Application of a microfluidic paper-based bioimmunosensor with laser-induced fluorescence detection in the determination of alpha-fetoprotein from serum of hepatopaths
Authors: Wang, Wei; Cai, Xiaoyu; Li, Qingling; Zheng, Lili; Yu, Xiufeng; Zhang, Huimin; Wang, Jian
As a common plasma protein, alpha-fetoprotein (AFP) is widely applied as the tumor biomarker for the diagnosis of many cancers. To develop a low cost, high sensitive and high-throughput method for the determination of AFP is significant for the disease diagnosis. In this work, an immunoassay with sandwich-type structures was performed on a paper-based chip for the analysis of AFP. AFP could be captured by the primary antibodies which were immobilized on the paper by chitosan. On the secondary antibodies, the modified initiator DNAs could trigger the hybridization chain reaction to amplify the fluorescence signals for AFP. A laser-induced fluorescence detector coupled with an interface was applied to detect the targets on the paper-based chip. Under the optimized conditions, the detection limit for AFP was 1.0 pg/mL. For every test, the sample solution consumption only was 10 mu L. Finally, the method was applied to determine the AFP in serum of normal person and hepatopaths with hepatic malignant tumor, chronic hepatitis B and other suspected liver diseases. The AFP could be found from all of the samples and the results were similar to that obtained by chemiluminescence immunoassay. The recoveries for AFP ranged from 93.8% to 106%, which indicated the method was reliable. The method based on paper chip had great potential in the application of AFP determination.
Influence of tea polyphenol and bovine serum albumin on tea cream formation by multiple spectroscopy methods and molecular docking
Authors: Yu, Xia; Cai, Xinghong; Luo, Liyong; Wang, Jie; Ma, Mengjun; Wang, Min; Zeng, Liang
The sensory qualities and shelf life of tea beverage strongly affected by tea cream that forms by the interaction of polyphenols and protein. The study aimed to investigate the effects of the interactions between tea polyphenols (TPs) and bovine serum albumin (BSA) on tea cream formation at different concentrations. The tea cream formation increased with TPs and BSA concentration increased. The optimal concentration (TPs: 800 mg/L, BSA: 40 mg/L), for high clarities and contents of phytochemicals, was selected by the technique for order preference by similarity to ideal solution (C = 0.7572). The interaction mechanism of TPs-BSA was investigated by fluorescence spectroscopy, UV-visible absorption spectroscopy, synchronous fluorescence spectroscopy, and molecular docking. TPs interacted with BSA via static quenching process, affecting tryptophan and tyrosine residue microenvironment of BSA. Ester catechins had more binding affinity than non-ester catechins. Hydrogen bonds were the main interaction forces of TPs-BSA.