Smartphone-Enabled Electrochemical Biosensor for Simultaneous Detection of Cancer Biomarkers Using f-WS₂@AuNPs...

The present work focuses on the development of a disposable electrochemical biosensor for simultaneous dual cancer biomarker detection onto a single-sensing platform. For this, an indigenously designed four-electrode system having two working areas of electrodes on a single screen-printed electrode (SPE) substrate was coated by graphite-based conductive ink. The first working electrode surface decorated by the prepared complex is composed of chitosan-functionalized 1T phase of tungsten disulfide-gold nanoparticles (f-WS₂@AuNPs) composite and activated antibodies of tagged Cancer Antigen 125 (ab-tg-CA-125), while the second working electrode contained f-WS₂@AuNPs and antibody of Human Epididymis protein 4 (ab-HE4). Further, both working electrodes were passivated by BSA to block nonspecific signals. Dual antibody-immobilized platforms of ab-tg-CA-125/f-WS₂@AuNPs/SPE and ab-HE4/f-WS₂@AuNPs/SPE were further used for simultaneous detection of two ovarian cancer biomarkers of CA-125 and HE4 using an electrochemical differential pulse voltammetry (DPV) technique. Fabricated electrochemical immunosensing platforms of ab-tg-CA-125/f-WS₂@AuNPs/SPE and ab-HE4/f-WS₂@AuNPs/SPE worked in the range of 0.001-25 μg mL^-1 for CA-125 detection and 0.001-10 ng mL^-1 for HE4 detection. The developed immunosensor showed a limit of detection of 0.001 μg mL^-1 for CA-125 and 0.001 ng mL^-1 for HE4. Also, the sensitivity of the developed electrochemical biosensor was calculated for CA-125 and HE4 and found to be 1.43 μA(log μg mL^-1)^-1 cm^-2 and 1.092 μA(log ng mL^-1)^-1 cm^-2, respectively. Both ab-CA-125 and ab-HE4 antibodies exhibit a larger value of association constant (K_a) and reveals strong binding affinity of antibodies toward respective cancer biomarkers. Moreover, the developed biosensors were tested with clinical ovarian patient serum samples, and the results were compared with the immunoassay kit. Therefore, these findings show the effective biosensor performance in terms of sensitivity, selectivity, accuracy, and faster response for simultaneous ovarian biomarker detection in clinical samples.