Development of a new aptasensor based on functionalized SBA-15 modified screen-printed electrode for determination of chloramphenicol

Aptamers are single-stranded oligonucleic acids, which are obtained by an in vitro selection process called systematic evolution of ligands by exponential enrichment (SELEX). Based ontheir three dimensional structure (3D), aptamers can specifically bind to a variety of targets, suchas enzymes, antibodies and drugs (1). In this project, aptamer is used as a molecular recognition element. Hemin also acts as an electrochemical indicator (2, 3). Controlling the immobilizationof the aptamer on the electrode surface is an important step in designing this aptasensor. For this purpose, a SPE was modified with the functionalized SBA-15. Then, the electrodeposition of the Au nanoparticles (AuNPs) was performed to transfer these particles on the functionalized SBA-15 surface. This step connects the thiolated aptamer on the electrode by Au-S bonds. In theabsence of Cap, hemin bound to the aptamer and produced 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 experimental parameters such as aptamer concentration, aptamer immobilization time, incubation time and pH were optimized for the analysis of the CAP. Under optimal conditions, two linear ranges were obtained from 0.03 to 0.15 μM and 0.5– 7.0 μM, respectively. The detection limit was 4.0 nM. This constructed biosensor had a good selectivity against the other non-target drugs. Thus the sensor could provide a promising plan for the fabrication of aptasensor.

Keywords:

Hemin , Chloramphenicol , Aptasensor , Screen-printed graphite electrode