Natural calcium carbonate for biomedical applications
  Sea shells are found to be a very rich natural resource for calcium carbonate. Sea shells are made up of CaCO3 mainly in the aragonite form, which are columnar or fibrous or microsphere structured crystals. The bioactivity of nanoparticles of sea shell has been studied in this work. The sea shells collected were thoroughly washed, dried and pulverized. The powder was sieved and particles in the range of 45 to 63 microns were collected. The powdered sea shells were characterized using X-Ray Diffraction and Field Emission Scanning Electron Microscopy. The XRD data showed that the particles were mainly microspheres. Traces of calcite and vaterite were also present. Experiments were conducted to study the aspirin and strontium ranelate drug loading into the sea shell powder using soak and dry method. Different concentrations of drug solution was made in ethanol and water. The shell powder was soaked in drug solutions and was kept soaking for 48 hrs with intermittent ultrasonication. The mixture was gently dried in a vacuum oven. The in vitro drug release studies were done using Phosphate Buffered Saline. The FESEM images displayed a distribution of differently sized and shaped particles. The sea shells due to its natural porosity and crystallinity are expected to be useful for drug delivery. About 50% drug entrapment efficiency for aspirin and 39% for strontium ranelate was seen. A burst release of the drug (80 percent) was observed within two hours for both the drugs studied. Rest of the drug was released slowly in 19 hrs. Further modification of the sea shell with non toxic polymers is also planned as a part of this work. Sea shell powder has become a potential candidate for drug delivery due to all the aforementioned advantages. 
Sonali S. Sali
q-bio.OT