A voltammetric immunoassay for the carcinoembryonic antigen using a self-assembled magnetic nanocomposite

Electrochemistry/Photoelectrochemistry-Based Immunosensing and Aptasensing of Carcinoembryonic Antigen

Recently, electrochemistry- and photoelectrochemistry-based biosensors have been regarded as powerful tools for trace monitoring of carcinoembryonic antigen (CEA) due to the fact of their intrinsic advantages (e.g., high sensitivity, excellent selectivity, small background, and low cost), which play an important role in early cancer screening and diagnosis and benefit people's increasing demands for medical and health services. Thus, this mini-review will introduce the current trends in electrochemical and photoelectrochemical biosensors for CEA assay and classify them into two main categories according to the interactions between target and biorecognition elements: immunosensors and aptasensors. Some recent illustrative examples are summarized for interested readers, accompanied by simple descriptions of the related signaling strategies, advanced materials, and detection modes. Finally, the development prospects and challenges of future electrochemical and photoelectrochemical biosensors are considered.

Design of organic/inorganic nanocomposites for ultrasensitive electrochemical detection of a cancer biomarker protein

A new type of nanocomposite composed of carboxylated single-walled carbon nanotubes (CNTs-COOH), reduced graphene oxide (rGO), bovine serum albumin-Ag hybride (Ag@BSA), and poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated to develop an ultrasensitive electrochemical platform for the detection of carcinoembryonic antigen (CEA) as a model of biomarkers. Two steps are involved for the fabrication of the organic/inorganic nanocomposites. The Ag@BSA nanoflowers were first synthesized to be doped with CNTs-COOH and rGO followed by the adsorption of PEDOT resulting in CNTs-COOH/rGO/Ag@BSA/PEDOT. The as-prepared nanocomposites were then deposited onto an Au electrode together with subsequent immobilization of CEA antibody (anti-CEA) to construct the electrochemical immunosensor. This unique structure and composition of the developed immunosensor can expect an excellent electrochemical response. The immunosensor offers a linear relationship between the electrochemical responses and the CEA concentrations from 0.002 to 50 ng∙mL^-1 with a detection limit of 1 × 10^-4 ng∙mL^-1. Moreover, the ultrasensitive immunoassay can detect CEA in real human serum samples, and the results are comparable to those obtained from the commercial ELISA. Therefore, this strategy can monitor diseases, offer clinical diagnosis, and may be valuable for the development of new biomedical devices.

Magnetic nanoparticles for smart electrochemical immunoassays: a review on recent developments

This review (with 129 refs) summarizes the progress in electrochemical immunoassays combined with magnetic particles that was made in the past 5 years. The specifity of antibodies linked to electrochemical transduction (by amperometry, voltammetry, impedimetry or electrochemiluminescence) gains further attractive features by introducing magnetic nanoparticles (MNPs). This enables fairly easy preconcentration of analytes, minimizes matrix effects, and introduces an appropriate label. Following an introduction into the fundamentals of electrochemical immunoassays and on nanomaterials for respective uses, a large chapter addresses method for magnetic capture and preconcentration of analytes. A next chapter discusses commonly used labels such as dots, enzymes, metal and metal oxide nanoparticles and combined clusters. The large field of hybrid nanomaterials for use in such immunoassays is discussed next, with a focus on MNPs composites with various kinds of graphene variants, polydopamine, noble metal nanoparticles or nanotubes. Typical applications address clinical markers (mainly blood and urine parameters), diagnosis of cancer (markers and cells), detection of pathogens (with subsections on viruses and bacteria), and environmental and food contaminants as toxic agents and pesticides. A concluding section summarizes the present status, current challenges, and highlights future trends. Graphical abstract Magnetic nanoparticles (MNP) with antibodies (Ab) capture and preconcentrate analyte from sample (a) and afterwards become magnetically (b) or immunospecifically (c) bound at an electrode. Signal either increases due to the presence of alabel (b) or decreases as the redox probe is blocked (c).