Spray-dried alginate microparticles carrying caffeine-loaded and potentially bioactive nanoparticles

Caffeine-loaded and potentially bioactive particles comprised of both sub-micron (>300 nm) and nano-scaled (<100 nm) populations were prepared from antioxidant peptides through desolvation with ethanol and then were dispersed in a sodium alginate solution. The alginate solution was subsequently spray-dried to form particles with an approximate mean size of 4 mu m. Calcium chloride was later used to cross-link the alginate microparticles in order to reinforce their structure. Cross-linking increased the size of the alginate particles to similar to 7.4 mu m and prevented their wrinkling during post-formation handling. Fourier transform infrared spectroscopy confirmed the cross-linking of the microparticles by calcium chloride and differential scanning calorimetry suggested a reinforced structure for the cross-linked microparticles. Microencapsulation of the peptidic nanoparticles within the alginate matrix increased the stability of nanoparticles to digestion and decreased the amount of the caffeine released within the simulated gastric fluid. This protective influence was amplified significantly due to the ion-mediated cross-linking of the alginate microparticles so that similar to 85% of the loaded caffeine into the enclosed peptidic nanopartides was not released in-the simulated gastric medium. (C) 2014 Elsevier Ltd. All rights reserved.