Design,Synthesis And Theranostic Applications Of Nir-? Emitting Organic-inorganic Nanocomposites

The second near infrared region ?(NIR-?,1000 nm-1700 nm)imaging is a promising technique to image fine structure of living tissue due to the deeper tissue penetration and higher spatial resolution.Based on the guidance of NIR-? imaging,drug delivery/release monitoring,photodynamic therapy(PDT)and photothermal therapy(PTT)have shown many advantages in accurate diagnosis and treatment of the cancer.Organic-inorganic nanocomposites are a kind of nano synthetic materials which are connected by organic and inorganic components through covalent or non-covalent interactions.Because it combines the flexibility of organic materials with the rigidity of inorganic materials,it has many extraordinary characteristics.The integration of organic and inorganic components in nanocomposites usually results in new synergistic properties due to the interaction between internal components.Hybrid nanostructures obtained by the combination of two or more components usually induce the regulation of physical and chemical properties and have unique functions.Thus,the unique chemical and photoelectric properties of the organic-inorganic nanocomposite make it excellent candidates for biomedical applications.In this paper,through reasonable design,inorganic materials and organic materials are combined to play their synergistic role,providing a multifunctional organic-inorganic nanotheranostic platform.This paper is mainly divided into the following two aspects:(1)A mild aqueous route for preparing NIR-? emitting silver sulfide(Ag₂S)quantum dots is proposed for in vivo tumor imaging.The original Ag₂S quantum dots are obtained by mixing sodium sulfide and silver nitrate in mercaptan-based polyethylene glycol(m PEG-SH)solution and then briefly heating in a water bath.Due to the strong interaction between metals and mercaptan groups,PEG chains with mercaptan groups can be fixed on the surface of nanoparticles,so PEG-grafted Ag₂S quantum dots with excellent water solubility can be obtained.By optimizing the ratio of sulfur to silver,PEG chain length,PEG dosage and heating time,Ag₂S quantum dots with adjustable particle size and high emission are obtained,and the quantum efficiency is 2.33%.The tumor targeting effect of original silver sulfide quantum dots is poor.The Ag₂S quantum dots with high peg grafting density can be produced by secondary modification of the original Ag₂S quantum dots with m PEG-SH.These secondary PEGylated Ag₂S quantum dots show better blood circulation and tumor accumulation in vivo,and capillaries with a diameter of 0.20 mm could be identified and tumor enrichment was maintained for more than 24 h,making them a potential fluorescent probe in NIR-?.(2)A multifunctional composite is developed for fluorescence imaging and cancer synergistic therapy by using metal-organic framework Zeolite imidazoline framework-8(ZIF-8)as the carrier with conjugated polymer(CP)encapsulated inside.By changing the amount of surfactant,the size of ZIF-8 nanoparticles can be adjusted,and ZIF-8 nanoparticles with ideal morphology and suitable size for biological application are obtained.A universal method is developed for ZIF-8 to encapsulate different CP,and the encapsulation effect of PCPDTBT is better.The photothermal conversion efficiency of PCPDTBT@ZIF-8 can reach 42.5%in vitro,and the photothermal stability is pretty good.Modify the surface of PCPDTBT@ZIF-8 with block copolymer F127 can obtain PCPDTBT@ZIF-8-F127,which has good dispersion and stability in water.The drug loading rate of PCPDTBT@ZIF-8-F127 is 25.06%,and the drug could be released efficiently under the additional laser irradiation under slightly acidic conditions.Cell experiments were conducted in vitro and the therapeutic potential of PCPDTBT@ZIF-8-F127-DOX to inhibit cancer cell survival was anticipated.On this basis,the composite nanoparticles PCPDTBT@ZIF-8-F127-DOX loaded with anti-cancer drugs(DOX)can achieve synergistic chemotherapy and photothermal therapy,and the tumor inhibition effect is 74.4%.