Highly sensitive biosensor based on graphene-poly (3-aminobenzoic acid) modified electrodes and porous-hollowed-silver-gold nanoparticle labelling for prostate cancer detection

Recent studies show that electrochemical biosensors offer simple, robust and low-cost solution for point-of-care applications. To meet rigorous requirements of early disease diagnosis and other medical applications, nanomaterials have been investigated to increase sensitivity and selectivity of electrochemical sensors. Herein, we successfully developed graphene-poly(3-aminobenzoic acid) (GP-P3ABA) nanomaterial-conductive polymer composite for electrode modification and metal ion loaded porous-hollowed-silver-gold core-shell nanoparticles (PHSGNPs) labelling for signal amplification. With GP-P3ABA modified electrodes, the sensing response is about 16 times higher than ones without nanocomposite due to reduction in electrode impedance and more probe binding sites from P3ABA terminals, respectively. Incubation time and volume of CuCl2 solution were optimized for maximum absorbed Cu ions on the nanoparticles and electrochemical current. It is found that our investigated system has about 3 folds higher electrochemical current from PHSGNPs than from gold nanoparticles (AuNPs) due to larger surface area of PHSGNPs to anchor Cu ions. With combination of GP-P3ABA electrode modification and PHSGNP labelling, sensing performance is improved by 120 folds over AuNP labelling and the limit of detection (LOD) reaches 0.13 pg/mL or 4 orders of magnitude better than the clinically relevant level in human serum. With good sensitivity and specificity, these inexpensive sensor strips could be applied for early diagnosis of prostate cancer and other medical applications in the future.