ABSTRACT
Copper nanoparticles were introduced into chitosan/fluorescein (Ch/f) film and hydrogel matrices by immersion of the respective matrix into an aqueous solution containing the precursor metallic salt and further reduction in aqueous medium at 75°C for 3h under nitrogen (N2) atmosphere. TGA was used to estimate the metallic content of Ch/f-Cu film and hydrogel nanocomposites. The prepared nanocomposites were proven to be effective as catalytic materials in the reduction of methylene blue (MB) employing N2H4 as reducing agent. In addition, rate constants of the reduction reaction using Ch/f-Cu film and hydrogel nanocomposites as catalysts were determined. The experimental results showed that the catalytic activity and order of reaction of the MB-N2H4 reduction system depended strongly on the type of nanocomposite used. Finally, the recyclability of the film and hydrogel nanocomposites as catalytic materials was also studied.
ABSTRACT
Lately, many efforts have been devoted to finding more efficient methods to prepare metal nanoparticles with controlled shapes and sizes, low polydispersity, high purity and good stability in a specific dispersion medium. Therefore, it is highly desired to develop synthetic routes that can contribute to tune the properties of metal nanoparticles for their potential applications in diverse scientific and technological fields. Thus, the application of polymers in the synthesis of metal nanoparticles has attracted great interest due to the better understanding of the parameters involved in the stabilization processes of metal nanoparticles. In addition, the use of polymers in the chemical reduction of metal ions in solution has also attracted much attention recently. Thus, this field of research is growing in importance because it would be possible, for example, to prepare hybrid nanocomposites by using non-toxic reagents and simplified synthetic routes. However, control of the shape, improvement of the size distribution and establishing correlations between polymer structure and characteristics of noble metal nanoparticles are still challenging tasks that should be considered in the synthesis processes in order to obtain hybrid nanomaterials with desirable properties.
ABSTRACT
Self-assembling polymers in aqueous solution have attracted significant attention with recent research efforts focused on the development of new strategies to design devices useful in the field of controlled drug delivery. In this context, amphiphilic copolymers having specific structural features and self-assembling behaviors in aqueous media that would enable controlled drug release over longer time periods. In this work, we report on the synthesis and characterization of a Poly (É-caprolactone)-grafted Dextran copolymer and its use in the preparation of micellar nanoaggregates. The characterization and study of the morphology, topography, size distribution and stability of micellar nanoaggregates by Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Zeta Potential (ζ), respectively, were carried out. Spherical-shaped morphologies and an average size of approximately 83 nm, for drug-free nanoaggregates, were observed. In addition, Zeta Potential studies showed that drug-free nanoaggregates are more stable than drug-loaded structures measured in a phosphate buffer (pH 7.2) medium. UV-vis spectrophotometry of both the drug entrapment efficiency (EE%) and in vitro drug release behavior were assessed. The EE% was determined to be 78% (w/w), and a combination of diffusion and eroding polymer matrix mechanisms for drug release were established. Finally, these results indicate that Dx-g-PCL micellar nanoaggregates are suitable for use as a potential nanocarrier having both biodegradable and biocompatible properties.
