Electrochemical Biosensor for the detection of low density lipoprotein based on gold nanoparticles mediated bi-enzymes catalytic silver deposition reaction
Ruiyu Luo, J. Li, Guoying Huang, Guiyin Li, Shibin Guo, Yulin Yuan
Abstract
Low-density lipoprotein (LDL) levels are utilized in the assessment of an individual's cardiovascular disease risk and serve as a valuable tool in the determination of appropriate treatment plans. This study aimed to design and evaluate a novel electrochemical biosensor using a modified glassy carbon electrode (GCE) coated with gold nanoparticles (Au-NPs) and poly-o-aminobenzenethiol (poly(oATP)) films. The novel biosensor was designed to effectively detect and measure LDL levels in biological samples. In this study, antibody apolipoprotein B (AAB) was employed as a biorecognition element to capture LDL and was subsequently immobilized on the surface of the GCE/poly(oATP)/AuNPs. Cholesterol esterase and cholesterol oxidase bi-enzymes were applied to the GCE/poly(oATP)/AuNPs/AAB/LDL surface, catalyzing the oxidation of LDL and producing hydrogen peroxide (H2O2). The generated H2O2, in turn, facilitated the reduction of silver (Ag) ions in the solution to metallic Ag, depositing it on the GCE/poly(oATP)/AuNPs surface. The quantification of the deposited Ag, originating from the LDL, was achieved using linear sweep voltammetry. Further, we found a linear relationship between the oxidation current of the deposited Ag and the concentration of LDL, spanning from 10 to 1,000 ng/mL, with an optimal correlation coefficient of 0.9982. The limit of detection for the assay was established at 3.25 ng/mL, determined by a signal-to-noise ratio of 3. In addition, the ultrasensitive LDL biosensor demonstrated high specificity, acceptable reproducibility, and prolonged stability. These findings highlighted the successful application of this novel method for detecting LDL levels in human serum samples.