| In recent years,the drug delivery systems,such as the controlled and sustained-release systems,the targeted drug delivery system s and the transdermal drug delivery systems,have developed rapidly and provided more choices for clinical treatment.Among of the drug delivery systems,the controlled and sustained-release systems are the fastest developing drug delivery systems.It can not only release drugs in a controlled manner,but also maintain the therapeutic effect and reduce the dose at the same time,thereby reducing or avoiding toxic side effects and improving the stability of drugs.As one kind of commonly used carrier for the controlled and sustained-release systems,polymeric nanoparticles are those with a small diameter of 1-1000 nm so that they can penetrate the tissue gap,be absorbed by the cells and get through the smallest capillaries of the human body.The carrier used for the preparation of polymer nanoparticles is mainly composed of synthetic biodegradable polymer and natural macromolecule,in which polylactic acid?PLA?is widely used because of the good biocompatibility and biodegradability.Naringenin is a flavonoids derivative with multiply effects such as anti-oxidation,anti-ulcer,inhibit liver fibrosis,antibacterial and anti-tumor activity.However,its medical applications was limited by the rapid metabolism,uncontrollable concentration in blood,enterohepatic circulation and low oral bioavailability.To conquer these problems,naringenin encapsulated in polylactic acid nanoparticles were prepared by modified solvent evaporation method.Moreover,the feasibility of preparation,the characterization and the properties of naringenin encapsulated in polylactic acid nanoparticles were investigated,which is expected to provide some valuable information for the preparation of novel naringenin agents.The main work are as follows:1.Naringenin loaded PLA nanoparticles were prepared by modified solvent evaporation method.The single factor experiment was used to study the effects of PLA molecular weight,PLA c oncentration,oil/water volume ratio,ultrasonic time,feed ratio of PLA/drug and emulsifier concentration on the particle size,drug loading and entrapment efficiency of the nanoparticles,as a result,the optimized technology parameters were obtained.Moreover,the morphology,composition,particle size distribution,drug loading rate,encapsulation efficiency,release properties and antibacterial properties of nanoparticles were characterized by field emission scanning electron microscopy?FESEM?,fourier transform infrared spectroscopy?FTIR?,X-ray diffractometer?XRD?,laser particle size analyzer,UV-Vis spectrophotometer and microplate reader.The results showed that the optimum preparation conditions were as follows: PLA molecular weight 80000,PLA concentration 0.03 g·m L-1,PVA concentration 1 %,oil/water volume ratio 1: 5,ultrasonic time 1 min,feed ratio of PLA/drug 5: 1.The nanoparticles had uniform particle size distribution with the mean size of 135.2 nm and good sustained-release effect,in addition,the drug loading rate and the entrapment efficiency were 22.3 % and 64.7 %,respectively.However,the antibacterial effect was not very satisfactory.2.In order to improve the antibacterial properties of nanoparticles,the PLA composite nanoparticles encapsulating starch–capped silver nanoparticles and naringenin were prepared by modified solvent evaporation method.At first,starch–capped silver nanoparticles were prepared through liquid phase reaction method by using starch as protectant and glucose as reductant.Moreover,the morphology,composition and particle size distribution of starch –capped silver nanoparticles were characterized by field emission scanning electron microscopy?FESEM?,transmission electron microscopy?TEM?,fourier transform infrared spectroscopy?FTIR?,X-ray diffractometer?XRD?and laser particle size analyzer.Then,the PLA composite nanoparticles encapsulating starch–capped silver nanoparticles and naringenin were prepared by modified solvent evaporation method.The optimum conditions were obtained by orthogonal test.Moreover,the morphology,composition,particle size distribution,drug loading,encapsulation efficiency,release properties and antibacterial properties of the composite nanoparticles were characterized by field emission scanning electron microscopy?FESEM?,transmission electron microscopy?TEM?,X-ray diffractometer?XRD?,laser particle size analyzer,UV-Vis spectrophotometer and microplate reader.The results showed that the diameter of starch–capped silver nanoparticles was 10.1 nm,the PLA composite nanoparticles 379 nm,and the drug loading rate and the entrapment efficiency of the PLA composite nanoparticles were 20.8 % and 53.8 %,respectively.Moreover,the PLA composite nanoparticles showed excellent antibacterial and sustained-release properties. |
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