Silsesquioxane Mediated Morphology Transition of Nano‐Gold and Its Laponite Composites for Controlled Release Applications

Abstract Silsesquioxane‐mediated morphology transition of nano‐gold is reported. The silsesquioxane obtained through the hydrolysis and condensation of 3‐aminopropyltriethoxysilane and vinyltriethoxysilane in ethanol–water mixture was used as the reducing‐cum‐stabilizing agent to synthesize nano‐gold. A transition of morphology of nano‐gold from predominantly nanoprisms (GNPMs) to quasi‐spherical nanoparticles (GNPs) was observed between silsesquioxane concentrations of 10.12 and 16.8 mM. Unhydrolyzed silane mixture of the same composition as that of the silsesquioxane or hydrolyzed silane with aminopropyl groups alone, or ethanol/water ratio below 2.3:1 and above 4:1 failed to produce stable colloidal gold and the morphology transition. Therefore, it is proposed that hydrophobic interaction of the vinyl groups with ethanol, hydrophilic interaction of amino groups with water, steric factors due to the rigid cage‐like structures of the silsesquioxanes, and variation of the reduction time with increasing concentration of silsesquioxanes were the reasons for the observed morphology transition of the nano‐gold from GNPMs to GNPs. The GNPs and GNPMs were modified with doxorubicin intercalated laponite to obtain composite nanoparticles. In vitro evaluation of the doxorubicin‐intercalated laponite composites of GNPs and GNPMs using the human cervical cancer cell line (HeLa) indicated a concentration‐dependent cytotoxicity profile.