Label-free and sensitive aptasensor based on dendritic gold nanostructures on functionalized SBA-15 for determination of chloramphenicol

A highly sensitive and low-cost electrochemical aptasensor was developed for the determination of chloramphenicol (CAP). The system was based on a CAP-binding aptamer, a molecular recognition element, and 1,4-diazabicyclo[2.2.2]octane (DABCO)-supported mesoporous silica SBA-15 on the surface of a screen-printed graphite electrode for formation of dendritic gold nanostructures and improving the performance and conductivity of the biosensor. Hemin has been applied as an electrochemical indicator which interacted with the guanine bases of the aptamer. In the absence of CAP, hemin binds to the aptamer and produces a weak differential pulse voltammetric (DPV) signal. The presence of CAP led to stabilization of the folded aptamer, which generated an amplified DPV signal. The peak current of hemin increased linearly with the concentration of CAP. Under optimal conditions, two linear ranges were obtained from 0.03 to 0.15 mu M and 0.15 to 7.0 mu M, respectively, and the detection limit was 4.0 nM. The prepared biosensor has good selectivity against other non-target drugs. Thus, the sensor could provide a promising platform for the fabrication of aptasensors. The feasibility of using this aptasensor was demonstrated by determination of CAP in a human blood serum sample.