Encapsulation and release of Beauveria bassiana from alginate–bentonite nanocomposite

Abstract

The present work is devoted to the study of polymer/layered silicate nanocomposite (PLN) of alginate–bentonite as a bead matrix for the entomopathogenic fungus Beauveria bassiana strain CPATC032. In particular, we investigate the encapsulation efficiency and surface morphology of beads presenting different concentrations of bentonite, where the effects associated with the drying method of the samples were analyzed. The internal structure of alginate–bentonite beads are studied by means of X-ray diffraction and Fourier transform infrared spectroscopy, determining the impact of the drying process on the crystalline structure of bentonite domains inside the polymeric matrix. By using Scanning Electron Microscopy (SEM) and fluorescence microscopy techniques, we identify a monolithic distribution profile for beads inside the PLN matrix, which is independent of the concentration of bentonite and of the drying method employed. However, our results demonstrated that the in vitro release of the fungus is sensitive to the bead preparation method due to the emergence of a barrier phenomenon as the concentration of silicate is increased. Swelling degree and release kinetics were also investigated, where a strong dependence on the drying method was observed.