Characteristic of Starch-Poly(N-Vinyl-Pyrrolidone) for an encapsulation material in floating drug delivery system

Abstract

Modified starch has been widely used in many studies in the field of drug delivery for gastrointestinal drug release. In this study, the starch was modified with poly(N-vinyl-pyrrolidone) by interpenetrating polymer network (IPN) method. Characterizations were done to observe its characteristics in floating drug delivery applications. Three modified starch-based hydrogels were synthesized, i.e. crosslinked starch, semi-IPN, and full-IPN hydrogels. Non-modified starch hydrogel was also synthesized for benchmark purpose. All materials were characterized and analysed by Swelling Test, Buoyancy Test, Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR). Swelling test showed that the crosslinked-starch hydrogel has the lowest swelling percentage compared to other hydrogels, whereas non-modified hydrogels tend to have similar swelling percentage to Semi-IPN. Morphology and visual analysis results showed that non-modified hydrogels were physically the most fragile, followed by a crosslinked-starch, semi-IPN-starch, and full-IPN-starch hydrogel. Therefore, full-IPN-starch hydrogel had the highest elasticity. From IR spectrum result, it can be seen that a wavenumbers shift was observed for the modified starch compared with the IR spectrum of pure starch powder. TGA and DSC characterizations showed the degradation temperature for non-modified hydrogel was at 250°C. The degradation temperature for both crosslinked and semi-IPN starch were at 275°C. For full-IPN, however, the degradation temperature was at 225°C. On the other hand, the degradation level could be observed from DSC and TGA results as well. Full-IPN appeared to be the slowest, while non-modified hydrogel seem to be the fastest to degrade. CaCO3 was used as the pore forming agent (PFA) in this research for buoyancy characterization. Buoyancy test showed that the full-IPN had the fastest floating lag and longest floating time followed by semi-IPN-starch, crosslinked-starch, and non-modified starch. From all characterizations done in this research, it can be suggested that the full-IPN provided the most suitable characteristics as an encapsulation material candidate in a floating drug delivery system.