| A large amount of aromatic pollutants,particularly aromatic dyes and aromatic surfactants,exist in the environment and have toxic effects on organism.Aromatic pollutants or aromatic combined pollutants may interact with DNA directly or indirectly,changing the structure and conformation of DNA or causing DNA damage, thus affect DNA function or change the genetic character of DNA.Therefore,the study of the interaction between aromatic pollutants and DNA and the genotoxicity assessment methods of aromatic pollutants and aromatic combined pollutants will contribute to the understanding of the toxicity mechanism of aromatic pollutants in the molecular level of gene,also to the correct understanding and evaluation of the toxicity of aromatic pollutants.Utilizing spectroscopy techniques,the dissertation investigate the genotoxicity mechanism of aromatic pollutants and aromatic combined ones.The genotoxicity assessment methods of them are also established utilizing the spectroscopy responding signals.The dissertation consists of the following four parts.In the first part,utilizing UV-Vis spectrophotometry and circular dichroism(CD) techniques,the toxic effects of methyl violet(MV) to calf thymus DNA(ctDNA) was studied in the molecular level.The results showed that MV interacted with ct DNA by two binding models.At low MV concentrations,MV intercalated into ctDNA base pairs.At higher MV concentrations,MV was attached to the negative charged phosphate groups.The binding constant(Kθ25℃) of the electrostatic binding model was 1.80×103 L·mol-1.Utilizing the absorbency signal,the genotoxicity of MV was estimated.MV had a strong genotoxicity interaction intensity at the 4.0×10-5 mol L-1 MV and pH 6.50.The genotoxicity of MV decreased with the time in 0～40 min;the weakening extent the genotoxicity of MV decreased gradually with the time in 40～120 min.When the NaCl concentration was greater than 0.008 mol/L,the interaction intensity of MV with ctDNA decreased significantly with increasing ionic strength,further illuminating that MV was attached to the negative charged phosphate groups.CD results showed that MV can change the conformation of DNA,showing a significant linear dose-response relationship. In the second part,the genotoxicity mechanism of toluidine blue(TB) was examined in vitro.The absorption spectra,fluorescence spectra and fluorescence polarization showed that TB interacted with ctDNA by two binding models to show gene toxicity.At low dye concentrations,TB intercalated into base pairs of ctDNA.At higher dye concentrations,TB was attached to the negative charged phosphate groups. The binding constant of the intercalation binding model and electrostatic binding model was 2.17×107 L mol-1 and 1.01×106 L mol-1 and the number of binding sites was 0.4 and 0.9,respectively.CD results showed that the two binding models had different effects on ctDNA conformation.Utilizing the fluorescence quenching extent of TB by ctDNA,the genotoxicity interaction intensity of TB was estimated and the interaction intensity of TB was strongest at the 4.0×10-1 mol L-1 TB and pH range 6.50～8.50.In the third part,the genotoxicity of the azo dye chrysoidine hydrochloride combined with cetyltrimethyl ammonium bromide(CTMAB) in the living tissue was studied in vitro.The absorption spectrum,resonance light scattering(RLS),CD and transmission electron microscopy(TEM) results showed that the genotoxicity of chrysoidine hydrochloride itself was weak,while the chrysoidine hydrochloride-CTMAB combined aromatic pollutant showed obvious genotoxicity. The assembly of the contaminants on ctDNA,which can be shown by RLS,is considered as a sign of genotoxicity.The genotoxicity of chrysoidine hydrochloride-CTMAB combined aromatic pollution was evaluated by the change of the RLS intensity signal of the system due to the addition of ctDNA.The genotoxicity interaction intensity of the combined pollutant to ctDNA showed a strong co-effect at the dose of 3.0×10-4 mol L-1 chrysoidine hydrochloride,1.6×10-5 mol L-1 CTMAB and pH higher than 7.00.The CD results showed that the conformation of ctDNA changed in the genotoxic process of chrysoidine hydrochloride-CTMAB combined contamination.The TEM results showed that ctDNA interact with the chrysoidine hydrochloride-CTMAB combined contamination to form an ion associated complex. The experimental results showed that the combination of chrysoidine hydrochloride-CTMAB had higher genotoxicity than either chrysoidine hydrochloride or CTMAB individually.In the last part,the environmental genotoxic behavior of the aromatic detergent cetylpyridine bromide(CPB) combined with silver nanoparticles(nanoAg) was examined in vitro.The experimental results showed that the genotoxicity of nanoAg itself was very weak,but when combined with CPB,nanoAg showed obvious genotoxicity.By means of the change of the RLS intensity signal of the nanoAg-CPB system caused by the addition of ctDNA to it,the genotoxicity interaction intensity of nanoAg-CPB combined pollution was estimated.The combined materials had a strong co-effect on ctDNA at the concentration of 3.3×10-6 g mL-1 nanoAg and 6.0×10-6 mol L-1 CPB and pH 7.6.After the formation of a nanoAg-CPB complex,the nanoAg aggregate.After the addition of ctDNA to the nanoAg-CPB system,the particles were scattered and the diameter decreased,which illuminated that CPB-nanoAg has genotoxicity.
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