Functionalization of silica-coated iron oxide nanoparticles via the silanol-alcohol condensation reaction

The surface properties of nanoparticles play an important role in their interactions with their surroundings. Silane reagents have been used for surface modifications to silica shells on iron oxide nanoparticles, but using these reagents presents some challenges. Some of these challenges include the moisture sensitivity of silane reagents and the formation of multilayers. An alternative approach to modifying the surfaces of these silica shells was developed to impart different terminal functional groups, such as a thiol, alcohol, or carboxylic acid, through the use of alcohol-based reagents. This reaction was initiated through convective heating and microwave-assisted heating. This approach to surface functionalization of the core-shell particles was verified through analytical measurements and the attachment of gold nanoparticles. The silanol-alcohol condensation reaction was also extended to the mixed functionalization of the silica-coated iron oxide nanoparticles with both thiol and carboxylic acid functionalized alcohol reagents. The processes and results for the silanol-alcohol condensation reaction were also compared with silanization process. The use of the silanol-alcohol condensation reaction could be extended further to other surface functionalization through the use of additional alcohol-based reagents