ZnO Chitosan Research Articles

Industrial method of cotton fabric finishing with chitosan–ZnO composite for anti-bacterial and thermal stability

Chitosan–ZnO composites were prepared by hydrothermal method using commercial chitosan, 0.1M zinc nitrate and 1.6M sodium hydroxide. The advantage of this method is direct and a relatively easy ways of getting large amounts of chitosan–ZnO at lower temperature. Presence of chitosan was confirmed by FTIR spectroscopic analysis and crystalline structure of ZnO by XRD pattern. Photoluminescence spectra showed a yellow luminescence at ~620–630nm and blue-violet emission at ~410–430nm. TG/DTA analysis of the prepared chitosan–ZnO composites revealed higher thermal stability than commercial chitosan. SEM analysis shows that more number of chitosan–ZnO composite particles was dispersed within the micrometer scale. Antibacterial activity of chitosan–ZnO composite shows higher for gram-positive bacterium compared to gram-negative bacterium. The chitosan–ZnO composite cross linked cotton fabric exhibits very good antimicrobial activities and better durability than chitosan cross linked cotton fabric. To conclude, the preparation of chitosan–ZnO composites by this way will give bulk quantity with low cost for industrial bio-finishing.

Chitosan–ZnO/polyaniline hybrid composites: Polymerization of aniline with chitosan–ZnO for better thermal and electrical property

A new chitosan–ZnO/polyaniline (CPA–ZC/ZO) hybrid composite is prepared by single-step in situ oxidation polymerization of aniline hydrochloride in the presence of (NH4)2S2O8 and chitosan–ZnO (CS–ZO). The structural and morphological features of CPA and CPA–ZC/ZO hybrids were analyzed using FT-IR, UV–vis, SEM, EDXS and XRD analysis. The chemical bonding established between CPA and CPA–ZC/ZO, confirmed by FT-IR, is likely to be responsible for the enhanced chemical stability. The UV–vis spectra of CPA–ZC/ZO were found to red/blue shift as compared to those CPA molecular chains. From SEM observation, the ratio of ZnO nanoparticles to CPA altered the morphology of the hybrids from granular to plate like structure, which was confirmed by EDXS. The XRD patterns of the as-prepared hybrids show the wurtzite structure of ZnO is well maintained after the impregnation of CPA. Thermal property was studied using TG/DTA analysis shows the residual weight (TGA curves) and its weight derivative (DTA curves) of the CPA–ZC/ZO are more stable than CPA and CS–ZO. In addition, the cyclic voltammetry on the obtained hybrid materials revealed that the plate-like structure was more advantages for the electrochemical stability. Overall, the results show that the introduction of the ZnO nanoparticles into CPA matrix enhanced the thermal and electrode stability.

Effect of annealing temperature on optical and electrochemical properties of chitosan–ZnO nanostructure

Chitosan–ZnO nanostructures were prepared by chemical precipitation method using different concentration of zinc chloride and sodium hydroxide solutions. Nanorod-shaped grains with hexagonal structure for samples annealed at 300 °C and porous structure with amorphous morphology for samples annealed at 600 °C were revealed in SEM analysis. X-ray diffraction patterns confirmed the hexagonal phase ZnO with crystallite size found to be in the range of ~24.15–34.83 nm. Blue shift of UV–Vis absorption shows formation of nanocrystals/nanorods of ZnO with marginal increase in band gap. Photoluminescence spectra show that blue–green emission band at 380–580 nm. The chitosan–ZnO nanostructures used on surface of a glassy carbon electrode gives the oxidation peak potential at ~0.6 V. The electrical conductivity of chitosan–ZnO composites were observed at 2.1 × 10−5 to 2.85 × 10−5 S/m. The nanorods with high surface area and nontoxicity nature of chitosan–ZnO nanostructures observed in samples annealed at 300 °C were suitable as a potential material for biosensing.

Effect of zinc chloride and sodium hydroxide concentration on the optical property of chitosan–ZnO nanostructure prepared in chitin deacetylation

Chitosan–ZnO nanostructures are prepared by eco-friendly way of synthesis. With same amount of chitin, three different ratios of zinc chloride and sodium hydroxide concentrations are used for preparation. The hexagonal shape of chitosan–ZnO nanostructures with size range of 40–100 nm are confirmed by transmission electron microscopy (TEM). Surface morphology is characterized by scanning electron microscopy. Maximum Zn/O atomic ratio of 77:23 is noticed by energy dispersive X-ray (EDAX) analysis. Presence of chitosan and ZnO structure are confirmed with FTIR spectra. Absorbance at 364 nm in the UV–vis spectra indicates the presence of ZnO. X-ray diffraction pattern indicates the size of crystallites are in 16–53 nm range. Optical studies revealed that chitosan–ZnO nanostructure with band gap of 3.4 eV have been prepared by slow addition of 45% sodium hydroxide into 15% zinc chloride and chitin solution.

Construction of a triglyceride amperometric biosensor based on chitosan–ZnO nanocomposite film

A method is described for construction of a novel amperometric triglyceride (TG) biosensor based on covalent co-immobilization of lipase, glycerol kinase (GK) and glycerol-3-phosphate oxidase (GPO) onto chitosan (CHIT) and zinc oxide nanoparticles (ZnONPs) composite film deposited on the surface of Pt electrode. The enzymes–ZnONPs–CHIT composite was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The sensor showed optimum response within 6s at pH 7.5 and temperature of 35°C. The sensor measures current due to electrons generated at 0.4V against Ag/AgCl from H2O2, which is produced from triolein by co-immobilized enzymes. A linear relationship was obtained between a wide triolein concentration range (50–650mg/dl) and current (mA) under optimum conditions. The biosensor showed high sensitivity, low detection limit (20mg/dl) and good storage stability (half-life of 7 months at 4°C). The biosensor was unaffected modified by a number of serum substances at their physiological concentrations. The biosensor was evaluated and employed for determination of TG in sera in apparently healthy subjects and persons suffering from hypertriglyceridemia.

Preparation of chitosan–zinc oxide complex during chitin deacetylation

Novel chitosan–ZnO complexes are prepared using zinc chloride, sodium hydroxide and chitin as source materials by direct precipitation method. Four chitosan–ZnO complexes are prepared for different concentrations of source material. The chitosan–ZnO complex formations have been confirmed by FTIR spectroscopic analysis. Hexagonal structure and crystalline size (35–51 nm) of zinc oxide are determined by XRD. Rod-like particle shape of chitosan–ZnO complex from SEM images, higher UV rays absorption in the region of 200–275 nm by UV–vis and higher UV emission at 422 nm by photoluminescence spectrophotometer are recorded. The rod-like chitosan–zinc oxide was obtained with optimum concentration of 45% NaOH and 15% ZnCl 2. The size of the complex was increased with increase of sodium hydroxide concentration.