The Design, Synthesis And Study On Sensing Performance Of Novel Fluorescent Probe For Cell Analysis

After entering twenty-first century, with the rapid development of life science, intracellular trace and even single molecule（ion, small molecules, nucleic acids, and proteins） detection becomes more and more important, because change of intracellular specific biological molecules is often the beginning of great changes of the system. Therefore, at the initial stage of change in the life system,achieve a variety of intracellular biological trace detection for control system change and improve system undoubtedly has a very important significance. In recent years, with the excellent performance of various new materials（conjugated polymer, small molecule dyes and upconversion nanomaterials） for the emergence of intracellular biological analysis provides a solid foundation and possible for the preparation of novel fluorescent probe. Therefore based on new materials the establishment of implementation of biomolecule fluorescent probe has the high sensitivity and high sp ecificity detection, provide strong support for the life science research will. It has a strong theoretical significance and practical significance.We combined the fluorescent materials and a new type of chemical and biological fluorescence detection in this doctoral dissertation, and prepared the Fe³⁺ probe based on cationic conjugated polymer, small molecule time-resolved fluorescence probe based on fluorescence resonance energy transfer, nano probes based on fluorescent upconversion nanomaterials, and the solid state fluorescence probe based on ESIPT, to achiever high sensitive specificity analysis for a variety of intracellular biological molecule. The main contents are as follows:（1） In the secondary chapter, we have designed and synthesized a rhodamine-appended water-soluble conjugated polymer CP 1 as a FRET-based ratiometric probe for intracellular Fe³⁺ probing. With no requirement of any organic cosolvent, CP 1 exhibits excellent solubility in pure aqueous solution. Because of the molecular wire effect, probe CP 1 show high selectivity and good reversibility to Fe³⁺, which benefits for the dynamic monitoring the concentration change of Fe³⁺ in practical complex samples and living cells.（2） In the third chapter, we have designed and synthesized a novel bispyrene-fluorescein hybrid FRET cassette pH probe PF to serve as a ratiometric time-resolved sensing platform for bioanalytical applications. The platform possesses both the advantage of ratiometric fluorescent probe which can eliminate interferences from environmental factors, and the advantage of time-resolved probe which can well discriminate the response signal of probe from endogenous autofluorescence background in biological samples. Cellular experimental results demonstrate its low cytotoxicity, good biocompatibility, and could be applied for ratiometric quantitative monitoring of pH changes in living cells with satisfying results.（3） In the fourth chapter, we designed and prepared a ratiometric upconversion luminescence nanoplatform for LRET-based biosensing and bioimaging with high sensitivity and selectivity. By optimizing the thickness of the spacer layer, a LRET system with higher energy transfer efficiency can be obtained, affording a ratiometric sensing system for pH with two well-resolved and comparable luminescence peaks which can be used for biosensing and bioimaging.（4） In the fifth chapter, based on previous work, we adjusted the doping amount of rare earth elements to synthesize different fluorescence upconversion materials, and the rhodamine B-ethylenediamine（Rh B-2NH2） as a recognition group for a very good response to Hg²⁺, in order to expand the scope of application of the biosensor system based on upconversion nanomaterials to verify the generality. Furthermore, the USR nanosystems have the capacity to monitor changes in the distribution of Hg²⁺ in live cells by upconversion luminescence bioimaging. In this work, and previous work based on the experimental results, our successful ratiometric multilayer core/shell-structured UCNPs/silica nanosystem-based LRET for biosensing and bioimaging provides a new platform for further novel probes for highly sensitive biosensing and bioimaging studies.（5） In the sixth chapter, based on ESIPT, we design and synthesis probe MA-HPQ as solid state fluorescence probe to detect intracellular Cys. The ESIPT effect and solid state fluorescence characteristics of probe MA-HPQ can detect Cys with high sensitivity, so it can dynamically monitor concentration changes of Cys in actual complex sample and living cells.