The Preliminary Research Of Hollow Carbonated Hydroxyapatite Microspheres Loaded With Aspirin As Drug Sustained Release System

Backgrounds:The most important thing in vital pulp preservation technology is to choose a suitable capping agent.However,we use capping agents?calcium hydroxide and mineral trioxide aggregate?have certain disadvantages in recently.It is necessary to explore new capping agent to achieve the best therapeutic effect.Studies have shown that aspirin can promote the proliferation and differentiation of dental pulp stem cells at low concentrations.In order to control the concentration of aspirin,it is necessary to find a suitable carrier to build an aspirin sustained release system for capping pulp treatment.Common carriers for drug delivery systems are hollow carbonate hydroxyapatite microspheres synthesized by different methods.Objectives:Hollow carbon hydroxyapatite microspheres are synthesized by proline and sodium dodecyl sulfonate.Aspirin is loaded into the microspheres to construct a sustained release system.To calculate the drug entrapment efficiency and drug loading efficiency,and explore the drug-loaded microspheres release conditions in vitro.Methods:?1?Three groups of templating solutions:?1?proline:0 mmol/L,sodium dodecyl sulfonate:30 mmol/L;?2?proline:50 mmol/L,sodium dodecyl sulfonate:0 mmol/L;?3?proline:50 mmol/L,sodium dodecyl sulfonate:30 mmol/L.0.1 mol/L CaCl₂solution and 0.1 mol/L Na₂CO₃ solution was added into the above solution to synthesize calcium carbonate.A certain amount of calcium carbonate powder was formed into a suspension in distilled water,and 0.03 mol/L Na₂HPO₄ was dropped into the suspension.The p H of the reaction system was adjusted to 9-11,and the reaction was aged for 2h.The product was isolated to obtain carbonate hydroxyapatite powder.The synthetic calcium carbonate and carbonate hydroxyapatite powder were characterized by FESEM,XRD,FTIR and BET.?2?The aspirin-phosphate solution was set up,and the aspirin standard curve was plotted.Aspirin and carbonate hydroxyapatite microspheres with different mass ratios were used to constitute drug-loaded microspheres,and the drug entrapment efficiency and drug loading rate were calculated.?3?Compared the release experiments of three groups of synthetic carbonate hydroxyapatite with different morphologies loaded aspirin in vitro.Results:?1?The hollow microspheres were synthesized by 50 mmol/L of proline and 30mmol/L of sodium dodecyl sulfonate.The average diameter of microspheres was 3-5?m by electron microscopy.The surface of microsphere was composed of short rod-shaped nanoparticles and the interior of the microsphere was hollow structure.?2?The analysis of X-Ray Powder Diffraction and Infrared Absorption Spectrum suggested the hollow microsphere was carbonate hydroxyapatite.?3?The average pore size of microspheres was 32 nm,and it was the mesoporous material.The adsorption-desorption isotherm curve belonged to type III.The hysteresis loop was H3 type,indicating that there were many slit-type pores between the microparticles of microspheres.?4?When the mass ratio of drug and carrier was 5:1,we obtained the highest encapsulation efficiency and drug loading efficiency?22.3%,52.71%?.?5?In vitro sustained-release control experiments showed that the hollow carbonate hydroxyapatite microspheres loaded aspirin d id not burst release at early.The release of drug-loaded microspheres tended to be gentle at 216h,and showed good sustained-release properties.Conclusions:Hollow carbonate hydroxyapatite microspheres were synthesized successfully by using proline and sodium dodecyl sulfonate as a template.The microspheres loaded aspirin had high drug encapsulation efficiency and drug loading efficiency.The microspheres loaded aspirin showed slow release performance in vitro.