Fabrication And Characterization Of Calcium Phosphate Modified Drug Loaded Nanoparticles

Self-assembling nanoparticles as drug delivery carriers have advantages to overcome the poor drug absorption issues, controlled drug release and prolonged action of drug action. Both hydrophobic and hydrophilic drug can be loaded or encapsulated into nano-carriers and delivered to the target cells or issues. Therefore nano-carrier has been the research focus in recent years. In this research, two types of core-shell structure nanoparticles were prepared by using novel surfactant Pa-Brij78.Pamidronate was first conjugated to Brij78 to prepare a novel surfactant Pa-Brij78. Pa-Brij78/E-wax nanoparticles for loading hydrophobic drug curcumin with surface bisphosphate group were prepared by an emulsion method using Pa-Brij78 as emulsifier and stabilizer. The Pa-surface modified nanoparticles were able to bind calcium ions and phosphate ions in the solution to form CaP shell on the surface nanoparticle. SEM pictures showed that Pa-Brij78/E-wax nanoparticles had spherical shape with smooth while CaP/Pa-Brij78/E-wax nanoparticles’surfaces were rough. The drug loaded core-shell nanoparticles CaP/Pa-Brij78/E-wax(Cur) had poor stability and only hydrophobic drug can be loaded, so the nanoparticles has certain limitations in application.Model antigen OVA was encapsulated in PLGA nanoparticles using novel surfactant Pa-Brij78 by a water-oil-water double emulsion method. The calcium phosphate coated PLGA(OVA) nanoparticles were fabricated by a co-precipitation method. Then, Toll like receptor ligand CpG and poly Ⅰ:C were coated on the surface of nanoparticles to form CpG/CaP/PLGA(OVA) and poly Ⅰ:C/CaP/PLGA(OVA) which were novel drug-loaded core-shell nanoparticles. The nanoparticles were characterized by Dynamic light scattering (DLS) particle size analyzer, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The loading capacity and encapsulation efficiency of OVA, CpG and poly Ⅰ:C were determined. The results of SEM and TEM showed PLGA(OVA) nanoparticles had spherical shape with smooth and even surface while CaP PLGA(OVA) nanoparticles were spherical but due to uneven distribution of calcium phosphate form nanoparticles surfaces were rough and irregular. The coating of calcium phosphate shell were confirmed to be Ca3(PO4)2 by X-ray diffraction analysis. The average loading efficiency of OVA, CpG, pory Ⅰ:C were 5%,0.47%,2% when the encapsulation efficiency of them were 80%,89%,95.2%, respectively. In conclusion, the composite drug loaded core-shell nanoparticles of small size and good dispersib ility in water can be kept under 4℃ for a period of time. The new preparation method of the nanoparticles provides a new way for the synthesis of novel multifunctional nanomaterials.