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Eyal Shimoni
vesicles, which have diameters that range from tens of nanometers. These so-called nanoliposomes have similar structural, physical, and thermodynamic properties to the liposomes described previously. An important point is that, while in nanoscience and technology we often refer to self-assembly phenomenon as the preferred tool for structuring matter, the manufacture of nanoliposomes (e.g. liposomes) requires high energy for the dispersion of lipid/phospholipid molecules in the aqueous medium (Mozafari and Mortazavi, 2005; Mozafari, 2005). The underlying mechanism for the formation of liposomes and nanoliposomes is basically the hydrophilic– hydrophobic interaction between phospholipids and water molecules. As do all dynamic entities, vesicles prepared in nanometric size tend to aggregate or fuse and may end up growing into micron-size particles during storage. For food applications, probably the most important issue is the foodgrade status of the materials making the liposome. Therefore, the study of food-grade liposomes made down to the nanoscale level is an essential component. The effect of edible lipid composition on size, stability, and entrapment efficiency of polypeptide antimicrobials in liposomal nanocapsules was investigated by Were et al. (2003). A mixture of phosphatidylcholine (PC), phosphatidylglycerol (PG), and cholesterol was used to form liposomes with antimicrobial peptides. With calcein and nisin, the entrapment reached 54–70%, and the size of the liposomes 85–233 nm. The highest concentration of antimicrobials was encapsulated in 100% PC liposomes. Their results show that stable nanoparticulate aqueous dispersions of polypeptide antimicrobials for food products depend on the selection of suitable lipid–antimicrobial combinations. In order to evaluate the feasibility of using lecithins for nanocapsules, including functional food materials, Takahashi et al. (2007) prepared liposomes from different lecithins and examined their physicochemical properties. There was little difference in the trapping efficiency among the three types of liposomes. In all cases, the trapping efficiency clearly increased with an increase of the lecithin concentration up to 10% wt, and the maximal efficiency reached 15%. Confocal laser scanning microscopy (CLSM) showed that the particle size of liposomes prepared from SLPWHITE was significantly smaller than that of other lecithins. This liposomal solution remained well dispersed for at least 30 days. After using a homogenizer and microfluidizer to improve the efficiency and stability, the particle size of the SLP-WHITE liposomes decreased and reached between 73 and 123 nm based on the measurement with dynamic light scattering (DLS). Using these liposomes, the authors demonstrated the trapping of curcumins up to over 85%. Thus, their results show that the method may have the potential for manufacturing nanocapsules, which serve as novel carriers of functional food materials.