PEP-on-DEP: A competitive peptide-based disposable electrochemical aptasensor for renin diagnostics

Abstract Antibody-based immunosensors are relatively less accessible to a wide variety of unreachable targets, such as low-molecular-weight biomarkers that represent a rich untapped source of disease-specific diagnostic information. Here, we present a peptide aptamer-based electrochemical sensor technology called ‘PEP-on-DEP’ to detect less accessible target molecules, such as renin, and to improve the quality of life. Peptide-based aptamersrepresent a relatively smart class of affinity binders and show great promise in biosensor development. Renin is involved in the regulation of arterial blood pressure and is an emerging biomarker protein for predicting cardiovascular risk and prognosis. To our knowledge, no studies have described aptamermolecules that can be used as new potent probes for renin. Here, we describe a portable electrochemical biosensor platform based on the newly identified peptide aptamermolecules for renin. We constructed a randomized octapeptide library pool with diversified sequences and selected renin specific peptide aptamersusing cDNA display technology. We identified a few peptide aptamersequences with a K D in the µM binding affinity range for renin. Next, we grafted the selected peptide aptamersonto gold nanoparticles and detected renin in a one-step competitive assay using our originally developed DEP (Disposable Electrochemical Printed) chip and a USB powered portable potentiostat system. We successfully detected renin in as little as 300 ng mL −1 using the PEP-on-DEP method. Thus, the generation and characterization of novel probes for unreachable target molecules by merging a newly identified peptide aptamerwith electrochemical transduction allowed for the development of a more practical biosensor that, in principle, can be adapted to develop a portable, low-cost and mass-producible biosensor for point-of-care applications.