Preparation And Application Of Activated Sulfur Molecular Fluorescence Probe

Active sulfur species,including thiols,sulfide,sulfur dioxide,sulfonic acid derivatives,are molecules widely existing in organisms and play an important role in regulating the balance between human body and the environment,especially in the aspects of inflammation regulation,nerve regulation and vascular tension regulation.Among them,cysteine?Cys?,homocysteine?Hcy?and glutathione?GSH?are widely concerned because of their importance in the maintenance of biological systems and their concentration levels in living cells is associated with many diseases,such as cancer,liver injury,Alzheimer's disease,HIV/AIDS,cardiovascular disease and neurodegenerative diseases.Moreover,they are of interest to researchers because of their similar and indistinguishable chemical structures.Hydrogen sulfide?H₂S?is a gaseous species produced by bacteria and higher eukaryotes?including mammalian vertebrates?.It is one of the three major gas signaling molecules in the human body and can act as a cytoprotective agent and gas transmitter in tissues,including Mediating vascular tone in blood vessels and neuromodulation in the brain has drawn attention in recent years due to its contribution to human health and disease.Sulfur dioxide?SO₂?has traditionally been considered an environmental pollutant,and studies have shown that long-term exposure to SO₂-containing environments often leads to neurological diseases,cardiovascular diseases and venous cancers.However,SO₂ has recently become an important gas transporter because of its beneficial biological functions,including antioxidant and cardiovascular regulation.In addition,it has been found that SO₂ can be endogenous from sulfur-containing amino acids and is balanced by sulfite/bisulfite in biological systems.Fluorescent probes are non-invasive and have high spatial and temporal resolution due to their high sensitivity,fast,low cost and non-destructive in-microscopic environment,in-situ on-line detection,real-time visual traceability to live and even single cells.The combination of fluorescent probes and imaging instruments has become an effective means for detecting active sulfur species.Therefore,the design and synthesis of related molecular fluorescent probes are of great significance for studying the role of active sulfur species in living systems.Based on the coumarin and naphthalimide fluorescence platform,three different fluorescent probe systems were designed and synthesized,which are proportional-type Cys fluorescent probe based on FRET mechanism,two-photon fluorescent probe simultaneous detection of Cys/Hcy/GSH/H2S based on PET mechanism and a ratiometric fluorescent probe based on the FRET mechanism for specifically detecting SO₂.In the second chapter,a novel aromatic substitution-rearrangement based ratiometric fluorescent probe Cou-SBD-Cl was synthesized,which is capable of specifically detecting Cys by using coumarin and sulfonyl benzoxazole as a platform.The probe is capable of specifically recognizing Cys without interference from other thiols and exhibits a good response effect.Before the reaction with Cys,since the excitation spectrum of the energy donor Cou has almost no overlap with the absorption spectrum of the energy acceptor SBD,when excited by the donor excitation wavelength,the probe will only emit blue fluorescence of coumarin;After the reaction with Cys,the absorption spectrum of SBD is red-shifted and partially overlaps with the Cou emission spectrum,which causes the fluorescence energy to be transferred from the donor to the acceptor to emit yellow fluorescence of SBD,thereby realizing the detection of Cys.In the third chapter,an turn-on fluorescent probe NP-S based on a naphthalene imide fluorescent signal platform for simultaneous detection of various thiols and H₂S was designed and synthesized.As an electron donor,naphthalimide undergoes electron transfer after photoexcitation,while benzenesulfonyl chloride has a relative low energy of frontier lowest unoccupied molecular orbital,which allows it to accept excited state electrons of naphthalimide,resulting in fluorescence quenching.After reacting on the thiols and H₂S,the hydroxyl group has a strong electron donating ability,and forms a push-pull electron system with the naphthalimide to emit yellow-green fluorescence of the naphthalimide.At the same time,naphthalene imide,as a typical two-photon platform,shows good two-photon properties in living organism imaging experiments such as cells,tissues and zebrafish.In the forth chapter,a fluorescent probe Cou-PCL based on the coumarin and anthocyanidin platform for specifically detecting SO₂ was designed.The coumarin group and the anthocyanidin group act as donor and receptor,respectively,existing FRET process between them,that is,when the probe is excited by the excitation wavelength of the donor coumarin,the energy supplied by the donor transfer to the receptor so that the red fluorescence of anthocyanidin can be observed.When the probe is reacted with SO₂,the active double bond of the anthocyanidin to form the product Cou-PCL-SO₃H undergo a Michael addition reaction,resulting in the destruction of the anthocyanidin structure,and the FRET process is inhibited,and emitting a blue fluorescence of coumarin for realizing the detection of SO₂.In addition,the probe also showed good results in cell and zebrafish bioimaging.