Preparation Of Near-infrared Fluorescence Probe Based On Benzonitrile

For the past several decades,fluorescent probes have gained immense popularity for tracking and monitoring a range of different physiological and pathological processes such as cellular dynamics,cell metabolism and nutrient uptake,enzyme activities,and regulation of signaling cascades.Among them,near-infrared fluorescence probe plays a critical role in biomedical sciences as it has advantages of deep tissue penetration,less tissue damage,and minimal interference caused by tissue absorption and autofluorescence.Compared to the traditional near-infrared dyes,benzopyranitrile and its derivatives which have excellent photophysical properties and highly diverse structural tunability have gained the attention of researchers to construct fluorescent probes and chemosensors.Therefore,three NIR fluorescent probes(DS,DCM-NO,and DP)in this paper were synthesized by designing and modifying the structures of benzopyranitrile for the detection of H₂S and polarity in complex biological environments.(1)Using benzopyranitrile as the research object,the benzopyranonitrile derivatives was prepared by modifying its structure with 2-hydroxybenzaldehyde.Subsequently,a novel near-infrared fluorescent probe DS was designed and constructed for the detection of H₂S via modifying the fluorescent matrix benzopyranonitrile derivatives with thiophenecarboxylic ester(H₂S recognition group).Based on the design concept,systematic DFT calculations were further performed for probe DS,the fluorophore DCM-OH and its anion form DCM-O^-with B3LYP functional using Gaussian 09 program,and the results highly supported the rationality of this design strategy.In addition,optical investigation showed that the probe DS exhibited a considerable Stokes shift(125 nm)and long emission wavelength(680 nm),and was successfully applied for the detection of H₂S in living Hela cells.More importantly,the probe-doped Polymethyl methacrylate(PMMA)portable fluorescent nanofibrous film prepared by electrospinning could be successfully used to visualization detection of H₂S.(2)Bnzopyranitrile was combined with 4-diethylaminosalicylaldehyde to construct a fluorophore of benzopyranitrile derivatives.Subsequently,a novel near-infrared fluorescent probe DCM-NO was designed and synthesized for the detection of H₂S via modifying the fluorescent matrix benzopyranitrile derivatives with dinitrophenyl ether of H₂S recognition group.Density Functional Theory(DFT)calculation was performed with B3LYP functional using Gaussian 09 program,and the results illustrated the rationality of this design strategy.In addition,the spectral analysis of the probe DCM-NO showed that the probe DCM-NO exhibited the advantages of high specificity and sensitivity,fast response time(3min),etc.In addition,in the range of 0.0-10.0?M,the linear equation was y=0.0102 x-5×10~5(absorbance ratio,R~2=0.9915)/y=11.153x-1.9842(maximum fluorescence intensity,R~2=0.9919).The application studies indicated that probe DCM-NO could sensitively detect H₂S in Hela cells,real water samples and be prepared for test strips and nanofibrous film for the qualitative detection of H₂S.(3)Based on the design concept of D-?-A conjugated structure,a near-infrared fluorescent probe DP was designed and synthesized for the detection of polarity by incorporating4-(dimethylamino)cinnamaldehyde into the backbone structure of benzopyranitrile.Based on this D-?-A conjugated structure,the proposed probe DP showed shifts in emission wavelength and changes in signal intensity according to the different polarities of the environment.More importantly,the systematic DFT calculations was carried out by using B3LYP functional with Gaussian09 program,the theoretical calculation results corroborated the excellent polar-sensitive performance of probes DP from the perspective of the structure-function relationship.The analysis of optical properties showed that the probe DP not only exhibited near-infrared fluorescence emission,but also showed high selectivity and photostability for polarity.At the same time,excellent linearities were calculated between the solvent polarity parameter versus maximum emission wavelength,the linear equations were?_em=338.08x+10.57E_T(30),R~2=0.9719.In addition,the MTT assays results showed that the probe DS displayed negligible toxicity to cells,which laid a foundation for the subsequent detection of intracellular polarity.In addition,the probe DP was applied to the determination of moisture in organic solvents.