Objective To compare the nature of the metabolites formed from the phase I metabolism （hydroxylation and oxidation） and phase II metabolism （glutathionyl conjugation） of PCBs that have different chlorine substitution patterns. To discuss the structure-activity relationships and metabolic mechanisms of PCBs. Methods 4-CI-biphenyl （PCB3）, 4,4＇-CI-biphenyl （PCB15）, 3,4,3＇,4＇-Cl-biphenyl （PCB77） were used for in vitro metabolic study. LC/MS and UV-Vis studies were performed for metabolites identification. Results The cytochrome P-450 catalyzed hydroxylation rate decreased as the number of chlorine substitutions increased. In this reaction, PCB3 was fully metabolized, approximately half of the PCB15 was metabolized and PCB77 was not metabolized at all. The oxidation rate of PCB15-HQ was higher than that of PCB3-HO. under various oxidation conditions. The LC/MS and UV-Vis data suggest that in the conjugation reaction of PCB15-Q and GSH, the Michael addition reaction occurs preferentially over the displacement reaction. Conclusion The metabolic profiles of polychlorinated biphenyls （PCBs） are dramatically affected by chlorine substitution patterns. It is suggested that the metabolic profiles of PCBs are related to their chlorine substitution patterns, which may have implications for the toxicity of PCB exposure.
SONG Er QunMA Xiao YanTIAN Xing GuoLIU JingLIU Li ChaoDONG HuiSONG Yang
With the development of nanotechnology,many kinds of nanomaterials have been applied in analytical chemistry,i...
Pu Zhang~(a,b),Cheng Zhi Huang~(a*) (a Education Ministry Key Laboratory on Luminescence and Real-Time Analysis,College of Pharmaceutical Sciences,Southwest University,Chongqing 400715. b College of Physical Sciences and Technology,Southwest University,Chongqing,400715.)
Composite materials were synthesized by encapsulating Au and Ag nanoparticles in an agar gel matrix. These metallic nano-particles were found to be separately stored, so their optical, catalytic, and antibacterial properties were retained both in the composite gel and a composite membrane. The composite gels were stable under hard external conditions. Based on this, a sensor for the detection of Hg2+ was developed using the Au nanoparticle/agar composite gel. Antibacterial materials were achieved using the Ag nanoparticle/agar composite gel and composite membrane. These two Ag nanoparticle-based materials showed good antibacterial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus.
With the development of nanosciences, both localized surface plasmon resonance light scattering （LSPR-LS） and dynamic light scattering （DLS） techniques have been widely used for quantitative purposes with high sensitivity. In this contribution, we make a comparison of the two light scattering techniques by employing gold nanoparticles （AuNPs） aggregation induced by mercuric ions. It was found that citrate-stabilized AuNPs got aggregated in aqueous medium in the presence of mercuric ions through a chelation process, resulting in greatly enhanced LSPR-LS signals and increased hydrodynamic diameter. The enhanced LSPR-LS intensity （A/） is proportional to the concentration of mercuric ions in the range of 0.4-2.5 laM following the linear regression equation of A/= -84.7＋516.4c, with the correlation coefficient of 0.983 （n = 6） and the limit of determi- nation （3o-） about 0.10 gM. On the other hand, the increased hydrodynamic diameter can be identified by the DLS signals only with a concentration of Hg2＋ in the range of 1.0-2.5 gM, and a linear relationship between the average hydrodynamic diame- ters of the resulted aggregates and the concentration of Hg2＋ can be expressed as d = -6.16 ＋ 45.9c with the correlation coeffi- cient of 0.994. In such case, LSPR-LS signals were further applied to the selective determination of mercuric ions in lake water samples with high sensitivity and simple operation.
