Effect Of Surface Potential On Plasmid Carrying Capacity Of Cationic Lipid Microbubbles

Objective:To prepare cationic lipid microbubbles with different proportions and dosages of materials,to study the relationship between potential and plasmid carrying capacity,and to obtain the optimal ratio of materials in microbubbles with maximum plasmid carrying capacity.Methods:Preparation of lipid microbubbles using thin film hydration mechanical oscillation method.Two materials,DPPC and Dc-Chol,were added to the lipid membrane materials DSPC and DSPE-PEG2000 to prepare cationic lipid microbubbles.C3F8 gas was used to create the gas core of the microbubbles,and Dil labeled microbubbles were prepared to observe the surface physical characteristics of the microbubbles.The quality of DSPC and DSPE-PEG2000 in the preparation material is fixed.The microbubbles are divided into group A(DPPC:Dc-Chol=1:1),group B(DPPC:Dc-Chol=1:2),and group C(DPPC:Dc-Chol=2:1)based on the different mass ratios of DPPC and Dc-Chol added,and are divided into 6 subgroups according to the different quality of the added material.The surface potential and particle size of the microbubbles in each group were analyzed by Malvern test.The concentration changes of the microbubbles were detected by white blood cell counting method.The morphological characteristics of the microbubbles were observed by light microscope,scanning electron microscope and fluorescence electron microscope.Results:(1)The stability of microbubbles within 1 hour and plasmid loaded microbubbles within 24 hours is excellent;(2)The particle size of microbubbles decreases with increasing surface potential;(3)The plasmid carrying capacity of microbubbles increases continuously with the increase of surface potential of microbubbles.Conclusions:Cationic lipid microbubbles were prepared by thin film hydration method and plasmids were connected by electrostatic adsorption method.The plasmid carrying capacity of the microbubbles continued to increase with the increase of the surface potential of the microbubbles.The optimal ratio for preparing microbubble materials in this experiment is DSPC:DSPE-PEG2000:DPPC:Dc Chol=3:1:3:6,with a surface potential of 44.5±1.8m V,a particle size of 459.6±27.1nm,and a maximum plasmid carrying capacity of 31.30μg/10~6CMBs.