| Because of the basic properties of nanoclusters,discrete levels,there are essential differences between nanoparticles in optical,electrical,and chemical properties.Metal nanoclusters,such as gold nanoclusters,silver nanoclusters exhibit unique optical,electrical and chemical properties.Because of its small volume,non-toxic and good biocompatibility,its promising prospect in the field of biological labeling optical sensing and metal ions detection and so on.In this paper,we used denatured fish sperm DNA as the templat,and a fluorescent silver nanocluster and silver nanoparticles were synthesized in aqueous.The silver nanoclusters explored the application on heavy metal ions and drug molecules detection.Determined hydrogen sulfide by resonance light scattering technique based on silver nanoparticles.The main contents were summarized as following:?1?In this study,fluorescent Ag nanoclusters?Ag NCs?were synthesized using denatured fish sperm DNA as the template.Different from others methods,this method did not use artificial DNA as the template.After the reaction of denatured fish sperm DNA with Ag+ ions,the Ag+ ions were reduced by NaBH4 to form Ag NCs.The Ag NCs showed a strong fluorescence emission at 650 nm when excited at 585 nm.The fluorescence intensity increased by four times at pH 3.78,controlled with Britton-Robison?BR?buffer solution.The fluorescence of the Ag NCs was quenched in the presence of trace mercury ions?Hg2+?in a weakly acidic medium and nitrogen atmosphere.The extent of the fluorescence quenching of the Ag NCs strongly depends on the Hg2+ion concentration in the linear range from 2.0 nmol L-1 to 3.0 mmol L-1.The detection limit?3s/k?for Hg2+ was 0.7 nmol L-1.Thus,a sensitive and rapid method was developed for the detection of Hg2+ ions.?2?A novel DNA-directed AgNCs?DNA-Ag NCs?was synthesized with economical raw material?natural fish sperm DNA?through a simple and rapid approach.Whereas,when berberine hydrochloride?BHC?entered the solution system,it would interact and combine efficiently with DNA on the surface of Ag NCs,which could lead to subtle change of charge distribution on its surface,inducing aggregation of DNA-Ag NCs.As a result,fluorescence of the system was quenched visually;the process represented a colo rvariance from yellow to hot pink under HAc medium,then back to yellowish brown when BHC worked.Based on above phenomenon,a selective and accurate spectrofluorometric method for BHC detection wasestablished.It can be applied to detect trace amounts of BHC inaqueous solution in the linear range from 1.0nM to 2000.0 nM;and the detection limit?3s/k?was 0.3 nM.Simultaneously,a semi-quantitative determination by visual evaluation from 5.0 nM to 2000.0 nM was also achieved.This method provided excellent selectivity for the detection of BHC in the presence of ten kinds of common natural amino acids and nine kinds of common mentalions.Furthermore,the BRH content in compound berberine tablets from drugstore was successfully investigated by this method and the results showed high accuracy.?3?We have developed a green approach to prepare DNA-templated silver nanoparticles?Ag NPs?from the direct reaction between Ag+and ascorbic acid in the presence of DNA and sodium hydroxide.The Ag NPs showed strong resonance light scattering?RLS?intensity property.Then,the interaction between hydrogen sulfide?H2S?and Ag NPs was studied by measuring their RLS spectra.The results showed that there is strong interaction between Ag NPs and H2 S,which resulted in decrease the size of Ag NPs and decrease in the RLS intensity of the Ag NPs solution at the wavelength of 467 nm.The results demonstrated that the RLS technique offers a sensitive and simple tool for investigating the interaction between Ag NPs and H2 S,which can be applied to detect H2 S with high sensitivity and selectivity without complex readout equipment.The linear range for H2 S determination was found to be the range from 5.0 × 10-9 to 1.0 × 10-7 mol L-1,and the detection limit?3s/k?was 2.8 × 10-9 mol L-1.Moreover,the proposed method was applied for the determination of H2 S in natural water samples with satisfactory results.?4?Here a dual-functional spectrum probe was developed based on novel gold nanoclusters?Au NCs?for the detection of heavy metal ions targeting copper ions?Cu2+?and mercury ions?Hg2+?with high selectivity and sensitivity.Small sized Au NCs?3.9 nm?with highly orange emitting fluorescent were synthesized via an one-pot reaction by using citrate-stabilized stannous ions?Sn?II?-citrate?as reducing and capping agent.The dual spectrum probe was conceived in such a way to utilize both the fluorescence?FL?quenched by Cu2+ and resonance light scattering?RLS?enhanced by Hg2+.Two different ions in the corresponding discrete spectral response appeared completely independent of each other by different mechanism.The intensity of fluorescence decreasing at 575 nm in FL spectra and the scattering increasing at 520 nm in RLS spectra has linear relationships with Cu2+ and Hg2+ ion concentrations in the ranges of 0.5 to 70 and 0.25 to 10 ?mol L-1,respectively.The detection limits are as low as 0.38 ?mol L-1and 0.05 ?mol L-1for Cu2+and Hg2+ions,respectively.Furthermore,these Au NCs could be readily applied to Cu2+ and Hg2+ detection inenvironmental water samples,indicating their promising to serve as a convenient,dual-functional,and label-free probe for related ions monitoring. |
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