Fabrication of chitosan-coated konjac glucomannan/sodium alginate/graphene oxide microspheres with enhanced colon-targeted delivery

Microspheres play an increasingly important role in the food and medicine industries. In this study, konjac glucomannan (KGM)/sodium alginate (SA)/graphene oxide (GO) solution was injected into CaCl 2 solution under high-voltage static electricity assistance to fabricate microspheres. Then, chitosan (CS) was coated on the surface of the microspheres to enhance their stability. SEM images confirmed that increasing voltage decreased the particle size of microspheres obviously. Furthermore, GO was beneficial in maintaining the full structure of freeze-dried microspheres, and the CS membrane improved the surface of the microspheres with no relatively obvious gully. Results indicated that KGM interacted with SA by hydrogen bond, and GO improved this interaction in microspheres. Furthermore, swelling tests showed that the microspheres exhibited different swelling properties in different media, and the CS membrane could improve the stability of microspheres in simulated intestinal fluid and simulated colon fluids. Moreover, GO could greatly improve the ciprofloxacin (CPFX) loading efficiency of microspheres, and achieving a sustained release effect of CPFX. Thus, CS-coated KGM/SA/GO microspheres showed great potential application in drug and/or nutrition factor colon-targeted delivery.