Detection of Tumor Marker Using ZnO@Reduced Graphene Oxide Decorated with Alkaline Phosphatase-Labeled Magnetic Beads

Abstract

The magnetic-bead-based electrochemical enzyme-linked immunoassay (MB-eElisa) represents an attractive approach to develop cost-effective systems that are suitable for sensing complex biological samples. Its sensitivity essentially depends on the transduction efficiency of enzyme catalytic reactions into electrochemical responses. Here, an ultrahigh signal-to-noise alkaline phosphatase (ALP)-based MB-eElisa system is developed with a renewable zinc oxide-reduced graphene oxide composite modified carbon paste electrode (ZnO@rGO/CPE). This biosensing system employs one antibody decorated MB (MB-Ab1) to capture a model tumor markercarcinoembryonic antigen (CEA)from samples, while other antibody coated gold nanoparticles-ALP bioconjugates (Ab2-AuNPs-ALP) convert 1-naphthyl phosphate (1-NPP) into electroactive 1-naphthol (1-NP). Benefitting from the unique electrochemical properties of a ZnO@rGO/CPE, including nearly zero background and significantly enhanced responses toward the hydrolyzed 1-NP in the presence of trace surfactants, the MB-eElisa system detects selectively CEA in a calibration range of 0.01–6.0 ng mL–1 and with a detection limit of 4.0 pg mL–1 (S/N = 3). Such a system was further applied to the detection of CEA in serum samples of cancer patients. The combination of MB-based ALP-linked immunoassay with a ZnO@rGO/CPE thus establishes a reusable and inexpensive electrochemical sensing platform for the rapid and sensitive detection of ultratrace biomarkers in complex biological samples.

Label free, electric field mediated ultrasensitive electrochemical point-of-care device for CEA detection

“…Thedistinguishable features of this aptasensor with respect to the existing ones includeelectric field mediated label free electrochemical detectioncoupled with the deployment of graphene/ZnO nanorod working electrode on screen printed PET substrate. This unique combination has pushed down the detection limit bymore than three orders of magnitude in comparison to recently reported labeled ZnO nanoparticle-RGO electrochemical sensor 3 . The ZnO nanorods have been immobilized with DNA aptamers against CEA using silanization protocol.…”

“…However, during the formation of early tumors, the level of this biomarker in blood starts increasing slowly. Thus, detection of CEA at ultralow concentration will help in monitoring the gradual elevation of CEA level, thereby indicating the progress of tumors which has profound impact on early stage diagnosis, condition monitoring and therapeutic evaluation of diseases 3 – 5 . Most of the commercially available CEA diagnosis procedures are based on enzyme-linked immunosorbent assay (ELISA), electrochemiluminescence and chemiluminescence enzyme immunoassay.There are also reported practices for CEA detection based on radioimmunoassay, fluorescence assay and others.…”

Recent advances of graphene–biomacromolecule nanocomposites in medical applications

“…Hao et al developed a magnetic bead-based electrochemical enzyme-linked immunoassay (MB-eElisa) system based on alkaline phosphatase (ALP)-labeling for the detection of carcinoembryonic antigen. 163 The platform based on an ALP-MB-eElisa system and ZnO–rGO carbon paste electrode has the advantages of high repeatability and low cost. This platform could be applied to clinical analysis for rapid and sensitive detection of ultra-trace biomarkers in complex biological samples.…”

An ALP enzyme-based electrochemical biosensor coated with signal-amplifying BaTiO3 nanoparticles for the detection of an antiviral drug in human blood serum

“…17 These advantages include excellent mobility, high sensitivity, quick response, affordability, reliability, low background current, simplicity in handling, and automation. 18,19 However, due to the presence of proteins, 21 electrochemical techniques may face difficulties such as electrode fouling, which hinders electron transport, 20 and causes interference when analyzing real samples for free drug (pharmacologically active) concentrations. 21 Unmodied electrodes have a few drawbacks in electrochemical sensing, including slower electron transfer kinetics, reduced reproducibility, and sensitivity at high potentials.…”