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Gold Nanoparticles Quenching Fluorescence Probe for Glucose Detection and Cell Imaging Based on Fluorescence Resonance Energy Transfer (fret)

Author: YeJian
Tutor: TangBo
School: Shandong Normal University
Course: Analytical Chemistry
Keywords: Fluorescent probe Gold nanoparticles (AuNPs) Fluorescence resonance energy transfer (FRET) Glucose Living cells
CLC: Q503
Type: Master's thesis
Year: 2010
Downloads: 407
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Abstract

Semiconductor nanoparticles or quantum dots having a unique optical physics characteristics of example, the emission wavelength of the quantum dot can be tuned by controlling its size and composition, and a high fluorescence quantum yield, strong resistance to photobleaching. It is because of these advantages, the quantum dots are widely used in biological sensing fluorescent markers. Modification in the biological material on the surface of the nanoparticles the novel multifunctional nano biological compounds can be synthesized. Nano fluorescent probes as a new probe, it is specific to the quantum size effect and the small particle size showing many homogeneous single molecule or a chunk of objects of different optical properties, has been successfully applied to biological samples the detection and imaging of living cells. Recently, protein-modified nanoparticles assembled bio-nano sensor has caused widespread concern, for example, semiconductor quantum dots have been as an excellent material for biological analysis and application of the enzyme reaction which. Therefore, the design a novel fluorescent nanobiosensors with good performance used to biologically active molecules or the intracellular reactive substances analysis and testing has become a huge challenge for scientists. Fluorescence resonance energy transfer (FRET) as a the important photophysical technology has been widely applied to biological macromolecules distance between the qualitative and quantitative detection. Fluorescence resonance energy transfer efficiency is determined by the distance between the donor receptors and their degree of spectral overlap. Wherein the energy given by the donor (donor), luciferase, the quantum yield is the most commonly used donor molecule. The energy recipients as receptor (Acceptor) receptor may transmit their characteristic fluorescence, fluorescence enhancement, and can also be used as a quencher no fluorescence (fluorescence quenching), does not produce fluorescence receptors its advantages is to be able to reduce possible fluorescence background interference generated directly by the receptor itself. As a fluorescence quencher, gold particles may quench the fluorescence of the fluorophore. Gold nanoparticles with a wide range of quenching, the quenching efficiency of fluorescent reagents, as well as good stability, can improve the sensitivity and specificity of the FRET process, making it a hotspot of research and application. Compared with traditional organic quenchers, gold particles have special structural features and optical properties, low toxicity and good biocompatibility, gold as an excellent quencher has opened up a high-sensitivity The prospects for detection of the biologically active molecule of glucose is an important biologically active substances, and plays a very important role in the health of the cell growth. Glucose deficiency or excess will have a negative impact on the body's metabolism. There are a lot of reports found to consume more glucose metabolism of cancer cells relative to normal cells. Reasons which so far is not very clear, but the cancer cells of sugar metabolism that is generally accepted. Currently, it has been reported a method for detecting many kinds of information about the content of glucose. Wherein the fluorescence detection method based on dextran, glucose, and glucose oxidase competitive binding because it has good selectivity and a low degree of damage has been widely applied to the detection of glucose which. However, the detection limits of these methods are generally not high, and toxicity problems still exist, limiting the direct detection of the glucose content of the biological sample, thereby limiting the conversion of cell signaling and cell imaging aspects of the application, so the design of a stable high selectivity Nano fluorescent probes for imaging living cells glucose is very meaningful. This paper mainly to carry out the research work of the following two parts: (a) based on the principle of fluorescence resonance energy transfer (FRET) designed a simple and effective fluorescent nanoprobes for glucose detection. The idea of ??the probe derived from glucose and apo-glucose oxidase (apo-GOx) is a specific binding, and its binding force is greater than the binding force of dextran (Dextran) and apo-GOx. Probe apo-GOx-Dextran as a carrier of the occurrence of FRET, FITC-Dextran as an energy donor, apo-GOx - modified gold nanoparticles (AuNPs) as energy receptors. Of glucose in the system does not exist, since the binding force between the apo-GOx Dextran, making Dextran-FITC and AuNPs-apo-GOx close to each other, to meet the conditions of resonance energy transfer, when excited by excitation wavelength in the FITC FITC fluorescence emitted is absorbed by the gold nanoparticles appear as fluorescence quenching. When adding glucose, glucose will with Dextran compete with apo-GOx combination makes the FITC-Dextran AuNPs-apo-GOx away from energy transfer disappear, FITC fluorescence signal restoration. The experimental results show that under optimal experimental conditions, the fluorescent spectrum showed that the fluorescence intensity with the glucose concentration gradually increases made linear enhancement, the linear range of 20 nm - 0.2μM. At the same time, the probe has a high sensitivity and selectivity, the detection limit of 5 nM. Cells in the presence of other sugars and most of the biological species is not measured in the it impact on the success of the nanoparticle probes applied to the imaging of living cells glucose. (B) the fluorescent probe constructed based on two different scales of gold to achieve the detection of glucose in the living cells. 2 nm mercaptoundecanoic acid modified gold (LAuND) apo-GOx modified on 10 nm Dextran modified gold particles (Dex-Au-NP) as a receptor as the donor. Glucose and Dextran with apo-GOx competitive binding, when the presence of glucose, glucose and apo-GOx specific binding competition down by Dextran cause LAuND fluorescence recovery. To detect glucose in accordance with the change in fluorescence intensity, and thus glucose in the living cell imaging.

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