Nanocarriers Based On Eudragit As Drug Delivery Systems For PH-responsive Controlled Release

Recently,people have focused on nanomaterials with their rapid development.There are many ways to prepare them,but most can’t be controlled properly.Electrospinning is a method to fabricate nanomaterials by using high-voltage static electricity.Electrospinning or electrospraying is simple and easy to operate.The nanomaterials prepared from them have large specific surface and high porosity,which can be used as wound dressings,tissue engineering scaffolds and drug carriers.Responsive drug delivery system is new.Polymers with different properties can promote the drug release in a specific site and increase the drug concentration in the lesion site,improving the therapeutic effect.The application of electrospinning in the preparation of responsive drug-loaded system is conducive to provide a simple and easy-to-use method for preparing new drug system,providing more possible prospects of controlled release systems.The purpose of this paper is preparing different pH-sensitive drug delivery systems.We used Eudragit as raw material,ethylcellulose and soybean lecithin as adjuvant,ketoprofen as a model drug to prepared two different pH sensitive drug delivery systems.We also researched and compared their performance in this paper.(1)We prepared Eudragit,Eudragit / EC nanofibers and their drug-loaded nanofibers by using electrospinning.And we also combined electrospraying and molecular self-assembly to fabricate Eudragit / PC liposome self-assembly nanoparticles and their drug-loaded nanoparticles.(2)Scanning electron microscopy and transmission electron microscopy were used to observe the morphology of nanofibers and liposomes.The results showed that the morphology of Eudragit nanofibers was related to the concentration of polymer.When the polymer concentration was 20%,the surface of nanofibers was smooth and uniform.The morphology of blended nanofibers and their drug loaded nanofibers was good when the polymer concentration was 20%.When the ratio of EC to Eudragit was 1: 2,the diameter distribution of nanofibers was the most uniform.No obvious phase separation occurred.Liposome nanoparticles were spherical,and modified by Eudragit.The particle size was significantly smaller than that of nanofibers.Dynamic light scattering showed that as the pH of the solution changed,the size of the liposome nanoparticle changed due to the property of Eudragit.(3)The nanomaterials and their drug-loaded systems were characterized by FTIR and XRD,indecating the successful preparation of them.And all the polymers and drug in these materials were amorphous.(4)Cytotoxity of the two drug-loaded systems was studied and compared by using cytotoxicity experiments.The results showed that both of them had no toxic effects on cells,which indecated good biocompatibility and the presence of PC could also promote cell growth.(5)The drug release properties of drug-loaded nanofibers and drug-loaded liposome nanoparticles were investigated at two different pH values.The results showed that the drug release rates of the two systems were low at the pH of 4.5.But when the pH was 7.4,the drug release rates of them were significantly increased.The release time of the nanofibers was longer than that of liposomes due to their morphology and the addition of EC.Therefore,we fitted the pharmacokinetic modelsproposed the drug release mechanism.The solubility of Eudragit chains changed due to the ionization of the COO-groups.In nanofibers,the Eudragit chains had an increased solubility due to weake protonation of the COO-group when the pH of the solution is above 6.0.The structure of nanofibers gradually collapsed and the drug released slowly.However,the presence of EC slowed down the entire process.However,the stability of the liposome nanoparticles was poor.After the Eudragit was dissolved,the drug in the liposome could be released quickly.