Detection of naphthalene by real-time immuno-PCR using molecular beacon

Multi-class organic pollutants in PM2.5 in mixed area of Shanghai: Levels, sources and health risk assessment

The occurrence of 25 multi-class pollutants comprising phthalate esters (PAEs), polycyclic aromatic hydrocarbons (PAHs), and synthetic musks (SMs) were studied in PM2.5 samples collected at an industrial/commercial/residential/traffic mixed area in Shanghai during four seasons. During the whole period, a slight exceedance of the PM2.5 annual limit was observed, with an average of 36.8 μg/m3, and PAEs were the most predominant, accounting for >70 % of the studied organic pollutants in PM2.5, followed by PAHs and SMs. Statistically significant differences were observed for the concentrations of PM2.5, PAEs, PAHs, and SMs in winter and summer. This seasonal variation could be derived from anthropogenic activities and atmospheric dynamics. Principal component analysis (PCA) and PAHs ratios suggested a mixed source mainly derived from vehicle emissions and industrial processes. Moreover, gaseous pollutants were also accounted for, indicating the emission of PAHs might accompany the NO2 emission process. Finally, inhalation of PM2.5-bound organic pollutants for carcinogenic and non-carcinogenic risks were estimated as average values for each season, showing outside the safe levels in autumn and winter in some cases, suggesting that new policies should be to developed to reduce their emissions and protect human health in this area.

Colorimetric Detection of Acenaphthene and Naphthalene Using Functionalized Gold Nanoparticles

Polycyclic aromatic hydrocarbons are a class of chemicals that occur naturally. They generally demonstrate a high degree of critical toxicity towards humans. Acenaphthene and naphthalene contain compounds that are commonly found in the environment as compared to other PAHs. Consequently, a reliable method of detecting PAHs is crucial for the monitoring of water quality. A colorimetric method based on sodium nitrite-functionalized gold nanoparticles was developed in this study for acenaphthene and naphthalene detection. Different functionalized parameters are determined for the optimization of assay conditions. A linear relationship was found in the analyte concentration range of 0.1–10 ppm with the limit of detection for acenaphthene and naphthalene being 0.046 ppm and 0.0015 ppm, respectively, under the optimized assay conditions. The method’s recovery rate for actual samples falls within the range of 98.4–103.0%. In selective and anti-interference tests, the presence of cations and anions has minimal impact on the detection of the analyte. The colorimetric detection method proposed in this study effectively determines the presence of the analyte in real water samples and has a high recovery rate.

Development of a quantitative immuno-polymerase chain reaction assay to detect and quantify low levels of human thyroid stimulating hormone

In the present study, we developed both a conventional enzyme-linked immunosorbent assay (ELISA) and a highly sensitive immuno-polymerase chain reaction (IPCR) assay specific for detection of human thyroid stimulating hormone (hTSH). Several anti-hTSH monoclonal antibodies (MAbs) were generated using hybridoma technology. Two pairs of MAbs (B-4 and B-9) were rationally selected and the optimal assay conditions of sandwich ELISAs were established. The ELISA prototypes were evaluated with standards calibrated with WHO 2nd International Reference Preparation for hTSH and in comparison with a commercial ELISA Kit. Although the limit of detection (LOD) was 0.1 μIU/ml in all cases, B-9-ELISA showed an analytical performance similar to commercial ELISA Kit. Therefore, we selected the B-9 ELISA to develop a hTSH-IPCR assay applying an "Universal-IPCR" format in standard PCR tubes without pretreatment. The signal amplification was achieved through the interaction between the biotinylated detection MAb and mono-biotinylated DNA probe pre-self-assembled with neutravidin. The hTSH-IPCR assay showed a significant increase in terms of the slope definition of sensitivity in low levels range. Our results support the potential of IPCR technique for being applied in clinical diagnosis of thyroid states.

Production of monoclonal antibodies and development of a quantitative immuno-polymerase chain reaction assay to detect and quantify recombinant Glutathione S-transferase

GST-tagged proteins are important tools for the production of recombinant proteins. Removal of GST tag from its fusion protein, frequently by harsh chemical treatments or proteolytic methods, is often required. Thus, the monitoring of the proteins in tag-free form requires a significant effort to determine the remnants of GST during purification process. In the present study, we developed both a conventional enzyme-linked immunosorbent assay (ELISA) and an immuno-polymerase chain reaction (IPCR) assay, both specific for detection of recombinant GST (rGST). rGST was expressed in Escherichia coli JM109, using a pGEX4T-3 vector, and several anti-rGST monoclonal antibodies were generated using hybridoma technology. Two of these were rationally selected as capture and detection antibodies, allowing the development of a sandwich ELISA with a limit of detection (LOD) of 0.01 μg/ml. To develop the rGST-IPCR assay, we selected "Universal-IPCR" format, comprising the biotin-avidin binding as the coupling system. In addition, the rGST-IPCR was developed in standard PCR tubes, and the surface adsorption of antibodies on PCR tubes, the optimal neutravidin concentrations, the generation of a reporter DNA and the concentration effect were studied and determined. Under optimized assay conditions, the rGST-IPCR assay provided a 100-fold increase in the LOD as well as an expanded working range, in comparison with rGST-ELISA. The proposed method exhibited great potentiality for application in several fields in which measurement of very low levels of GST is necessary, and might provide a model for other IPCR assays.

Novel methodologies in analysis of small molecule biomarkers and living cells

Enzyme-linked immuno-sorbent assay (ELISA) is widely used for biomarker detection. A good biomarker can distinguish patients from healthy or benign diseases. However, the ELISA method is not suitable for small molecule or trace substance detection. Along with the development of new technologies, an increasing level of biomaterials, especially small molecules, will be identified as novel biomarkers. Quantitative immuno-PCR, chromatography-mass spectrometry, and nucleic acid aptamer are emerging methodologies for detection of small molecule biomarkers, even in living cells. In this review, we focus on these novel technologies and their potential for small molecule biomarkers and living cell analysis.

Real-time fluorescent quantitative immuno-PCR method for determination of fluoranthene in water samples with a molecular beacon

A reliable and sensitive competitive real-time fluorescent quantitative immuno-PCR (RTFQ-IPCR) assay using a molecular beacon was developed for the determination of trace fluoranthene (FL) in the environment. Under optimized assay conditions, FL can be determined in the concentration range from 1 fg/mL to 100 ng/mL, withy = 0.194x + 7.859, and a correlation coefficient of 0.967 was identified, with a detection limit of 0.6 fg/mL. Environmental water samples were successfully analyzed, recovery was between 90% and 116%, with intra-day relative standard deviation (RSD) of 6.7%-12.8% and inter-day RSD of 8.4%-15.2%. The results obtained from RTFQ-IPCR were confirmed by ELISA, showing good accuracy and suitability to analyze FL in field samples. As a highly sensitive method, the molecular beacon-based RTFQ-IPCR is acceptable and promising for providing reliable test results to make environmental decisions.