Electrochemical DNA biosensor based on platinum-gold bimetal decorated graphene modified electrode for the detection of Vibrio Parahaemolyticus specific tlh gene sequence

Background: By using bimetal nanocomposite modified electrode, the electrochemical DNA biosensor showed the advantages of high sensitivity, low cost, rapid response and convenient operation, which was applied for disease diagnosis, food safety, and biological monitoring. Objective: A nanocomposite consisting of platinum (Pt)-gold (Au) bimetal and two-dimensional graphene (GR) was synthesized by hydrothermal method, which was modified on the surface of carbon ionic liquid electrode and further used for the immobilization of probe ssDNA related to Vibrio Parahaemolyticus tlh gene to construct an electrochemical DNA sensor. Method: Potassium ferricyanide was selected as electrochemical indicator, cyclic voltammetry was used to study the electrochemical behaviours of different modified electrodes and differential pulse voltammetry was employed to test the analytical performance of this biosensor for the detection of target gene sequence. Results: This electrochemical DNA biosensor could detect the Vibrio Parahaemolyticus tlh gene sequence as the linear concentration in the range from 1.0×10-13 mol L-1 to 1.0×10-6 mol L-1 with the detection limit as 2.91×10-14 mol L-1 (3σ). Conclusion: This proposed electrochemical DNA biosensor could be used to identify the special gene sequence with good selectivity, low detection limit and wide detection range.

Investigation of Electrochemical DNA Biosensor for Detection of Specific nuc Gene of Staphylococcus aureus Based on Gold Nanoparticles and Thiol Graphene Nanocomposite

Background: Based on gold nanoparticles (AuNPs) and thiol graphene (TGR) nanocomposite modified carbon ionic liquid electrode, an electrochemical DNA biosensor was prepared to detect specific nuc gene of Staphylococcus aureus, which was further used to the analysis of PCR amplification samples from unfrozen pork. Objective: The construction of DNA biosensor with AuNPs and TGR could be used as a new sensing platform to detect specific ssDNA sequence in real biological samples. Method: Electrochemical behaviors of working electrodes were studied by cyclic voltammetry and electrochemical impedance spectroscopy with electrochemical performances of this biosensor investigated by differential pulse voltammetry. Results: This gene sensor could detect the specific nuc gene of Staphylococcus aureus in the linear concentration range from 1.0×10-15 mol L-1 to 1.0×10-6 mol L-1 with the detection limit as 4.5×10-16 mol L-1 (3σ), and it was applied to the detection of PCR amplification sample of Staphylococcus aureus with satisfactory results. Conclusion: This gene biosensor showed high sensitivity and good selectivity, wide detection range and low detection limit, which demonstrated an effective tool to detect specific nuc gene sequences of Staphylococcus aureus.

Sensitive Electrochemical Monitoring of Piroxicam in Pharmaceuticals Using Carbon Ionic Liquid Electrode

Background: Piroxicam is a non-steroidal anti-inflammatory drug. The prevailing clinical use and investigation of piroxicam necessitate a rapid and sensitive method for its determination. A carbon ionic liquid electrode, fabricated using graphite and the ionic liquid 1-octylpyridinium hexafluorophosphate (OPFP) was used as an electrochemical sensor for piroxicam determination. Methods: The surface of the proposed electrode was characterized by scanning electron microscopy. Cyclic voltammetry (CV) was applied to study the oxidation of piroxicam and to acquire information about the reaction mechanism. Differential pulse voltammetry was also used as an analytical technique for quantification of the sub-micromolar concentration of piroxicam. Results: One oxidation peak at 0.55V was observed at CILE. The oxidation peak at the CPE was weak, while the response was notably increased at the CILE. The proposed electrode exhibited interesting sensitivity towards the determination of piroxicam and the anodic peak current versus piroxicam concentration was linear in the ranges of 0.2-60 µM. The detection limit of 40 nM was achieved. Conclusion: The electroxidation process was irreversible and revealed adsorption controlled behavior. The method was successfully applied for the determination of piroxicam content in pharmaceutical samples.

Gold Nanocage-Based Electrochemical Sensing Platform for Sensitive Detection of Luteolin

A simple and sensitive electrochemical sensor was developed for the detection of tracelevels of luteolin. The sensoris based on a novel type of chemically modified electrode: gold nanocage (AuNCs)-modified carbon ionic liquid electrode (CILE). To construct this electrochemical sensing platform for luteolin, CILE is initially prepared by using 1-hexylpyridinium hexafluorophosphate as the binder and then AuNCs are coated on the surface of CILE to fabricate AuNCs-modified CILE (AuNCs/CILE). Electrochemical studies have shown that AuNCs/CILE can exhibit enhanced electrocatalytic activity toward the redox reaction of luteolin, therefore, the redox peak current of luteolin can be greatly improved, resulting in the high sensitivity of the developed sensor. Under the optimal conditions, the oxidation peak currents of the sensor increase linearly with an increase in the luteolin concentration in a range from 1 to 1000 nM with a detection limit of 0.4 nM, which is lower than those of most reported electrochemical luteolin sensors. Moreover, the reproducibility, precision, selectivity, and stability of this sensor are excellent. Finally, the sensing system was applied to the analysis of luteolin-spiked drug samples and the recovery in all cases was 95.0–96.7%, indicating the potential application of this simple, facile, and sensitive sensing system in pharmaceutical analysis.