Determination of electrical conductivity for the study of the gelling process of injectable organogel system

The purpose of the present study was to develop a simple electrical conductivity-based determination method to trace the gelling process of injectable organogels after administration. Influential factors of gelling were firstly found in order to obtain an injectable organogel with suitable degradation and release behavior. The feasibility of conductivity measurement-based simulation of gelation process was studied, and the effects of the different kinds and amount of gelators and anti-gelling solvents as well as temperature on the gelling process were evaluated. Results indicated that the electrical conductivity of PBS solution was linearly proportional to the amount of anti-gelling solvent and that the change of the conductivity could trace the diffusion behavior of anti-gelling solvents in gelation process and obtain the gelation time. Structure of gelators and different kinds of anti-gelling solvents could observably affect the diffusion rate and diffusion percentage of anti-gelling solvent. The increase of N-stearoyl L-alanine methyl ester(SAM)and decrease of temperature could lead to the decrease of diffusion rate and extension of diffusion time. The gelation process of SAM organogel could be completed in two hours, indicating that the finishing time of sharpreleaseand the starting time of controlledrelease was two hours.