In situ monitoring of gating approach on mesoporous silica nanoparticles thin-film generated by the EASA method for electrochemical detection of insulin

Abstract An innovative label-free electrochemical aptasensing platform has been designed for detection of insulin using functionalized mesoporous silica thin-film (MSTF) coated on a glassy carbon electrode through the one-step electrochemically assisted self-assembly (EASA) method. This strategy is contingent upon the covalent attachment of a complementary DNA (cDNA) oligonucleotide sequence on the mesoporous silica surface, for which further hybridization with its labeled aptamer as a gating molecule restricts the diffusion of the electroactive probe (Fe(CN)63-/4-) toward the electrode surface by the closing of mesochannels. Upon insulin introduction as the stimulus target molecule, hybridization between aptamer and cDNA is efficiently destroyed, which triggers the opening of nanochannels to facilitate redox probe diffusion toward the electrode with a noticeable increase in differential pulse voltammetry signal. The proposed aptasensor showed a wide detection ranging from 10.0 to 350.0 nM and a suitable detection limit of 3.0 nM. This method offers the sensitive and rapid detection of insulin without the need for cargo (dye/fluorophore) as an electrochemical marker inside the pore, at low cost and with a fast modification time.