Preparing And Characterizing Of Controllable Morphologies Calcium Citrate For Biomedical Application

Calcium citrate is widely applied in calcium supplement at this stage because it is excellent biocompatibility,nonhazardous on the human body and efficient on calcium supplement.Due to the further study of knowledge management and technological advancement,nano calcium citrate is a concern as it exhibited high activity and get attention by better effect on calcium supplementation.Calcium citrate is very highly worth researching in the hard tissue repair as it can be natural degradation in human body,provide beneficial calcium ion concentration to the growth of bone cell,citrate eliminate inflammation and promote the bone growth.The morphology of materials has a great influence on their performance but the morphology control of calcium citrate has not received adequate attention.This research produced controllable morphologies of calcium citrate through the method of precipitation and test its performance.The sheet calcium citrate was precipitated by adding alcohol to the mixture of soluble calcium salts and citrate.The width of the sheet calcium citrate which precipitated at room temperature by the alcohol-water proportion of 1:2 is about 50-500nm and the thickness is 8-30nm and it is easy to pile up together.The result of the X-ray diffraction showed that the sheet calcium citrate was calcium citrate tetrahydrate.In addition,the relative intensity of(12)crystal face is strong,but the(200)is weak.The crystallinity of sheet calcium citrate precipitated by alcohol decreases with the increase ratio of alcohol.The crystallinity of sheet calcium citrate precipitated by isopropanol is lower than the sample precipitated by ethyl alcohol and the morphology is similar.The spherical calcium citrate was self-assembling by the sheet calcium citrate which was precipitated by heating the mixture of soluble calcium salts and citrate with stirring.The diameter of the spherical calcium citrate which heating 2~30 min is 10~50?m.The specific surface area of the spherical calcium citrate heating and stirring 5min is the biggest and it can reach 50 m~2/g.The temperature of releasing crystal water was 105°C and 147°C,it was 20~30°C higher than the sheet calcium citrate precipitated by alcohol.The result of drug-release shows that the spherical calcium citrate has preliminary sustained release effect.The strip calcium citrate was produced by spherical calcium citrate with ageing after ultrasonic dispersion.The thickness is about 10~30 nm and the length of the strip calcium citrate ageing 8 h after ultrasonic dispersion is 10~60?m.The draw ratio of strip calcium citrate can be 80.The fibrous calcium citrate was produced by the sheet calcium citrate with ageing which was precipitated by alcohol.The length of fiber which ageing by the alcohol-water proportion of 1:2 after 8 h can be 120?m and the draw ratio of strip calcium citrate can reach 500.In the X-ray diffraction pattern,the relative intensity of(200)crystal face is increase obvious with time and(200)crystal face is the the preferential crystal plane.The crystallinity of fiber is increase with time.When the ratio of alcohol increase,the fiber is uneven width,shorten and crimp.The fiber ageing by isopropanol is shorter and more curly than alcohol,the space between fibers is smaller.At last,the sheet,spherical and fibrous calcium citrate were selected to the preliminary experiment research on animals bone repair.The observation of tissue section shows that these three kinds of calcium citrate have a preliminary effect on promoting osteogenesis but there are clear differences.Lots of new bone generated around the defect in the sheet group.There was obvious fibrous capsule formation in the spherical group.In the fiber group,fewer new bone generated around the defect but there was much collagen grow into the defect.This research produced controllable morphologies of calcium citrate through simple method and enriched the morphology of calcium citrate.The formation mechanism of calcium citrate morphology is discussed.At the same time,various morphologies of calcium citrate were test.We can have a preliminary understanding on the properties of calcium citrate which is influence by the change of morphology.This is a good basic for future research and application of calcium citrate in the repairing of hard tissue.