An Electrochemical Sensor Based on Gold-Nanocluster-Modified Graphene Screen-Printed Electrodes for the Detection of β-Lactoglobulin in Milk

Abstract

A simple and low-cost electrochemical sensor based on multimodified screen-printed electrodes (SPEs) was successfully synthesized for the sensitive detection of β-lactoglobulin (β-Lg). The surface treatment of SPEs was accomplished by a simple drip coating method using polyethyleneimine (PEI), reduced graphene oxide (rGO), and gold nanoclusters (AuNCs), and the treated SPEs showed excellent electrical conductivity. The modified SPEs were then characterized with UV-Vis, SEM, TEM, and FTIR to analyze the morphology and composition of the AuNCs and the rGO. An anti-β-Lg antibody was then immobilized on the composite material obtained by modifying rGO with PEI and AuNCs (PEI-rGO-AuNCs), leading to the remarkable reduction in conductivity of the SPEs due to the reaction between antigen and antibody. The sensor obtained using this novel approach enabled a limit of detection (LOD) of 0.08 ng/mL and a detection range from 0.01 to 100 ng/mL for β-Lg. Furthermore, pure milk samples from four milk brands were measured using electrochemical sensors, and the results were in excellent agreement with those from commercial enzyme-linked immunosorbent assay (ELISA) methods.

An Electrochemical Molecularly Imprinted Polymer Sensor for Rapid β-Lactoglobulin Detection

“…Furthermore, the obtained electrochemical sensor was successfully applied in the determination of β-Lg in real-world samples, and the results were similar to a commercial ELISA kit, which is considered as reliable analysis. The expensive β-Lg antibody from our previous research [27] was replaced with MIP, which significantly increased the selective surface area of PEI-rGO-Au-NCs@MIP and improved its sensitivity by providing a large number of imprinted sites, which resulted in a low detection limit (LOD = 10 −9 mg/mL) and a wide linear range (10 −9 to 10 −4 mg/mL). In addition, MIP transformation by changing the template molecule may provide a new strategy for the development of electrochemical sensors, not only for β-Lg, but also for other substances.…”

“…The PEI-rGO-Au-NCs were prepared according to our previous report [27]. Briefly, GSH-modified Au-NCs and PEI-rGO were synthesized separately.…”

Recent Advances in Electrochemical Sensing Strategies for Food Allergen Detection

“…Coming back to β-LB detection, already introduced at the end of the previous section, we consider an electrochemical immunosensor based on screen-printed carbon electrodes (SPCEs) modified by a simple drip coating using a nanocomposite. The nanocomposite (PEI-rGO-AuNCs) included reduced graphene oxide (rGO) functionalized with polyethyleneimine (PEI) and gold nanoclusters (AuNCs) modified with glutathione (GSH) [ 72 ]. A β-LB antibody (β-LB-Ab) was then immobilized on the nanocomposite, inducing a reduction in SPE conductivity and the current change due to the immunoreaction reaction between antigen and antibody was recorded for the β-LB detection.…”

Electrochemical Biosensors in Food Safety: Challenges and Perspectives

“…An electrochemical immunosensor based on modified screen-printed electrodes (SPEs) was designed to detect β -lactoglobulin (β-Lg) [ 215 ]. The surface modification of SPEs was accomplished by a simple drip coating using polyethyleneimine (PEI), reduced graphene oxide (rGO), and gold nanoclusters (AuNCs), and the obtained SPEs showed a good electrical conductivity.…”