Immunosensors for detection of Annexin II and MUC5AC for early diagnosis of lung cancer

Amperometric immunosensors were developed to diagnose lung cancer through the detection of Annexin II and MUC5AC. To fabricate the sensor probe, a conducting polymer (poly-terthiophene carboxylic acid; poly-TTCA) was electropolymerized onto a gold nanoparticle/glassy carbon electrode (AuNP/GCE) and a dendrimer (Den) was covalently bonded to the poly-TTCA through amide bond formation, where AuNPs were doped onto the dendrimer. To obtain the final sensor probe, an antibody (anti-Annexin II) and hydrazine (Hyd), which is a catalyst for the reduction of H2O2 generated by glucose oxidase (GOx), were covalently attached onto the Den/AuNP-modified surface. Each surface was then characterized by SEM, impedance spectroscopy and XPS. The final sensor probe was examined before and after interaction with Annexin II and MUC5AC using impedance-spectroscopic, quartz crystal microbalance and amperometric methods. The performance of the immunosensor for the Annexin II was evaluated for the apical surface fluid labeled with GOx by the standard addition method. In this case, the detection limit of the proposed method was 0.051 ng/mL (k = 3, n = 5). The Annexin II concentration in the secretions collected from squamous metaplastic cells was determined to be 280 +/- 8.0 pg/mL (n = 5). (C) 2009 Elsevier B.V. All rights reserved.