Effect of Process Parameters on the Initial Burst Release of Protein-Loaded Alginate Nanospheres

The controlled release or delivery of proteins encapsulated in micro/nanospheres is an emerging strategy in regenerative medicine. For this, micro/nanospheres made from alginate have drawn considerable attention for the use as a protein delivery device because of their mild fabrication process, inert nature, non-toxicity and biocompatibility. Though promising, one key issue associated with using alginate micro/nanospheres is the burst release of encapsulated protein at the beginning of the release, which may be responsible for exerting toxic side effects and poor efficiency of the delivery device. To address this issue, this study aimed to investigate the effect of process parameters of fabricating protein-loaded alginate nanospheres on the initial burst release. The alginate nanospheres were prepared via a combination of water-in-oil emulsification and the external gelation method and loaded with bovine serum albumin (BSA) as a model protein. The examined process parameters included alginate concentration, ionic cross-linking time and drying time. Once fabricated, the nanospheres were then subjected to the examination of BSA release, as well as the characterization of their morphology, size, and encapsulation efficiency. Our results revealed that by properly adjusting the process parameters, the initial burst release can be reduced by 13%. Taken together, our study demonstrates that regulating process parameters of fabricating alginate nanospheres is a possible means to reduce the initial burst release.