A two-photon excitable small organic molecule (abbreviated as TP-NH 2) with large two-photon absorption cross section and competitive fluorescence quantum yield was prepared, which emitted fluorescence in the visible region upon excitation at 800 nm. Using the TP-NH 2 molecule as an energy donor, a two-photon excitation fluorescence resonance energy-transfer (TPE-FRET) based homogeneous immunoassay method was proposed. The donor and the acceptor (DABS-Cl, a dark quencher) were labeled to bovine serum albumin (BSA) separately, and anti-BSA protein was determined by employing an antibody bridging assay scheme. Rabbit anti-BSA serum containing other biomolecules was intentionally used as the sample to introduce interference. A parallel assay was performed using the traditional one-photon excitation FRET model, which failed to carry out quantitative determination due to the serious background luminescence arising from those biomolecules in the sample. The TPE-FRET model showed its strong ability to overcome the problem of autofluorescence and provided satisfying analytical performance. Quite good sensitivity and wide linear range (0.05-2.5 nM) for anti-BSA protein was obtained. The results of this work suggest that TPE-FRET could be a promising technique for homogeneous assays excluding separation steps, especially in complicated biological sample matrixes.
As an effective method, the fingerprint technique, which emphasized the whole compositions of samples, has already been used in various fields, especially in identifying and assessing the quality of herbal medicines. High-performance liquid chromatography (HPLC) and near-infrared (NIR), with their unique characteristics of reliability, versatility, precision, and simple measurement, played an important role among all the fingerprint techniques. In this paper, a supervised pattern recognition method based on PLSDA algorithm by HPLC and NIR has been established to identify the information of Hibiscus mutabilis L. and Berberidis radix, two common kinds of herbal medicines. By comparing component analysis (PCA), linear discriminant analysis (LDA), and particularly partial least squares discriminant analysis (PLSDA) with different fingerprint preprocessing of NIR spectra variables, PLSDA model showed perfect functions on the analysis of samples as well as chromatograms. Most important, this pattern recognition method by HPLC and NIR can be used to identify different collection parts, collection time, and different origins or various species belonging to the same genera of herbal medicines which proved to be a promising approach for the identification of complex information of herbal medicines.
Thermal decomposition kinetic reaction parameters of KZn2(PO4)(HPO4) was investigated by non-isothermal measurement used in a multivariate non-linear regression analysis. The anticorrosive performance of the phosphate extracts in different pH 3.5% NaCl was studied by polarization and open circuit potential measurements. Kinetics analysis shows that the decomposition of KZn2(PO4)(HPO4) acts as a double-step reaction of : a n order autocatalytic reaction (Cn) with n =1.0791, E1 = 365.06 kJ/ mol, A1 =8.69×1022s−1 is followed by a expended Prout-Tompkins reaction (Bna) with n=2.6548, E2 = 390.91 kJ /mol, A2 = 5.37×1024 s−1. In different pH 3.5% NaCl extracts, KZn2(PO4)(HPO4) functions as a cathodic inhibitor on steel and is even superior to other phosphates in efficiency. The inhibiting efficiency of the pigments on steel decrease in the order: KZn2(PO4)(HPO4) > aluminum zinc phosphate > zinc phosphate ≧ aluminum triphosphate
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