Experimental Research On Drug-loaded Fibers Anddrug Release Properties By Melt Electrospinning

The drug controlled release system is attracting more and more researchers’ interest.Controlled drug delivery systems offer numerous advantages,including improved therapeutic effects,reduced toxicity,and increased patient compliance and convenience,over conventional dosage forms.In such systems,natural and synthetic polymer materials are used as the drug vehicles to enhance the efficiency of the system.At present,the unresolved issues of polymer-based drug delivery systems include the low efficiency of the preparation of nanoparticles and vesicles,the complex process,and low drug release efficiency.However,electrospinning provides a simple,low-cost,and versatile processing method for preparing polymer nanofibers.Solution electrospinning is commonly used to prepare drug controlled release systems,but the solvents in the spinning process do not evaporate completely and residual solvents can be toxic to cells and tissues.In contrast,melt electrospinning provides a solvent-free method for preparing polymer fibers.This process is safe and environmentally friendly.Therefore,to overcome the problems existing in the controlled release of drugs at present,in this paper,a novel drug release system was prepared by melt electrospinning with dipyridamole(DPD)as a model drug and PLLA and PHB as carriers.The following is the main research content:First,fibers of different ratios of PLLA and PHB were prepared using melt electrospinning,and then explored the effects of different process conditions,blend ratios,and drug content on fiber diameter and morphology.The results showed that with the increase of temperature,the diameter of the fiber appeared to increase,then decrease and increase again,but the overall fiber diameter did not change much.As the distance increases,the average diameter of the fibers becomes coarser and narrower.With the increase of the voltage,the diameter of the fiber increases,then decreases,and rises again.The distribution of the diameter gradually decreases.The increase of PHB and drug content will gradually reduce the diameter of the fiber.In terms of morphology,distance,voltage,temperature,and blend ratio have little effect on the morphology of the fiber,and the content of drug significantly makes a rough surface.In 7:3/1%,the diameter of the fiber is not uniform,and morphology similar to a lotus root crevice is present in the fiber.Second,we studied the changes in the crystal structure,thermal properties,and functional groups of drug controlled release system.Next,the dynamic behavior of the polymer molecules is assessed by segmental mobility and drug diffusion,which is the most important part for drug controlled release.The results showed that there was an intermolecular hydrogen bond between PLLA and PHB,and a transesterification reaction occurred.As the PHB content increases,the crystallinity of PLLA slightly decreases.The addition of DPD promotes the movement of the molecular chains and lowers the melting temperature of the blend.The segmental motion of PLLA and PHB gradually decreases with the increase of PLLA,and the intercrystalline region in the fiber has a dense structural organization.The 9:1 system is more resistant to polymer hydrolysis than the 7:3.At the same time,the simultaneous collation of the effective DPD diffusivities in combination with the DPD mobile fractions shows that the rate of diffusion transport is approximately two times higher for the 7:3 PLLA/PHB fibers than for the 9:1 PLLA/PHB fibers.Finally,we used polyvinylpyrrolidone(PVP)as a carrier to prepare different ratios of sangusis draconis-PVP fiber by electrospinning to improve the drug dissolution and the bioavailability.First,we designed an orthogonal test to determine the optimal spinning conditions:voltage is 18 kV,distance is 17 cm,flow rate is 0.3 ml·h-1.Under this condition,the diameter of fiber is 1.02 ± 0.27 μm.Then XRD,DSC,and FTIR were used to characterize the properties of fiber.It was found that the blend of PVP and sangusis draconis was mainly an amorphous structure,forming a eutectic mixture.The hydrogen bond is formed between the sangusis draconis and PVP,and there is no chemical reaction.In the end,the dissolution profile of the sangusis draconis shows that the fibers with different content can significantly increase the dissolution of the drug,but as the content of sangusis draconis increases,the dissolution of drug in the fiber gradually decreases.