A New Surface Modifying Material "Mercaptosilatrane" for Particle Plasmon Resonance Sensor

The self-assembled monolayer (SAM) of mercaptoalkoxysilane is wildly used as a molecular linker between metal and silica. The mercapto group is known to bond with many metals, including gold, silver, copper, and lead. The mercaptoalkoxysilane system, like 3-mercaptopropyltrimethoxysilane, usually uses a concentration of 100 mM and takes 12 h in methanol or 6 h in anhydrous organic solvent,[1-3] such as toluene and benzene, to form the SAM. Unfortunately, MPTMS is very sensitive to moisture,[4, 5] generally leading to agglomeration and polymerization on a substrate during deposition, and hence multilayer deposition and irregular surface morphology. Herein, a novel concept for preparing the mercaptosilane SAM via a precursor with a silatrane head-group is proposed. We have successfully synthesized mercaptopropylsilatrane (MPS) from mercaptopropylsilane and utilized it to modify the silica surface for immobilization of gold nanoparticles (AuNPs). Results show that at a low concentration (0.46 mM) of AuNPs in aqueous solution, a good surface coverage of AuNPs can be achieved in a short time (10 min).