Development and Characterization of Methods to Encapsulate Nisin for Use as an Antimicrobial Agent
Technical Report,01 Mar 2015,31 Mar 2017
ARMY NATICK SOLDIER RESEARCH DEVELOPMENT AND ENGINEERING CENTER MA NATICK United States
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Polyelectrolyte complexation is a useful technique to encapsulate sensitive molecules for increased stability and sustained, controlled delivery. It can be performed under mild conditions and is highly tailorable. Combinations of polyacrylic acid PAA and polyethyleneimine PEI were used to encapsulate the bacteriocin nisin. In its crude form, nisin has significant antimicrobial activity, but impurities made it difficult to encapsulate, so a purification protocol was developed using fast liquid protein chromatography FPLC methods. Once purified, the nisin was incorporated into optimized formulations PAANisinPEI, PAAPEI Nisin, PAANisin and a control PAAPEI, and compared for loading efficiency and antimicrobial activity. Loading efficiencies were high for PAANisinPEI and PAANisin, but dropped by more than half when the Nisin was incorporated as an outer coating PAAPEINisin. In quantitative assays all nisin-containing particle types demonstrated antibacterial activity, even at reduced concentrations. The level of activity did vary somewhat, and none of the optimized formations performed as well as the purified nisin, nor did they confer any more stability on the nisin than in crude form. More studies are needed to be able to harness controlled release kinetics for long-term anti-microbial activity from a biological molecule.