Spectroelectrochemical Nanosensor for the Determination of Cystatin C in Human Blood

Abstract

The detection of protein biomarkers for the clinical diagnosis of diseases requires selective and sensitive methodologies and biosensors that can be easily used at pathology laboratories and points of care. An ideal methodology would be able to conduct multimode screening of low and high concentrations of proteins in biological fluids using recyclable platforms. In this work, we demonstrate a novel nanosensing methodology for the dual detection of cystatin C (CST-C), as a protein biomarker model, in blood plasma by surface-enhanced Raman spectroscopy and electrochemistry. The new methodology utilizes the thiol chemistry of biomolecules to develop a target-specific and recyclable extractor chip for the rapid isolation of protein biomarkers from blood plasma. This is followed by the rapid reduction of the disulfide bonds within the isolated protein to influence its oriented immobilization onto a conductive gold coated silicon nanopillar substrate via stable gold-sulfur (Au-S) bonds. The oriented immobilization led to reproducible surface-enhanced Raman spectroscopy (SERS) measurements of the reduced protein (RSD = 3.8%) and allowed for its direct electrochemical determination. After the SERS measurement, differential pulse voltammetry (DPV) was used to desorb the analyte from the substrate and generate a reduction current that is proportional to its concentration. CST-C was determined down to 1 pM and 62.5 nM by SERS and DPV, respectively, which satisfies the requirements for monitoring Alzheimer's and kidney failure diseases. The new dual nanosensing methodology has strong potential for miniaturization in a lab-on-a-chip platform for the screening of many protein biomarkers that have a disulfide bond structure.

Toward Label-Free SERS Detection of Proteins through Their Disulfide Bond Structure

“…The software algorithm of the instrument (OceanView Spectroscopy 1.5.07) automatically averages and corrects the background noise and fluorescence within the acquired spectra. 3,21…”

Gold-Deposited Nickel Foam as Recyclable Plasmonic Sensor for Therapeutic Drug Monitoring in Blood by Surface-Enhanced Raman Spectroscopy

“…The SERS spectra were collected using 10 accumulations and an acquisition time of 1 s per measurement. The background noise and fluorescence in the Raman measurements were automatically corrected by the instrument software algorithm (OceanView Spectroscopy 1.5.07, Dunedin, FL, USA) [ 16 , 22 ]. The high-performance liquid chromatography (HPLC) measurements were carried out using Agilent HPLC Series 1100 with a Diode array detector (Waldbronn, Germany) and the detector was set at 298 nm.…”

Spectroelectrochemical Sensing: Current Trends and Challenges

“…A huge variety of information can be obtained using SEC, for example, formal potentials , electron transfer rate constants , diffusion coefficients , number of electrons , molar absorption coefficients , band‐gaps , among many others. SEC has also been used in different types of quantitative analysis such as pharmaceutical , food , clinical , environmental or industrial .…”

“…Nanostructured electrodes have been used to determine cystatin C, which is used as a protein biomarker model useful for the early diagnosis of Alzheimer's disease, in blood plasma down to 1 pM and a low RSD (3.8 %) . In this work, cystatin is determined using both SERS and differential pulse voltammetry.…”