Microfluidic-integrated patterned ITO immunosensor for rapid detection of prostate-specific membrane antigen biomarker in prostate cancer

Abstract(#br)An optically transparent patterned indium tin oxide (ITO) three-electrode sensor integrated with a microfluidic channel was designed for label-free immunosensing of prostate-specific membrane antigen (PSMA), a prostate cancer (PCa) biomarker, expressed on prostate tissue and circulating tumor cells but also found in serum. The sensor relies on cysteamine capped gold nanoparticles (N-AuNPs) covalently linked with anti-PSMA antibody (Ab) for target specificity. A polydimethylsiloxane (PDMS) microfluidic channel is used to efficiently and reproducibly introduce sample containing soluble proteins/cells to the sensor. The PSMA is detected and quantified by measuring the change in differential pulse voltammetry signal of a redox probe ([Fe(CN) 6 ] 3– /[Fe(CN) 6 ] 4– ) that is altered upon binding of PSMA with PSMA-Ab immobilized on N-AuNPs/ITO. Detection of PSMA expressing cells and soluble PSMA was tested. The limit of detection (LOD) of the sensor for PSMA-based PCa cells is 6/40\u003cce:hsp sp=\"0.25\"/\u003eµL (i.e., 150 cells/mL) (n=3) with a linear range of 15–400 cells/40\u003cce:hsp sp=\"0.25\"/\u003eµL (i.e., 375–10,000 cells/mL), and for the soluble PSMA is 0.499\u003cce:hsp sp=\"0.25\"/\u003eng/40\u003cce:hsp sp=\"0.25\"/\u003eµL (i.e., 12.5\u003cce:hsp sp=\"0.25\"/\u003eng/mL) (n=3) with the linear range of 0.75–250\u003cce:hsp sp=\"0.25\"/\u003eng/40\u003cce:hsp sp=\"0.25\"/\u003eµL (i.e., 19–6250\u003cce:hsp sp=\"0.25\"/\u003eng/mL), both with an incubation time of 10\u003cce:hsp sp=\"0.25\"/\u003emin. The results indicate that the sensor has a suitable sensitivity and dynamic range for routine detection of PCa circulating tumor cells and can be adapted to detect other biomarkers/cancer cells.