Synthesis Of Fluorescent Probes Based On NBD And Detection For Sulfur-containing Biomolecules

Nitrobenzofuran（NBD）,7-NO₂ benzofurazine derivative,was a heterocyclic compound.The compound could emit fluorescence because of electron push-pull effect when an electron-donating group was connected to its 4-position.Therefore,it was often selected as a classic fluorophore in probe design.Sulfhydryl-containing biological small molecule,mainly including hydrogen sulfide（H₂S）and small molecule biothiol（RSH）,played important roles in physiological process.Based on these,three fluorescent probes based on NBD for detecting H₂S/RSH were constructed in this paper.Chapter 1: The research progress and status of fluorescent probes based on NBD were summarized in the chapter.Firstly,the structure and properties of BD and NBD were presented.Secondly,the recent researches of NBD fluorescent probes,including detection objects,detection mechanisms and applications were highlighted.Finally,the thesis background,research content and the innovation were brought forward based on these.Chapter 2: In this chapter,probe TBT-NBD for Cys / Hcy was synthesized through one-step reaction by connecting benzothiazole and nitrobenzofuran（NBD）.TBT-NBD was induced by Cys / Hcy,then rearrange to produce the corresponding amino-NBD derivative,while GSH only induced the substitution reaction and produced the corresponding thio-NBD derivative.The amino-NBD derivative showed strong fluorescence emission at 551 nm,so it could selectively recognize Cys / Hcy with low detection limits（12.6 n M and 20.4 n M,respectively）,and short response time（5 min）.In addition,TBTNBD was also successfully used for SNU-423 cell imaging to detect endogenous and exogenous Cys / Hcy.Chapter 3: The probe NA-NBD for H₂ S was constructed by the condensation reaction of p-nitrobenzoic acid and NBD piperazine derivatives.NA-NBD was amino-NBD derivative and emited a yellow-green fluorescent.It became thio-NBD derivative a specific C-N bond cleavage reaction with H₂ S.The thio-NBD derivative hardly emited fluorescence and its solution had a unique pink color.Therefore,H₂ S could be detected from two aspects: fluorescence quenching and solution color（from light yellow to pink）.NANBD had good selectivity and high sensitivity for H₂ S with a linear range of 0-50 m（44）and a detection limit of 3.07 m（44）.Chapter 4: Based on the research of Chapter 3,a novel fluorescent probe TPA-NBD was prepared by condensing triphenylamine carboxylic acid with NBD through a piperazine ring.Triphenylamine derivative and thio-NBD derivative were generated after the C-N bond cleavage reaction between TPANBD and H₂ S.The fluorescence of triphenylamine derivative enhanceed and the fluorescence of thio-NBD derivative weakened,which could selectively response to H₂ S at two different excitation wavelengths and display different fluorescence characteristics.TPA-NBD has high sensitivity and wide linear range(0-125 m（44）（8）to H₂ S and the detection limit can be as low as 0.70 mM.The detection results with dual-channel detection was more accurate and reliable than that with the single excitation and single emission detection.