A label-free electrochemical biosensor based on tubulin immobilized on gold nanoparticle/glassy carbon electrode for the determination of vinblastine.

Vinblastine (VLB) is prescribed for a wide variety of cancers. Therefore, development of sensitive methods for early diagnosis is urgently required. In this work, a highly sensitive and label-free impedimetric biosensor was fabricated for the electrochemical detection of VLB. First, the gold nanoparticles (AuNPs) were electrodeposited on the surface of a glassy carbon electrode (GCE). 3-Mercaptopropionic acid (MPA) was self-assembled over the AuNPs. Then, tubulin (TUB), as a receptor, was covalently immobilized at the AuNPs/GCE surface via carbodiimide coupling reaction using N-(3 dimethylaminopropyl)-N'-ethyl carbodiimide (EDC) and N-hydroxy succinimide (NHS). The step-by-step modification process was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the presence of a redox probe [Fe(CN)6 ]3-/4- . The VLB concentration was measured through the increase of impedance values in the corresponding specific binding of VLB and TUB. The increased electron-transfer resistance (R et ) values were proportional to the value of VLB concentrations in the range of 0.4 to 65.0 nmol L-1 with a detection limit of 8.4 × 10-2  nmol L-1 (SN-1  = 3). The practical analytical performance of the proposed method was demonstrated by determination of VLB in plant extracts and human serum samples with satisfactory recoveries.