Light-responsive CO₂ Bubble-generating Micelles And Artificial Biomimetic Rbc Nanoparticles For Anticancer Effect Research

Conventional chemotherapy of cancer has caused severe systemic toxicity and multidrug resistance.Some stimuli-sensitive polymeric micelles can encapsulate chemotherapeutic drugs and regulate drug release by spatial and temporal control,thereby reduce the side reactions to a certain extent.But in the process of tumor delivery,there are still some free drugs damage to normal cells.To solve these problems,we prepared a special light-labile polymeric prodrug micelles based on DEACM without loading any drugs,called light-responsive CO₂ bubble-generating PMs.The PMs used DEACM-PEG as backbone and could generate CO₂ bubbles under UV light exposure owing to the photolysis of?7-diethylaminocoumarin-4-yl?methyl?DEACM?.This is the first time to use light to induce the explosion of bubbles generated from the nano-carrier per se and ablate tumor cells.Normal nano-carriers may bring out immunogenicity and toxicity when injected into body,and they are easy to be trapped by reticuloendothelial system?RES?.RBC?red blood cell?membrane as a natural drug carrier has many advantages such as good biocompatible,biodegradable,and non-immunogenicity.So we use it to wrap anti-tumor nanoparticles and make it into bionic RBC drug system.This system can avoid nanoparticles being cleared by immune system so that extend its residence time in vivo and enhance its anti-tumor ability.This paper can be divided into three parts.The first part is synthesis,morphological characterization and light-responsive CO₂ bubble-generating characterization of PMs.First,we synthesized amphiphilic block copolymers DEACM-PEG using photosensitive compound DEACM as hydrophobic segment and PEG as hydrophilic segment.Then DEACM-PEG self-assembled and fonned PMs in the water.The PMs were observed to be spherical with particle size of about 200 nm by TEM and DLS,then irradiated into smaller particles by UV.During the irradiation,the UV absorption band of the micelle solution underwent a blue shift with a concomitant change in color from yellow to orange.All of this confirm the PMs' disruption.The degradation mechanism of PMs backbone were substantiated by the magnetic resonance imaging and Fourier transform IR spectra.The generation of CO₂ bubbles was also captured by videos.The second part is pharmacodynamics study of PMs by establishing cell model in vitro.It proved that PMs could significantly cause cell death with the disruptive force produced during the generation of bubbles.We performed a series of cytotoxicity tests using Renca cell in vitro.Through these tests,we first screened the intensity and duration of UV irradiation that was harmless to cells.Secondly,we excluded the cytotoxicity of the micelles per se and its photolysis products.Then we proved that the DEACM monomer can't killed tumor cells under UV irradiation,too.Finally,cytotoxicity experiments of different concentrations of PMs showed that the micelles caused effective cell death under 8s UV irradiation,and PI staining further confirmed the death of tumor cells.The third part is the establishment,in vitro characterization and long-circulation research of biomimetic RBC nanoparticles We demonstrated the integrity and stability of bionic RBC drug system through several detection methods including TEM,DLS and flow cytometer.Then protein contents of the RBC membrane-coated nanoparticles was verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis?SDS-PAGE?.In the end,we did some experiments in vivo and vitro to prove that the RBC membrane-coated nanoparticles could escape from the macrophage phagocytosis,prolong drugs half-life to increase their accumulation in tumor and achieve better anti-cancer effect.According to this research,we established two different anti-tumor nano-carriers.One is a UV-responsive CO₂-generating polymeric micelle system without loading any drugs.This PMs can dual-target tumor according to EPR effect and light-control in vitro,also avoid the toxicity of chemotherapy drugs to normal tissues.Another is biomimetic RBC nanoparticles.Wrapped by erythrocyte membrane,the anti-tumor nanoparticles can effectively extend its circulation time in vivo,increase its accumulation in the tumor site and improve the anti-cancer effect.Both of them provide new insights for tumor therapy.