Preparation of fucoidan-shelled and genipin-crosslinked chitosan beads for antibacterial application

• A fucoidan-shelled chitosan bead containing a genipin cross-linked inner core.
• pH-dependent drug release of the berberine-loaded beads.
• A nanoparticles/beads complex system showed delayed berberine release in SGF.
• Inhibition the growth of S. aureus and E. coli over 24 h.

In this study, a fucoidan-shelled chitosan bead was developed with the purpose of oral delivery of berberine to inhibit the growth of bacteria. The cross-linking level and swelling property of the beads were affected by the pH value and the composition of the genipin/fucoidan combined gelling agent. The drug release of the berberine-loaded beads was faster in simulated gastric fluid (pH 1.2) than those in simulated intestinal fluid (pH 7.4). Furthermore, a nanoparticles/beads complex system was developed by incorporation of berberine-loaded chitosan/fucoidan nanoparticles in the fucoidan-shelled chitosan beads. The nanoparticles/beads complex served as a drug carrier to delay the berberine release in simulated gastric fluid, with an estimated lag time of 2 h. Our results showed that the berberine-loaded beads and nanoparticles/beads complex could effectively inhibit the growth inhibition of common clinical pathogens, such as Staphylococcus aureus and Escherichia coli, and have the advantage of continually releasing berberine to inhibit the growth of the bacteria over 24 h.