Plastic Antibody of Polypyrrole/Multiwall Carbon Nanotubes on Screen-Printed Electrodes for Cystatin C Detection

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.

Biomarkers: Promising and valuable tools towards diagnosis, prognosis and treatment of Covid-19 and other diseases

“…Hepcidin-25 is an iron-binding protein associated with acute kidney injury that is used as a novel kidney biomarker in serum and urine specimens for major adverse kidney events after cardiac surgery [ 152 ]. A novel synthetic antibody of polypyrrole/Multiwall carbon nanotubes on a carbon screen-printed electrode was designed to detect the kidney biomarker cystatin C at the point of care [ 153 ]. Recently, FDA approved a panel of six urine creatinine-normalized biomarkers, including clusterin, cystatin C, kidney injury molecule 1, N -acetyl-β- d -glucosaminidase, neutrophil gelatinase-associated lipocalin, and osteopontin for the detection of preclinical ASO-induced kidney pathology [ 154 ].…”

Advances in Biosensor Technologies for Acute Kidney Injury

“…65 Recently, a study combined MIP and carbon-stemmed SPEs to determine Cys C levels. 66 Creating molecularly imprinted poly(Py) matrix (MPPy) on the electrode enabled a rapid and simple procedure, as well as resulting in good reproducibility, accuracy, and linearity within the biomarker concentrations. During the polymerization, pyrrole (Py) was used to improve electrocatalytic properties of the electrode.…”

“…The concentration of Cys C was determined via CV and DPV, and the LOD was quantified as 0.5 ng/mL at pH 6.0 along with a linear dynamic range from 0.5 to 20.0 ng/mL when 20 min incubation was applied. 66 ■ PLASMONIC-BASED SENSOR SYSTEMS Most of the state-of-the-art plasmonic biosensors measure binding affinity and monitor kinetic rates in real-time through the tracking of the refractive index (RI). 67 Plasmonic resonance nanostructures have attracted notable interest in the scientific community to develop biosensors due to sensitive detection capability of biomolecules in biological fluids.…”

“…Consequently, the platform provided 0.58 ng/L of LOD, and sensitivity was measured as 1583.49 μA cm –2 μg –1 , holding a pivotal potential as a portable device for AKI diagnosis . Recently, a study combined MIP and carbon-stemmed SPEs to determine Cys C levels . Creating molecularly imprinted poly­(Py) matrix (MPPy) on the electrode enabled a rapid and simple procedure, as well as resulting in good reproducibility, accuracy, and linearity within the biomarker concentrations.…”

“…Integrating MWCNTs formed more porous and larger surface area; therefore, 3D MPPy structures could be attained with enhancements in the sensitivity. The concentration of Cys C was determined via CV and DPV, and the LOD was quantified as 0.5 ng/mL at pH 6.0 along with a linear dynamic range from 0.5 to 20.0 ng/mL when 20 min incubation was applied …”