Avidin-gated mesoporous silica nanoparticles for signal amplification in electrochemical biosensor

We report herein a novel sensing strategy for electrochemical biosensors, by using mesoporous silica nanoparticles loaded with the redox probe methylene blue and capped with an avidin/imminobiotin stimulus-responsive gate-like ensemble as signal amplification element. As a proof of concept, an aptasensor for carcinoembryonic antigen (CEA) was constructed by attaching a biotin and thiol-functionalized anti-CEA DNA hairpin aptamer on gold nanoparticles modified carbon screen-printed electrodes. The biosensing approach relied on the unfolding of the aptamer molecule after specific recognition of CEA, unmasking the biotin residue and allowing further association with the avidin-capped mesoporous nanocarrier. Incubation with H2SO4 trigger the release of the encapsulated redox probe allowing the detection of the cancer biomarker from 1.0 pg/mL to 160 ng/mL.