Investigation of the relationship between porosity and luminescent properties of porous silicon

In this work, we obtained porous silicon with different porosity by electrochemical etching and studied their photoluminescence. Two well-known photoluminescence mechanisms of porous silicon related to the composition and morphology of the surface have been discovered, and it has been established at what porosity values they prevail. It is shown that an increase in the porosity index leads to an increase in the intensity of photoluminescence

Carboxymethyl Cellulose-Based Polymers as Promising Matrices for Ficin Immobilization

The present work is devoted to research on the interaction between carboxymethyl cellulose sodium salt and its derivatives (graft copolymer of carboxymethyl cellulose sodium salt and N,N-dimethyl aminoethyl methacrylate) with cysteine protease (ficin). The interaction was studied by FTIR and by flexible molecular docking, which have shown the conjugates’ formation with both matrices. The proteolytic activity assay performed with azocasein demonstrated that the specific activities of all immobilized ficin samples are higher in comparison with those of the native enzyme. This is due to the modulation of the conformation of ficin globule and of the enzyme active site by weak physical interactions involving catalytically valuable amino acids. The results obtained can extend the practical use of ficin in biomedicine and biotechnology

Features of the Composition and Photoluminescent Properties of Porous Silicon Depending on Its Porosity Index

Porous silicon samples with a porosity index of 5% to 80% were obtained in this work by electrochemical etching, and their photoluminescence properties were also studied. The porosity index was calculated according to the data from X-ray reflectometry. The composition of the surface was controlled by ultra-soft X-ray spectroscopy and infrared (IR) spectroscopy. The degree of the sample surface oxidation increased with the porosity enhancement. Two known mechanisms of photoluminescence in porous silicon were detected that are related to the composition and morphology of its surface. The values of the porosity index specifying the dominations of these mechanisms were determined. Enhancement of photoluminescence was shown to be attributed to an increase in the porosity index