Polysilsesquioxane nanoparticles for targeted platin-based Cancer chemotherapy. (a) Generalized scheme showing the formation of polysilsesquioxane nanoparticles (PSQ) from the Pt(IV) precursor, dachPtSi. Upon cellular internalization and reaction with endogenous biomolecules, the Pt(IV) complexes in PSQ will be reduced, thereby releasing the active Pt(II) agent. (b) Tumor growth inhibition curves. Mice were administered at 5 mg Pt/kg on days 0, 7, and 14 against an AsPC-1 subcutaneous mouse xenograft. Abbreviations chPtSi:Pt(dach)Cl2(triethoxysilylpropylsuccinate)2 (dach = R,R-diaminocyclohexane); PBS, phosphate buffered saline; PEG, polyethylene glycol; PEG-PSQ, surface PEGylated PSQ. (Reprinted with permission from Ref [103]. Copyright 2011 Wiley-VCH Verlag GmbH & Co [Angewandte Chemie-International Edition].)