We report on a sensitive electrochemical immunoassay for the prostate specific antigen (PSA). An immunoelectrode was fabricated by coating a glassy carbon electrode with multiwalled carbon nanotubes, poly(dimethyldiallylammonium chloride), CeO2 and PSA antibody (in this order) using the layer-by-layer method. The immunosensor is then placed in a sample solution containing PSA and o-phenylenediamine (OPD). It is found that the CeO2 nanoparticles facilitate the electrochemical oxidation of OPD, and this produces a signal for electrochemical detection of PSA that depends on the concentration of PSA. There is a linear relationship between the decrease in current and the concentration of PSA in the 0.01 to 1,000 pg mL?1 concentration range, and the detection limit is 4 fg mL?1. The assay was successfully applied to the detection of PSA in serum samples. This new differential pulse voltammetric immunoassay is sensitive and acceptably precise, and the fabrication of the electrode is well reproducible. Figure
A novel electrochemical immunoassay for prostate specific antigen (PSA) was developed. Ceria (CeO2) mesoporous nanospheres facilitated the electrochemical oxidation of o-phenylenediamine (OPD). The developed immunoassay has high sensitivity and can be successfully applied for the detection of PSA in serum samples相似文献
The authors describe a sandwich-type electrochemical immunoassay for sensitive determination of the carcinoembryonic antigen (CEA). It is based on the use of iridium nanoparticles (Ir NPs) acting as electrochemical signal amplifier on the surface of a glassy carbon electrode. At first, polydopamine-reduced graphene oxide (PDA-rGO) was employed to immobilize primary antibody (Ab1) against CEA. Secondly, Ir-NPs were used as a support for the immobilization of secondary antibody (Ab2) to afford signal labels. The large surface area of PDA-rGO and the excellent electro-oxidative H2O2-sensing properties of Ir NPs result in a sensitive assay for CEA. Operated best at a working voltage of ?0.6 V (vs. SCE), the assay has a linear range that extends from 0.5 pg?mL?1 to 5 ng·mL?1, and the lower detection limit is 0.23 pg?mL?1. The immunosensor displays satisfactory reproducibility and stability, thus demonstrating a reliable immunoassay strategy for tumor biomarkers. It was applied to the determination of CEA in spiked serum samples.
Graphical abstract Schematic of an amperometric sandwich immunoassay for the carcinoembryonic antigen using a glassy carbon electrode modified with polydopamine, reduced graphene oxide and iridium nanoparticles
We describe a micro fluxgate based device with rectangular magnetic core for the determination of prostate specific antigen (PSA) labeled with Dynabeads. A sandwich immunoassay was employed where PSA is captured on a gold film modified with a self-assembled monolayer of antibody. The secondary antibody is labeled with Dynabeads. By applying a DC magnetic fields in the range of 460 to 700 μT, PSA can be detected with detection limit as low as 0.1 ng mL?1. This micro fluxgate-based assay offers the advantages of miniaturization, simple and conveniently manipulation, re-usability and stability. In our perception, it offers a viable approach towards clinical determination of PSA or other biomarkers.
Graphical abstract A separable detection method based on micro fluxgate and immunomagnetic beads was developed for detection of prostate specific antigen (PSA). Sandwich immunoassay was employed where PSA is captured on a gold film modified with a self-assembled monolayer of antibody. By applying a DC magnetic fields in the range of 460 to 700 μT, PSA can be detected with detection limit as low as 0.1 ng mL?1, and this bio-sensing system can also give an approximate quantitation to the concentrations of them.
In this work, a simple experimental procedure was reported for the electroanalytical determination of selenium (IV) using reduced graphene oxide (rGO) to modify glassy carbon electrode (GCE). The rGO was obtained by reduction of graphene oxide obtained via Hummer’s method. The synthesised rGO was characterised using X-ray diffraction, Raman spectroscopy, scanning electron microscope (SEM), energy-dispersive spectroscopy and transmission Electron microscopy (TEM). GCE was modified with rGO and the electrochemical properties of the bare and modified electrode were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The results obtained showed that the modified electrode exhibited more excellent electrochemical properties than the bare GCE. The optimum conditions for detection of selenium in water using square wave anodic stripping voltammetry were as follows: deposition potential ?500 mV, pH 1, pre-concentration time of 240 s and 0.1 M nitric acid was used as supporting electrolyte. The linear regression equation obtained was I (µA) = 0.8432C + 9.2359 and the detection limit was calculated to be 0.85 μg L?1. However, Cu(II) and Cd(II) are the two cations that interfered in the analysis of selenium in water.The sensor was also applied for real sample water analysis and the result obtained was affirmed with inductively coupled plasma optical emission spectroscopic method. It is believed that our proposed sensor hold promise for practical application. 相似文献
A composite consisting of chitosan containing azidomethylferrocene covalently immobilized on sheets of reduced graphene oxide was drop-casted on a polyester support to form a screen-printed working electrode that is shown to enable the determination of nitrite by cyclic voltammetry and chronoamperometry. Both reduction and oxidation of nitrite can be accomplished due to the high electron-transfer rate of this electrode. Under optimal experimental conditions (i.e. an applied potential of 0.7 V vs. Ag/AgCl in pH 7.0 solution), the calibration plot is linear in the 2.5 to 1450 μM concentration range, with an ~0.35 μM limit of detection (at a signal-to-noise ratio of 3). The sensor was successfully applied to the determination of nitrite in spiked mineral water samples, with recoveries ranging between 95 and 101 %.
Graphical abstract We describe the design of ferrocene-functionalized reduced graphene oxide electrode and its electrocatalytic properties towards the determination of nitrite. Compared to a reduced graphene oxide electrode, the sensor exhibits enhanced electrocatalytic activity towards both oxidation and reduction of nitrite.
Glycine‐functionalized reduced graphene oxide (GRGO) was prepared through the reaction of glycine and chlorine‐functionalized reduced graphene oxide. The product was characterized by SEM, HRTEM, IR, Raman, and XPS. The nitrogen content (8.28%) was high in product, peak at 285.8 eV was assigned to the C–N bond, which implied that the chlorine residues in raw material were substituted by amine group of glycine. The intensity ratio of D and G peak was about 1.5, which also implied that more saturated carbon atoms were present in the product. Results of SEM, IR, and XPS confirmed that glycine molecules were attached to graphene sheets. Compared with reduced graphene oxide (61.5 mg/g) and active carbon (45.2 mg/g), GRGO had a good adsorption capacity (98.9 mg/g) for methylene blue. The adsorption process was fitted to three kinetic models and three adsorption isotherm models. The adsorption process complied with pseudo‐second order kinetic model and Langmuir model. 相似文献
We developed nanosized, reduced graphene oxide (nano-rGO) sheets with high near-infrared (NIR) light absorbance and biocompatibility for potential photothermal therapy. The single-layered nano-rGO sheets were ～20 nm in average lateral dimension, functionalized noncovalently by amphiphilic PEGylated polymer chains to render stability in biological solutions and exhibited 6-fold higher NIR absorption than nonreduced, covalently PEGylated nano-GO. Attaching a targeting peptide bearing the Arg-Gly-Asp (RGD) motif to nano-rGO afforded selective cellular uptake in U87MG cancer cells and highly effective photoablation of cells in vitro. In the absence of any NIR irradiation, nano-rGO exhibited little toxicity in vitro at concentrations well above the doses needed for photothermal heating. This work established nano-rGO as a novel photothermal agent due to its small size, high photothermal efficiency, and low cost as compared to other NIR photothermal agents including gold nanomaterials and carbon nanotubes. 相似文献
We report on the modification of a graphene paste electrode with gold nanoparticles (AuNPs) and a Nafion-L-cysteine composite film, and how this electrode can serve as a platform for the construction of a novel electrochemical immunosensor for the detection of hepatitis B surface antigen (HBsAg). To obtain the immunosensor, an antibody against HBsAg was immobilized on the surface of the electrode, and this process was followed by cyclic voltammetry and electrochemical impedance spectroscopy. The peak currents of a hexacyanoferrate redox system decreased on formation of the antibody-antigen complex on the surface of the electrode. Then increased electrochemical response is thought to result from a combination of beneficial effects including the biocompatibility and large surface area of the AuNPs, the high conductivity of the graphene paste electrode, the synergistic effects of composite film, and the increased quantity of HBsAb adsorbed on the electrode surface. The differential pulse voltammetric responses of the hexacyanoferrate redox pair are proportional to the concentration of HBsAg in the range from 0.5–800?ng?mL?1, and the detection limit is 0.1?ng?mL?1 (at an S/N of 3). The immunosensor is sensitive and stable.
Figure
We report on the modification of a graphene paste electrode with gold nanoparticles and a Nafion-L-cysteine composite film, and how this electrode can serve as a platform for the construction of a novel electrochemical immunosensor for the detection of hepatitis B surface antigen. The immunosensor is sensitive and stable. 相似文献
Novel nanocomposites were prepared from graphene oxide (GO) and octahedral tin dioxide (SnO2) through a facile process that included synthesis of octahedral SnO2 and the reduction of GO with ascorbic acid. The morphology and structure of the nanocomposites were characterized by UV–vis spectroscopy, transmission electron microscopy, and Raman spectroscopy. The nanocomposites were placed on a glassy carbon electrode where they displayed excellent performance in terms of differential pulse voltammetric determination of dopamine (DA). This is attributed to (a) the synergetic interactions between reduced graphene oxide (r-GO) and octahedral SnO2, and (b) the presence of a large number of active sites on the nanocomposites surface. The sensor responds to DA in the concentration range of 0.08 to 30 μM, with a 6 nM detection limit if operated at 0.24 V (vs. Ag/AgCl). The modified electrode also widely suppresses the background current resulting from excess ascorbic acid and uric acids. The method was applied to the determination of DA in spiked human urine and gave satisfactory results, with recoveries in the range from 96.4 to 98.2 %.
Green and facile synthesis of reduced graphene oxide-octahedral SnO2 (r-GO-SnO2) nanocomposites for the sensitive and selective electrochemical detection of dopamine.
