Silver Nanoclusters As Fluorescent Probes For Detection Of Hydroquinone And MiRNA

Recently, noble metal nanoclusters with a few metal atoms have attracted considerable interest. The AgNCs capped with single-stranded oligonucleotides exhibit excellent photochemical and photophysical properties. It has been demonstrated that the fluorescent properties of AgNCs changed with the DNA secondary structure, and its sequence Furthermore, DNA-templated AgNCs possess fascinating properties, such as low toxicity, good biocompatibility, prominent photostability and water solubility. With these attractive properties, DNA-AgNCs have been widely used in biosensing and bioimaging.Phenol, a toxic chemical pollutant, which adversely affects human health and ecosystem. As a result, fast and sensitive detection of phenol pollutants is in urgent demand. In this thesis, a simple strategy for sensitive detection of hydroquinone using fluorescent silver nanoclusters (AgNCs) has been developed. In the presence of H2O2and peroxidase, the fluorescence of AgNCs was quenched efficiently by phenolic compounds. The mechanism inherent in the fluorescence quenching could be mainly ascribed to the formation of the quinone intermediates via enzyme-catalyzed oxidation of phenolic compounds. The method could determine phenolic compounds with a linear range from8.0×10-8to3.2×10-6mol·L-1and a detection limit of10-8mol·L-1. The sensing protocol may serve as an alternative for evaluation of environmental pollution.MiRNA is a class of endogenous non-coding RNAs (17-25nucleotides) with functions in gene regulation. It plays an important role in cell development, differentiation, metabolism, and apoptosis. MiRNA is also a clinically important biomarker. In this thesis, relying on the cluster transfer between polymer PAA and DNA template, a new method for label-free detection of miRNA has been developed. The transfer of AgNCs from PAA to C-rich single-strand DNAresulted in the formation of more stable AgNCs with enhanced fluorescent intensity. Mismatched DNA sequences R and F have been designed for AgNCs transfer and miRNA detection, respectively. The work described here presents a new biosensing mode, being of great significance to early diagnosis of some diseases.