Amoxicillin-loaded bionanocomposite hydrogels: swelling, dehydration, and in vitro drug release kinetics and mechanism.

This study deals with preparing and characterizing polyvinyl alcohol/egg white/montmorillonite bionanocomposite hydrogels as antibacterial drug delivery systems. The cyclic freezing/thawing method was utilized to fabricate the hydrogels. To study the performance of the prepared hydrogels as drug delivery systems, amoxicillin, as a model antibiotic drug, was loaded into the hydrogels by mixing with the precursor polymer solution and gelation. From the diverse microstructural characterization techniques, i.e. XRD, SEM, AFM, DLS, and gel fraction estimation, it was possible to infer that montmorillonite has been successfully incorporated into the hydrogel network and acted as an additional crosslinker to bind the chains of egg white and polyvinyl alcohol. Scrutinizing the physical properties of the produced hydrogels demonstrated that increasing incorporated montmorillonite content adversely affects the prepared hydrogels' swelling ability and prolongs their dehydration period. Additionally, the Swelling characteristics of the hydrogels were evaluated at different pHs. Results showed an increase in the swelling ability of all samples by raising the pH value of the medium. Additionally, it was proved that both swelling and dehydration of the hydrogels follow non-Fickian diffusion. In vitro drug delivery experiments demonstrated that the cumulative fractional release of amoxicillin was adversely dependent on the amount of incorporated montmorillonite into the hydrogels and positively dependent on the pH of the release solution. It was also found that, in all examined samples, the mechanism by which the release of clindamycin happens is non-Fickian or anomalous transport.

Towards environmental friendly multi-step processing of efficient mixed-cation mixed halide perovskite solar cells from chemically bath deposited lead sulphide.

Organic-inorganic hybrid perovskite is the most promising active layer for new generation of solar cells. Despite of highly efficient perovskite active layer conventionally fabricated by spin coating methods, the need for using toxic solvents like dimethylformamide (DMF) required for dissolving low soluble metal precursors as well as the difficulties for upscaling the process have restricted their practical development. To deal with these shortcomings, in this work, lead sulphide as the lead metal precursor was produced by aqueous chemical bath deposition. Subsequently, PbS films were chemically converted to PbI2 and finally to mixed-cation mixed halide perovskite films. The microstructural, optical and solar cell performance of mixed cation mixed halide perovskite films were examined. Results show that controlling the morphology of PbI2 platelets achieved from PbS precursor films enabled efficient conversion to final perovskite films. Using this processing technique, smooth and pin hole-free perovskite films having columnar grains of about 800 nm and a bandgap of 1.55 eV were produced. The solar cell performance consisting of such perovskite layers gave rise to a notable power conversion efficiency of 11.35% under standard solar conditions. The proposed processing technique is very promising towards an environmentally friendly method for the production of large-scale high efficient perovskite solar cells.