We report on a novel hydrogen peroxide biosensor that was fabricated by the layer-by-layer deposition method. Thionine was first deposited on a glassy carbon electrode by two-step electropolymerization to form a positively charged surface. The negatively charged gold nanoparticles and positively charged horseradish peroxidase were then immobilized onto the electrode via electrostatic adsorption. The sequential deposition process was characterized using electrochemical impedance spectroscopy by monitoring the impedance change of the electrode surface during the construction process. The electrochemical behaviour of the modified electrode and its response to hydrogen peroxide were studied by cyclic voltammetry. The effects of the experimental variables on the amperometric determination of H2O2 such as solution pH and applied potential were investigated for optimum analytical performance. Under the optimized conditions, the biosensor exhibited linear response to H2O2 in the concentration ranges from 0.20 to 1.6?mM and 1.6 to 4.0?mM, with a detection limit of 0.067?mM (at an S/N of 3). In addition, the stability and reproducibility of this biosensor was also evaluated and gave satisfactory results.
Figure
A novel hydrogen peroxide biosensor was fabricated via layer-by-layer depositing approach. Thionine was first deposited on a glassy carbon electrode by electropolymerization to form a positively charged surface (PTH). Negatively charged gold nanoparticles (NPs) and positively charged horseradish peroxidase (HRP) were then immobilized onto the electrode via electrostatic adsorption. 相似文献
An immunosensor for determination of salbutamol was developed. It based on glass carbon electrode (GCE) modified with a conductive multilayer film comprised of multi-wall carbon nanotubes, polythionine and gold nanoparticles. Salbutamol antibody was immobilized on the surface of the modified GCE which then was blocked with bovine serum albumin (BSA). The stepwise self-assembly process of the immunosensor was studied by cyclic voltammetry. The detection scheme is based on competitive binding of salbutamol to the sensor surface whose differential pulse voltammetric signal decreases after competitive binding of the salbutamol-BSA conjugate and free salbutamol to the salbutamol antibody. The sensor responds to salbutamol in 5 to 150 nM concentration range, with a detection limit of 1 nM. This method was applied to the precise and sensitive determination of salbutamol in spiked feed samples.
Figure
In this work, we constructed a salbutamol immunosensor which was based on salbutamol-Ab adsorbed on the AuNPs/PTH/MWCNTs/GCE. Just as the procedures shown in Graph 1, competitive immunoreaction was the experimental principle. The percentage of current response of the immunosensor was proportional to salbutamol concentrations in the range of 5–150 nM. 相似文献
We describe a supersandwich type of electrochemical DNA biosensor based on the use of a glassy carbon electrode (GCE) modified with reduced graphene oxide (rGO) sheets that are decorated with gold nanoparticles (Au NPs). Thiolated capture DNA (probe DNA) was covalently linked to the Au NPs on the surface of the modified GCE via formation of Au-S bonds. In presence of target DNA, its 3′ terminus hybridizes with capture probe and the 5′ terminus hybridizes with signal probe labeled with Methylene Blue (MB). On increasing the concentration of target DNA, hybridization between signal probe and target DNA results in the formation of three different DNA sequences that form a supersandwich structure. The signal intensity of MB improves distinctly with increasing concentrations of target DNA in the sample solution. The assembling process on the surface of the electrode was studied by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was used to monitor the hybridization event by measuring the changes in the peak current for MB. Under optimal conditions, the peak currents in DPV for MB linearly increase with the logarithm of target DNA concentration in the range from 0.1 μM to1.0 fM, with a detection limit of 0.35 fM (at an signal/noise ratio of 3). This biosensor exhibits good selectivity, even over single-base mismatched target DNA.
Figure
We designed a sensitive supersandwich electrochemical DNA biosensor based on rGO sheets decorated with Au NPs. SEM and electrochemical methods were employed to investigate the assembly process of the biosensor. The biosensor exhibits high sensitivity and good specificity. 相似文献
We describe a sensitive chronocoulometric biosensor for the sequence-specific detection of DNA. It is based on a glassy carbon electrode modified with multi-walled carbon nanotubes, polydopamine, and gold nanoparticles. The ruthenium(III)hexammine complex acts as the electrochemical indicator. Electrochemical impedance spectra and scanning electron microscopy are employed to investigate the assembly of the electrode surface. The signals of the ruthenium complex electrostatically bound to the anionic phospho groups of the DNA strands are measured by chronocoulometry before and after hybridization. The difference in signal intensity is linearly related to the logarithm of the concentration of the target DNA in the range of 1.0 nM to 10 fM with a detection limit of 3.5fM (S/N?=?3) under optimal conditions. This biosensor exhibits excellent sensitivity and selectivity and has been used for an assay of complementary target DNA in human serum sample with satisfactory results.
Figure
We describe a sensitive chronocoulometric biosensor based on a glassy carbon electrode modified with gold nanoparticles, poly(dopamine), and carbon nanotubes. The biosensor exhibits excellent sensitivity and selectivity and has been used for an assay of Helicobacter pylori in human serum with a satisfactory result. 相似文献
A novel glucose biosensor is presented as that based on a glassy carbon electrode modified with hollow gold nanoparticles (HGNs) and glucose oxidase. The sensor exhibits a better differential pulse voltammetric response towards glucose than the one based on conventional gold nanoparticles of the same size. This is attributed to the good biological conductivity and biocompatibility of HGNs. Under the optimal conditions, the sensor displays a linear range from 2.0?×?10?6 to 4.6?×?10?5?M of glucose, with a detection limit of 1.6?×?10?6?M (S/N?=?3). Good reproducibility, stability and no interference make this biosensor applicable to the determination of glucose in samples such as sports drinks.
Figure
A novel glucose biosensor was prepared based on glucose oxidase, hollow gold nanoparticles and chitosan modified glassy carbon electrode. The electrode showed a good response for the glucose. The sensor has been verified by the determination of glucose in sport drink 相似文献
Graphene oxide doped with nitrogen and sulfur was decorated with gold nanoparticles (AuNP-SN-GO) and applied as a substrate to modify a glassy carbon electrode (GCE). An aptamer against the model protein thrombin was self-assembled on the modified GCE which then was exposed to thrombin. Following aptamer-thrombin interaction, biotin-labeled DNA and aptamer 2 are immobilized on another AuNP-SN-GO hybrid and then are reacted with the thrombin/AuNP-SN-GO/GCE to form a sandwich. The enzyme label horseradish peroxidase (HRP) was then attached to the electrode by biotin–avidin interaction. HRP catalyzes the oxidation of hydroquinone by hydrogen peroxide. This generates a strong electrochemical signal that increases linearly with the logarithm of thrombin concentration in the range from 1.0?×?10?13 M to 1.0?×?10?8 M with a detection limit of 2.5?×?10?14 M (S/N?=?3). The assay is highly selective. It provides a promising strategy for signal amplification. In our perception, it has a large potential for sensitive and selective detection of analytes for which appropriate aptamers are available.
Graphic abstract A sandwich-type electrochemical aptasensor is fabricated for detection of thrombin using a glassy carbon electrode modified with nitrogen- and sulfur-doped graphene oxide and gold nanoparticles.
We described a sensitive, label-free electrochemical immunosensor for the detection of carcinoembryonic antigen. It is based on the use of a glassy carbon electrode (GCE) modified with a multi-layer films made from Prussian Blue (PB), graphene and carbon nanotubes by electrodeposition and assembling techniques. Gold nanoparticles were electrostatically absorbed on the surface of the film and used for the immobilization of antibody, while PB acts as signaling molecule. The stepwise assembly process was investigated by differential pulse voltammetry and scanning electron microscopy. It is found that the formation of antibody-antigen complexes partially inhibits the electron transfer of PB and decreased its peak current. Under the optimal conditions, the decrease of intensity of the peak current of PB is linearly related to the concentration of carcinoembryonic antigen in two ranges (0.2–1.0, and 1.0–40.0 ng·mL?1), with a detection limit of 60 pg·mL?1 (S/N?=?3). The immunosensor was applied to analyze five clinical samples, and the results obtained were in agreement with clinical data. In addition, the immunosensor exhibited good precision, acceptable stability and reproducibility.
Figure
We described a sensitive electrochemical immunosensor for the detection of the carcinoembryonic antigen. It was based on the use of a glassy carbon electrode modified with a multi-layer films made from Prussian blue, graphene, and carbon nanotubes by electrodeposition and assembling techniques. The immunosensor exhibited good precision and acceptable stability and has been applied to analyze clinical sample with a satisfactory result. 相似文献
We describe a highly sensitive and selective amperometric sensor for the determination of nitrite. A glassy carbon electrode was modified with a composite made from gold nanoparticles (AuNPs) and sulfonated graphene (SG). The modified electrode displays excellent electrocatalytic activity in terms of nitrite oxidation by giving much higher peak currents (at even lower oxidation overpotential) than those found for the bare electrode, the AuNPs-modified electrode, and the SG-modified electrode. The sensor has a linear response in the 10 μM to 3.96 mM concentration range, a very good detection sensitivity (45.44 μA mM?1), and a lower detection limit of 0.2 μM of nitrite. Most common ions and many environmental organic pollutants do not interfere. The sensor was successfully applied to the determination of nitrite in water samples, and the results were found to be consistent with the values obtained by spectrophotometry.
Figure
A highly sensitive amperometric sensor for nitrite using a glassy carbon electrode modified with gold nanoparticles/sulfonated graphene (AuNPs/SG) composites is presented 相似文献
A novel sensitive electrochemical biosensor based on magnetite nanoparticle for monitoring DNA hybridization by using MWNT-COOH/ppy-modified glassy carbon electrode is described. In this new detection system, mercapatoacetic acid (RSH)-coated magnetite nanoparticles, capped with 5′-(NH2) oligonucleotide, is used as DNA probe to complex 29-base polynucleotide target (a piece of human porphobilinogen deaminase PBGD promoter from 170 to 142). Target sequence hybridized with the probe results in the decrease of the reduction peak current of daunomycin connected with probe. The response of non-complementary sequence was almost the same as the blank, and the response of three-base mismatched sequence within 29-base polynucleotide was obviously distinguished from complementary sequence, which can easily identify point mutation of DNA. The equation of calibration plot is ip (μA) = 0.8255 − 0.0847ctarget oligonucleotide × 1013 in the range of 6.9 × 10−14 to 8.6 × 10−13 mol/L, and correlation coefficient is 0.9974. The detective limit is 2.3 × 10−14 mol/L of target oligonucleotide. This device can be optimized for the detection of complex sequence. 相似文献
We have developed an ultra-sensitive electrochemical DNA biosensor by assembling probe ssDNA on a glassy carbon electrode modified with a composite made from molybdenum disulfide, graphene, chitosan and gold nanoparticles. A thiol-tagged DNA strand coupled to horseradish peroxidase conjugated to AuNP served as a tracer. The nanocomposite on the surface acts as relatively good electrical conductor for accelerating the electron transfer, while the enzyme tagged gold nanoparticles provide signal amplification. Hybridization with the target DNA was studied by measuring the electrochemical signal response of horseradish peroxidase using differential pulse voltammetry. The calibration plot is linear in the 5.0?×?10?14 and 5.0?×?10?9 M concentration range, and the limit of detection is 2.2?×?10?15 M. The biosensor displays high selectivity and can differentiate between single-base mismatched and three-base mismatched sequences of DNA. The approach is deemed to provide a sensitive and reliable tool for highly specific detection of DNA.
Figure
We have developed an ultra-sensitive electrochemical DNA biosensor by assembling probe (ssDNA) on a glassy carbon electrode modified with a composite made from molybdenum disulfide, graphene, chitosan and gold nanoparticles. The nanocomposite on the surface acts as relatively good electrical conductor for accelerating the electron transfer, while the enzyme tagged gold nanoparticles provide signal amplification. The biosensor displays high selectivity and can differentiate between single-base mismatched and three-base mismatched sequences of DNA 相似文献
We have developed a non-enzymatic glucose sensor by using a composite prepared from copper nanoparticles (CuNPs) and graphene which can be prepared by simple 1-step electrochemical reduction using graphene oxide (GO) and copper ion as the starting materials. The GO is electrochemically reduced to graphene at a voltage of ?1.5 V, and this is accompanied by the simultaneous formation of CuNPs on the surface of the graphene. This novel nanocomposite combines the advantages of graphene and of CuNPs and displays good electrocatalytic activity toward glucose in alkaline media. The performance of the respective glucose electrode was evaluated by amperometric experiments and revealed a fast response (<2 s), a low detection limit (200 nM), and high sensitivity (607 μA mM?1). The sensor also exhibits good reproducibility and very good specificity for glucose over ascorbic acid, dopamine, uric acid, fructose, lactose and sucrose.
Figure
(A) CVs of Cu NPs/graphene electrode (a), graphene electrode (b),and Cu/GC electrode (c) in 0.1 M NaOH solution with 0.5 mM glucose; (B) The response of the Cu NPs/graphene electrode to successive addition of glucose from 5 μM to 0.2 mM. 相似文献
Microchimica Acta - The authors describe an electrochemical DNA biosensor based on a glassy carbon electrode modified with gold nanoparticles (AuNPs) and reduced graphene oxide that was... 相似文献
A glassy carbon electrode (GCE) was modified with gold nanoparticles (AuNPs) coated on monolayer graphene (AuNP/MG) by direct in situ sputtering of AuNPs on CVD-generated graphene. This process avoids complicated polymer transfer and polymer cleaning processes and affords AuNPs with a clean surface. The monolayer graphene is ductile and well dispersed. The clean surface of the AuNPs renders this sensor superior to GCEs modified with AuNPs on reduced graphene oxide in terms of the amperometric non-enzymatic determination of hydrogen peroxide. The detection limit is 10 nM (S/N = 3) at 0.55 V (vs. SCE), which is lower than that for similar methods, and the response time is as short as 2 s. Another attractive feature of the sensor is its feasibility for large-scale production via CVD and sputtering.
Graphical abstract Gold nanoparticles deposited onto monolayered graphene generated by chemical vapor deposition (CVD) are used for electrochemical sensing of H2O2, with the detection limit of 10 nM (S/N = 3) and response time of less than 2 s.
We report on a sensitive electrochemical sensor for dopamine (DA) based on a glassy carbon electrode that was modified with a nanocomposite containing electrochemically reduced graphene oxide (RGO) and palladium nanoparticles (Pd-NPs). The composite was characterized by scanning electron microscopy, energy dispersive spectroscopy, and electrochemical impendence spectroscopy. The electrode can oxidize DA at lower potential (234 mV vs Ag/AgCl) than electrodes modified with RGO or Pd-NPs only. The response of the sensor to DA is linear in the 1–150 μM concentration range, and the detection limit is 0.233 μM. The sensor was applied to the determination of DA in commercial DA injection solutions.
Figure
Schematic representation showing the oxidation of DA at RGO-Pd-NPs composite electrode. 相似文献
The hepatotoxic microcystins, especially microcystin?CLR (MC?CLR), are causing serious problems to public health and fisheries. We describe here a label-free amperometric immunosensor for rapid determination of MC?CLR in water sample. The sensor was prepared by immobilizing antibody on a gold electrode coated with L-cysteine-modified gold nanoparticles. The stepwise self-assembly of the immunosensor was monitored and characterized by means of electrochemical impedance spectroscopy and differential pulse voltammetry. A 0.60?mmol L?1 solution of hydroquinone was used as the electron mediator. The immunosensor was incubated with MC?CLR at 25?°C for 20?min, upon which the differential pulse voltammetric current changed linearly over the concentration range from 0.05 to 15.00???g L?1, with a detection limit of 20?ng L?1. The developed biosensor was used to determine MC?CLR in spiked crude algae samples. The recovery was in the range from 95.6 to 105%. This method is simple, economical and efficient, this making it potentially suitable for field analysis of MC-LR in crude algae and water samples.
Figure
The present investigation combines SAM monolayer with gold nanoparticles monolayer to prepare a stable film to immobilize the antibody, and takes hydroquinone as electron mediator, establishes a miniature, economic, compatible and label-free amperometric immunosensor for the quick detection of MC-LR. 相似文献
In this paper, a novel biosensor was prepared by immobilizing glucose oxidase (GOx) on carbon nanotube-gold-titania nanocomposites (CNT/Au/TiO2) modified glassy carbon electrode (GCE). SEM was initially used to investigate the surface morphology of CNT/Au/TiO2 nanocomposites modified GCE, indicating the formation of the nano-porous structure which could readily facilitate the attachment of GOx on the electrode surface. Cyclic voltammogram (CV) and electrochemical impedance spectrum (EIS) were further utilized to explore relevant electrochemical activity on CNT]Au/TiO2 nanocomposites modified GCE. The observations demonstrated that the immobilized GOx could efficiently execute its bioelectrocatalytic activity for the oxidation of glucose. The biosensor exhibited a wider linearity range from 0.1 mmol L-1 to 8 mmol L^-1 glucose with a detection limit of 0.077 mmol L^- 1. 相似文献