High-Performance Fluorescent Microspheres Based on Fluorescence Resonance Energy Transfer Mode for Lateral Flow Immunoassays.

The label with a large Stokes shift and strong fluorescence properties could improve the sensitivity of the lateral flow immunoassay (LFIA). Herein, two aggregation-induced emission (AIE) luminogens with spectral overlap were encapsulated in polymers by using the microemulsion method as a label, and the construction of a fluorescence resonance energy transfer mode was further verified via theoretical calculation and spectral analysis. Satisfactorily, the doped AIE polymer microspheres (DAIEPMs) exhibited a large Stokes shift of 285 nm and a 10.8-fold fluorescence enhancement compared to those of the AIEPMs loaded with acceptors. Benefiting from the excellent optical performance, DAIEPMs were applied to the LFIA for sensitive detection of chlorothalonil, which is an organochlorine pesticide. The limit of detection of the proposed DAIEPMs-LFIA was 1.2 pg/mL, which was 4.8-fold and 11.6-fold lower than those of quantum dot bead LFIA and gold nanoparticle LFIA, respectively. This work provides a new strategy to improve the optical properties of fluorescent materials and construct a sensitive and reliable detection platform.

Comparative study on the chemical composition, anthocyanins, tocopherols and carotenoids of selected legumes.

Twenty-nine legumes were assessed for their nutritional and phytochemical compositions. Soybean and black soybean had the highest protein contents (34.05-42.65 g/100 g DW, dry weight of legumes), particularly being a rich source of lysine (1.78-2.23 g/100 g DW. Soybean and black soybean had the highest fat contents (14.13-22.19 g/100 g DW). Broad beans had the highest unsaturated fatty acids (83.57-89.01 g/100 g fatty acid), particularly rich in α-linolenic and linoleic acid. The highest and the lowest dietary fiber were found in red kidney beans (35.36 g/100 g DW) and mung beans (22.77 g/100 g DW), respectively. Except for soybean and white kidney bean, 6 major anthocyanins in the legumes samples were identified. The soybean contained the highest total tocopherols content (90.40-120.96 µg/g dry weight of beans), followed by black soybean (66.13-100.76 µg/g DW). The highest carotenoids were found in lentils (4.53-21.34 µg/g DW) and red kidney beans (8.29-20.95 µg/g DW).

Highly selective colorimetric bacteria sensing based on protein-capped nanoparticles.

A rapid and cost-effective colorimetric sensor has been developed for the detection of bacteria (Bacillus subtilis was selected as an example). The sensor was designed to rely on lysozyme-capped AuNPs with the advantages of effective amplification and high specificity. In the sensing system, lysozyme was able to bind strongly to Bacillus subtilis, which effectively induced a color change of the solution from light purple to purplish red. The lowest concentration of Bacillus subtilis detectable by the naked eye was 4.5 × 10(3) colony-forming units (CFU) mL(-1). Similar results were discernable from UV-Vis absorption measurements. A good specificity was observed through a statistical analysis method using the SPSS software (version 17.0). This simple colorimetric sensor may therefore be a rapid and specific method for a bacterial detection assay in complex samples.

Label-free fluorometric method for monitoring conformational flexibility of laccase based on a selective laccase sensor.

A facile and selective fluorescence sensor for laccase determination has been proposed depending on the interaction between 3-azidocoumarin and trametes versicolor (Tv) laccase in this paper. The azido group of 3-azidocoumarin that is electron-rich α-nitrogen can directly interact with histidines that coordinate to three copper sites through hydrogen bonds and forms a new complex, which decreases the electron-donating ability of the azido group, leading to enhance the fluorescence intensity of the sensing system. Also, other common proteins have no significant interference for the proposed laccase sensor. Additionally, the proposed fluorescence sensor is extended to demonstrate the conformational flexibility of Tv laccase by the urea denaturant. A good consistency of the results obtained with the presented laccase sensor and CD spectra is performed. Furthermore, the relationship between the catalytic activity and the unfolding percentage of the unfolded Tv laccase through the proposed laccase sensor is also elucidated well.