H O -Responsive Organosilica-Doxorubicin Nanoparticles for Targeted Imaging and Killing of Cancer Cells Based on a Synthesized Silane-Borate Precursor.

Doxorubicin (Dox) is a widely used fluorescent chemotherapy drug. Its primary delivery systems, based on physical adsorption to silica nanoparticles, can lead to low drug loading. Direct loading of Dox via covalent bonds during the formation of silica nanoparticles has never been reported. In this work, we designed and synthesized a silane-borate precursor, which contains not only an alkoxysilane moiety to form organosilica nanoparticles but also a phenylboronic acid moiety to react with diol-containing compounds. Using this compound, the covalent loading of Dox during the preparation of organosilica nanoparticles was effectively realized with a high drug loading content up to 22.4 %. Further modification by hyaluronic acid (HA) bestowed the Si-Dox@HA nanoparticles with the ability to target CD44-overexpressing cancer cells. The Si-Dox@HA nanoparticles exhibited H O -responsive release of about 80 % Dox and displayed seven-fold selectivity for killing cancer cells over normal cells, relative to Dox and Si-Dox nanoparticles. Moreover, these Si-Dox@HA nanoparticles are also suitable for targeted fluorescence imaging of CD44-overexpressing cancer cells.