Study On Dual Aptamers-targeted Intelligent Controlled Release Theranostic Nanosystem

Objective: In order to increase the accumulation of drugs in the tumor site,improve the therapeutic efficiency and monitor the therapeutic effect,a near-infrared photothermal response dual-target intelligent controlled-release system?DTX/ABC@TSLs@Au-DA?was prepared.The paper investigated therapeutic and imaging effects of the drug delivery system under 808 nm laser.The physical and chemical properties,in vivo and in vivo antitumor activity,targeting,ultrasound imaging and pharmacokinetic characteristics were investigated systematically.Methods:?1?In this study,thermosensitive liposomes loaded with docetaxel?DTX?and ammonium bicarbonate?ABC?were prepared by thin film dispersion method and modified gold nanoshells by the method of reducing chloroauric acid?HAuCl₄?.Then the thiolated AS1411 and S2.2 DNA aptamers were coated on the surface of DTX/ABC@TSLs@Au for targeting.Finally the DTX/ABC@TSLs@Au-DA nano drug delivery system was successfully synthesized.The nanocomposites were characterized by UV-Vis,agarose gel electrophoresis and differential scanning calorimetry?DSC?.The size and zeta were measured by laser nanometer particle size analyzer and the morphological and EDS element analysis were observed by transmission electron microscopy?TEM?.The encapsulation efficiency and drug release rate were determined by high performance liquid chromatography?HPLC?.The ability of ultrasound contrast-enhanced was measured by small animal ultrasound imaging.?2?In vitro an-titumor activity study: MCF-7 breast cancer cells were used as the model.The cytotoxicity of the blank vector and the cell proliferation inhibition efficiency of the nano drug devilery system were determined by SRB method.Cell uptake was observed by fluorescence microscope with FITC marker.Cell cycle and cell apoptosis were measured by cytometry.?3?In vivo pharmacokinetics and tissue distribution studies: The plasma concentrations of DTX in rats were determined by HPLC method after intravenous injection.PK Solver software was used to calculate the pharmacokinetic parameters.With IR783 labeled the nano drug devilery system,drug distribution in tissues of mice were observed by vivo fluorescence imaging of mouse models.?4?In vivo pharmacodynamics and ultrasound imaging studies: Taking S180 ascites tumor-bearing mice as an animal model,the synergistic effect of chemotherapy,hyperthermia and biotherapy was studied by tumor volume.The toxicity of nanosystem was analyzed by the body weight and HE staining.The diagnostic ability of the DTX/ABC@TSLs@Au-DA was examined byultrasound imaging in mice.Results: Transmission electron microscopy?TEM?and laser nanometer particle size analyzer investigations showed that DTX/ABC@TSLs@Au-DA was spherical and the size was about 215 nm.The zeta potential was about-47 mV and the encapsulation efficiency was about 92%.The nanocomposites displayed a good heat performance under 808 nm laser irradiation.The results of in vitro drug release showed that the nano drug delivery system could release rapidly under the condition of pH5.5 and 808 nm laser,and the release amount was up to 80%.The ultrasound imaging in vitro showed that the ultrasonic contrast was better.Cytology experiments in vitro showed that the toxicity of blank carrier is small.And double targeting efficiency was high.The cell uptake rate was up to 67% at 4h after administration.In the role of 808 nm laser,the nanosystem showed significant cell proliferation inhibition and could arrest breast cancer cell cycle in G2/M phase,causing apoptosis.The results of pharmacokinetic study showed that the preparation could increase the retention time of DTX in vivo and prolong half life.The in vivo fluorescence imaging revealed that the drug was mainly distributed in the tumor site and had the largest aggregation at 2h.Pharmacodynamics in vivo results showed that DTX/ABC@TSLs@Au-DA was able to combine chemotherapy,hyperthermia,biotherapy,and significantly inhibit tumor growth.In addition,ultrasound imaging in mice showedthat the contrast agent was able to pass through the tumor microvascular gap and was stable at the tumor site for long-term ultrasound imaging.Conclusions: The DTX/ABC@TSLs@Au-DA prepared in this study was safe and could rapidly release drug at the tumor target site under the 808 nm laser irradiation.The combination of chemotherapy,hyperthermia and biotherapy could effectively inhibit tumor growth.And the nanosystem could investigate tumor treatment effect under ultrasound image monitoring to achieve diagnostic and treatment integration.