Synthesis And Application Of Immobilized Fluorescent Probes

During the past decade, fluorescent probes have become an important research field of supramolecular chemistry and have attracted great attention because of their simplicity, high selectivity and sensitivity in fluorescent assays. Furthermore, improved sensing materials can be achieved by immobilizing fluorescent probes onto carrier materials, and will have more comprehensive applications.Three fluorescent hybrid materials were synthesized by immobilization of fluorescence probes within the channels of the SBA-15. Hybrid material SBA-P2 exhibits several different properties compared to the free fluorescent probe, such as higher selectivity and blue-shift of the fluorescence spectra due to special spatial environment in the channels of the SBA-15. SBA-P2 was able to selectively detect Cu2+ with a detection limit for Cu2+ of ca.0.65 ppb under optimized conditions. The adsorption of SBA-P2 for Cu2+ was dramatically enhanced due to the introduction of the Cu2+ fluorescence probes. Preliminary fluorescence microscopy experiments show that the SBA-P2 is a useful functionalized material for studying biological processes involving Cu2+ within living cells and living organisms. SBA-P1 can recognize and absorb Hg2+ with a high degree of selectivity among heavy metal ions in natural aqueous solution. The quenching fluorescence detection is also reversible by treating with EDTA/base. SBA-RT presents Cr3+-selective fluorimetric and colorimetric responses in aqueous solution. The fluorescence responses are reversible by treating with EDTA and do not vary over a broad pH range suitable for Cr3+ bioimaging application. Through isolating the metal ions within the mesopores of the silica, SBA-RT can extract Cr3+ from solution with only trace amounts remaining. The fluorescence images experiment also demonstrated the possibility of further application in monitoring Cr3+ in living cells and organisms.A series of grafted-probes chitosan materials were also synthesized. Fluorescent material H-CS-RB can selectively and sensitively detect Hg2+ by spectroscopic and "naked-eye" method in suspension solution with detection limit of 10 ppb. Fluorescent materials L-CS-Fluo, L-CS-Cb feature excellent water-solubility and biocompatibility and have been applied to selectively detect Fe3+ by fluorescent quenching method in environment and biological fields. The detection limit of L-CS-Fluo and L-CS-Cb for Fe3+ were 0.2 ppm and 0.6 ppm, respectively. Fluorescent molecule probes AG-Fluo, AG-Cb and AG-RB coupling the D-Glucosamine were also synthesized and exhibited consistent recognition abilities with corresponding fluorescent materials. Adsorption abilities of H-CS-RB, H-CS-Fluo and H-CS-Cb for Hg2+ and Fe3+ were more than doubled compared to free H-CS.Two rhodamine-based probes were designed and synthesized. Both RB-TP and RB-Py can detect NO with high selectivity and sensitivity in water assisted by Cu2+. RB-TP and RB-Py could be degraded to RB-NH2 as a result of Cu2+-promoted hydrolysis in water. Furthermore, the presence of NO will lead to reduction of Cu2+ to Cu+, and concomitant NO+ reacted with RB-NH2 generating the N-nitroso amide, opening the spirolactam ring of rhodamine B and evoking the emission and absorption increases. Fluorescence intensities of RB-TP and RB-Py showed 9.5-fold and 6.5-fold increases in 20 min, respectively. At the same time, the solutions turned pink to achieve "nake-eyed" detection. The detedction limit of RB-TP and RB-Py for NO were 5 nM and 20 nM, respectively. Other biologically relevant reactive species such as NO2-、NO3-、ONOO-、H2O2、1O2 and Clo- did not give any interference. Both of them have been applied to detect the intracellular NO by fluorescence imaging method.