Abstract
This work reports the design of a novel plastic antibody for cystatin C (Cys-C), an acute kidney injury biomarker, and its application in point-of-care (PoC) testing. The synthetic antibody was obtained by tailoring a molecularly imprinted polymer (MIP) on a carbon screen-printed electrode (SPE). The MIP was obtained by electropolymerizing pyrrole (Py) with carboxylated Py (Py-COOH) in the presence of Cys-C and multiwall carbon nanotubes (MWCNTs). Cys-C was removed from the molecularly imprinted poly(Py) matrix (MPPy) by urea treatment. As a control, a non-imprinted poly(Py) matrix (NPPy) was obtained by the same procedure, but without Cys-C. The assembly of the MIP material was evaluated in situ by Raman spectroscopy and the binding ability of Cys-C was evaluated by the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) electrochemical techniques. The MIP sensor responses were measured by the DPV anodic peaks obtained in the presence of ferro/ferricyanide. The peak currents decreased linearly from 0.5 to 20.0 ng/mL of Cys-C at each 20 min successive incubation and a limit of detection below 0.5 ng/mL was obtained at pH 6.0. The MPPy/SPE was used to analyze Cys-C in spiked serum samples, showing recoveries <3%. This device showed promising features in terms of simplicity, cost and sensitivity for acute kidney injury diagnosis at the point of care.
Highlights
Worldwide, chronic kidney disease (CKD) constitutes a great economic impact with high rates of morbidity and mortality [1]
acute kidney injury (AKI) is characterized by a rapid decline in the glomerular filtration rate, biomarkers should be continuously monitored in chronic renal patients to increase their survival rates [3,4]
Cystatin C (Cys-C) is a single non-glycosylated polypeptide chain consisting of 120 amino acid residues with a molecular mass of 13 kDa, and is more specific as a renal biomarker for glomerular filtration than creatinine, because it does not depend on gender, age, diet and muscle mass [4,5,6,7,8]
Summary
Chronic kidney disease (CKD) constitutes a great economic impact with high rates of morbidity and mortality [1]. Due to the major advances in nanotechnology [9], several biosensors for Cys-C have been developed for this purpose Most of these are immunosensors and employ naturally derived antibodies. As an alternative to immunosensors, enzymatic-based sensors have been developed [17] Overall, all these sensing materials are of natural origin, making the devices less stable, less reproducible and more expensive. MIPs are known as plastic antibodies for mimicking the behavior of antibodies obtained from biological sources These polymers can selectively recognize a given target molecule to which they are designed. This work reports, for the first time, MIP material for Cys-C, produced by electropolymerizing in situ Py-based monomers in the presence of the target protein. MIP synthesis was optimized, characterized and suitable and applied to check application feasibility of the final biosensor
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