Black Phosphorus Quantum Dots And Polymerized Vorinostat Self-assemblying Polyplex For A Combination Of Photothermal And Chemotherapy

In recent years,the incidence of cancer has been increasing gradually,which threat human health seriously.At present,the clinical treatment of cancer mainly includes surgery,chemotherapy and radiotherapy.However,their development is limited by the disadvantages such as incomplete clearance of surgery,low efficiency of chemotherapy and large side effects of radiotherapy.Photothermal therapy(PTT)is a new minimally invasive anti-cancer technology emerging after surgery,chemotherapy and radiotherapy.The principle of PTT is to inject photothermal agents into the human body,then collect them near the tumor with targeted identification technology,and next convert the light energy into heat energy to kill tumor cells through NIR irradiation.The ideal photothermal agent should have good photothermal conversion efficiency.So far,a variety of inorganic nanomaterials have been developed and applied in the photothermal therapy of tumors.However,compared with other biodegradable small molecules,inorganic nanomaterials are generally less biodegradable and remain in the body for longer periods which increased the risk of harmful effects.Therefore,it is necessary to develop photothermal agents not only have excellent photothermal effect but also biodegradable.Black phosphorus quantum dots(BPQDs),a new kind of nanomaterial,which is prepared by the stripping of Black phosphorus(BP)crystals.BPQDs has a large extinction coefficient at 808 nm,which can quickly and effectively convert NIR light into heat energy.Moreover,BPQDs has good biocompatibility and biodegradability.The final degradation product of BPQDs in vivo is non-toxic phosphate^[1],which can be discharged harmlessly from the body.It is an excellent photothermal agent.Photothermal therapy has the advantages of small trauma and high tumor specificity.However,photothermal therapy can only kill the primary tumor,not the metastatic tumor cells.Combined administration mode can effectively improve this problem and improve the efficiency of anti-tumor^[2].Histone deacetylase inhibitors(HDACis)are a kind of targeted anticancer drugs,which can inhibit the proliferation of tumor cells and induce cell differentiation and apoptosis by increasing the acetylation degree of Histone in cells and the expression level of p21 and other genes.Vorinotat(SAHA)is the representative drug of HDACis.It can inhibit cell migration,invasion and metastasis,and has obvious synergistic effect when used in combination with other anti-tumor drugs^[3,4].This paper designed and synthesized a drug co-loading system of photothermal therapy and chemotherapy,which can co-administer photothermal agent BPQDs and HDACis SAHA together.The co-loading system combine the different mechanisms of photothermal therapy and chemotherapy,complement each other's advantages,and achieve better anti-tumor activity.The research content of this topic includes the following three parts:In the first part,We`designed and synthesized a self-assembled compound of BPQDs and SAHA.First,the PEG-b-PAsp-SAHA(PPS)was synthesized.The ¹HNMR spectra showed the characteristic absorption peaks of PPS,which indicated that the prodrug was successfully constructed.PPS can form micelles by self-assembly.After mixing BPQDs with PPS,hydrophobic interaction can encapsulate the refractory BPQDs inside the PPS micelles,and complete the construction of the two-mode anti-tumor self-assembly complex BPQDs@PPS.The results show that BPQDs@PPS is a regular spherical morphology with an average particle size of 115.3nm and a Zeta potential of-28.8m V.It has a good photothermal conversion efficiency.BPQDs@PPS for BPQDs drug loading28.46%.The results of drug release experiments showed that the cumulative release rate of BPQDs was 69.66%at 72 h in the release medium of p H5.2.The cumulative release rate of BPQDs in the release medium of PH7.4 for 72 h was 49.18%.This indicates that the BPQDs@PPS can be p H-sensitive to drug release.In the second part,In vitro anti-tumor effect of black phosphorus quantum dots and Vorinostat prodrug self-assembled compound BPQDs@PPS.We used Cell function analyzer(RTCA)to test the cytotoxicity of BPQDs@PPS,BPQDs and PPS,respectively.The results showed that for mouse melanoma cells(B16-F10),the cytotoxicity of BPQDs@PPS group was stronger.The apoptotic effect of BPQDs@PPS,BPQDs on B16-F10 cells were determined by flow cytometry.The results showed that BPQDs@PPS could significantly inhibit the proliferation of tumor cells,induce the apoptosis of tumor cells.The cycle arrest of BPQDs@PPS,BPQDs and PPS on B16-F10 cells was determined.The results showed that BPQDs@PPS showed stronger arrest effect,and had stronger anti-tumor activity compared with free BPQDs and PPS.Finally,the ability of free drugs and polymer-coated drugs to be absorbed into B16-F10 cells was measured by scanning confocal laser microscopy.The results showed that the fluorescence intensity in the drug group coated with the polymer micelle was higher than that in the free drug group,indicating that the polymer material was helpful for drug uptake by B16-F10 cells.In the third part,In vivo anti-tumor effect of black phosphorus quantum dots and Vorinostat prodrug self-assembled compound BPQDs@PPS.First,we established the melanoma model of C57BL/6 mice.Setting up normal saline group,BPQDs@PPS group,PPS group and BPQDs group,with 5 mice in each group.The BPQDs@PPS group and the BPQDs group were given laser irradiation with a wavelength of 808nm.The drug was given every two days for a total of 5 times.The body weight and tumor size of the mice were measured every two days and the survival of the mice was recorded.The lung tissue sections of mice in each group were observed by H&E staining.The results showed that the growth rate of tumor in BPQDs@PPS group was the slowest and the survival time of mice in BPQDs@PPS group was the longest,which reflected the good therapeutic effect of combined administration.Lung tissue sections of dead mice in each group were stained with H&E to observe the lung metastasis of melanoma in each group.It was found that there were more metastatic melanoma lesions in the normal saline group,a small number of metastatic melanoma lesions in the BPQDS group,and few metastatic melanoma lesions in the PPS group.No metastatic melanoma was found in the lungs of mice in BPQDs@PPS group.These results indicated that SAHA had a strong inhibitory effect on the metastasis of melanoma cells.It can be seen that SAHA and BPQDS have a good synergistic anti-tumor effect and effectively inhibit the growth and metastasis of tumor cells.In conclusion,we successfully constructed a kind of black phosphorus quantum dots and vorinotat polymer prodrug self-assembly composite BPQDs@PPS.The drug co-loading system combined PTT and chemotherapy,made up for the deficiency of monotherapy,showed a good combination effect,and realized the purpose of synergistic effect,which is expected to provide a new idea for anti-tumor therapy.