Preparation,Response Mechanism And Imaging Exploration Of Distyrene Amine Fluorescent Probes

Recently,because of advantages in noninvasive detection,multi-samples parallel monitoring as well as minimally-invasive imaging,organic small fluorescent probes have witnessed promising applications in environmental monitoring and biological diagnosis.Distyrene amines based fluorescent probes with unique photo-physcical properties,good biocompatibility,facile synthesis and modification,have delivered obvious advanced in metal ions,anions,biological small molecules detection,and can which be applied to biological imaging,et al.However,limited by the short excitation wavelength,poor targeting of subcellular organelles,it’s still a great challenge to develop highly sensitive multifunctional fluorescent bioprobes applied in in vivo bio-imaging and biological diagnosis.In this dissertation,based on distyrene amines as luminophores,we developed a series of highly efficient and sensitive bioprobes by virtue of structural modulation of the recognition group as well as strengthening intramolecular charge transfer process.The as-obtained bioprobes can response to metal ions,biological small molecules as well as intracellur micro-environment with high specificity.Furthermore,the staining property in the dysfunctional subcellular organelles were also investigated,so was bioimaging of tissues and living organism.Detailed contents are in the following:1.Preparation,properties and imaging exploration of Cu2+fluorescent probesa novel fluorescence dye L was designed and synthesized based on triphenylamine as fluorescent group,styrene as bridge and bis(2-pyridylmethyl)amine(DPA)moieties as binding sites of metal ions.We explore the synthetic route and optimize the process conditions.Moreover,L exhibited high selectivity and sensitivity for Cu2+ by preliminary screening of metal ions and DL of L+Cu2+ was estimated to be 5.72 × 10-7 M,which could detect Cu2+ in water samples.Furthermore,confocal fluorescence imaging of HeLa cells demonstrated that L could be used for detecting the exogenous Cu2+,and applied for realizing an "on-off-on" process within biological system.2.Preparation,recognition mechanism and imaging exploration of glutathione(GSH)two-photon fluorescent probewe increase the number of recognition sites and molecular flexibility by fine-tuning the molecular structure.A series of fluorescent probes(5a,5b and 5c)were designed and synthesized.The intramolecular charge transfer(ICT)system constituted of triphenylamine as strong electron donor and the electron-rich nucleophilic pyridine as the electron acceptor would increase the two-photon absorption(TPA)performance.Mitochondrial specific targeted two-photon cell imaging was achieved.To further explore its cellular applications,the probe(6a,6b and 6c)were prepared and the metal complexes were fonmed by 5a,5b and 5c with Hg2+.Based on the strategy of metal complexes-displace coordination,the probes 6a-c exhibited high selectivity and sensitivity for GSH with fluorescence enhancement,and the DLs were estimated to be about 10-7 M.Furthermore,the 6a-c could qualitatively monitor the endogenous cellular GSH in real-time.3.Preparation,mechanism and imaging exploration of cell microenvironment viscosity responsive fluorescent probesSmaller molecule bioprobes are more susceptible to the resistance induced by intracellular viscosity,which would change their conformation and be conducive to realization of "off-on" fluorescence response.The probe(Lyso-TA)composed of a molecular rotor moiety and a targeted group was constructed with the small conjugate system of two benzene rings and the bridging double bond.Without external resistance,this molecular rotor moiety in Lyso-TA could efficiently rotate,forming the non-planar conformation and resulting in the fluorescence "off" because of the non-radiative decay process of excited states.In cellular microenvironment with viscosity-induced resistance,the rotation is hindered,enabling it to stay the planar conformation and forming a strong ICT system,which could show a fluorescence"on" emission and increase TP absorption performance.Therefore,lyso-TA can achieve real-time monitoring of the interaction between specific targeted organelles and the viscosity-induced conformation-response fluorescent probes by two-photon fluorescence imaging techniques.The probe Lyso-TA could realize the real-time monitor of lysosomal fusion,migration and mitophagy process and measure qualitatively the relationship between viscosity and probe conformational change in lysosomes.Considering that the tertiary amine(TA)unit of lyso-TA containing the lone pair electrons on nitrogen is easily converted into a positively charged quaternary ammonium salt(QA),which is a recognized mitochondrial targeting group.Mito-QA was designed and synthesized by one-step facile nucleophilic substitution reaction with CH3I at room temperature,accomplishing switch of targeted organelles from lysosomes to mitochondria.Mito-QA could serve a valid tool for visualizing the dysfunctional mitochondria through shift from mitochondria to nucleoli.The experimental results showed that mito-TA could be used as an effective tool to observe dysfunctional mitochondria in cell migration from mitochondria to nucleoli.With superior two-photon absorption cross-section,good biocompatibility and greater penetration depth,two small bioprobes were both applied in vivo bio-imaging of brain tissues and zebrafishes.