Alkaline Phosphatase Delivery System Based on Calcium Carbonate Carriers for Acceleration of Ossification

Composite bioceramic and hydrogel-based containers harboring alkaline phosphatase are generated through encapsulation of this enzyme by its immobilization into CaCO₃-based bioceramic materials in combination with a hydrogel assembly technique and subsequent gelification. A refined way of synthesis and modification allows preparing the enzyme delivery system with functionalized protection layers. The particles are characterized by electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and enzyme activity measurements. Loading efficiency and loading capacity are investigated depending on particle size, time of enzyme loading, and various container compositions and enzyme concentrations. Our results reveal that the size of particles influences their morphology and this, in turn, affects the activity of the encapsulated enzymes. Various functionalizations of the surfaces, including protection by the hydrogel layer, formation of hollow silver alginate, or calcium alginate encapsulation, decrease the enzymatic activity. The presence of a good therapeutic effect on osteoblastic cells coupled with a relatively high loading capacity, biocompatibility, and ease of fabrication suggests that the developed carriers are promising candidates for efficient drug delivery, especially in the field of bone reconstruction.