Fabrication of KDF-loaded chitosan-oligosaccharide-encapsulated konjac glucomannan/sodium alginate/zeolite P microspheres with sustained-release antimicrobial activity

Abstract

Potassium diformate(KDF) is a non-antibiotic growth promoter. To improve the utilization of KDF in the intestinal tract, P-type zeolite molecular sieve (zeolite P) was used as the drug-binding effector of KDF and was encapsulated in sodium alginate (ALG)/konjac glucomannan (KGM)/chitosan oligosaccharide (COS) composite hydrogel microspheres to prepare environment friendly, intelligent and pH-sensitive composite hydrogel microspheres for controlling the release of KDF. The composite hydrogel microspheres were characterized using XRD, FT-IR, TGA, and SEM. In addition, the swelling behavior of the composite hydrogel microspheres in three buffered media was determined. Thus, the phase composition, structural characteristics, thermal stability, apparent morphology and swelling properties were determined. Results indicated that the composite hydrogel microspheres possessed pH sensitivity, compatibility and porous 3D network structure. Furthermore, ALG formed polyelectrolyte complexes with COS, providing the composite hydrogel microspheres a complete three-dimensional network structure. The embedded network structure of zeolite P, which limited the size of the inner capsule, assisted in improving the thermal stability, and allowed expansion and controlled release of KDF. Under a simulated gastrointestinal environment, the in vitro release conformed to a good pH-sensitive drug release pattern and prevented premature release of KDF in the gastric juice. In the in vitro antibacterial test, the maximum inhibition rate of the antibacterial agent against Escherichia coli, Staphylococcus aureus and Bacillus subtilis were 96.63%, 93.81% and 93.31%, respectively, indicating its considerable potential as an intestinal antibacterial.