| It is well known that mercury, copper and sulfur ions play an important role in the whole life system. Therefore, it is helpful to establish an efficient, rapid and sensitive method for the detection of these ions in the physiological and pathological processes. Among various detection techniques, fluorescence technique has been widely used in biological detection and bioimaging due to its ease of use, high sensitivity, high selectivity, excellent temporal-spatial resolution and fairly simple technical implementation. In this study, based on the fluorescence resonance energy transfer(FRET) and intramolecular charge transfer(ICT), we designed and synthesized several novel fluorescence probes, and use them for mercury ions,copper ions and sulfide ions detection and cell imaging studies. The main contents of this paper are divided into the following aspects:1. Taking 7-nitro-2,1,3-benzoxadiazole(NBD) as donor and rhodamine B as acceptor, a novel fluorescent probe was synthesized based on FRET principle. And we explored its fluorescence response to Hg2+ in aqueous solution. When without the addition of Hg2+, the FRET cannot occur between the donor(NBD) and acceptor(rhodamine B). Thus, only the fluorescent emission signal of the donor can appear,and the absorption peak of the probe only appeared at the absorption position of the donor. But after the addition of Hg2+, Hg2+ can induce the ring-opening mechanism of rhodamine spirolactam, and then making the effective FRET occurred between the donor and acceptor. Meanwhile, the fluorescence of the donor was decreased and the fluorescence of the receptor was increased. The bsorption intensity of the donor was not changed, the bsorption intensity of the acceptor was increased. Then we measured the absorbance value of two different absorption peaks of the probe and calculated their ratio of them, which can be used to highly selective for the colorimetric recongation of Hg2+ and the detection limit can reach 120 n M. In addition, the probe can detect Hg2+ in a wide range of p H values.2. Based on the FRET principle, using a combination of a facile one-pot miniemulsion polymerization and surface modification technology, we synthesized a fluorescent probe based on fluorescent polymer nanoparticles, which has dual response function. Firstly, copolymerization of styrene, vinylbenzylchloride and fluorescein-O,O-bis-propene(FBP) were used as raw materials to prepare the fluorescent polymeric nanoparticles via one-pot miniemulsion polymerization. Then,Cyclen(1,4,7,10-tetraazacyclododecane) was grafted onto the surface of fluorescent polymer nanoparticles probe by the surface modification method, and prepared the fluorescent polymer nanoparticles probe. Before and after the effect of Cu2+, the fluorescence emission intensity of FBP has obvious change. This is because therewould be an effective FRET process appeared between FBP(donor) and Cyclen-Cu2+ complex. The as-prepared nanoparticles probe has higher selectivity and anti-interference performance for the detection of Cu2+ in 100% aqueous solution and lower detection limit(~340 n M); in addition, when the S2- was added into the advance through processing with Cu2+ in the detection system, due to Cu2+ can combine with S2- and form the stable Cu S precipitate, the fluorescence of FBP restored. And the fluorescent probe also has higher selectivity and anti-interference performance for the detection of S2-. In addition, the dual polymer nanoparticle probe demonstrated excellent fluorescence "off-on" reversible cycle characteristics and a wide p H detection range(p H 4.0-10.0) and higher long-term stability(≥40 days). Therefore, the probe can be successfully applied to the detection of copper ions and sulfur ions.3. Based on the principle of FRET, using the surface modification technology, we successfully prepared a Cyclam(1,4,8,11-four nitrogen ring tetradecane) functionalized carbon quantum dots fluorescent probe(CCDs), which has high sensitivity and high selectivity for the detection of Cu2+ and S2-. In the experiment, carbon dots as the donor and the Cyclam-Cu2+ of the probe as receptor, because the FRET process can effectively occur between them. The as-prepared CCDs probe can highly sensitive(detection limit: 100 n M) and highly selective for the detection of Cu2+ and S2- in 100% aqueous solution. In addition, due to S2- can effectively combine the Cu2+ of the CCDs and form Cu S compound, and then realizing the detection of S2- for the probe, the detection limit can reach 130 n M. More importantly, the novel fluorescent probe has a wide p H detection range(p H 4.0-10.0),higher long-term stability(≥35 days), better cell biological compatibility, and which can detect the Cu2+ and S2- in living cells.4. Based on the principle of ICT, taking 4-bromine-1,8-naphthalimide as the fluorophore and the H2 S response site, the polyethylene glycol as the hydrophilic chain. We synthesized a kind of "turn-on" type fluorescent probe based on polyethylene glycol. In the presence of hydrogen sulfide system, the strong reduction of hydrogen sulfide will make the ICT process of probe occurred. The fluorescence intensity of the probe gradually increased. Then, the as-prepared probe can realize high fluorescent detection of hydrogen sulfide, and the detection limit can reach 100-150 n M. Moreover, the probe has highly selectivity and anti-interference performance for the detection of hydrogen sulfide, outstanding stability and excellent applicability. |
PDF Full Text Request