Design And In Vitro Study Of Dual-modified Doxorubicin Liposome Antitumor Drug Delivery System

Brain tumors are one of the diseases that are currently seriously threatening human health.However,the presence of blood-brain barrier severely limit the treatment efficiency of drug.Hence,in this thesis,according to the physiological and environmental characteristics of the tumor,a peptide targeting blood brain barrier and brain tumor was designed using molecular simulations.Furthermore,a dual modified doxorubicin liposome antitumor delivery system was developed to improve the uptake of targeted cels and enhance the anti-tumor effect.The research of this subject includes the following three aspects:(1)Peptide design: Due to large molecular weight and high synthesis cost of the current ligands,we first used molecular simulation to analyze the interaction between ligands and receptors for the existing ligand amino acids.Candidate sequences were determined subjected to dynamics simulation in a water environment by GROMACS.(2)Preparation of dual modified DOX liposome: The liposome(LIP)was prepared by thin film ultrasonic dispersion method.Particle size and potential as the main indicators were determined using particle analyzer.Then the drug doxorubicin was loaded by a p H gradient method.The PEG chain was inserted into the surface of doxorubicin liposome by a post-insertion method.A series of doxorubicin liposomes including polypeptide liposome(LIP/DOX),mono-ligand modified doxorubicin liposome(LIP-PEG-IR12/DOX,LIP-PEG-RC8/DOX),dual ligand modified doxorubicin liposome(LIP-PEG-RC8-IR12/DOX)were prepared.Encapsulation efficiency,particle size and other properties were monitored.The results shows that the particle size of each type of liposome is about 100 nm on average,and the encapsulation efficiency is around 75%,which is in line with the performance required treating brain tumors.(3)In vitro detection of doxorubicin liposome: The cellular uptake of the doxorubicin liposomes was qualitatively analyzed by laser confocal.The experimental results show that the fluorescence of the unmodified doxorubicin liposome entering the cell at the same time point is lower that of the ligand-modified doxorubicin liposome.Further,the amount of DOX delivered into the cels was quantitatively analyzed using a flow cytometry.The results shows that the drug delivery of the drug with the dual ligand modification is the best.The toxicity of different drug-loading systems on Neuro-2-a cels was analyzed by MTT method using a microplate reader.The results show that the ligand-modified vector has a cell survival rate nearly two times lower than that of the unmodified system.