Microfluidic electrochemical immunosensor for the determination of cystatin C in human serum
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ORIGINAL PAPER
Microfluidic electrochemical immunosensor for the determination of cystatin C in human serum K. S. Shalini Devi 1,2 & Uma Maheswari Krishnan 1,2,3 Received: 9 March 2020 / Accepted: 18 August 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The fabrication of a nanointerfaced electrochemical immunosensor is described for the rapid determination of cystatin C, a biomarker that is elevated in diabetic retinopathy. A dispersion of graphene oxide-chitosan (GO-Chit) nanocomposite was used to modify the carbon working electrode, allowing for a high conjugation of anti–cystatin C antibody. This modified sensor was characterized both morphologically and electrochemically, and the sensor performance was evaluated towards selective quantification of cystatin C in simulated as well as serum samples using cyclic voltammetry and differential pulse voltammetry. The sensor was able to detect cystatin C in the concentration range1 - 10 mg/L with a detection limit of 0.0078 mg/L. The preparation time of the sensor was 420 s, which was faster than that of conventional ELISA and other electrochemical sensors reported in literature. The clinical applicability of the proposed electrochemical biosensor was demonstrated through quantification of cystatin C in human serum samples and identification of diabetic retinopathy. A cutoff value of 1.2 mg/L of cystatin C was used beyond which the samples were classified as positive for diabetic retinopathy. Two different working electrodes, namely a glassy carbon electrode (GCE) and paper electrodes, were used in the study. The working potential was set to 0.25 V vs. Ag/AgCl for experiments with the GCE and 0.15 V for the paper electrodes. The prediction was validated by clinical diagnosis wherein the prediction accuracy of the sensor exceeded 85%. The sensor platform was translated onto a paper substrate and characterized for achieving an optimum sensing performance. This work is the first attempt to employ an electrochemical cystatin C sensor for the diagnosis of diabetic retinopathy from serum samples. Keywords Cystatin C . Immunosensor . Diabetic retinopathy . Electrochemical detection . ELISA
Introduction Over the years, there has been an increasing incidence of diabetic retinopathy (DR) in Indian population due to high blood pressure, smoking and alcohol consumption, time since Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-020-04503-4) contains supplementary material, which is available to authorized users. * Uma Maheswari Krishnan [email protected] 1
Centre for Nanotechnology and Advanced Biomaterials (CeNTAB), SASTRA Deemed-to-be University, Thanjavur, Tamil Nadu 613401, India
2
School of Chemical and Biotechnology, SASTRA Deemed University, Thanjavur 613401, India
3
School of Arts, Science and Humanities, SASTRA Deemed University, Thanjavur 613401, India
onset of diabetes, ethnicity, gestational diabetes, and serum lipid levels in an individual. Despite several biomarkers indicat
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