Detection of inducible nitric oxide synthase using a suite of electrochemical, fluorescence, and surface plasmon resonance biosensors
Noah, Naumih M
Sadik, Omowunmi A.
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A suite of biosensors for rapid detection of inducible nitric oxide synthase (iNOS) is described. First, a metal-enhanced electrochemical detection (MED) sensor, which relied on the redox properties of a silver monolayer, was developed. The linear detection range was between 8.64×10(-2) and 5.4×10(1)ng/ml with a detection limit of 1.69×10(-4)ng/ml. This method was compared with surface plasmon resonance (SPR) biosensors in which polyclonal mouse anti-iNOS was covalently immobilized onto a gold surface using an iNOS antigen. The linear detection range recorded was between 3.37×10(1) and 5.4×10(-2)ng/ml with a detection limit of 2×10(-3)ng/ml. Finally, an ultrasensitive portable capillary (UPAC) fluorescence immunosensor, in which a mouse anti-iNOS antibody was covalently immobilized onto the inner surface of a capillary and a rabbit anti-iNOS antibody was employed as the secondary antibody, was developed. The resulting signals were found to be directly proportional to iNOS concentrations between 1.52×10(-1) and 1.52×10(-2)ng/ml with a detection limit of 1.05×10(-3)ng/ml. These immunosensors exhibit low cross-reactivity toward potential interferents such as human serum albumin and ovalbumin. The SPR and UPAC biosensors were validated using simulated blood spiked with recombinant iNOS, resulting in recoveries of 85% and 88.5%, respectively. The research presented in this article could potentially provide new ways of detecting NO for diagnostic and biomarker purposes in medical research.