Abstract: In this study, chitosan microflowers (CSMF) were prepared by an ionic cross-linking method and were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The loading capacity of CSMF for procyanidins (PC) as a model drug under different conditions was investigated, and the in vitro sustained release and antioxidant properties of procyanidins-loaded microflowers (PC-CSMF) were analyzed. The results showed that the morphology of CSMF was a three-dimensional multi-layer micro-flower structure with a diameter of approximately 1.5 μm, and there was a gap between layers. The FTIR spectrum of PC-CSMF showed an absorption peak at 1 448 cm-1, and XPS showed that the ratio of carbon to oxygen on the surface of PC-CSMF increased, which proved that PC was successfully loaded onto CSMF. The results of X-ray diffraction (XRD) and thermogravimetric analysis (TG) demonstrated that the crystallinity and thermal stability of PC-CSMF did not change significantly. The results of single factor experiments showed that the maximum PC load of CSMF of 352.88 mg/g was obtained at room temperature (27 ℃) and a PC concentration of 10 mg/mL. PC-CSMF had sustained release properties and antioxidant activity in vitro.

Key words: procyanidins; chitosan microflowers; characterization; sustained release in vitro; antioxidant activity