Quantification of Carcinoembryonic Antigen by Capillary Electrophoresis–Chemiluminescence Detection using Internal Standard Method

Ultrasensitive Detection of Carcinoembryonic Antigen by Chitosan/Polythiophene/CdTe Electrochemical Biosensor

A facile method for the in situ fabrication of chitosan/polythiophene/CdTe (CS/PTh/CdTe) nanocomposite has been developed. It was then connected with anti-CEA (Ab), which was evoked for the electrochemical detection of carcinoembryonic antigen (CEA, Ag) within K₄Fe(CN)₆. The results indicate that CS/PTh/CdTe/GCE has a high selectivity for the detection of CEA with a wide linear range of 0.0001-10000 ng/mL and excellent sensitivity with a low detection limit of 40 fg/mL. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and in situ FT-IR spectra are evoked to study the mechanism of detection of CEA via CS/PTh/CdTe/GCE. The high sensitivity of the electrochemical sensor is due to the fact that the electrochemical oxidation products of K₄Fe(CN)₆ can directly oxidize CdTe from a low energy state to a high energy state (CdTe)*, making CdTe more prone to be oxidized and facilitate electron transfer. The developed electrochemical biosensor can be used for the detection of real samples, providing a precise method for the detection of CEA with potential application in the clinical detection of tumors.

Aptamer-Templated Silver Nanoclusters Embedded in Zirconium Metal-Organic Framework for Bifunctional Electrochemical and SPR Aptasensors toward Carcinoembryonic Antigen

This study reported a novel biosensor based on the nanocomposite of zirconium metal-organic framework (Zr-MOF, UiO-66) embedded with silver nanoclusters (Ag NCs) using the carcinoembryonic antigen (CEA)-targeted aptamer as template (AgNCs@Apt@UiO-66). The synthesized AgNCs@Apt@UiO-66 nanocomposite not only possesses good biocompatibility, active electrochemical performance, and strong bioaffinity, but also can be dispersed to form two-dimensional nanocomposite with nanoscale thickness. As such, the use of the AgNCs@CEA-aptamer enables AgNC@Apt@UiO-66 with sensitive and selective detection capacity of trace CEA, further concurrently being exploited as scaffold for surface plasmon resonance spectroscopy (SPR) and electrochemical biosensors. The results showed that the proposed electrochemical AgNC@Apt@UiO-66-based aptasensor exhibits high sensitivity with a low detection limit (LOD) of 8.88 and 4.93 pg·mL^-1 deduced from electrochemical impedance spectroscopy and differential pulse voltammetry, respectively, within a broad linear range of the CEA concentration (0.01-10 ng·mL^-1). Meanwhile, the developed SPR biosensor exhibited a slightly high LOD of 0.3 ng·mL^-1 within the CEA concentration of 1.0-250 ng·mL^-1. Both the electrochemical and SPR aptasensors displayed high selectivity, good reproducibility, stability, acceptable regenerability, and applicability in real human serum samples. These results proved that the proposed aptamer-targeted Zr-MOF nanocomposite can be utilized in multiple-functionally biosensing, further promoting the potential application of Zr-MOF-related nanomaterials in clinical diagnosis.

Applications of capillary electrophoresis with chemiluminescence detection in clinical, environmental and food analysis. A review

This paper reviews the latest developments and analytical applications of chemiluminescence detection coupled to capillary electrophoresis (CE-CL). Different sections considering the most common CL systems have been included, such as the tris(2,2'-bipyridine)ruthenium(II) system, the luminol and acridinium derivative reactions, the peroxyoxalate CL or direct oxidations. Improvements in instrumental designs, new strategies for improving both resolution and sensitivity, and applications in different fields such as clinical, pharmaceutical, environmental and food analysis have been included. This review covers the literature from 2010 to 2015.

Aptasensor based on tripetalous cadmium sulfide-graphene electrochemiluminescence for the detection of carcinoembryonic antigen

A facile label-free electrochemiluminescence (ECL) aptasensor, based on the ECL of cadmium sulfide-graphene (CdS-GR) nanocomposites with peroxydisulfate as the coreactant, was designed for the detection of carcinoembryonic antigen (CEA). Tripetalous CdS-GR nanocomposites were synthesized through a simple onepot solvothermal method and immobilized on the glassy carbon electrode surface. L-Cystine (L-cys) could largely promote the electron transfer and enhance the ECL intensity. Gold nanoparticles (AuNPs) were assembled onto the L-cys film modified electrode for aptamer immobilization and ECL signal amplification. The aptamer modified with thiol was adsorbed onto the surface of the AuNPs through a Au-S bond. Upon hybridization of the aptamer with the target protein, the sequence could conjugate CEA to form a Y architecture. With CEA as a model analyte, the decreased ECL intensity is proportional to the CEA concentration in the range of 0.01-10.0 ng mL(-1) with a detection limit of 3.8 pg mL(-1) (S/N = 3). The prepared aptasensor was applied to the determination of CEA in human serum samples. The recoveries of CEA in the human serum samples were between 85.0% and 109.5%, and the RSD values were no more than 3.4%.

Aptamer-based detection and quantitative analysis of human immunoglobulin E in capillary electrophoresis with chemiluminescence detection

A novel aptamer-based CE with chemiluminescence (CL) assay was developed for highly sensitive detection of human immunoglobulin E (IgE). The IgE aptamer was conjugated with gold nanoparticles (AuNPs) to form AuNPs-aptamer that could specifically recognize the IgE to produce an AuNPs-aptamer-IgE complex. The mixture of the AuNPs-aptamer-IgE complex and the unbounded AuNPs-aptamer could be effectively separated by CE and sensitively detected with luminol-H2 O2 CL system. By taking the advantage of the excellent catalytic behavior of AuNPs on luminol-H2 O2 CL system, the ultrasensitive detection of IgE was achieved. The detection limit of IgE is 7.6 fM (S/N = 3) with a linear range from 0.025 to 250 pM. Successful detection of IgE in human serum samples was demonstrated and the recoveries of 94.9-103.2% were obtained. The excellent assay features of the developed approach are its specificity, sensitivity, adaptability, and very small sample consumption. Our design provides a methodology model for determination of rare proteins in biological samples.

Chemiluminescence detection of protein in capillary electrophoresis using aptamer-functionalized gold nanoparticles as biosensing platform

Highly sensitive and selective detection of disease-related proteins play critical roles in clinical practice and diagnostic assays. Herein, we proposed a highly selective and ultrasensitive chemiluminescence (CL) method for protein detection in capillary electrophoresis (CE) using aptamer-functionalized gold nanoparticles (AuNPs) as biosensing platform. In this protocol, AuNPs were synthesized and conjugated with aptamer to form AuNPs-aptamer. Using thrombin and thrombin binding aptamer as an initial proof-of-concept recognization pair, AuNPs-aptamer was linked to thrombin to produce an AuNPs-aptamer-thrombin complex. The resulted complex and unbound AuNPs-aptamer were separated in CE and detected with luminol-H2O2 CL system. The developed strategy produced an ultrasensitive detection of thrombin down to 13.5 fmol/L (S/N=3) with a linear range from 0.033 to 66.0 pmol/L. The application of the present protocol was demonstrated by analyzing thrombin in human plasma samples with the recoveries of 87.6-116.8%. This novel strategy has many outstanding merits including high specificity of aptamer, excellent catalysis behavior of AuNPs, high sensitivity of CL detection, and high separation efficiency of CE.

Kinetic-spectrometric three-dimensional chemiluminescence as an effective analytical tool. Application to the determination of benzo(a)pyrene

Kinetic and spectroscopic methods were used in combination in this work to develop a new analytical tool for use in chemiluminescence detection processes. Specifically, time-resolved chemiluminescence was used jointly with a stopped-flow assembly in order to monitor the chemiluminescence produced in the oxidation of bis(2,4-dinitrophenyl)oxalate (DNPO) by hydrogen peroxide in the presence of a polycyclic aromatic hydrocarbon. Recording of successive two-dimensional spectra during the emission process and treating the acquired spectral data with dedicated software allows the obtainment of three-dimensional chemiluminescence spectra, a result of the joint use of two analytical techniques. Thus, using a flow cell specifically designed for direct coupling to the charge-coupled device (CCD) detector increases the emission intensity without the need for fibre optics. Also, using dedicated software to process the acquired two-dimensional spectra affords a comprehensive kinetic and spectroscopic characterization of the chemiluminescence signal via the three-dimensional spectrum previously obtained. The analytical potential of this new tool was assessed by application to the chemiluminescent reaction between a peroxyoxalate and an oxidant (hydrogen peroxide); the reaction is induced by benzo(a)pyrene, which was used to determine this polycyclic aromatic hydrocarbon in an organic solvent. A linear calibration graph was obtained between 0.5 and 20 mg L(-1). The limit of detection found to be 3.97 μg L(-1) and a relative standard error of 0.64% and a relative standard deviation of 1.87% were obtained. The results reached testify to the usefulness of the proposed analytical tool for simple determinations and its potential for the resolution of complex mixtures or determinations in complex matrices.

Electrogenerated ferrate(VI) for CE-chemiluminescence detection to determine benzenediol isomers

Based on the quenched chemiluminescence intensity of the luminol reaction sensitized by ferrate(VI) in alkaline medium, a novel CE with on-line inhibited method for the simultaneous analysis of benzenediol isomers was developed. The ferrate(VI) solution was freshly prepared by electrochemical technique before electrophoresis. The parameters influencing detection and separation were carefully investigated. Baseline separation of benzenediols including catechol, resorcinol, and hydroquinone was achieved in less than 8 min with 5.0 mmol/L sodium tetraborate and 2.0 mmol/L luminol at an applied voltage of 18 kV. The LODs (S/N=3) for catechol, resorcinol and hydroquinone were determined to be 8.5 x 10(-9), 8.0 x 10(-7) and 6.5 x 10(-9) mol/L, respectively. Finally, the proposed method was applied for phenolic compounds in hair dye.