Preparation Of Chlorin Chlorophyll Photosensitizer And Its Photodynamic Therapeutic Activity

Photodynamic Therapy?PDT?has been used in the clinical treatment of many cancers because of its unique therapeutic characteristics,such as low toxicity,good repeatability,non-drug resistance,low cost,safety and effectiveness.PDT consists of three elements:light of specific wavelength,tissue oxygen and photosensitizer?PS?.Among them,the key element is PS.Most photosensitizers are porphyrins.Chlorophyll degradation products are important natural photosensitizers,which have strong absorption in PDT window?650-850 nm?,and are of great significance in the diagnosis and treatment of cancer.However,some degradation products of natural chlorophyll a have strong hydrophobicity and poor water-solubility,and most of them are easy to aggregate in vivo,causeing the PDT effect to weaken;some have short absorption wavelength causing the shallow treatment depth;some have poor targeting and long cycle enrichment time in vivo.To solve these problems,the structure of chlorophyll degradation products was modified in order to improve the biocompatibility by changing their water solubility and dispersibility,expand the conjugate system to increase the treatment depth,and also construct nano-drug delivery system to achieve precise targeting.This study is divided into three parts.The first part is the preparation of chlorin amide P6?Amido Chlorine P6,ACP6?and its anti-tumor activity in vitro.Using methyl pheophorbide-a?MPa?as raw material,introduce two amide bonds into the ring opening of the E ring of chlorin dihydrochloride and synthesized a new photosensitizer?ACP6?.The structure of ACP was verified by NMR and elemental analysis.The maximum absorption wavelength was 663 nm and the hydrophilicity increased due to the introduction of hydroxyl groups.Biological experiments in vitro showed that ACP6 had low dark toxicity and high phototoxicity(IC₅₀=1.17±0.029?g/mL).The yield of singlet oxygen was only 29.3%,because ACP6 exerted PDT efficacy mainly through type I photodynamic reaction?hydroxyl radical generation?.ACP6 could regulate the expression of Survivin gene and induce apoptosis.The second part is the preparation of graphene-loaded chlorophyll phenylhydrazone photosensitizer and its anti-tumor activity in vitro.A new chlorophyll derivative?BPMppa?with extended conjugate structure was synthesized by hydrazone formation of carbonyl group and p-bromophenylhydrazine on the peripheral E ring of methyl pyropheophorbide a,which the maximum absorption wavelength was red shifted to 683 nm.Carbon material photosensitizer?G-BPMppa?has Tyndall effect and absorption wavelength of 698 nm was prepared by loading chlorophyll derivatives of hydrazone on graphene through?-?interaction.The loading rate of BPMppa is 48 wt%,and the yield of singlet oxygen is 60.55%.In vitro photodynamic biological experiments showed that G-BPMppa enhanced the photodynamic activity(IC₅₀=1.36±0.35?g/mL)of HeLa cells and the uptake of photosensitizers.The third part is the preparation of mitochondrial targeted photosensitizer and its anti-tumor activity in vitro.Mitochondrial targeted GO-Fe₃O₄-FA-PEI-TPP-PPa?GFFP-TPa?was prepared by combining triphenylphosphorus with pyropheophorbide-a?PPa?and loading it into a novel magnetic graphene oxide nanodrug delivery system modified by folic acid and polyethyleneimine.GFFP-TPa NPs have magnetic targeting properties.When preparing composite nanoparticles,the target compounds could be separated by the action of an external magnetic field.The singlet oxygen yield was high?47.38%?.Only 10%of the photosensitizers were bleached after 50 min under the light exposure,which indicated that the photostability was good.GFFP-TPa has good PDT activity(IC₅₀=1.04±0.02?g/mL)and multiple targeting?magnetic targeting,tumor targeting,mitochondrial targeting?has been verified.A novel biocompatible nano-drug delivery system?GFFP?provides an effective PDT strategy for cancer treatment.