Wenwei Ma

An aptamer-based chromatographic strip assay for sensitive toxin semi-quantitative detection

An aptamer-based chromatographic strip assay method for rapid toxin detection was developed. The aptamer-based strip assay was based on the competition for the aptamer between ochratoxin A and DNA probes. The sensing results indicated that the sensitivity of the aptamer-based strip was better than that of conventional antibody-based strips. The visual limit of detection of the strip for qualitative detection was 1 ng/mL while the LOD for semi-quantitative detection could down to 0.18 ng/mL by using scanning reader. The recoveries of test samples were from 96% to 110%. All detections could be achieved in less than 10 min, indicating that the aptamer-based strip could be a potential useful tool for rapid on-site detections.

Development and validation of a sandwich ELISA for quantification of peanut agglutinin (PNA) in foods

Abstract In this study, two anti-peanut agglutinin (PNA) polyclonal antibodies were successfully prepared. Using mouse anti-PNA polyclonal antibody as the capture antibody and rabbit anti-PNA polyclonal antibody as the detection antibody, a novel sandwich enzyme-linked immunosorbent assay (ELISA) was developed to quantify PNA. The detection limit of the ELISA method was low (0.49 ng/mL), and the linear dynamic range was between 0.78 and 100 ng/mL. The recovery ranged from 93.86% to 139.3%, whereas the intra- and inter-assay coefficients of variation were less than 10.25% and 12.06%, respectively. Sample analysis verified this method as a reliable tool for the detection of PNA in processed foods.

Wash-free magnetic oligonucleotide probes-based NMR sensor for detecting the Hg ion

An easily applied and sensitive sensor for the detection of heavy metal ion residues based entirely on magnetic nanoparticle and oligonucleotide was developed. The tool is established on the relaxation of magnetic nanoparticles with different dispersion states. The target analyte, Hg ions, induce the aggregation of the MNP oligonucleotide probes. Accordingly, the light produced by the magnetic relaxation image and the transverse relaxation time (T(2)) all change due to the effect of the aggregation. The limit of qualitative detection of the sensor is 0.15 ppt. The recoveries from test samples range between 97.1-101.8%. Using the nuclear resonance instrument, the method is a high throughput and sensitive sensor.

Rapid on-site detection of Acidovorax avenae subsp. citrulli by gold-labeled DNA strip sensor

Acidovorax avenae subsp. citrulli (AAC) is one of the most harmful diseases in cucurbit production. A rapid and sensitive DNA strip sensor was constructed based on gold nanoparticle-labeled oligonucleotide probes for the detection of AAC. Both the qualitative and semi-quantitative detections of target DNA were successfully achieved using the developed DNA strip sensor. The qualitative limit of detection (LOD) of the strip sensor was determined as 4 nM. The LOD for the semi-quantitative detection was calculated to be 0.48 nM in the range of 0-10 nM. The genomic DNA was detected directly using the DNA strip sensor without any further treatment. This DNA strip sensor is a potentially useful tool for rapid on-site DNA screening.