Immobilization of aptamer on gold nanoparticles

Aim and Background: Biosensors are composed of two sections including bioreceptor and transducer. Aptamers can be used as a bioreceptor for the detection of bio-chemical analytes. In this work, gold nanoparticle modified carbon electrode was selected as a working electrode and aptamer as a bioreceptor. Methods: Gold nanoparticles was electrodeposited on the carbon electrode surface. Then aptamer was placed on the gold nanoparticles modified carbon electrode. Two parameters including pH and temperature was chosen for investigation of maximum immobilization of aptamer on the surface of carbon electrode. The electrode characterizatied using cyclic voltammetry (CV) and scanning electron microscope (SEM). Results and discussion: First, the bare carbon electrode was characterized by cyclic voltammetry. After electrodeposition of gold nanoparticles on the carbon electrode, the current enhanced due to conductivity of gold nanoparticles. Afterwards, Aptamers were placed on the surface of gold nanoparticles modified carbon electrode. The results exhibited that the current decreased as aptamer acts as a non-conductive bioreceptor. Moreover, the structural features of the gold nanoparticles on the surface of carbon electrodes were confirmed by SEM. Conclusion: Results shown that temperature and pH are considered as two important factors for immobilization of aptamers as a bioreceptor on the electrode surface for the application in the electrochemical biosensors.