Fabrication and characterization of PSi smart particles containing 20(S)-camptothecin-functionalized germanium nanoparticles.

Porous silicon (PSi) smart particles containing 20(S)-Camptothecin (CPT)-functionalized germanium nanoparticles (Ge-NPs) for a noble drug delivery system were developed. PSi samples were prepared by anodization of a highly doped P(++)-type Si wafer in ethanolic HF solution using a platinum-meshed counter electrode. In this work, PSi was generated by an electrochemical etching of two discrete porous multilayered dielectric mirrors into Si, a top layer was referred to as the "DBR" multilayer, and a bottom layer was the "host" layer intended to infuse CPT-functionalized Ge-NPs. The DBR layer was chemically further passivated with (3-aminopropyl)trimethoxysilane groups. Resulting PSi was removed from the Si substrate by an applying of electropolishing current. CPT-functionalized Ge-NPs were infused into the host layer of PSi free-standing film. Samples were then made into particles by ultrasonic fracture in organic solutions. PSi smart particles were characterized by FE-SEM, FT-IR, EDX, UV-vis absorption, and fluorescence spectroscopy. PSi smart particles containing CPT-functionalized Ge-NPs displayed a linear release profile for the first 12 h, and then perfectly released CPT-functionalized Ge-NPs for 18 h.