Preparation of Calcium-Loaded Liposomes and Their Use in Calcium Phosphate Formation
نویسندگان
چکیده
Liposome encapsulation technology has been used to entrap aqueous calcium salts within dipalmitoylphosphatidylcholine lipid vesicles, which were then used to form calcium phosphate minerals. The calcium encapsulation efficiency was found to depend upon a number of factors that included calcium salt concentration, vesicle size, lipid concentration, and method of vesicle preparation. Removal of unencapsulated calcium by ion exchange resulted in calcium-loaded liposome suspensions with calcium concentration as high as 85 mM. Addition of inorganic phosphate to the calcium-loaded liposomes resulted in liposome suspensions that, although highly supersaturated with respect to calcium phosphates, exhibited metastability as a result of the physical separation of calcium (intravesicular) and phosphate (extravesicular) ions. Calcium ion release and mineral formation was activated by a bilayer-to-micelle mesophase transformation induced by the addition of lipid surfactant. Characterization of the mineral product by infrared spectroscopy, X-ray diffraction, and electron microscopy revealed the formation of apatite and brushite mineral under basic and acidic conditions, respectively. The potential use of calcium-loaded liposomes for in situ formation of mineral for medical and dental applications is discussed.
منابع مشابه
Thermally Triggered Calcium Phosphate Formation from Calcium-Loaded Liposomes
A thermally triggered liposome-based mineralization system is described that is metastable at ambient temperature but rapidly forms calcium phosphate mineral upon warming to physiologic temperature. Mixing of a calcium-loaded lipid vesicle suspension with aqueous inorganic phosphate resulted in a stable liposome suspension whose bulk ionic concentration was highly supersaturated with respect to...
متن کاملCalcium Acetate Versus Calcium Carbonate as Oral Phosphate Binder: Preparation and In Vitro Assessment
Calcium acetate is used as an oral phosphate binder to control hyperphosphatemia in patients with chronic renal failure. Compared to calcium carbonate, control of hyperphosphatemia can be achieved at lower calcium administration with calcium acetate which likely reduces the risk of hypercalcemia. In this study, various formulations of calcium acetate tablets were prepared and their disint...
متن کاملThermal assembly of a biomimetic mineral/collagen composite.
A strategy is described for exploiting temperature driven self-assembly of collagen and thermally triggered liposome mineralization to form a mineralized collagen composite from an injectable precursor fluid. Optical density and rheological experiments demonstrated the formation of a collagen gel when acid-soluble type I collagen solutions (1-7 mg/ml) were heated to 24-30 degrees C. Scanning ca...
متن کاملEffect of pulsed current densities on co-electrodeposition of Graphene Oxide/ Calcium-Phosphate coatings and their biocompatibility
In this study, calcium-phosphate (Ca-P) and graphene oxide (GO)/ calcium-phosphate (Ca-P) coatings were electrodeposited with different pulsed current densities on TiO2 nanotubes. Results showed that the co-electrodeposition rate in the presence of GO, especially at low current densities of 2 and 5 mA/cm2, significantly decreased. This might be due to the large size of GO sheets as compared to ...
متن کامل