Preparation Of Porous Hydroxyapatite And The Properties Of Drug Delivery In Vitro

Hydroxyapatite (Ca10(PO4)6(OH)2,HAP) is a very widely used biomedicalmaterial, which is the main inorganic constituent of the teeth and bones ofhuman and animal, with a high bio-compatibility and chemical stability. PorousHAP, as a drug carrier, can make the drug plasma concentration stable, avoidside effects caused due to the high plasma concentration, reduce the frequency ofadministration, and improve patient medication compliance. Porous HAP,prepared with different methods, has a very high value for the clinical treatmentof osteomyelitis and other bone diseases as a drug delivery system for drugrelease.In the preparation of porous sphere HAP, porous spherical calciumcarbonate was firstly got in the emulsion law system, then it was reacted withdisodium hydrogen phosphate under hydrothermal conditions. The preparedporous spherical hydroxyapatite was characterized by X-ray diffraction, scanningelectron microscopy to investigate its composition, morphology and structure.Effects of temperatures, the amount of surfactant and the reaction time on thechemical composition, size, morphology and structure of porous spherical HAPcrystal were investigated. The specific surface was determined by the surfacearea analyzer. Porous spherical HAP, loaded with gentamicin solution bychemical or physical absorption, was detected by the ultravioletspectrophotometry to research drug release in vitro. The entrapment efficiencyand loading efficiency of the porous spherical hydroxyapatite biological materialwere also studied.The results showed that porous spherical hydroxyapatite biomaterial withuniform particle size can be prepared when the synthesis temperature is25℃, thesurfactant concentration is3%and the reaction time is30h. It has a diameter ofabout10μm, specific surface area of16.07m~2/g. The drug release property ofHAP in vitro was also investigated with a model drug of gentamicin sulfate. Porous spherical HAP was well dispersed and its entrapment efficiency andloading efficiency were46.0%and l8.0%respectively. Porous spherical HAPhad favorable drug release behavior in vitro as a drug delivery vehicle for itcould release gentamicin sulfate for about10days.In the preparation of porous block HAP, chitosan was used as apore-forming agent. The prepared porous block HAP was characterized by X-raydiffraction, scanning electron microscopy to investigate its composition,morphology and structure. Effects of the amount of chitosan on the chemicalcomposition, the crystal size, morphology and structure of the material wereinvestigated. The specific surface was determined by the surface area analyzer.Porous block HAP, loaded with gentamicin solution, was detected by theultraviolet spectrophotometry to research drug release in vitro. The entrapmentefficiency and loading efficiency of the porous block hydroxyapatite biologicalmaterial were also studied.The results showed that porous block hydroxyapatite biomaterial with poresize of about1μm can be prepared by adding30mL pore-forming agent ofchitosan. The drug release property of HAP in vitro was also investigated with amodel drug of gentamicin sulfate. The entrapment efficiency and loadingefficiency of porous block HAP were35%and14.8%respectively. Gentamicinsulfate in porous block HAP can be maintained for seven days of sustainedrelease. The cumulative release rate of gentamicin sulfate can reach96%. In thetreatment of osteomyelitis and other bone diseases, porous block HAP as a drugdelivery system has great application potential.