Study of protoporphyrin IX-loaded silica hollow spheres for Photodynamic therapy

G-H Tseng, T-Y Liu
National Yang-Ming University of Taiwan, TW

Keywords: protoporphyrin IX, photodynamic therapy, silica hollow sphere


In this study, PpIX was loaded in the shell of silica hollow sphere with the expectation that PpIX-loaded silica hollow spheres (PpIX-SHS) might be employed as a PDT agent with ultrasound image contrast. The PpIX-loaded silica hollow spheres were fabricated using DMDES (dimethyldiethoxysilane) which could be transformed into PDMS (polydimethylsiloxane) templates. The PDMS templates were crosslinked via TEOS (tetraethoxysilane), followed by the addition of PpIX and APTES (3-aminopropyl triethoxysilane) to obtain biocompatible silica hollow spheres with the PpIX-containing shell. The morphology of the resulting samples was observed using transmission electron microscopy (TEM).A hollow structure was clearly observed under TEM. The PpIX-containing silica structure was confirmed using fourier-transform infrared spectroscopy (FTIR). The FTIR peak around 1030 cm-1 was assigned to the characteristic peak of silica, indicated the shell was formed by silica. The singlet oxygen generation ability of the sample was confirmed using UV-Visible spectroscopy and singlet oxygen probe (DPA, diphenyl anthracene). After combining with singlet oxygen, the photo absorption of DPA at 376 nm would decrease. The UV-Visible spectrum of DPA mixed with PpIX-loaded silica hollow spheres suggested that PpIX-SHS still generated singlet oxygen after UV irradiation.