Development and characterization of phosphatidylcholine nanovesicles containing the antimicrobial peptide nisin

Abstract

a b s t r a c tTwo methodologies were compared to encapsulate nisin in liposomes of partially purified soybean phosphatidylcholine: reversed-phase and hydration film. In the hydration film method, both probe-type and bath-type ultrasound were evaluated. The size of liposomes was evaluated by light scattering analysis and residual antimicrobial activities by agar diffusion assay using Listeria monocytogenes ATCC 7644 as indicator strain. The size of liposomes prepared by reversed-phase, hydration film using probe-type and bath-type ultrasound were 190, 181 and 148 nm with residual antimicrobial activities after encapsulation of 25%, 50% and 100%, respectively. The methodology of film hydration using bath-type ultrasound was chosen for assessment of its physicochemical characteristics. Nisin had entrapment efficiency of 94.12%. Measured Zeta potentials for unfiltered and filtered (0.22 lm) liposomes were À55.8 and À54.5 mV, respectively. The antimicrobial activity of free nisin, encapsulated nisin and filtered was evaluated for a period of 24 days. It was observed that the free nisin remained 100% of residual activity while the liposomes containing nisin were losing their antimicrobial activity over time reaching 25% residual activity after 10 days. The size (132-149 nm) and pH (4.5) remained constant over time. It was observed by microscopy that the liposomes maintained their spherical morphology. The stability observed by size and pH was not the same regarding antimicrobial activity and Zeta potential, indicating that the liposomes should be applied shortly after its preparation.

Development of a Novel Selective and Differential Medium for the Isolation of Listeria monocytogenes

“…The results suggest that soya lecithin is an appropriate alternative to phosphatidylinositol. Soya lecithin is a cheap and easily available product and could be used for the detection of PI-PLC and PC-PLC activity (22,32). In this study, LL medium contains soya lecithin for the differentiation of L. monocytogenes from other Listeria spp.…”

Distribution ofMelaleuca alternifoliaessential oil in liposomes with Tween 80 addition and enhancement ofin vitroantimicrobial effect

“…[28] Briefly, the lipid components, 100 mg PC and 18 mg Cho were dissolved in 10 ml chloroform. The solvents were removed using a rotary evaporator at room temperature, 15 rpm, and a high vacuum, which resulted in a uniform, thin lipid membrane on the vessel wall.…”

Development of an Encapsulation System for the Protection and Controlled Release of Antimicrobial Nisin at Meat Cooking Temperature

“…Liposomes were then held at 50°C for 20 min to ensure that phospholipids were above their gel-liquid crystalline phase transition temperature (T m ) before sonication to promote uniform sizes and to reduce the size of the vesicles. Multilamellar vesicles (MLV) were exposed to five cycles of sonication (Sonic Dismembrator, Model 500, Fisher Scientific, Pittsburgh, PA, USA) for 1 min, followed by 3 min of cooling on ice (Malheiros et al, 2010). The sample remained on ice for 15 min and then the liposomes were separated from unencapsulated nisin by ultracentrifugation (model L8-70 M ultracentrifuge; Beckman, Palo Alto, CA, USA) at 85 000 x g for 1 h at 20°C, washed twice, and recentrifuged (Benech et al, 2002).…”

“…Because nisin is released in its active from the liposome after a certain time, it may be advantageous for use in a food system for controlled release during storage. Malheiros et al (2010) have demonstrated that the decrease in antimicrobial activity of nisin containing liposomes is time dependent and up to 25% of the activity can remain inside the liposome after 10 days at 4°C. Images include liposomes (A) before and (B) after sonication, respectively.…”

“…Encapsulation in liposomes allows for the timely liberation of acids as the liposomes melt during cooking. This approach has already been successfully applied to protect nisin in a cheese matrix (Benech, Kheadr, Laridi, Lacroix, & Fliss, 2003) and other food systems (Malheiros, Micheletto, da Silveira, & Brandelli, 2010). Liposomes are spherical bi-layer vesicles formed by the dispersion of polar lipids in aqueous solvents and may consist of single or multiple bilayers composed of polar lipids (Mertins, Sebben, Pohlmann, & da Silveira, 2005).…”