Amino-functionalized vertically ordered mesoporous silica film on electrochemically polarized screen-printed carbon electrodes for the construction of gated electrochemical aptasensors and sensitive detection of carcinoembryonic antigens

Disposable electrochemical biosensors with high sensitivity are very fit for point-of-care testing in clinical diagnosis. Herein, amino-functionalized, vertically ordered mesoporous silica films (NH₂-VMSF) attached to an electrochemically polarized screen-printed carbon electrode (p-SPCE) are prepared using a simple electrochemical method and then utilized to construct a gated electrochemical aptasensor for rapid and sensitive determination of carcinoembryonic antigen (CEA). After being treated with the electrochemical polarization procedure, p-SPCE has plentiful oxygen-containing groups and improved catalytic ability, which help promote the stability of NH₂-VMSF on SPCE without the use of an adhesive layer and simultaneously generate a highly electroactive sensing interface. Owing to the numerous uniform and ultrasmall nanopores of NH₂-VMSF, CEA-specific aptamer anchored on the external surface of NH₂-VMSF/p-SPCE serves as the gatekeeper, allowing the specific recognition and binding of CEA and eventually impeding the ingress of electrochemical probes [Fe(CN)₆ ^3-/4-] through the silica nanochannels. The declined electrochemical responses of Fe(CN)₆ ^3-/4- can be used to quantitatively detect CEA, yielding a wide detection range (100 fg/mL to 100 ng/mL) and a low limit of detection (24 fg/mL). Moreover, the proposed NH₂-VMSF/p-SPCE-based electrochemical aptasensor can be applied to detect the amount of CEA in spiked human serum samples, which extends the biological application of a disposable NH₂-VMSF/p-SPCE sensor by modulating the biological recognition species.