Hydrogel microspheres based on Bletilla striata polysaccharide as a promising cervical positioning drug delivery system

Due to female cervical mucosa is smooth and covered with a mucous layer, so the spreadability and mucoadhesion are crucial for the development of cervical positioning drug delivery system (CPDDS). In this work, the natural polymer Bletilla striata polysaccharide (BSP) as a hydrogel matrix-forming material was used for the preparing of hydrogel microspheres (HMs) by an improved emulsion crosslinking method. The prepared HMs have a spherical or quasi-spherical shape with a size of 115 ± 27 μm, resulting a good fluidity for spreading well at the administration site. By the physical entanglements of hydrophilic polymer chains of BSP, the matrix of HMs presents a microporous structure. With microporous matrix, the HMs could absorb water from mucous layer and achieve an optimum hydration required for mucoadhesion when they contact the cervical mucosa, also could keep their mucoadhesion behavior and morphology for a long time even after absorbing more water. As a result, the cervical positioning drug release behavior and long retention time at the cervical mucosa obtained. The loaded drug release profile of HMs include a low initial burst release and subsequent a longer sustained release, this is beneficial for the local treatment of cervical diseases. Owing to the BSP is a natural biodegradable polymer, the HMs have better biocompatibility with mucosal tissues and without causing irritation. In conclusion, this work suggest that the HMs based on BSP polymer is a promising CPDDS for clinical applications.