Fluorescence Properties Of Peptides And Application In Metal Ions Detections

Peptides have been applied in various fields such as biology, pharmaceuticals and medicine, for their good biocompatibility and plasticity. Fluorescence spectroscopy is an ideal tool for studies on properties of fluorophore since it can provide abundant details. In this work, we studied the mechanism of fluorescence quenching of a new kind of single-Trp peptide via using steady-state fluorescence spectroscopy.We first synthesized a series of gold nanoparticles with different sizes by reducing gold chloride with sodium citrate. Then we investigated the interactions between those gold nanoparticles and the single-Trp peptide with fluorescence spectrometry. We found that the fluorescence of the peptide was quenched by all our gold nanoparticles. According to theories on metal enhanced fluorescence, we concluded that the direct contact of the peptide and gold nanoparticles could increase non-radiative decay rate which leaded to the quenching of fluorescence.We have also studied quenching efficiencies of fluorescence on the same peptide using various concentrations of copper ions under different pH conditions. With a series of selectivity experiments the interference of other metal ions was excluded. The results have shown that the peptide is a good detector to copper ions with strong anti-interference ability, high sensitivity and good selectivity.Some innovation points of the research were as follows.1. We designed a novel peptide and studied its fluorescence properties via using steady-state fluorescence spectroscopy. The peptide was very sensitive to copper ions.2. The effects of nanoparticles on enhancing fluorescence of the peptide was tested by changing sizes of nanoparticle. Experiment results were fully discussed basing on theories on metal enhanced fluorescence.3. The effects of metal ions and pH on fluorescence property of the peptide were systematically studied and the mechanism of quenching was explained in physical chemistry.In conclusion, we studied the fluorescence properties of a novel peptide with steady-state fluorescence spectroscopy. Based on that its application in physiology was developed. The research laid a foundation and gave some suggestions for researches on metal enhancing fluorescence of peptides. The achievement of this research also paved a way for high precision and sensitive biosensors.