A highly sensitive immunosensor based on ITO thin films covered by a new semi-conductive conjugated polymer for the determination of TNF alpha in human saliva and serum samples


BIOSENSORS & BIOELECTRONICS, vol.97, pp.169-176, 2017 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 97
  • Publication Date: 2017
  • Doi Number: 10.1016/j.bios.2017.05.056
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.169-176
  • Keywords: Tumor necrosis factor alpha, Label free biosensor, Electrochemical impedance spectroscopy, Saliva biomarker, TUMOR-NECROSIS-FACTOR, LABEL-FREE, ELECTROCHEMICAL IMMUNOSENSOR, EARLY-DIAGNOSIS, BIOSENSOR, INTERLEUKIN-6, APTASENSOR, BIOMARKERS, NANOPARTICLES, PROGRESSION
  • Çanakkale Onsekiz Mart University Affiliated: Yes


A novel, ultrasensitive impedimetric immunosensor was constructed for the detection of tumor necrosis factor alpha (TNF alpha) by using Poly(3-thiophene acetic acid) (P3), a conjugated polymer as an immobilization matrix. The polymer P3 contains a lot of carboxylic acid groups on its surface that provide a larger biorecognition surface. This developed immunosensor was prepared on hydroxy-bearing ITO surface via an ester bond linkage of polymer P3 to immobilize anti-TNF alpha antibodies. The ITO electrode modification steps and interaction between anti-TNF alpha antibody and TNF alpha antigen were monitored by cyclic voltammetry (CV) and by electrochemical impedance spectroscopy (EIS) method. After the analytical parameters optimization, a linear detection response from 0.01 pg/mL to 2 pg/mL, a limit of detection LOD of 3.7 fg/mL and a limit of quantification (LOQ) of 12.4 fg/mL were achieved, which provided accurate results (relative standard deviation; 4.03%). The characterization of this developed immunosensor was performed by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive X-ray (EDX) mapping and atomic force microscopy (AFM). The immunosensor allowed a simple and fast detection of TNF alpha antigen in human serum and satisfied recoveries (98.69-105.20%) were obtained by using standard addition method.