Aptamer-Based Approach as Potential Tools for Construction the Electrochemical Aptasensor.

Herein, a simple and feasible electrochemical sensing strategy is reported for ultrasensitive detection of urea based on the direct electron transfer of [Fe(CN)6]^3−/4− redox probe. Label-free electrochemical assay of urea was carried out based on signal amplification of carbon nanotubes (CNTs)/amine-functionalized graphene oxide (NH2-GO) as a sensing platform and utilizing urea-aptamer as recognition probe. GO was functionalized with primary amine by a one-pot solvothermal process using ethylene glycol as solvent and ammonia water as nitrogen precursor. The significant current signal of aptasensor was recorded in the presence of redox probe unless the aptamer interacted with target molecule. Upon addition of target urea, the analyte reacted with the aptamer and induced folding and conformational change of aptamer structure. Due to the formation of urea/aptamer complex at the surface of modified electrode and electron transfer hindrance, a week electrochemical signal was expected in the presence of urea. Effect of various factors such as urea incubation time and pH of incubation solution on the function of aptasensor were evaluated. Under optimum condition, the limit of detection for biosensor was found to be 370 pM with linear response extending to 2000 nM. Also, the reproducibility, stability and selectivity of the system were acceptable. [ABSTRACT FROM AUTHOR]

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