Jianwu Sheng

Sensitive and rapid chemiluminescence enzyme immunoassay for microcystin-LR in water samples

A highly sensitive, specific, simple, and rapid chemiluminescence enzyme immunoassay (CLEIA) was developed for the determination of microcystin-LR (MC-LR). Several physicochemical parameters such as the chemiluminescent assay mediums, the dilution ratio of MC-LR-OVA conjugate, monoclonal antibody concentration, and peroxidase labeled antibody concentration were studied and optimized. Under optimum conditions, calibration curve obtained for MC-LR had detection limits of 0.032+/-0.003 microg L(-1), the 50% inhibition concentration (IC50) was 0.20+/-0.02 microg L(-1) and the quantitative detection range was 0.062-0.65 microg L(-1). The proposed methods was successfully applied to the monitoring of MC-LR in spiked water samples without significant effect of the matrix, and the recovery of MC-LR added to water samples at different concentrations ranged from 80% to 115% with the coefficients of variation (CVs) less than 9%. The LOD attained from the calibration curves and the results obtained for the real samples demonstrate the potential use of CLEIA as a screening tool for the analysis of MC-LR in environmental samples.

Compact quantitative optic fiber-based immunoarray biosensor for rapid detection of small analytes

Immunoarrays have been proven to be powerful tools for high-throughput analysis of multiple analytes. In this paper, a proof-of-concept development of a novel optic fiber-based immunoarray biosensor for the detection of multiple small analytes is presented. This was developed through immobilization of two kinds of hapten conjugates, MC-LR-OVA and NB-OVA, onto the same fiber optic probe. The technique is significantly different from conventional immunoarray sensors. Microcystin-LR (MC-LR) and trinitrotoluene (TNT) could be detected simultaneously and specifically within an analysis time of about 10 min for each assay cycle. The limits of detection for MC-LR and TNT were 0.04 μg/L and 0.09 mg/L, respectively. Good regeneration performance, binding properties, and robustness of the sensor surface of the proposed immunoarray biosensor ensure the cost-effective and accurate measurement of small analytes. The change in concentration of the hapten conjugates immobilized onto the sensor surface was also proven to have no significant effection on the performance of immunoarray sensor, which is essential to the application of the immunoarray in real samples detection. This compact and portable quantitative immunoarray provides an excellent multiple assay platform for clinical and environmental samples.

Matrix Effects on the Microcystin-LR Fluorescent Immunoassay Based on Optical Biosensor.

Matrix effects on the microcystin-LR fluorescent immunoassay based on the evanescent wave all-fiber immunosensor (EWAI) and their elimination methods were studied. The results indicated that PBS and humic acid did not affect the monitoring of samples under the investigated conditions. When the pH was less than 6 or higher than 8, the fluorescence signals detected by immunosensor systems were obviously reduced with the decrease or increase of pH. When the pH ranged from 6 to 8, IC50 and the linear working range of MC-LR calculated from the detection curves were 1.01∼1.04 μg/L and 0.12∼10.5 μg/L, respectively, which was favourable for an MC-LR immunoassay. Low concentrations of Cu2+ rarely affected the detection performance of MC-LR. When the concentration of CuSO4 was higher than 5 mg/L, the fluorescence signal detected by EWAI clearly decreased, and when the concentration of CuSO4 was 10 mg/L, the fluorescence signal detected was reduced by 70%. The influence of Cu2+ on the immunoassay could effectively be compromised when chelating reagent EDTA was added to the pre-reaction mixture.

Adsorption kinetics of pesticide in soil assessed by optofluidics-based biosensing platform

The adsorption of pesticides in soil is a key process that affects transport, degradation, mobility, and bioaccumulation of these substances. To obtain extensive knowledge regarding the adsorption processes of pesticides in the environment, the new green assay technologies for the rapid, sensitive, field-deployable, and accurate quantification of pesticides are required. In the present study, an evanescent wave-based optofluidics biosensing platform (EWOB) was developed by combining advanced photonics and microfluidics technology for the rapid sensitive immunodetection and adsorption kinetics assay of pesticides. The robustness, reusability, and accuracy of the EWOB allow an enhanced prediction of pesticide adsorption kinetics in soil. Using atrazine (ATZ) as the target model, we found that the adsorption kinetics in soil followed a pseudo-second-order kinetic model. EWOB was compared with liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) method and yielded a good correlation coefficient (r(2)=0.9968). The underestimated results of LC-MS/MS resulted in a higher adsorption constant of ATZ in soil derived from LC-MS/MS than that of a biosensor. The proposed EWOB system provides a simple, green, and powerful tool to investigate the transport mechanism and fate of pesticide residues.