Co-assemblies Of Tetraphenylporphyrin Derivatives For Photodynamic Combinational Therapy

Photodynamic therapy(PDT)is a novel cancer treatment modality.In the PDT process,the laser-irradiated photosensitizers(PSs)deliver energy to oxygen(O2),generating reactive oxygen species(ROS),particularly singlet oxygen(1O2),and exerting a curative effect.The oxygen concentration is a major factor affecting the PDT efficacy.However,the tumor is hypoxic as a whole,and the anti-cancer efficacy of PDT is greatly limited.In addition,the lifetime of therapeutic 1O2 was reported to be extremely low with a limited diffusion length,which greatly impairs the PDT efficacy.Accordingly,therapeutic effect of PSs alone is limited,and the combinational therapy was applied to improve the PDT efficacy.Co-assembled nanoparticles(NPs)are built by two drug molecules under non-covalent intermolecular interactions,including hydrophobic interaction,?-? stacking,electronic force and hydrogen bond.With the co-assembling drugs themselves as building blocks,the resulting co-assemblies had an ultra high drug-loading capacity,which greatly avoids potential toxicity of overused carriers.Therefore,co-assembled NPs seem to be a good candidate for combinational therapy.Herein,we constructed two kinds of co-assembled nanoparticles using tetraphenylporphyrin derivatives to improve PDT efficacy by releveing tumor hypoxia or extend 1O2 lifetime,respectively.The arginine(Arg)was used to relieve tumor hypoxia.We applied the 5,10,15,20-Tetrakis(4-hydroxyphenyl)porphyrin(THPP)co-assemble with a chemically modified Arg(Fomc-L3-Arg).The THPP/Fomc-L3-Arg NPs presented spherical shapes,with a uniform size and good stability.It was found that hydrophobic interaction,?-?stacking,electronic force and hydrogen bond played a key role in nanopaiticles formation.The co-assemblies could be efficiently uptaken by tumor cells,and rapidly released the THPP in tumor cells.Meanwhile,the Fomc-L3-Arg molecules could effectively generate NO under high level of ROS in tumor cells.The NO could competitively inhibited the activity of mitochondrial respiratory chain complex ?(CcO),which is responsible for almost 90%of O2 consumption of the tumor cells.Accordingly,the Fomc-L3-Arg enhanced phototoxicity of THPP in an "open source"strategy.After injection,the AUC of THPP/Fomc-L3-Arg NPs was 1.5-fold higher than that of THPP solution.What is more,the nanoparticles demonstrated greatly enhanced tumor targeing ability in vivo,and significantly inhibit tumor growth upon irradiation.The unsaturated fatty acids(UFA)were used to "extend" the lifetime of the 1O2.Specifically,the 5,10,15,20-tetrakis(4-aminophenyl)porphyrin(TAPP)was co-assembled with three UFAs,namely,oleic acid(OA),linoleic acid(LA)and linolenic acid(LNA).The TAPP/OA NPs,TAPP/LA NPs and TAPP/LNA NPs presented spherical shapes,with a uniform size and good stability.It is the first time that the assembling ability of UFA was found and the nanoparticles formation under the dricing forces including hydrophobic interaction,?-? stacking,and elecstastic force.The co-assemblies could be efficiently uptaken by tumor cells,and responsively released the TAPP under the intracellular acidic/oxidative conditions.Interestingly,the double bond of UFAs had a remarkable impact on the intracellular release characteristics of the nanoparticles,the order of release speed was TAPP/OA NPs?TAPP/LA NP>TAPP/LNA NPs.Under irradiation,released TAPP produces 1O2,which directly attacks tumor cells and simultaneously oxidizes UFAs to generate lipid hydroperoxides(LOOHs).As primary products of the UFA oxidation,LOOH are typically long-lived and able to release free radicals,including 1O2,·OH radicals,alkoxy radicals and peroxyl radicals after rearrangement,making up for the spatiotemporal insufficiency of 1O2 and exacerbating overall damage.In other words,the UFAs could enhanced the PDT effect in a"reduce expenditure" manner.Among three nanoparticles,the TAPP-LA NPs efficiently released PSs and LAs and induced the highest ROS yield in tumor cells,demonstrating the strongest cytotoxicity.After injection,the AUC of TAPP/UFA NPs was 2-fold higher than that of free TAPP.Additionally,the nanoparticles demonstrated significantly enhanced tumor-homing ability in vivo,leading to a more potent therapeutic efficacy than TAPP solution.Specially,the TAPP-LA NPs efficiently released PSs and LAs and induced the highest ROS yield in tumor cells,demonstrating the best combinational PDT effect.In conclusion,the tetraphenylporphyrin derivatives exhibited a great potential in constructing co-assembled nanoparticles.With different substituents on the benzene ring,they could co-assembled with Fomc-L3-Arg or UFA and improve the efficacy of PDT in an "open source" or "reduce expenditure" way,respectively.