Generation of mucin gel particles with self-degradable and -releasable propertiesElectronic supplementary information (ESI) available: Fig. S1 CD spectra of aqueous solutions of native mucin and trimmed mucin (tMucin20, tMucin50 and tMucin80); Fig. S2 Temperature-dependent enzymatic degradation of tMucin20 by lysozyme in 10 mM CaCl2 aqueous solution at pH 6.0 for 2 days. The percentage of degradation was estimated by the amount of sugar chains released from tMucin20 upon enzymatic cleavage accor

Herein, we focused on mucin, which is a large viscous glycoprotein in terms of materials science, and reported preparation of mucin gel particles and incorporation of enzymes to provide the particle with self-degradable and releasable properties. To expose the hydrophobic peptide cores, trimming of sugar moieties was carried out by β-elimination reaction under alkaline conditions (tMucin). Nano-sized tMucin particles were prepared by the assembly of tMucin with the aid of a cationic surfactant. Then, cross-linking of tMucin particles was carried out via heat treatment (annealing) to induce thermal aggregation of the polypeptide chains. The hydrodynamic diameter of tMucin particles reversibly changed in response to calcium ions. Next, in an attempt to render the particle degradable, lysozyme was incorporated into the tMucin particles for the hydrolysis of oligosaccharide chains. These particles were gradually degraded upon enzymatic cleavage of the mucin molecules, facilitating the release of their incorporated substances. Also, the degradation of the mucin particles and the release of lysozyme were tunable by environmental conditions, such as temperature and calcium ions, in addition to the degree of cross-linking of the particles. Preparation of nano-sized particles via assembly of mucins and incorporation of lysozymes made it possible to gradually degrade mucin particles upon enzymatic cleavage of mucin molecules, facilitating the release of incorporated substances including lysozyme.