Polyelectrolyte Coated Calcium Carbonate Microparticles as Templates for Enzyme Encapsulation

Calcium carbonate (CaCO3) has been widely used for biomedical and pharmaceutical applications. Mesoporous CaCO3 microparticles produced by precipitation were evaluated for macromolecular encapsulation using model macromolecules like Fluorescein isothiocyanate-dextran (FITC-dextran) and Enzymes [Horse radish Peroxidase (HRP) and Glucose oxidase (GOx)]. Encapsulation efficiency of FITC-dextran (70, 150 and 500 KDa), HRP and GOx was calculated to be 64.0 (+/- 3.1), 33.2 (+/- 0.7), 3.9 (+/- 0.3), 82.3 (+/- 12.2) and 27.6 (+/- 6.3)%, respectively. Layer-by-layer nanoengineering using polystyrene sulphonate (PSS) and polyallylamine hydrochloride (PAH) was performed on macromolecule loaded CaCO3 microparticles and the surface charge was found to alternate with each layer. Uncoated and coated microparticles were characterized by Optical microscopy, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Confocal laser scanning microscopy (CLSM), Zeta potential and X-ray diffraction (XRD). Release of macromolecules was performed on uncoated and coated microparticles and the release of encapsulated macromolecules was found to decrease with multilayer buildup. The results demonstrate that polyelectrolyte coated CaCO3 particles can be applied as micro/nano-template towards an enzyme based biosensor.