Novel Fluorescence Probes For Bio/Chemosensing

Fluorescent probe is an important technical mean, which is used to selectively monitor chemical information of analytes by fluorescent signal. Because of the excellent properties of high sensitivity, better selectivity, in situ and real-time detection, fluorescent probes have been widely used in analytical chemistry, biochemistry, molecular biology, microbiology, medicine engineering, chemical engineering and so on.In this thesis, highly sensitive and selective biosensors were developed based on water-soluble conjugated polymers and pyrene derivatives as optical probes. These works have been demonstrated as follows:(1) We investigated the influence of different surfactants including sodium dodecyl sulfate(SDS), polyethylene glycol-4000 (PEG-4000) and cetyl trimethyl ammonium bromide (CTAB) on the emission properties of the water-soluble poly(phenylene ethynylene) conjugate polymer containing pyridyl groups in the backbone (PI). Both the fluorescence and photostability of P1 can be enhanced with the addition of different surfactants. The study may provide guidelines for tuning high sensitivity of bio/chemosensors based on conjugated polymer.(2) A new assay was developed for the biothiols detection based on the fluorescence recovery of PI-containing system. The fluorescence of P1 can be significantly quenched by Ag+and restored when biothiols were added into the P1-Ag+ system due to competition effect between P1 and bithiols with Ag+. After a series of investigation and optimization on experimental conditions, a possible mechanism of the method was proposed and the quantitative detection of biothiols was achieved. Under optimum conditions, the system exhibits a good linear relationship for GSH from 100 to 4200 nM with a detection limit of 80 nM (S/N=3). In particular, the proposed method has been successfully used to quantitatively detect total biothiols in Hela cell lysates. The first CPE-based fluorescence probe for biothiols has been developed, and the approach is simple, fast, highly sensitivity and selectivity.(3) A pyrene derivative-based ratiometic fluorescence probe was designed and synthesized for selective detection of Pb2+. Pyrene is often used as the fluorophore of ratiometric probes, which can form an excimer when an excited-state molecule is brought into close proximity (-3.5A) with another ground-state molecule. Thus, the distance between excited-state and ground-state molecules is the key factor for the formation, adjustment and damage of excimer. In the thesis, a pyrene derivative with carboxyl as the recognized group was synthesized for ratiometic fluorescence detection of Pb2+. In the methanol/water (7:3, v:v) mixture, the probe show high sensitivity and excellent selectivity for Pb2+ detection. The coordinated mode of the probe to Pb2+ is 4:1. The ratiometric fluorescence signal of the proposed probe can effectively eliminate the variable interference from environmental conditions, probe concentration and so on. Thus the probe can be utilized for the highly specific detection in complex systems.