| Cancer is a major threat to human health.Accurate and timely diagnosis,along with radical tumor surgery,is crucial in cancer diagnosis and treatment,helping to prevent further spread of tumor cellls.Compared to preoperative static imaging diagnosis,fluorescence imaging offers excellent safety,high spatiotemporal resolution,and high sensitivity,enabling real-time fluorescence-guided surgery and pathological tissue margin visualization.This significantly enhances disease detection and image-guided surgical treatment.Near-infrared fluorescence imaging(NIR,700-1700nm)holds advantages over visible and ultraviolet imaging,including low tissue autofluorescence,high signal-to-noise ratio,and deep tissue penetration.These characteristics make NIR fluorescence imaging a versatile platform for non-invasive and real-time molecular imaging.Clinically,NIR-I fluorescence imaging(700-900nm)based on indocyanine green(ICG)has demonstrated significantly improved therapeutic effects in oncological,lymphatic,and neurological imaging.These characteristics make NIR fluorescence imaging a versatile platform for non-invasive and real-time molecular imaging.The discovery of the NIR-II imaging window(900-3000 nm)has revealed substantial clinical potential for deep tissue imaging due to its reduced background signals and enhanced signal-to-noise ratio at longer wavelengths.However,currently,only a few NIR-I cyanine probes(ICG,IRDye800 CW,ZW800-1)are approved for clinical use.There remains a lack of bright,stable,highly biocompatible,and deeply penetrating NIR-II fluorescence probes for clinical disease diagnosis.Organic molecular probes offer the advantages of rational chemical structure design and controllable biosafety,making them suitable for NIR-II bioimaging with significant translational potential in clinical applications.Hence,this study focuses on optimizing the structure of organic small-molecule fluorescent probes to develop high-performance NIR-II fluorescence probes suitable for bioimaging.A systematic exploration and optimization were conducted from multiple perspectives,including physicochemical properties,biocompatibility,molecular mechanisms,and NIR-I/II visualization applications,to address various limitations encountered in the clinical translation of NIR-II fluorescence probes and promote their clinical visualization applications.Specifically,this work comprises the following three parts:Firstly,we employed an atomic substitution strategy to red-shift the absorption wavelength and emission wavelength of the NIR-II/IIb probe(NIR-920)with a donor-acceptor-donor(D-A-D)structure.Further,NIR-920 were prepared to be water-soluble NIR-920 nanoparticles(NIR-920 NPs).NIR-920 NPs exhibited typical aggregation-induced emission characteristics with bright fluorescence,and achieved high-performance bone imaging,vascular imaging,tumor imaging,and lymph node imaging within the NIR-IIa/ IIb imaging window.Compared to the clinically used indocyanine green(ICG),NIR-920 NPs demonstrated superior retention time,penetration depth,signal-to-noise ratio,and photostability.Additionally,NIR-920 NPs facilitated accurate surgical navigation for tumor sentinel lymph nodes(SLNs).Secondly,the self-assemble size of D-A-D type dyes were reduced through optimizing the donor unit,and obatained the dye nanoclusters with liver-renal excretion ability.The dye nanoclusters provided high-performance NIR-II vascular and lymphatic imaging,and enabled accurate NIR-II imaging-guided SLN surgery,which significantly improved surgical outcomes in a mouse orthotopic breast cancer model.Finally,we developed a series of tumor receptor-targeted heptamethine cyanine dyes through structure optimizing.These dyes could rapidly form covalent bonds with specific thiols in tumor-specific proteins at room temperature,resulting in stable dye@protein complexes with significantly enhanced fluorescence intensity.The pan-tumor markers labeling ability of tumor receptor-targeted dyes not only avoided the sensitivity limits,but also avhieved rapid intraoperative frozen tumor section identification of breast cancer and lung cancer with extremely high accuracy and clinical translation potential.This paper focuses on the structural optimization and biological applications of D-A-D structure and cyanine structure fluorescent probes,aiming to address the current shortage of high-performance NIR-II fluorescent probes.The goal is to provide new insights into enhancing the application of NIR-I/II organic fluorescent probes in surgical navigation and intraoperative rapid testing. |
