Nanoengineered electrochemical sensor based on mesoporous silica thin-film functionalized with thiol-terminated monolayer

A mesoporous silica thin film was synthesized via a surfactant-templating process, where a silica sol gel is spin-coated onto the surface of a microchip-based gold microelectrode. Within the film was a cubic lattice of pores having a primary size of 77 Angstrom. Thiol (-SH) functional groups were subsequently immobilized onto the mesoporous silica thin film through a self-assembly process. The thiol-functionalized mesoporous silica (SH-FMS) thin film was used as the electrode sensing layer for detection of lead(II) in aqueous solutions by employing a square wave adsorptive stripping voltammetry technique. The electrode modified with the SH-FMS thin-film utilized the binding affinity of lead( II) to the thiol ligands to perform the preconcentration step under an open circuit, with no additional electrolytes. The voltammetric responses for lead( II) increased linearly with the preconcentration time from 1 to 30 min. The responses also increased linearly with lead( II) concentrations ranging from 250 to 5000 ppb after 5 min preconcentration and from 25 - 100 ppb after 30 min preconcentration.