Preparation And Performance Study Of Fluorescent Sensors Based On Rhodamine B Derivatives/carbon Nanodots

The recognition and sensing of the biological and environmental substance such as mercury ions (Hg2+), L-cysteine (L-Cys) and trinitrophenol (TNP) have emerged as a significant goal in the field of chemical sensors in recent years. Fluorescent spectrometry has been a powerful tool due to its simplicity, low detection limit and real-time detection, among which rhodamine B-bsed fluorescent probes have received increasing attention. Carbon dots (CDs), a new class of photoluminescent nano materials with excellent water solubility and good biocompatibility, have been extensively applied in biological imaging and detection field. This work focuses on the design, synthesis and performance of fluorescent sensor and their application. The main contents are as follows:1, Core-shell structured magnetic chitosan microspheres (Rho-MCS) were synthesized by loading magnetic chitosan microspheres to a rhodamine spirolactam fluorescent probe. FTIR and TGA analysis confirmed the successful loading of rhodamine probe. The microspheres can act as excellent bare-eye colorimetric and fluorescent "turn-on" probes for Hg2+, whose detection limit can reach 15 nM. The effects of pH, temperature, reaction time and initial concentration of Hg2+ on adsorption were also investigated. The results indicated that Rho-MCS possessed high adsorption capacity (337 mg g-1), superb removal capability (up to 97%) and good recycle property.2, Water-soluble carbon dots (CD1) were easily prepared by hydrothermal treatment of a sucrose phosphate solution with a fluorescence quantum yield of 21.8%, which could be applied to the selective sensing of TNP. The results showed a limit of detection of 16.9 nM for TNP and a linear range of 0.2-17.0 mM. The recovery results for TNP in real samples confirmed the potential use of CD1 as a fluorescence sensor. Furthermore, the resulting CD1 solution could replace traditional colorings and was successfully applied for Escherichia coli labeling and intracellular imaging.3, Citric acid and biuret were introduced as carbon and nitrogen source in the preparation of CD2, respectively. The CD2-based sensor was used as a quick approach for highly sensitive and selective detection of Hg2+ and L-Cys. Under optimized conditions, good linearity for detecting Hg2+ was attained over the concentration range from 2 to 22?M with a detection limit of 0.017?M. The concentrations of L-Cys ranging from 2 to 20?M exhibited a linear relationship with the relative fluorescence intensity. Moreover, this CD2-based sensor was successfully applied for fluorescence imaging of NIH-3T3 cells with satisfying resolution.4, A new kind of nanomaterial CDs-niacin was synthesized through covalently conjugating nicotinic acid derivative onto the surface of CDs, which can be used as fluorescent probes for rapid and sensitive detection of water. The fluorescence of CDs-niacin can be quenched by water, which can be attributed to the efficient photoinduced electron transfer process from the nitrogen atom of the nicotinic acid to CDs acceptor. Moreover, the resulting CDs-niacin nanoparticles were shown to exhibit high affinity to actual cellular membranes, and successfully serve as effective fluorescent markers of cells.