Research On Sustained Drug Release Based On Microfluidic Technology

Selecting appropriate materials to encapsulate drug can make the drug release grad-ually for long period of time,it can extend the interval time between the administrationa thus reduce the frequency of administration and relieve the pain of patients.There are kinds of methods to fabricate drug-loaded formulations,microfluidic technology is one of them.Monodispersed microcapsules with suitable size and structure can be atained,by changing the size and structure of the microfluidic device and controlling the flow rates of each phase.Polydimenthylsiloxane(PDMS)is a commonly used ma-terial for microfluidic devices,however the fabrication of PDMS microfluidic devices and the hydrophilic surface treatment is relatively complicated,moreover,it is diffi-cult to be reused.It is relatively easy and cheap to fabricate microfluidic devices based on glass-capillary and flow-focusing technique.Microcapsules with uniform size and structure can be fabricated using glass-capillary flow-focusing microfluidic devices.Natural polymer materials and synthetic polymer materials can both be used to encap-sulate drugs.Among them,lactic acid-glycolic acid copolymer(PLGA)is a commonly used synthetic biodegradable polymer,and sodium alginate is another widely used natu-ral biodegradable polymer.They are both non-toxic,biodegradable and with excellent biocompatibility.The release kinetics of the encapsulated drug have profound influence on the ther-apeutic result,so in recent years there are many researches on drug release kinetics of drug-loaded microcapsules.Much attention has been paid on the release kinetics of nano-scale microcapsules loaded with anti-cancer drugs,however the study of release kinetics on micron-scale microcapsules loaded with peroral drugs is relatively absent.In our defined work we used home-made glass-capillary flow-focusing microflu-idic devices and to fabricate drug-loaded microcapsules,rifampicin was used as a rep-resentative drug.PLGA and sodium alginate were used as packaging materials respec-tively.The effect of size and structure of microcapsules,temperature,pH and osmotic pressure of the medium,and initial drug concentration on the in vitro release kinetics were studied systematically.During the study we found that the smaller size of the microcapsules and the higher the temperature,the initial and average release rate of en-capsulated drugs would be faster.Furthermore,the structure of the microcapsule also strongly affected the release profile.The higher the osmotic of the release medium,the release rate would be slower.The effect machanism of pH of the release medium on release kinetics were different for PLGA and alginate microcapsules.However,in a cer-tain range,the initial drug concentration had little effect on release kinetics.The work in this report is conducive to understanding the relationship between the drug carrier char-acter and their release kinetics,thus tailor-designed drug carriers with pre-determined release profile that meet the needs of specific applications can be fabricated.