Application Study Of Fluorescence Nanomaterials In The Detection Of Small Biomolecules

Important small biomolecules, such as amino acids and ATP, are the building blocks of biological functions and composition of biological macromolecules and basic life-sustaining normal activities. They play a crucial role in nutritional supplements living body, providing energy, regulating metabolism, strengthening immol/Lunity, tissue repair, and ontogeny of information transfer and so on. The content and activity of these small biomolecules is directly related to the health of an organism. It is very important for researchers to expound the secrets of life, to develop new functionalized medicine to surmount many difficult diseases and promote the development informatic science. Therefore, what we should do is to further penetrate the interaction of the biomolecules and to develop rapid, convenient, accurate and sensitive assay for small biomolecules. This project is the forward position and hot point in bio-analytical chemical research. Aiming at the research goals mentioned above, this thesis utilized the advantages of fluorescent nanomaterials and nucleic acid probe to develop a series of methods for detection of biotiols and ATP. The main points of this thesis are summol/Larized as follows:1. A rapid fluorescence “switch-on” assay was developed to detect trace amount of GSH based on carbon dots-MnO2 nanocomposites, which was fabricated through in situ synthesis of MnO2 nanosheets in carbon dots colloid solution. Due to the formation of carbon dots-MnO2 nanocomposites, fluorescence of carbon dots could be quenched efficiently by MnO2 nanosheeets through fluorescence resonance energy transfer（FRET）. However, the presence of GSH would reduce MnO2 nanosheets to Mn²⁺ ions and subsequently release carbon dots, which resulted in sufficient recovery of fluorescent signal. This proposed assay demonstrated highly selectivity toward GSH with a detection limit of 300 nmol/L. Moreover, this method has also shown sensitive responses to GSH in human serum samples, which indicated its great potential to be used in disease diagnosis. As no requirement of any further functionalization of these as-prepared nanomaterials, this sensing system shows remarkable advantages including very fast and simple, cost-effective as well as environmol/Lental-friendly, which suggest that this new strategy could serve as an efficient tool for analyzing GSH level in biological samples.2. A novel label-free nanosensor has been developed for detecting biothiols including cysteine and glutathione based on poly（thymine）-templated fluorescent copper nanoparticles（CuNPs）, which were controlled through thymine-Hg（II）-thymine coordination. This assay provides a simple, cost-effective, and sensitive platform for the detection of biothiols. The detection limits for cysteine, homocysteine and glutathione are 12.5 nmol/L, 20 nmol/L and 15 nmol/L respectively, which is sufficiently sensitive for practical applications. The sensing system also exhibits high selectivity against other amino acids, and the application of the sensor for biological fluids shows that the proposed method works well for real samples.3. Detection of ATP using lable-free ssDNA probe. A highly sensitive and simple fluorimetric method for the determination of ATP based on multifunctional ss DNA, which holds the ability of synthesizing fluorescent copper nanoparticles（CuNPs） as well as recognizing ATP molecules. The probe was designed for detection of ATP with the aid of Exo I. In the absence of ATP, probe containing the ATP-binding aptamer（ATP–aptamer） and Poly T is digested upon the addition of Exo I, leading to failure of synthesizing CuNPs. Whereas, in the presence of ATP, the ATP-binding aptamer folds into a G-quadruplex structure that is resistant to Exo I digestion. Accordingly, CuNPs are synthesized and high fluorescence intensity is observed. This signal-on assay exhibits high sensitivity for ATP with a detection limit of 500 nmol/L in the range of 1⁸0 μmol/L. Further selective investigation and real sample anti-interference experiment, shows that this method also has high specificity and anti-interference ability. With good uvniversality, this method may also be used to detect other molecules or ions by design different probes.