Study on the dissolution of hollow mesoporous silica nanosphere-supported nanosized platinum oxide in biorelevant media for evaluating its potential as chemotherapeutics.

Platinum oxide (PtO) nanoparticles (NPs) have been shown to possess anticancer activity by releasing ionic Pt species under biological conditions. However, the dissolution kinetics and the changes in the chemical state of Pt during PtO dissolution have not yet been studied. To fill this gap, we prepared a composite (designated as PtO@MMT-2) containing PtO NPs on hollow mesoporous silica nanospheres and studied the dissolution of the material in different biorelevant media. We found that the release of Pt was retarded due to the adsorption of biomolecules on PtO NPs during the degradation of host silica. The biomolecules adsorption also lowered the accessibility of PtO NPs, resulting in the reduced catalase-like activity of the NPs. In line with the results, the cytotoxicity of PtO@MMT-2, which was positively correlated to the amount of Pt uptake, was reduced by biomolecules adsorption. Our findings should be applicable to other metal (oxide) NPs under biological conditions and may provide implications for the design of nanomaterials for practical therapeutic applications.