Preparation Of Core-shell CaCO₃ Microspheres And Their Application

ObjectiveCalcium carbonate microspheres?CaCO₃ MSs?,a common inorganic biomaterial,have been widely used as adsorbents in recent years due to their large porosity and specific surface area.Besides,CaCO₃ MSs are ideal carrier for drug delivery because of its characteristics of non-toxic and good biocompatibility.Nano and/or micro core-shell materials have unique structural characteristics and have great potential for application in controlled release,drug delivery and selective adsorption.Therefore,in this paper,the core-shell structured CaCO₃ MSs were prepared by one-pot mineralization method and their application in dye adsorption was studied.In addition,amino acid?L-lysine?Lys??was mineralized into core-shell structured CaCO₃ MSs to prepare the drug-carrier complex?Lys@CaCO₃ MSs?.And Tthe effect of Lys@CaCO₃ MSs on osteoblast proliferation and differentiation was investigated.MethodsThe core-shell structured CaCO₃ MSs were prepared by one-step mineralization method using hesperidin?Hesp?as a template regulator and NaHCO₃ as a source of carbonate.Besides amino acid?L-lysine?Lys??was mineralized into core-shell structured CaCO₃ MSs as drug carrier to prepare Lys@CaCO₃ MSs.Scanning electron microscopy?SEM?and transmission electron microscopy?TEM?were used to detect the morphology of the micro spheres.The crystalline phase was detected by X-ray diffraction?XRD?.The components of microspheres were detected by Fourier transform infrared spectroscopy?FTIR?.The adsorption for different dyes on CaCO₃ MSs was studied by UV-vis spectroscopy.The effects of Lys@CaCO₃ MSs on the proliferation and differentiation of osteoblasts under different conditions were studied by confocal laser scanning microscopy?CLSM?.The pH-responsive property and drug release behaviors were investigated by MTT assay and Lys in-vitro experiment under pH=7.4 and pH=5.5 conditions.Results?1?The prepared core-shell structured CaCO₃ MSs which can be used as adsorbent to adsorb dyes have good morphology and larger specific surface area with rough surface.Also amino acid?L-lysine?Lys??can be mineralized into core-shell structured CaCO₃ MSs as drug carrier to prepare Lys@CaCO₃ MSs.?2?The prepared core-shell CaCO₃ MSs can rapidly and efficiently remove anionic dyes.The adsorption efficiency for Coomassie Brilliant Blue G-250 and Congo Red was 99.57% and 99.6% within the first 2 min,respectively.?3?The prepared core–shell structured CaCO₃ MSs as dye adsorbent have a high recycling capability for removing dyes from water.It was found that 96.66% of Coomassie Brilliant Blue G-250,97.23% of Congo Red and 96.41% of Alcian blue was still adsorbed after the 5th cycle.?4?The prepared Lys@CaCO₃ MSs have a drug loading efficiency of 89.8 % and drug loading content of 22.3 wt%.?5?In drug in-vitro experiment,the release amount of Lys was only 11.2% at pH=7.4 after dialysis for 6 h.With time increasing from 6 h to 8 h,the release amount of Lys didn't increase obviously.On the other hand,at pH=5.5,the Lys release was very rapid?39.8%?within 1 h,and approximately 100% released within 8 h.?6?The prepared Lys@CaCO₃ MSs can effectively promote proliferation and differentiation of osteoblasts under stimulation of H₂O₂ at pH= 5.5 in MTT assay and kill Staphylococcus aureus in antibacterial experiment.Conclusions?1?The preparation method of CaCO₃ MSs is feasible with Hesp as a template regulator and NaHCO₃ as a source of carbonate.The prepared core–shell structured CaCO₃ MSs have efficient adsorption efficiency for anionic dyes and have good recycling ability.Therefore,the CaCO₃ MSs have a higher application prospect in treatment of dye wastewater.?2?The method of mineralizing Lys into core-shell structured CaCO₃ MSs as drug carrier to prepare Lys@CaCO₃ MSs is also feasible.And the drug-loaded particles have pH-responsive properties and can promote the proliferation and differentiation of osteoblasts under the stimulation of H₂O₂ at pH=5.5.Therefore,Lys@CaCO₃ MSs have a potential application prospect in the treatment of osteomyelitis.