A Carrier-free Metal-coordinated Dual-photosensitizers Nanotheranostics With GSH-depletion For Fluorescence/photoacoustic Imaging-guided Tumor Phototherapy

Phototherapy is an important auxiliary method for the treatment of cancer,mainly including photothermal therapy(PTT)and photodynamic therapy(PDT).However,the current a single photosensitizer(PS)usually has the shortcomings of insufficient photothermal conversion efficiency or insufficient active oxygen(ROS)productivity,that is,photothermal performance of PSs is good but its the photodynamic performance is poor,while the photodynamic performance of PSs is good but its photothermal performance is poor.In addition,due to the overexpression of glutathione(GSH)in cancer cells,ROS was consumed,which limits PDT.In order to overcome these problems,we chose indocyanine green(ICG)with excellent photothermal ability.Its sulfonic acid group can coordinate with Cu2+ to obtain flexible nano-scale fragments,and Cu2+can undergo redox reaction with GSH to consume GSH.On this basis,we introduced pheophytin A(PhA)with excellent photodynamic properties.It can form a "J"-shaped aggregation with ICG through the"head-to-tail"π-π stacking effect,and further curl into dense spherical nanoparticles under the hydrophobic effect of PhA.In addition,due to the photothermal and fluorescent properties of ICG,nanoparticles are capable of fluorescence imaging(FLI)and photoacoustic imaging(PAI).In this way,a multifunctional nano-platform for precise optical treatment of tumors with dual imaging guidance capabilities has been established.The synthesis of nanoparticles was verified by dynamic light scattering(DLS),transmission electron microscopy(TEM),Fourier infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),energy dispersive spectroscopy(EDS),ultraviolet visible light spectroscopy(UV-vis),etc.The experimental results show that the nano-platform is a spherical particle of about 140nm.ICG and copper ions are successfully coordinated and uniformly dispersed on the surface of the nanoparticle.NanoICG and PhA form "J" aggregates" through "head-to-tail"π-π accumulation,which can maintain stability in liquid for more than a week.Studies on the photothermal and photodynamic properties of nanoparticles in aqueous solution have shown that nanoparticles solution can reach a temperature of 53℃ at a concentration of 20 μg/mL,and have improved photothermal stability.It can generate ROS under successive irradiation of 808 nm and 630 nm lasers to achieve the effect of synergistic PDT.The carried copper ions can consume GSH in the aqueous solution.Cell-level experiments show that the formation of nanoparticles has a cellular uptake similar to that of free drugs.Nanoparticles can effectively consume GSH in cells and enhance the production of reactive oxygen species.The cell killing effect is stronger than that of the free drug group under the same treatment conditions.808nm/630nm dual-wavelength laser irradiation shows the strongest cancer cells inhibitory effect.In animal experiments,FL/PA dual-modal imaging shows that nanoparticles have more tumor enrichment in the body,and photothermal imaging shows that the effective PTT temperature can still be reached in body under 808nm laser stimulation.By comparing the tumor size,weight,tissue sections of different groups,it shows that the 808nm/630nm dual-wavelength laser irradiation shows the strongest tumor suppressive effect.Finally,an in vivo safety evaluation was made,including hemolytic experiments,blood biochemical indicators,and pathological sections of major organs,which showed that the drugs used had no obvious side effects and had good biological safety.In summary,the copper ion coordinated dual photosensitizer phototreatment nanoplatform prepared in this study has good stability,safety and enhanced tumor enrichment,which can be used for dual-wavelength(808 nm and 630 nm)laser excitation photothermal/photodynamic co-therapy of tumor under the guidance of fluorescence/photoacoustic(FL/PA)dual-modal imaging.This strategy effectively solves the shortcomings of a single photosensitizer with insufficient photothermal or photodynamics,and provides an important reference for precise tumor treatment and how to improve the efficiency of optical treatment.