| Compared with one of the single treatment methods,the photothermal and photodynamic synergistic therapy has a stronger ability to ablate tumor tissues and inhibit the growth of tumor cells,which provides new ideas for efficient treatment of tumors.Therefore,the construction of photothermal and photodynamic therapeutic system has become one of the research hotspots in the field of photothermal treatment for tumors.Gold nanoparticles(Au NPs)not only possess absorption in the near-infrared region,but also have high light-to-heat conversion efficiency.They also exhibit great chemical stability,low toxicity,and easy surface modification and functionalization.Therefore,it is often used as a nanocarrier for applied research in biomedical fields such as imaging,drug loading,and therapy.Chlorin e6(Ce6)is a photosensitizer with high singlet oxygen yield.It is widely used in photodynamic therapy.However,it is difficult to be dissolved in water and injected directily.This makes it difficult to achieve the expected effect of killing cancer cells during photodynamic therapy.To combine the photosensitizer Ce6 with Au NPs as carriers can improve the loading and delivery efficiency of Ce6.Polydopamine(PDA)is a polymer with good biocompatibility and strong light-to-heat conversion ability in the near-infrared region.It is easy to adhere to the surface of other materials during the formation process.Therefore,the coating of PDA on the surface of nanoparticles can not only effectively improve the photothermal conversion efficiency of Au NPs,but also further improve its biocompatibility.In addition,the presence of PDA layer is helpful for the sustained release of drugs.As reported so far,current research often fails to realize high photothermal conversion efficiency,high photosensitizer drug loading capacity,and fast cell uptake capacity at the same time,so we choose gold nanoflowers(Au NFs)as carriers,loaded with Ce6 with high singlet oxygen yield,and modified the polydopamine coating on the outermost layer,thus the nano-drug system with dual photothermal and photodynamic therapy was constructed.This subject started with the preparation of Au NFs as drug carriers.By changing the reaction temperature and the amount of reducing agent ascorbic acid,Au NFs with a particle size of 60-100 nm and a maximum absorption wavelength in the visible region of 575-650 nm were synthesized.Prepared at 0 ?C,the Au NFs were with most branches.After the coating of PDA(maximum about 14.2 nm),it was found that the Au NFs could be rapidly heated to 55 ?C,the photothermal properties were improved,and the cytotoxicity was further reduced.PDA has a positive effect on the construction of photothermal/photodynamic therapeutic system.In the subsequent experiments,we use the easy-formed property of Au-S to modify glutathione(GSH)on the surface of Au NFs,and conjugated Ce6 with GSH through the amidation reaction.Finally,the PDA layer was modified to obtain the composite nano-drug-loaded particles PDA-Ce6-GSH-Au NFs.The modification of the polydopamine layer resulted in a redshift of maximum absorption wavelength to the near-infrared region by about 80 nm,with one peak at 668 and 705 nm each.The former is a characteristic peak of Ce6,and the latter is generated by the red shift of the characteristic peak of Au NFs;The loading content of Ce6 is 13.9 wt.%;At p H = 5.8,due to the amphoteric nature of PDA,the release of Ce6 was slow;the singlet oxygen yield was 91.0% of pure Ce6;the light-to-heat conversion efficiency reached 23.6%,which was 7.0% higher than that of Au NFs;In vitro cell experiments,PDA-Ce6-GSH-AuNFs had low toxicity and entered tumor cells rapidly;photothermal/photodynamic therapy experiments in vitro and in vivo showed that PDA-Ce6-GSH-Au NFs had a highly effective killing capacity for tumor cells.These results demonstrated that PDA-Ce6-GSH-Au NFs is a therapeutic agent with dual photothermal and photodynamic therapeutic functions,and has great potential in the field of tumor treatment. |
PDF Full Text Request