Synthesis Of New Fluorescent Nanoprobes And Their Application In Sensing And Imaging Of Redox Active Moleculars

The balance of redox state is essential for the existence of living organisms. The activity and proportion of the oxidant and reductant respectively decide intracellular redox state. For cells, the changes of the redox state have the effect on cell signal transduction, gene transcription. Now the detection means are electrochemical analysis, high performance liquid chromatography, enzymatic analysis, electron paramagnetic resonance, etc. These methods, although have good selectivity and high sensitivity, which are suitable for indirect determination in vitro, cannot be used in the detection of cells and organisms.This paper adopts different method and technology to synthesize new nano fluorescent probes and use them to detect the biological redox active substances in the body, such as Nicotinamide Adenine Dinucleotide Hydrogen, peroxynitrite, etc. They can provide new ideas and methods for the detection of active material in organisms and cells. Full text is divided into four parts, as follows:Chapter 1. OverviewThis chapter simply introduce the physiological significance of oxidation-reduction equilibrium state and current detections of reactive oxygen species, reducing material and a reversible redox process. We focuses on the significance of the reversible redox fluorescent probe. Secondly we elaborate the fluorescence applications of the quantum hydrogel. Meanwhile, we summarize the fluorescence applications based on gold nanoclusters. Finally we expound the significance and contents of this research.Chapter 2. Functional surface engineering of quantum dot hydrogels for selective fluorescence imaging of extracellular lactate releaseSemiconductor quantum dots have been attracting wide interest due to their various potential characteristic such as easy preparation, optical stability, and biological fluorescence functionalization. We report the rational design and synthesis of a quantum-dot-hydrogel-based fluorescent probe for biosensing and bioimaging the extracellular lactate. Using transmission electron microscopy (TEM). ultraviolet spectrophotometer, we characterize the physical properties of the fluorescent probe, and the stability, linear range and other parameters of the fluorescent probe are investigated by fluorescence. Results show that based on fluorescence resonance energy transfer theory, the quantum dots gel can be used as a fluorescent probe to detect NADH. NADH is the reduction of NAD+enzymes and biochemical responses in biological products, based on which the probe can realize the enzyme reaction substrate fluorescence detection. Under the condition of NAD+and lactate dehydrogenase (LDH). NADH is produced and ditected by the fluorescence, so that we can indirectly detect the lactate. Lactic acid concentration in the range 0.05～10 mM with good linear relationship, and the minimum detectable concentration is 50 μM (S/N= 3). Moreover, the destabilized Nile-Blue-functionalized quantum dots can encapsulate isolated cancer cells when self-assembled into a hydrogel and thus specifically detect and image the extracellular lactate metabolism. By virtue of these properties, the functionalized quantum dot hydrogel was further successfully applied to monitor the effect of metabolic agents.Chapter 3. Selenomethionine modified gold nanoclusters for fluorescence imaging and sensing of intracellular peroxynitriteIn this chapter selenomethionine modified gold nanoclusters were prepared and applied to fluorescence detection of peroxynitrite. We used good biocompatibility gold nanoclusters as raw material, and modified selenomethionine on the surface of gold nanoclusters through Au-Se bond, and the fluorescent nanoprobe was prepared successfully. The probe was characterized by TEM, XPS, ultraviolet and fluorescence spectrometer. Functionalized gold nanocluster probe was researched under different pH value on the analysis feature of the peroxynitrite. The experimental results show that peroxynitrite can quench the fluorescence of the probe with a line range from 1 to 10 μM, and the minimum detection limit is 0.1 μM (S/N= 3). Moreover, it can be used in the redox equilibrium process detection of ONOO- and GSH. The probe was used in the fluorescence imaging and sensing of intracellular peroxynitrite.Chapter 4. Fluorescent probe based on Tellurium doped gold nanoclusters for monitoring peroxynitrite in brain microdialysateGold nanoclusters with the feature of small particle size and non-toxic properties are widely used in the field of sensing and imaging. Sulfur, selenium and tellurium element related substances are mostly involved in rerdox activity, and they can be used in the preparation of redox probe. In this chapter, one-pot synthetic method was put forward for the preparation of BSA-Te/Au NCs, while BSA is stabilizer and reducing agent and sodium tellurite was added. The probe exhibited good selectivity over other active oxygen and a linear range over ONOO- from 0.2μM to 100 μM. Moreover, the fluorescent probe has the ability of ONOO- and GSH redox equilibrium process detection. As a result, the fluorescent probe was successfully used for monitoring of peroxynitrite in the rat brain following the cerebral ischemia-reperfusion.