ABSTRACT
The resonance light scattering (RLS) spectral characteristics of the interaction between rose Bengal and mexiletine hydrochloride in the presence of cetylpyridinium bromide were investigated. A dual-wavelength resonance light scattering (DWO-RLS) method for the determination of mexiletine hydrochloride in drugs was established. In a weakly acidic solution, rose Bengal interacts with mexiletine hydrochloride and cetylpyridinium bromide to form a red ternary ion association complex, which led to a significantly enhanced resonance light scattering signal and produced two strong characteristic scattering peaks at 372 nm and 596 nm. In these two wavelengths the mass concentration of mexiletine hydrochloride was in the range of 0.004 to 0.65 mg·L-1 and had a good linear relationship with the resonance light scattering enhancement intensity (ΔIRLS), with detection limits of 0.003 2 mg·L-1 (372 nm) and 0.003 8 mg·L-1 (596 nm), respectively. When measured by the dual-wavelength resonance light scattering (DWO-RLS) technique, the detection limit was lower, only 0.001 8 mg·L-1. When the DWO-RLS method was applied to the determination of mexiletine hydrochloride in commercially available mexiletine hydrochloride tablets, and the recovery was 98.5%-103%, and the relative standard deviation was 2.0%-2.7%.
ABSTRACT
A peptide microarray-based fluorescence and resonance light scattering ( RLS ) two readout assay was developed for screening thrombin inhibitors in blood samples. In this assay, the biotinylated peptide microarray was used as the platform. The peptide C-terminal fragments carried biotin sites departed from the slide when the biotinylated peptides were digested by thrombin hydrolysis reaction. The hydrolysis progress was labeled by fluorescence and 30 nm peptide-stabilized gold nanoparticles through the biotin-avidin reaction. In the presence of thrombin inhibitors, the hydrolysis reactions were blocked, and the inhibition capability of inhibitors could be detected by the fluorescent and RLS signal changes. The order of the half maximal inhibitory concentration ( IC50 ) of thrombin inhibitors in pure thrombin solution and spiked human serum were argatrobanHAT-Ⅲ>trypsin inhibitor>E-64>AEBSF. The reversible or irreversible characters of argatroban and HAT-Ⅲ had been estimated in human plasma. Compared with the experimental data of fluorescent and RLS assay in blood sample, the RLS assay labeled by 30 nm gold nanoparticles are more suitable for the inhibitor detection in complicated blood sample.
ABSTRACT
In this study, based on its enhancement effect on resonance light scattering (RLS) of fluorosurfactant (FSN)-capped gold nanoparticles (GNPs), we reported a simple approach for the rapid sensing of captopril. Under optimum conditions, the lowest detectable concentration of captopril through this approach (S/N=3) was 0.01μg/mL. The calibration curve was linear over the range of 0.08-4.0μg/mL for the detection of captopril. The recoveries of captopril were found to fall in the range between 99% and 100%. We have validated the applicability of our method through the analyses of captopril in pharmaceutical formulations. Good agreements were obtained for the determination of captopril between the present approach and official method.
ABSTRACT
Objective To establish a rapid and sensitive method for detection of urinary protein.Methods In B-R buffer solution with pH 4.2,the signals of resonance light scattering by Poncesu S (PS) combined with protein in ?ex=?em=306nm were detected.Results There was a linear relation between the scattering signals of resonance light,and the protein concentration ranged from 0 to-1500 mg/l. The regression equation was ?I=2.24c-0.41,r=0.999 and the detection limit was 1.48 mg/l. The average recovery was 102.8% and the between-and within-subject coefficients of variation were 2.09% and 5.40% respectively.No significant difference was found compared with the method of PS.Conclusion The established method in this study is a simple,rapid and high sensitive method for determination of urinary protein.
ABSTRACT
Objective To understand the spectroscopic property of AO-H2SO4-KBrO3-naphthol system and the enhanced mechanism of resonance light scattering(RLS),and to develop a method for the determination of trace naphthols in urine.Methods In the dilute H2SO4 medium,naphthols could react with KBrO3 and AO to form ion-association complexes,which produced a new RLS spectrum and resulted in the great enhancement of RLS.The characteristics of RLS spectrum,three-dimensions fluorescence spectrum,absorption spectrum and fluorescence spectrum and the optimum conditions of reaction were studied.Results The enhanced intensity of RLS was 468 nm.The linear range was at 1.41?10-7-2.80?10-5 mol/L for ?-naphthol,1.28?10-7-3.00?10-5 mol/L for ?-naphthol.The relative coefficient and the limits were 0.999 6 and 0.422?10-7 mol/L,0.999 3 and 0.385?10-7 mol/L for ?-naphthol and ?-naphthol,respectively.The urine samples analysis of the relative standard deviation was 4.8%-7.3% and the average recovery rate was 90.7%(n=6).Conclusion This method is sensitive,simple,rapid and applicable to the determination of trace naphthols in human urine.