Research On Construction And Performance Of PH-Sensitive Small Molecule Nano Synergistic Delivery System For Diagnosis And Treatment

As a new chemotherapy treatment method,nanomedicine has advantages of improving the selectivity of anticancer drugs and reducing the toxicity and side effects.Recently,small molecule nano diagnosis and treatment strategies has attracted much attention in cancer treatment with its clear structure,simple preparation,high drug loading rate and stable blood circulation.By integrating the advantages of nanotechnology and diagnostic medicine,theranostics could overcome the existing limitations of different imaging agents or therapeutics in biodistribution and tumor selectivity and provide patients with safer and more targeted diagnosis and treatment.It is worth noting that 2,3,5-triiodobenzoic acid has a high iodine load and a clear CT imaging function.In addition,it could induce apoptosis of cancer cells through endogenous pathways and has certain anti-cancer ability.In this study,2,3,5-triiodobenzoic acid and ortho ester diamine monomer（OE）were subjected to an amide reaction to make a p H-sensitive drug-drug dimer.The synergistic doxorubicin（DOX）delivery system（TIBA-OE/DOX NPs）was prepared by emulsification and volatilization of PVA.Its structure and antitumor activity were investigated by a series of in vivo and in vitro experiments.（1）First,2,3,5-triiodobenzoic acid reacted with ortho ester diamine monomers to form a p H-sensitive small molecule dimer prodrug TIBA-OE.¹H NMR,¹³C NMR,FT-IR and mass spectrometry were used to determine the structure of the dimer prodrug.The thermal stability and crystal distribution of the dimer prodrug were investigated by synchronous thermal analyzer and X-ray crystal diffraction.The dimer prodrug TIBA-OE NPs was prepared by polyvinyl alcohol（PVA）oil-in-water method with good stability.Dynamic light scattering（DLS）analysis showed that the particle size of the nano-prodrugs was concentrated around187.4 nm,showing electronegativity.The morphology of the nano-prodrug was observed by transmission electron microscope（TEM）.The results showed that the size of the nanoparticle prodrug was uniform and spherical and the particle size was consistent with the DLS results.（2）The synergistic DOX transport system（TIBA-OE/DOX NPs）was successfully prepared by using intermolecular force between benzene rings.The results of DLS and microplate reader showed that the particle size of the DOX-loaded nano-cooperative delivery system was around 213.1 nm,the drug loading rate was 7.08%and the encapsulation rate was79%.In vitro simulation experiments found that the nanoparticle TIBA-OE NPs and TIBA-OE/DOX NPs have stable particle size at p H 7.4 and only a small amount of drug release.With the increase of acid strength,the particle morphology disintegrated and the drug release increased significantly,which was caused by the rupture of the ortho ester bond.The cytotoxic effects of TIBA-OE/DOX NPs on tumor cells were investigated by a series of cell-level experiments.Laser confocal analysis and flow cytometry showed that TIBA-OE/DOX NPs could be effectively uptake by various cancer cells.The results of apoptosis,toxicity assay and Hep G2 multicellular spheres（MCTS）showed that the synergistic delivery system had high tumor cell lethality and inhibiting ability.（3）The antitumor activity of TIBA-OE/DOX NPs in vivo was investigated by establishing a tumor-bearing mouse model.The drug distribution of DOX in vivo showed that the synergism delivery system TIBA-OE/DOX NPs had a longer blood circulation time and could enhance the enrichment of drugs in tumor sites.TIBA-OE/DOX NPs showed significant antitumor effect than the other groups after multiple dosed.In vivo CT imaging and biosafety assessment of TIBA-OE NPs showed that it could accumulate at the tumor site and has the function of angiographic diagnosis.In addition,it has no obvious liver or kidney toxicity,presenting good biosafety.To sum up,ortho ester coupled triiodobenzoic acid small molecule dimer prodrug TIBA-OE can be prepared into a coordinated delivery system TIBA-OE/DOX NPs after PVA emulsification and volatilization.Through a series of exploration,it shows both the functions of diagnostic CT angiography and in vivo antitumor efficacy,there will be broad prospect of applications in clinical theranostics.