Lysozyme distribution, structural identification, and in vitro release of starch-based microgel-lysozyme complexes

- The formation and distribution of microgel-lysozyme complexes were estimated.
- The structure of lysozyme in the complexes was evaluated by FT-IR and Raman spectra.
- In vitro release of lysozyme from the complexes has been investigated.
- The structure of lysozyme released from stomach fluid was identified by CD.

The formation and distribution of microgel-lysozyme complexes were identified by confocal laser scanning microscope (CLSM). The structure of lysozyme in the microgel was investigated by Fourier transform infrared (FT-IR) spectroscopy and Raman spectra. In vitro release of lysozyme from the microgel-lysozyme complexes was estimated. The structure of lysozyme released from stomach juice was further evaluated by circular dichroism (CD). The CLSM images showed that microgel-lysozyme complexes was formed and the lysozyme distributed quite homogeneously over the microgel particles. The FT-IR and Raman spectra indicated that lysozyme secondary structure maintained unchanged in the microgels. The microgels could be used as a carrier system to guard against the early release of lysozyme and protect lysozyme in the stomach and deliver targeted object to the intestine, as confirmed by the results of in vitro release and CD. This carboxymethyl starch-based microgel had potential as a specific delivery system for gastrointestinal environment.