract: In this study, the chitosan scaffold was modified with the simulated body fluid (SBF) which would create a biomimetic layer on the interface between tissues and scaffolds for the bone formation. To investigate the in vivo osteoinduction, the chitosan scaffolds immersed in the SBF for different times were implanted into the calf muscle in male Wistar rats. The tissues blocks containing the scaffolds were harvested at different periods for bone induction assay and examined histologically. Hematoxyline and Eosin staining (H & E staining), Masson’s Trichriome staining and alkaline phosphatase staining (ALPase), were performed for the observation of in vivo biocompatibility, collagen deposition and ALPase activity. Immunohistochemical staining of osteopontin (OPN) and bone sialoprotein (BSP) were used to examine gene expression of these bone proteins and to determine possible development stage of osteoinduction in the specimens with SBF modification. The results in this research suggested that the SBF modification would improve the biocompatibility of chitosan scaffolds, revealed by the decrease in foreign body reaction. With the SBF treatment, the expression of osteoblastic differentiation, including ALPase, OPN and BSP, would be also enhanced. Besides, the above tendencies would be more significant with the longer time for SBF immersion. In conclusion, the chitosan scaffolds modified by using SBF bioreactor would possess excellent biocompatibility and high potential in the promotion of bone regeneration.