Effect of chitosan and hydroxypropyl methylcellulose on size and antibacterial activity of copper nanoparticles

Background: Nanomaterials exhibit better antibacterial activity because of their distinct structural/ morphological characteristics. The particle size and shape of the nanomaterials are the two significant parameters which affect the resultant antibacterial property. Different biopolymers have been explored to prepare capped metal nanoparticles with controlled/desired particle size and morphology. Methods: The present research work explains the effect of chitosan (CH) and hydroxypropyl methylcellulose (HPMC) on the shape and size of the copper nanoparticles (Cu NPs) and their antibacterial activity. The CH-Cu and HPMC-Cu NPs were achieved by facile precipitation technique using ascorbic acid as a nucleating agent. Results: Instrumental analysis by fourier transform infrared spectroscopy, x-ray diffraction, field emission scanning electron microscopy-energy dispersive x-ray analysis and transmission electron microscope confirmed the successful synthesis of Cu NPs. Scanning and transmission electron microscopic studies revealed that the formed NPs have a spherical structure with different diameters of ~8 ± 2 nm for CH-Cu and ~38 ±2 nm for HPMC-Cu NPs. Crystalline size calculated using Debye–Scherrer equation from XRD results were also in good agreement with the above results. The developed materials CH-Cu NPs and HPMC-Cu demonstrated excellent antibacterial activity against both gram-positive and gram-negative bacteria. It was observed that the CH-Cu NPs showed a higher inhibition zone when compared to that of the HPMC-Cu NPs. Conclusions: The biopolymer capped Cu NPs of smaller particle size exhibit much better antibacterial activity and the particle size of the Cu NPs (nm) can be finetuned with the aid of selecting the most appropriate biopolymer

Electroactive Hydrogels Made with Polyvinyl Alcohol/Cellulose Nanocrystals

This paper reports a nontoxic, soft and electroactive hydrogel made with polyvinyl alcohol (PVA) and cellulose nanocrystal (CNC). The CNC incorporating PVA-CNC hydrogels were prepared using a freeze–thaw technique with different CNC concentrations. Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy results proved the good miscibility of CNCs with PVA. The optical transparency, water uptake capacity and mechanical properties of the prepared hydrogels were investigated in this study. The CNC incorporating PVA-CNC hydrogels showed improved displacement output in the presence of an electric field and the displacement increased with an increase in the CNC concentration. The possible actuation mechanism was an electrostatic effect and the displacement improvement of the hydrogel associated with its enhanced dielectric properties and softness. Since the prepared PVA-CNC hydrogel is nontoxic and electroactive, it can be used for biomimetic soft robots, actively reconfigurable lenses and active drug-release applications

Swelling Behavior of Polyacrylamide–Cellulose Nanocrystal Hydrogels: Swelling Kinetics, Temperature, and pH Effects

This paper reports swelling behavior of cellulose nanocrystal (CNC)-based polyacrylamide hydrogels prepared by a radical polymerization. The CNC acts as a nanofiller through the formation of complexation and intermolecular interaction. FTIR spectroscopy and XRD studies confirmed the formation of intermolecular bonds between the acrylamide and hydroxyl groups of CNC. The swelling ratio and water retention were studied in de-ionized (DI) water at room temperature, and the temperature effect on the swelling ratio was investigated. Further, the pH effect on the swelling ratio was studied with different temperature levels. Increasing the pH with temperature, the prepared hydrogel shows 6 times higher swelling ratio than the initial condition. The swelling kinetics of the developed hydrogels explains that the diffusion mechanism is Fickian diffusion mechanism. Since the developed hydrogels have good swelling behaviors with respect to pH and temperature, they can be used as smart materials in the field of controlled drug delivery applications

Transparent and semi-interpenetrating network P(vinyl alcohol)- P(Acrylic acid) hydrogels: pH responsive and electroactive application

In this paper, poly(vinyl alcohol)-poly(acrylic acid) based transparent semi-interpenetrating network (semi-IPN) hydrogels were synthesized by using a solvent mixture of dimethyl sulfoxide and deionized water via free radical polymerization and subsequent freeze-thaw technique. The formation of the semi-IPN hydrogels was conformed from FT-IR spectra. The acrylic acid concentration effect on the hydrogels was investigated in terms of transparency, crystalline structure and thermal stability by using UV-visible spectroscopy, X-ray diffraction and thermogravimetric analysis. Swelling behaviours of the semi-IPNPAP hydrogels were studied in deionized water and different pH solutions. The compression and electroactive behaviour was tested in fully hydrated stage by using compression test and by applying electrical voltage. The hydrogels showed displacements under the applying voltage and detailed experiment is illustrated

Chitosan-pluronic based Cu nanocomposite hydrogels for prototype antimicrobial applications

Copper nanoparticles were synthesized via precipitation technique using the pseudonatural cationic chitosan biopolymer as a stabilizing agent. The nanoparticles developed were successfully incorporated into the 1:1 ratio of blended chitosan: pluronic F127 polymer solution and made their nanocomposite hydrogels by solution casting method. The formed copper-based nanocomposite hydrogels were characterized by using Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy and transmission electron microscopy studies. The antimicrobial activity of the fabricated nanocomposite hydrogels was tested via an inhibition zone process against both E. coli (gram-negative) and S. aureus (gram-positive) bacteria. The results conveyed that the copper-embedded chitosan-pluronic\ F127 nanocomposite hydrogels can be used effectively for antimicrobial applications as well as for wound care applications.Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT), CONICYT FONDECYT: 3170272, 11160073 Universidad de Talca, Talca, Chile Proyecto de Investigacion enlace FONDECYT Universidad de Talca: 300061 CIPA, CONICYT Regional, GORE BIO-BIO: R17A1000