Multilayer composite beads constructed via layer-by-layer self-assembly for lysozyme controlled release

Alginate (ALG)-lysozyme (LZ) beads were fabricated by a cross-linking process. Negatively charged ALG and positively charged LZ were alternately deposited on the positively charged ALG-LZ beads via layer-by-layer (LBL) self-assembly technique. The mechanical properties and the enzymatic activity of these samples were studied by regulating the number of deposition bilayers and the composition of the outermost layer. The scanning electron microscopy images indicated that the resultant samples exhibited good sphericity and porosity. The Fourier transform infrared spectra results implied the presence of electrostatic interactions between ALG and LZ. The pore size distribution results revealed that the samples mainly possessed mesopores with radius in the range of 2-7 nm. In vitro LZ release test performed at different time intervals showed that LZ could be released from ALG-LZ beads and LBL film-coated beads. The amount of released LZ increased with extended time intervals.