Gold Nanoparticle-modified Screen-printed Carbon Electrode Research Articles

Development of an amperometric sensor based on the synergistic action between alginic acid and nPEDOT on a gold nanoparticle-modified screen–printed carbon electrode for As(III) determination in natural water samples

Development of an amperometric sensor based on the synergistic action between alginic acid and nPEDOT on a gold nanoparticle-modified screen–printed carbon electrode for As(III) determination in natural water samples

Impedimetric DNA E-biosensor for multiplexed sensing of Escherichia coli and its virulent f17 strains.

An impedance-based DNA multiplexed biosensor was designed to simultaneously detect Escherichia coli (yaiO gene) and its virulent f17 variant. The thiolated DNA dual probe was self-assembled onto the surface of the gold nanoparticle-modified screen-printed carbon electrode (AuNPs/SPCE) to recognize selected sequences from yaiO and f17 genes. The optimal conditions to prepare the bioelectrode were determined based on the monitoring of the impedimetric response fitted to an equivalent electrical circuit model. The charge transfer resistance of the bioelectrode increased by recognizing the target DNA sequences. Thelimit ofdetection was0.8fM and 1.0fM for yaiO and f17 target DNA, respectively, and the linearity ranged from 1 × 10-15 to 1 × 10-7M with a linear regression coefficient R ≥ 0.995. The nanodevice provided a novel strategy for simultaneous detection of E. coli and its virulence f17 gene with excellent discrimination with a single-base mismatch, two-base mismatch, and non-complementary sequences. Moreover, genomic DNA extracted from E. coli bacteria isolated from diarrheic camel calves and control animals in Tunisia was successfully detected using the as-prepared biosensor with minimal treatment of the extractedDNA samples.Graphical abstract.

A electrochemical biosensor for As(III) detection based on the catalytic activity of Alcaligenes faecalis immobilized on a gold nanoparticle–modified screen–printed carbon electrode

A electrochemical biosensor for As(III) determination has been developed by immobilization of the Alcaligenis faecalis bacteria on gold nanoparticle–modified screen–printed carbon electrode (AuNPs–SPCE). The detection of As(III) is due to the catalytic activity of arsenite oxidase enzyme which oxidizes As(III) to As(V) producing an analytical signal. To enhance the performance of the biosensor, was optimized the amount of bacteria, amount of glutaraldehyde and incubation time applied in the preparation of the electrode, in addition to the effect of pH and applied potential. The analytical application was carried out applying 300 mV (pH = 7) obtaining a LOD of 6.61 μmol L−1 (R = 0.9975) and 700 mV (pH = 12) obtaining a LOD of 1.84 μmol L−1 (R = 0.9983). AF/AuNPs–SPCE was applied to the determination of total arsenic in Loa river water samples after reduction, with satisfactory results.

Determination of vanillin by using gold nanoparticle-modified screen-printed carbon electrode modified with graphene quantum dots and Nafion.

A voltammetric analytical assay for the selective quantification of vanillin is described. It is based on the use of a gold nanoparticle-modified screen-printed carbon electrode (SPCE) modified with graphene quantum dots (GQD) in a Nafion matrix. The GQD were synthesized by an acidic thermal method and characterized by UV-Vis, photoluminescence, and FTIR spectroscopy. The modified SPCE displays a strongly enhanced response to vanillin. Linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) were applied to optimize the methods. The analytical assay has linear responses in the 13 to 660μM and 0.66 to 33μM vanillin concentration ranges. The detection limits are 3.9μM and 0.32μM when using LSV and DPV, respectively. The analytical assay is selective and stable. It was applied to the determination of vanillin in several food samples with satisfactory results. Recoveries from spiked samples ranged between 92.1 and 113.0%. Graphical abstract The selective and sensitive quantification of vanillin is carried out by the use of a gold nanoparticle-modified screen-printed carbon electrode modified with graphene quantum dots in a Nafion matrix.

Sensitive Impedimetric Immunoassay of Japanese Encephalitis Virus Based on Enzyme Biocatalyzed Precipitation on a Gold Nanoparticle-modified Screen-printed Carbon Electrode.

A sensitive and disposable electrochemical impedance biosensor to detect Japanese encephalitis virus (JEV) was developed based on a gold nanoparticle (AuNP)-modified screen-printed carbon electrode (SPCE). A biosensor was fabricated through covalent grafting of a mixed self-assembled monolayer on AuNPs with a specific antibody. To detect JEV and achieve signal amplification, the horseradish peroxidase (HRP)-labeled second antibody was linked to the biosensor through a sandwich immunity reaction. HRP was used to catalyze 4-chloro-1-naphthol oxidation to produce an insoluble precipitate, which introduced a barrier to electron transfer on the electrode. Electrochemical impedance spectroscopy (EIS) was used to monitor the precipitation on the electrode. The electron-transfer resistance (Ret) of the biosensor was directly correlated with the concentration of JEV in the solution. Under optimal conditions, the method generated a linear response range between 500 and 5 × 105 pfu mL-1, and the detection limit was 167 pfu mL-1. The biosensor exhibited good selectivity against other viruses.

Detection of Cryptosporidium parvum Oocysts on Fresh Produce Using DNA Aptamers.

There are currently no standard methods for the detection of Cryptosporidium spp., or other protozoan parasites, in foods, and existing methods are often inadequate, with low and variable recovery efficiencies. Food testing is difficult due to the low concentrations of parasites, the difficulty in eluting parasites from some foods, the lack of enrichment methods, and the presence of PCR inhibitors. The main objectives of the present study were to obtain DNA aptamers binding to the oocyst wall of C. parvum, and to use the aptamers to detect the presence of this parasite in foods. DNA aptamers were selected against C. parvum oocysts using SELEX (Systematic Evolution of Ligands by EXponential enrichment). Ten rounds of selection led to the discovery of 14 aptamer clones with high affinities for C. parvum oocysts. For detecting parasite-bound aptamers, a simple electrochemical sensor was employed, which used a gold nanoparticle-modified screen-printed carbon electrode. This aptasensor was fabricated by self-assembling a hybrid of a thiolated ssDNA primer and the anti- C. parvum aptamer. Square wave voltammetry was employed to quantitate C. parvum in the range of 150 to 800 oocysts, with a detection limit of approximately 100 oocysts. The high sensitivity and specificity of the developed aptasensor suggests that this novel method is very promising for the detection and identification of C. parvum oocysts on spiked fresh fruits, as compared to conventional methods such as microscopy and PCR.

A disposable label-free electrochemiluminescent immunosensor for transferrin detection based on a luminol-reduced gold nanoparticle-modified screen-printed carbon electrode

A disposable label-free electrochemiluminescent immunosensor based on luminol-reduced gold nanoparticles was designed for human transferrin detection.

Ultrasensitive norovirus detection using DNA aptasensor technology.

DNA aptamers were developed against murine norovirus (MNV) using SELEX (Systematic Evolution of Ligands by EXponential enrichment). Nine rounds of SELEX led to the discovery of AG3, a promising aptamer with very high affinity for MNV as well as for lab-synthesized capsids of a common human norovirus (HuNoV) outbreak strain (GII.3). Using fluorescence anisotropy, AG3 was found to bind with MNV with affinity in the low picomolar range. The aptamer could cross-react with HuNoV though it was selected against MNV. As compared to a non-specific DNA control sequence, the norovirus-binding affinity of AG3 was about a million-fold higher. In further tests, the aptamer also showed nearly a million-fold higher affinity for the noroviruses than for the feline calicivirus (FCV), a virus similar in size and structure to noroviruses. AG3 was incorporated into a simple electrochemical sensor using a gold nanoparticle-modified screen-printed carbon electrode (GNPs-SPCE). The aptasensor could detect MNV with a limit of detection of approximately 180 virus particles, for possible on-site applications. The lead aptamer candidate and the aptasensor platform show promise for the rapid detection and identification of noroviruses in environmental and clinical samples.

Aptamer-Based Viability Impedimetric Sensor for Bacteria

The development of an aptamer-based viability impedimetric sensor for bacteria (AptaVISens-B) is presented. Highly specific DNA aptamers to live Salmonella typhimurium were selected via the cell-systematic evolution of ligands by exponential enrichment (SELEX) technique. Twelve rounds of selection were performed; each comprises a positive selection step against viable S. typhimurium and a negative selection step against heat killed S. typhimurium and a mixture of related pathogens, including Salmonella enteritidis, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Citrobacter freundii to ensure the species specificity of the selected aptamers. The DNA sequence showing the highest binding affinity to the bacteria was further integrated into an impedimetric sensor via self-assembly onto a gold nanoparticle-modified screen-printed carbon electrode (GNP-SPCE). Remarkably, this aptasensor is highly selective and can successfully detect S. typhimurium down to 600 CFU mL(-1) (equivalent to 18 live cells in 30 μL of assay volume) and distinguish it from other Salmonella species, including S. enteritidis and S. choleraesuis. This report is envisaged to open a new venue for the aptamer-based viability sensing of a variety of microorganisms, particularly viable but nonculturable (VBNC) bacteria, using a rapid, economic, and label-free electrochemical platform.

Ultrasensitive DNA detection based on coulometric measurement of enzymatic silver deposition on gold nanoparticle-modified screen-printed carbon electrode

An ultrasensitive DNA detection method based on coulometric measurement of enzymatic silver deposition on gold nanoparticle (AuNP)-modified screen-printed carbon electrode (SPCE) was developed. The DNA sensor was prepared by self-assembly of a hairpin probe DNA, dually labeled with thiol at its 5′ end and biotin at its 3′ end, on AuNPs on SPCEs. The immobilized probe can shielded the biotin from being approached by a bulky alkaline phosphatase-linked streptavidin (Sv-ALP) conjugate. In the presence of the target DNA, hybridization caused conformational change in the probe DNA and forced biotin away from the surface of the AuNPs. Sv-ALP was bound to the biotin and catalyzed the hydrolysis of ascorbic acid 2-phosphate to form ascorbic acid. The latter reduced the silver ions for the deposition of metallic silver on the electrode surface. The deposited silver was then measured by coulometric analysis in the H2SO4 solution. A considerable increase in signal was obtained because of the accumulation and near-exhaustive coulometric oxidation of metallic silver. Under optimal conditions, the dynamic detection range of the target DNA was from 3.0×10−17 to 1.0×10−14molL−1, and the detection limit was 1.5×10−17molL−1. Further, the DNA sensor exhibited selectivity against single-base mismatched DNA.

A Disposable Copper (II) Ion Biosensor Based on Self-Assembly of L-Cysteine on Gold Nanoparticle-Modified Screen-Printed Carbon Electrode

A disposable copper (II) ion biosensor based on self-assembly of L-cysteine on gold nanoparticle-modified screen-printed carbon electrode was fabricated. The electrode was modified by attaching gold nanoparticles onto the surface of screen-printed carbon electrode through seed mediated growth method followed by self-assembly of L-cysteine. As demonstrated by differential pulse voltammetry, the sensor exhibited high sensitivity to copper (II) ion down to ppb (parts per billion) levels. Optimization of various experimental parameters such as pH, buffer concentration, and preconcentration time, which influenced the performance of the biosensor, was investigated. The sensor demonstrated a wide linear response range from 10 to 0.005 ppm(r=0.9870), with a lower detection limit of 8 ppb using 10 min of preconcentration time. The sensor based on screen-printed electrode provides a cost-effective means of application of copper ion sensor for the detection of ppb level of copper ions in water.