Preparation And Characterization Of Lysine-functionalized Gold Nanoclusters And Application In The Detection Of Cu²⁺

Enzyme labeling, radioactive labeling and fluorescent labeling are used as the conventional methods to achieve analyzing and detecting experimental materials in the fields of biomedical analysis and envirommental testing. The fluorescent labeling is one kind of the most commonly used method in the present analysis and detection among them. Organic dyes, fluorescent protein and quantum dots are the traditional fluorescent materials. The organic dyes are currently the most widely used fluorescent materials, but their optical stabilities are poor. Quantum dots as a class of more developed fluorescent nano-materials have excellent fluorescent properties (such as broad excitation spectrum, narrow and symmetric emission spectrum, larger Stokes shift, optical stability, the emission wavelength with size tunable, the "one element excitation, multiple emission" etc.). However, quantum dots contain toxic elements (such as Cd2+Pb2+, Hg2+) with a larger size (larger than10nm after biological function), the flicker phenomenon and these problems have limited its application in the fields of chemical analysis and biological analysis.In recent years, noble metallic nanoclusters (noble metallic nanoclusters, NMNCs) have attracted more and more attentions because of its advantages of easy preparation, high sensitivity, good stability and larger Stokes shift. NMNCs are molecular aggregates with fluorescence and good water solubility, which are generally composed of several to tens of atoms of Au, Ag or Pt and other precious metals. The quantum size effect makes the optical properties vary with the particle size of NMNCs. Therefore, the fluorescent emission spectra of NMNCs can be tuned in the visible to near infrared spectral range. Currently, NMNCs have been used for assaying and detecting DNA, proteins, metal ions, hydrogen peroxide, toxic anions and thiol compounds, in addition, they show great prospect in biomedical and environmental testing analysis. Research results showed that the AuNCs@Lys naono-materials synthesized by one step reduction method with a template of lysine have good stability. In addition, the changes of fluorescence signal strength were more sensitive when added into the copper ions after AuNCs@Lys and AuNCs@BSA were cooperated.Contents of this paper are as follows:1. Fluorescent lysine-functionalized gold nanoclusters were prepared by using a simple and one-pot method while lysine played a role as a temple in the presence of chloroauric acid and sodium hydroxide, then we characterized the particle size, morphology and luminescent properties.2. AuNCs@Lys cooperating with AuNCs@BSA were employed as a novel strategy for the quantification of Cu2+ions, which depends on Cu2+coordinates with-COOH and-NH2of both AuNCs@BSA and AuNCs@Lys, leading to quenching of their fluorescence. The calibration curve was constructed between the fluorescent intensity decrease (Fo-F) of the mixed AuNCs and the logarithmic plot of Cu2+concentration. At last, the practicality of this probe for detection of Cu2+in actual samples was validated.