Provided according to some embodiments of the invention are methods of forming co-condensed silica particles. In some embodiments, the methods include reacting a thiol-containing silane and a backbone alkoxysilane in a reaction solution that comprises water to form thiol-functionalized co-condensed silica particles, wherein the thiol-functionalized co-condensed silica particles include a polysiloxane matrix and at least some of thiol groups are present within the polysiloxane matrix and reacting the thiol-functionalized co-condensed silica particles with a nitrosating agent to provide the S-nitrosothiol-functionalized co-condensed silica particles. In some embodiments, provided are S-nitrosothiol-functionalized co-condensed silica particles.
