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Single-cell electrochemical sensor is widely used in the local selective detection of single living cells because of its high spatial–temporal resolution and sensitivity, as well as its ability to obtain comprehensive cellular physiological states and processes with increased accuracy. Functionalized nanoprobes can detect the oxidative stress response of cells in single-cell electrochemical sensors. Moreover, the T-2 toxin is one of the most toxic mycotoxins and widely occurs in field crops. T-2 toxin can cause mitochondrial damage in cells and increase intracellular reactive oxygen species (ROS) in various cells. As the most representative free radical of intracellular ROS, H2O2 can effectively reflect the toxic effects of intracellular T-2 toxin. In this study, a functionalized gold nanoprobe was used to dynamically monitor the production of H2O2 in a single live human hepatoma cell HepG2 stimulated by mycotoxin T-2. The concentration of H2O2 produced by HepG2 cells stimulated by T-2 toxin at 1 ppb–1 ppm was linearly correlated, R2 = 0.99055, and LOD = 0.13807 ng mL−1. Sample spiking experiments were conducted, and the recovery rate of spiking was 81.19%–130.17%. A comparative analysis of differences in the current produced by multiple toxins, HT-29 cells, as well as single cells in cell populations, was performed. This method can be applied in real-time monitoring of mycotoxin toxicity during food processing in living cells and provides a novel idea for enhancing food quality and safety in a nanoenvironment. [ABSTRACT FROM AUTHOR]

A novel electrochemical sensor for paraquat (PQ) detection based on molecularly imprinted polymer (MIP) membranes on a glassy carbon electrode (GCE) modified with Au nanocrosses-chitosan (AuNCs-CS) was constructed. P-Aminothiophenol (p-ATP) and 4,4′-bipyridine template were assembled on the surface of the modified GCE by the formation of Au–S bonds and hydrogen-bonding interactions, followed by polymer membrane formation by the electropolymerization in a polymer solution containing p-ATP, HAuCl4, tetrabutylammonium perchlorate (TBAP), and the template molecule 4,4′-bipyridine. The as-constructed molecularly imprinted sensor (MIP-AuNC-CS) was characterized by differential pulse voltammetry (DPV), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). This is the first time that molecularly imprinted polymer technology has been integrated with a modified AuNCs-CS to electrochemically detect PQ. The linear response of the MIP-AuNC-CS sensor was in the range from 1 × 10−14 to 1 × 10−10 mol L−1, and the limit of detection was 2.3 × 10−15 mol L−1. This sensor showed high-speed real-time detection capability, low sample consumption, high sensitivity, low interference, and good stability characteristics, and was proven to detect PQ. [ABSTRACT FROM AUTHOR]

A light-addressable potentiometric sensor (LAPS) is a semiconductor electrochemical sensor based on the field-effect which detects the variation of the Nernst potential on the sensor surface, and the measurement area is defined by illumination. Thanks to its light-addressability feature, an LAPS-based chemical imaging sensor system can be developed, which can visualize the two-dimensional distribution of chemical species on the sensor surface. This sensor system has been used for the analysis of reactions and diffusions in various biochemical samples. In this review, the LAPS system set-up, including the sensor construction, sensing and substrate materials, modulated light and various measurement modes of the sensor systems are described. The recently developed technologies and the affecting factors, especially regarding the spatial resolution and temporal resolution are discussed and summarized, and the advantages and limitations of these technologies are illustrated. Finally, the further applications of LAPS-based chemical imaging sensors are discussed, where the combination with microfluidic devices is promising. [ABSTRACT FROM AUTHOR]

A reduced graphene oxide and carbon-gold nanocomposite modified room temperature ionic liquid based electrochemical gas sensor for high sensitive gas detection. • Carbon-gold nanocomposites were for the first time introduced for high sensitive electrochemical gas detection. • Reduced graphene oxide and carbon-gold nanocomposites were synergically applied for gas sensing. • Thin film room temperature ionic liquid was used as the electrolyte to ensure long lifetime and good stability. • The RGO-CGN modified gas sensor presented significantly enhanced current response in oxygen sensing. Gas sensors have received extensive attractions due to their critical roles in environmental monitoring, industry manufacture and human safety. This paper for the first time introduces carbon-gold nanocomposites on a reduced graphene oxide based electrochemical gas sensor for high sensitive gas detection. Carbon-gold nanocomposites (CGNs) were synthesized by glucose carbonization and gold nanoparticles deposition using the hydrothermal method. Reduced graphene oxide (RGO) was electrochemically deposited on a screen-printed gold electrode with subsequent modification of CGNs. To achieve long lifetime and good stability, thin-film room temperature ionic liquid (RTIL) was utilized as the electrolyte featuring negligible evaporation and large potential window, thus implementing the high sensitive RTIL-based electrochemical gas sensor. The amplification effect of RGO and CGNs modification was investigated using cyclic voltammetry, chronoamperometry and transient double potential amperometry (DPA), which reveals the significant enhancement of sensor performance by synergic application of RGO and CGNs. The sensor was calibrated for oxygen detection from 0.42% to 21% with good sensitivity and linearity. The reproducibility of the sensor using chronoamperometry and transient DPA was also studied with excellent reproducibility. The study paves a new way to implementing high sensitive electrochemical gas sensors for rapid monitoring of gas exposure. [ABSTRACT FROM AUTHOR]

In this paper, molecular imprinting technique was applied to the electrochemical sensor. We used 2-oxindole as dummy template, ρ-Aminothiophenol (ρ-ATP) as functional monomers, combined with the high sensitivity of electrochemical detection, to achieve a specific and efficient detection of patulin in fruit juice. In addition, carbon dots and chitosan were used as the modifying material to improve electron-transfer rate, expand the electroactive surface of glassy carbon electrode and enhance strength of the signal. The Au–S bond and hydrogen bond were employed to complete the assembly of the ρ-ATP and 2-oxindole on the surface of the electrode. Then, polymer membranes were formed by electropolymerization in a polymer solution containing ρ-ATP, HAuCl 4 , tetrabutylammonium perchlorate (TBAP) and the template molecule 2- oxindole. After elution, the specific cavity can adsorb the target patulin. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were performed to monitor the electropolymerization process and its optimization. Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) analyses were used for characterization. This was the first time that the molecularly imprinted polymer (MIP) technology combined with carbon dots, chitosan and Au nanoparticles modification and was applied in the electrochemical detection of patulin. The linear response range of the MIP sensor was from 1 × 10 –12 to 1 × 10 −9 mol L −1 and the limit of detection (LOD) was 7.57 × 10 –13 mol L −1 . The sensor had a high-speed real-time detection capability, low sample consumption, high sensitivity, low interference, good stability and could become a new promising method for the detection of patulin. [ABSTRACT FROM AUTHOR]

A novel electrochemical sensor for cholesterol (CHO) detection based on molecularly imprinted polymer (MIP) membranes on a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWNTs) and Au nanoparticles (AuNPs) was constructed. p-Aminothiophenol (P-ATP) and CHO were assembled on the surface of the modified GCE by the formation of Au–S bonds and hydrogen-bonding interactions, and polymer membranes were formed by electropolymerization in a polymer solution containing p-ATP, HAuCl 4 , tetrabutylammonium perchlorate (TBAP) and the template molecule CHO. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were used to monitor the electropolymerization process and its optimization, which was further characterized by scanning electron microscopy (SEM). The linear response range of the MIP sensor was between 1×10 −13 and 1×10 −9 mol L −1 , and the limit of detection (LOD) were 3.3×10 −14 mol L −1 . The proposed system has the potential for application in clinical diagnostics of cholesterol with high-speed real-time detection capability, low sample consumption, high sensitivity, low interference and good stability. [ABSTRACT FROM AUTHOR]

In this paper, we reported the construction of new high sensitive electrochemical genosensor based on multiwalled carbon nanotubes–chitosan–bismuth complex (MWCNT–Chi–Bi) and lead sulfide nanoparticles for the detection of pathogenic Aeromonas . Lead sulfide nanoparticles capped with 5′-(NH 2 ) oligonucleotides thought amide bond was used as signalizing probe DNA (sz-DNA) and thiol-modified oligonucleotides sequence was used as fixing probe DNA (fDNA). The two probes hybridize with target Aeromonas DNA (tDNA) sequence (fDNA–tDNA–szDNA). The signal of hybridization is detected by differential pulse voltammetry (DPV) after electrodeposition of released lead nanoparticles (PbS) from sz-DNA on the surface of glass carbon electrode decorated with MWCNT–Chi–Bi, which improves the deposition and traducing electrical signal. The optimization of incubation time, hybridization temperature, deposition potential, deposition time and the specificity of the probes were investigated. Our results showed the highest sensibility to detect the target gene when compared with related biosensors and polymerase chain reaction (PCR). The detection limit for this biosensor was 1.0×10 −14 M. We could detect lower than 10 2 CFU mL −1 of Aeromonas in spiked tap water. This method is rapid and sensitive for the detection of pathogenic bacteria and would become a potential application in biomedical diagnosis, food safety and environmental monitoring. [ABSTRACT FROM AUTHOR]