Photochromic visual sensing chip for isothermal amplification detection of porcine transmissible gastroenteritis virus.

The outbreak of transmissible gastroenteritis virus (TGEV) will cause huge economic losses to the whole pig industry. Hence, there is urgent need to develop a rapid and ultrasensitive method for detection of TGEV. As a nucleic acid detection technique, loop-mediated isothermal amplification (LAMP) can achieve quantitative detection of targeted nucleic acids with high sensitivity and selectivity. Nevertheless, the signal outputs of LAMP method must be acquired by complicated instruments. In this work, we firstly developed a LAMP photochromic sensing chip for porcine TGEV detection by combination of the photochromic sensing chip and nucleic acid amplification. The detection signal was based on color change of electrochromic material rather than electrical signal, and thus the detection signal can be obtained by visualization without relying on complicated instrument. The entire test was performed with small fluorinated indium tin oxide electrodes modified with zinc oxide (ZnO) (a photocatalytic material) and Prussian blue (PB) (an electrochromic material). When photoinduced electrons produced by ZnO were injected into PB under light, the PB was reduced to Prussian white. The higher the concentration of TGEV, the more double-stranded DNA was produced after amplification. The amplified product produced greater impedance, and fewer electron was transferred, which affect the corresponding color change of PB. The sensing chip also showed highly sensitive response to TGEV, with the minimum limit of detection was determined to be 2.5 fg/µL. The sensing chip developed herein will provide a new avenue for DNA amplification detection by visualization.

Accurate and ultrasensitive detection for PEDV based on photoelectrochemical sensing coupling loop-mediated isothermal amplification.

Porcine epidemic diarrhea (PED) is a serious disease requiring a simple and accurate detection method. Accordingly, this study developed a novel, ultrasensitive photoelectrochemical (PEC) sensing platform using the loop-mediated isothermal amplification (LAMP) technique (LAMP-PEC). An amino (-NH2)-modified LAMP product is obtained by amplification of the PED virus gene with specially designed primers. The generated NH2-modified LAMP product is assembled on the surface of an electrode by forming imine linkages between aldehyde and amino groups based on the Schiff base reaction. A stable photocurrent is provided by a CdIn2S4 photoactive material, which possesses high photoelectric conversion efficiency. Amplified DNA assembled on the electrode surface increases steric hindrance and hinders electrons from moving from the electrode to electron acceptors, which decreases the photocurrent. This strategy can detect PEDV with a low detection limit of 0.3 fg µL-1 and a wide linear range of 1 × 10-3-1 × 102 pg/µL. The sensing platform has excellent specificity and sensitivity and can be used for the quantitative detection of many other pathogens with the assistance of LAMP.

Enhanced cathodic electrochemiluminescent microcystin-LR aptasensor based on surface plasmon resonance of Bi nanoparticles.

Sensitive testing for Microcystins-LR (MC-LR) is needed because of its serious environmental and human health hazards. In this work, a new type of surface plasmon resonance (SPR) enhanced cathodic electrochemiluminescence (ECL) aptasensing platform was designed in which boron and nitrogen co-doped graphene quantum dots (BN-GQDs) were used as the luminary and bismuth nanoparticles (Bi NPs) were used as the SPR source. SPR effect of non-precious metal Bi NPs can induce and enhance ECL signal of BN-GQDs because the fluorescence spectrum of BN-GQDs overlaps well with the ultraviolet-visible absorption spectrum of Bi NPs. On this basis, a sensitive sensing system based on the Bi NPs and BN-GQDs was established for MC-LR detection. The results showed that the ECL sensing signal obtained was linear with the negative logarithm of the target MC-LR concentration in the range of 0.01-5000 pM, and the detection limit was 0.003 pM. In addition, the sensor had high stability and good reproducibility, which can be applied to the detection of MC-LR in actual samples. The method had good specificity and can not be disturbed by its homolog, which can be used for sensitive and reliable detection of complex samples.

Nanoparticles-doped induced defective ZIF-8 as the novel cathodic luminophore for fabricating high-performance electrochemiluminescence aptasensor for detection of omethoate.

Although the use of omethoate (OMT) for pests control is enormously economically beneficial for agricultural production, the high toxicity of OMT to nontarget organisms has resulted in the contamination of soil, river water, and food materials. Developing sensitive and convenient techniques to detect OMT residues is vital to society. Electrochemiluminescence (ECL) is a powerful analytical tool and has been widely applied in biosensors. To boost the co-reaction efficiency and ECL intensity, we introduced defective ZIF-8 as the novel cathodic luminophore. At the same time, defect generated by the doping of MoTe2 nanoparticles into ZIF-8 could easily electrocatalytic reduce the co-reactor S2O82- to SO4•-. Hence, based on the catalysis of defective ZIF-8, the ECL intensity of MoTe2/ZIF-8 nanocomposites is much higher than both ZIF-8 and MoTe2 nanoparticles. By integration of as-prepared materials with specificity omethoate aptamer, the ECL sensor showed a broad linear range (10-10 g L-1 and 10-5 g L-1) and a comparatively low detection limit (3.3 × 10-11 g L-1). Besides, the ECL aptasensor appeared a good practical performance to detect potato and spinach extraction samples, which proposed a promising guideline for developing ECL aptasensors with high efficiency.