| Microspheres or microcapsules made out of polymer have excellent mechanical strength,stability,biocompatible,biodegradable and encapsulation capability.Hence,they can be load hydrophilic or hydrophobic nanoparticles,can used as magnetic drug carriers for targeted delivery,and be held in the specific area for a desired period of time by applying external localized magnetic fields.They can be surface modified with cellular epitopes or ligand,recognize disease antigens,thus enhancing the ability to distinguish diseased tissue from healthy tissue.They can serve as ultrasound contrast agents(UCAs)with good ultrasound contrast-enhanced capability,if are loaded with a drug either inside or on the surface of the shell,can specifically target the diseased tissue and trigger to release drug using external US at a desired location.In this work,the water-in-oil-in-water(W/O/W)double emulsion-solvent evaporation process has been employed to prepare Fe3O4-loaded polymeric gas-filled microcapsules,Ibuprofen-loaded polymeric magnetic microspheres and simvastatin-loaded polymeric microspheres with superparamagnetic nanoparticles,Ibuprofen and simvastatin.The characterizations such as microscope,LPS,IR,XRD,SEM and TEM were used to detect and analyze the morphology,composition and structure of the products.The preliminary formation mechanism of the microspheres or microcapsules was also explored.Furthermore,the properties including magnetic properties,drug delivery,and ultrasound imaging was studied.Polymeric microcapsules encapsulated Fe3O4 nanoparticles were fabricated by(W/O/W)double emulsion solvent evaporation method.Magnetic nanoparticles were synthesized by coprecipitation of iron oxide.The results indicated that the composite microcapsules have nitrogen gas in the core,Fe3O4 in the internal cavity with mean diameter of 3.6 ?m.Thus the alcohol as additive was applied to control the average size and size distribution of the microcapsules.Laser particle analyzer measurements indicated that the average size and size distribution decreases with the increasing of alcohol concentration,and the size and span increase at higher alcohol concentration.Moreover the prepared magnetic microcapsules with the coating of polymer have superparamagnetic behavior.Furthermore the size controlled polymeric composite microcapsules have potential to act as ultrasound contrast agents and magnetic triggered drug delivery system.Polylactide(PLA)microspheres containing magnetic nanoparticles(MNPs)and anti-inflammatory drug Ibuprofen(IBF)were synthesized by using(O/W)emulsion solvent evaporation technology.With surface modification,the magnetic nanoparticles/PLA composite drug carriers showed excellent magnetite content and magnetic susceptibility.SEM and TEM showed that the magnetic microspheres were spherical in shape with a smooth surface,and of a mean diameter in the micrometer range.The incorporation of MNPs and IBF into the PLA matrix was confirmed by FTIR.XRD and VSM further confirmed the existence of MNPs in the microspheres which maintained superparamagnetic behavior with a saturation magnetization of 31.4emu/g.The magnetite content of 28.4wt%was assessed by TGA.In addition,the drug release profiles showed that the IBF-loaded PLA magnetic microspheres can pH-responsed release of IBF and are promising for controlled release drug delivery.Simvastatin(Sim)loaded poly(lactic-co-glycolic acid)(PLGA)microspheres(MS)were synthesized by using(W/O/W)emulsion solvent evaporation technology.Several investigations were carried out to determine the structure and performance of the MS,including morphology,size distribution,and chemical composition.The release profiles showed that the MS were fast release,that is,44%of Sim released in 2 min when exposed to continuous ultrasound compared to 12%released in 2 min without ultrasound.Furthermore,the results demonstrated that Sim loaded UCAs triggered with focused ultrasound have the potential to exhibit excellent echogenic properties and provide sufficient drugs to vascular inflamed plaques. |
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