Investigation On Co-transport Nano-delivery System For NO Donor And Hypoxia Anticancer Drug

Titanium dioxide is a kind of good sonosensitizer,which can be used in sonodynamic therapy?SDT?.Under the action of ultrasound?US?,it can produce reactive oxygen species?ROS?that causes DNA damage and induces apoptosis of tumor cells.Because hollow mesoporous titanium dioxide nanoparticles?HMTNPs?have the advantages of easy surface modification,good biocompatibility,large specific surface area,low toxicity,good stability,and EPR characteristics,it was used as a new type of sonosensitizer and drug carrier received great attention from people.Moreover,the treatment concentration of NO?in the?M range?can damage DNA,produce cytotoxicity,and prevent tumor proliferation and metastasis.HMTNPs was used as the framework material in this paper.Firstly,the surface of HMTNPs was modified with NO donor of S-nitrosothiol?R-SNO?to prepare the targetting transporter HMTNPs-SNO.Then,the hypoxia drug Tirapazamine?TPZ?was loaded into HMTNPs-SNO to construct the TPZ/HMTNPs-SNO tumor-targeting nano-delivery system.The main research contents were as follows:1.Firstly,mercaptopropyltriethoxysilane?MPTES?and ammonia?NH₃·H₂O?were added into HMTNPs suspension and stirred for 10 h under nitrogen protection to get HMTNPs-SH.HMTNPs-SH was dissolved in in the mixture of methanol and toluene?v/v=3:1?.Added t-butyl nitrite to above solution and the mixed solution was stirred for another 12 h in dark,and then the HMTNPs-SNO nanoparticles were collected by centrifugation.Finally,HMTNPs-SNO and TPZ were dissolved in methanol,and stirred for 24 h to obtain TPZ/HMTNPs-SNO tumor-targeting nano-delivery system.The synthesis of nano-carrier HMTNPs-SNO and TPZ/HMTNPs-SNO tumor-targeting nano-drug delivery system were proved by UV and IR spectra.40?g/mL HMTNPs-SNO released NO up to 18.5?M after 80 s US irradiation(1 Wcm^-2,1 MHZ)to achieve“anti-cancer treatment window”for NO-based anti-tumor therapy.The release of NO of HMTNPs-SNO?40?g/mL?reached 18.5?M,reaching the“anti-cancer treatment window”for NO-based anti-tumor therapy.The average zeta potential of the preparation TPZ/HMTNPs-SNO was-21.3±2.6 mV,and it had high aqueous solubility.Compared with the TPZ group,the formulation group released the drug slowly.Furthermore,the amount of TPZ released from TPZ/HMTNPs-SNO in PBS at pH=5.8 was 39.7%higher than that in PBS at pH=7.4,which indicated that TPZ/HMTNPs-SNO had pH sensitivity.2.MCF-7 cells were used as the cell test object of the TPZ/HMTNPs-SNO tumor-targeting nano-delivery system.The cytotoxicity of carrier HMTNPS-SNO and the preparation TPZ/HMTNPs-SNO were investigated by SRB.The results showed that the cell viability was 89.2±2.2%in the case of oxygen partial pressure of 10%,even though the concentration of HMTNPS-SNO carrier was as high as 1mg/mL,which showed HMTNPS-SNO was no obvious cytotoxicity.However,the TPZ/HMTNPs-SNO+US group had significant cytotoxicity,and the cell viability decreased to 12.5±1.3%.The qualitative detection of the intracellular ROS and NO was carried out by DHE and DAF-FM DA detection reagents,respectively.The HMTNPs-SNO+US group showed red and green fluorescent in MCF-7 cells,which indicated that ROS and NO were produced by HMTNPS-SNO with US irradiation.3.In vivo anti-tumor activity study of TPZ/HMTNPs-SNO nano-delivery system,MCF-7-bearing mice were used as the research model.HMTNPs-SNO produces NO microbubbles with US irradiation.And it could be used for ultrasound imaging.It was found that the half-life of TPZ/HMTNPs-SNO group was?2.14±0.26 h?longer than that of the TPZ group?0.76±0.13 h?by pharmacokinetics studies,which contributed to the sustained release of TPZ/HMTNPs-SNO.The results of the pharmacodynamic study showed that the final relative tumor volume of the TPZ group was 4.02±0.18,while the relative tumor volume of the TPZ/HMTNPs-SNO+US group was 0.79±0.12.The tumor volume of the tumor was lower than the initial level,which indicateed that the combination of SDT,NO-based anticancer therapy and chemotherapy enhanced the anti-tumor effect of TPZ/HMTNPs-SNO tumor-targeting nano-delivery system.To sum up,the TPZ/HMTNPs-SNO tumor-targeting nano-delivery system has the potential clinical value in tumor therapy because of its pH sensitivity,US sensitivity,ultrasound imaging characteristics and ability to inhibit tumor effectively.