Mesoporous matrices for the delivery of the broad spectrum bacteriocin, nisin A.

Mesoporous matrices of different pore size and chemical composition were explored as potential delivery matrices for the broad spectrum bacteriocin, nisin A. The adsorption of nisin A onto two mesoporous silicates (MPS - SBA-15, MCM-41) and two periodic mesoporous organosilanes (PMO - MSE, PMO-PA) was examined. It was found that hydrophobic interactions dominated in the adsorption of this peptide to the matrices, lending the highest adsorption to MCM-41 with a small pore size of 2.8 nm. The hydrophobic ethylene-bridged MSE (6 nm pore) improved the loading and protection of nisin A from degradation by a non-specific protease pepsin, over un-functionalised SBA-15 which had a slightly larger pore size and less hydrophobic moieties. Nisin A did not adsorb onto an amine-functionalised PMO. Upon suspension in modified fasted state simulated gastric fluid (pH 1.6), the highest release of nisin A was observed from MCM-41, with a lower release from SBA-15 and MSE, with release following Higuchi release kinetics. No release was detected into modified fasted state simulated intestinal fluid (pH 6.5) but despite this, the suspended matrices loaded with nisin A remained active against Staphylococcus aureus.