Responsive Prodrug Liposome For In Vivo Nir-Ⅱ Fluorescence Imaging And Tumor Chemoimmunotherapy

The second near-infrared(NIR-Ⅱ)window fluorescent probes have attracted more and more attention in the fields of chemistry and biology.Compared with fluorescent probes of visible light and the first near-infrared window emission,NIR-Ⅱ fluorescent probes with characteristics such as less scattering,less self-absorption of biological tissues,and lower autofluorescence,display the superior fluorescence imaging results with higher resolution,higher signal-to-noise ratio and deeper tissue penetration.Therefore,they play important roles in in vivo imaging,surgical guidance and tumor treatment.Meanwhile,the incidence and mortality of malignant tumors have increased year by year,which has seriously affected the life quality of people.Current methods of tumor treatment include surgical resection,chemotherapy,radiotherapy,molecular targeted therapy and so on.Due to the unspecific tissue distribution and short circulation time of chemotherapeutics,it was urgent to develop controllable nanocarriers for drug delivery and release.The nanocarriers show specific responses in the organism and release drugs or fluorescent probes for anti-tumor therapy.However,single-drug-based tumor therapy has shown some shortcomings,such as poor stability,high toxic and side effects,and easy to trigger drug resistance.Thus,the combined strategies for anti-tumor therapy have been proposed and studied.Based on the above background,we constructed a responsive prodrug liposome IRG@JQ1/DOX which contained the NIR-Ⅱ fluorescent probe IR-1061,chemotherapy drug doxorubicin(DOX)and inhibitor JQ1,and explored its effect of in vivo fluorescence imaging and the combined anti-tumor therapy.The specific research content of this paper is as follows:Chapter 1.IntroductionIn this chapter,we introduced the characteristics and application of NIR-Ⅱfluorescent probes,the construction strategy and application of responsive prodrug liposomes,and the research status of anti-tumor chemotherapy and immunotherapy.Finally,we summarized the research significance and purpose of this work.Chapter 2.Construction and Characterization of IRG@JQ1/DOX Prodrug LiposomeIn this chapter,we synthesized matrix metalloproteinase 2(MMP-2)-sensitive NIR-Ⅱ fluorescent probe IR-1061-GP and glutathione(GSH)-responsive JQ1 modified phospholipid via covalent coupling.We combined these molecules with DOX to construct the stimuli-responsive prodrug liposome IRG@JQ1/DOX through membrane hydration method and ammonium sulfate gradient method.We examined the physical and chemical characterization through transmission electron microscopy(TEM)and particle size analyzer(DLS),which proved the stable particle size of IRG@JQ1/DOX.Under the irradiation of 1064 nm NIR-Ⅱ laser,IRG@JQ1/DOX exhibited a wellcontrolled photothermal effect,as well as accurate drug release performance in vitro.Chapter 3.Anti-tumor Mechanism Study of IRG@JQ1/DOX Prodrug Liposome in VitroIn this chapter,we detected cellular uptake,tumor cell spheroid penetration,cytotoxicity and photothermal toxicity,immunogenic cell death(ICD)effect of tumor cells and programmed cell death ligand-1(PD-L1)expression induced by IRG@JQ1/DOX in vitro.IRG@JQ1/DOX which pretreated with MMP-2 was removed PEG corona and enhanced the cellular uptake efficiency.When it entered the tumor cells,IRG@JQ1/DOX dissociated and released drugs under the irradiation of NIR-Ⅱlaser.DOX entered the nucleus to induce death of tumor cells,produce calreticulin(CRT)eversion,cause high mobility group protein B1(HMGB1)efflux from the nucleus,and trigger dendritic cells(DCs)maturation.JPC was stored into JQ1 by GSH,further inhibiting PD-L1 expression and overcoming immune tolerance.Chapter 4.Imaging and Combined Anti-tumor Chemoimmunotherapy of IRG@JQ1/DOX Prodrug Liposome in VivoIn this chapter,we studied the NIR-Ⅱ fluorescence imaging and anti-tumor chemoimmunotherapy of IRG@JQ1/DOX in vivo.The blood circulation time of IRG@JQ1/DOX was prolonged due to the shield of protein adsorption by PEG corona.And it promoted retention and accumulation in the tumor after removing PEG corona via MMP-2.The released drugs induced ICD effect in vivo,further causing anti-tumor immune response.IRG@JQ1/DOX-mediated combination therapy could significantly inhibit tumor growth,activate immune effect and overcome immune tolerance.