**2.2 Transformation of soybean oil to multilamellar stable vesicles (MLSV)**

Multilamellar stable vesicles with different shapes and size formation starts with the micelle formation in the zobell marine broth during the growth of marine *Bacillus* sp. Though internal component facilitates the bilayer formation it has been followed by transformation to multilayer and then thickening of oil. In the present study, the external physical agitation (200 rpm), accelerates the transformation of multilayer vesicles (microscopic) to stable macroscopic structures. The varied macroscopic morphological patterns and the stability observed (spherical to cylindrical shapes) might be due to the available interactions between the components of the medium. The cylindrical morphology observed in the present study may be due to the aggregation of micelles followed by transformation to multilamellar vesicles or the bilayer formation followed by aggregates rolled and transformed to rod like giant vesicle with concentric rings.

According to Yan et al., (2009), bipolar nature of amphiphilic is mostly responsible for multilamellar vesicles. The hydrophobicity of released fatty acids mediates the close arrangement with biosurfactants molecule or it may be due to the non-ionic nature of biosurfactants leads to the layer-by-layer formation resulting with multilayer structures. Further, difference in the ratio of number of molecules in the monolayer or bilayers also decides the shape of the vesicles. The reasons for the different macroscopic structures generated could also be explained by (i) decrease in electrostatic interaction and other forces at the bifurcation time; (ii) presence of sensitive reaction diffusion system and (iii) presence of gravity or electric or magnetic fields; (iv) other factors responsible for the weak orientation and finally (v) mismatching of hydrophilic heads of biosurfactants. In addition, self-assembly formed in the experiments is neither uni-directional nor multi-directional, due to the continuous generation of biosurfactants, fatty acids, protein and carbohydrates resulting with assumed morphological features in the solutes. Jiang et al., (2006) reported macroscopic self-assembly of hyper-branched polyester by simple solvent volatilizing route and obtained multi-walled strucutres with millimeter in diameter and centimeters in length. They also found nature of the solvent ratio of the solution, temperature, and molecular concentrations are the parameters deciding the self-assembly of macroscopic structures. Nevertheless, the surface of the self-assembly obtained in the present study is uniform, nonsticky and flexible, emphasizes, formation of MLV initiated with the formation of unilayer by the components as explained above followed by multilayer formation by action of external agents like agitation and finally transformed to stable macroscopic structures. The less bound water (<3%) in the individual macro-structures may be due to the dehydration of head groups, results with the decrease in effective area per molecule at interface (Singh et al., 2009). Further, we observed, salts present in the medium, also responsible for the stability of macroscopic structures.

Transformation of Soybean Oil to Various Self-Assembled Supramolecular Structures 287

Fig. 3. Supramolecular capsules from sunflower oil.

composed of coagulated or fused colloid particles.

colloidosomes.

and sunflower oil (B).

**2.4 Transformation of soybean and sunflower oil to colloidosomes** 

Colloidal particles are elementary to nature and technology. Self-assembly of colloids at liquid - liquid interface is well documented. Recently, there has been mounting concern in using this self-assembly system to form efficient superstructures, such as emulsions, microcapsules, particles and colloidal crystals. One of the most significant applications of this method is to formulate microcapsules known as colloidosomes, whose shells are

Based on this method, noval colloidosomes with coagulated or colloidal particles were produced in the presence of oil in water emulsion. Mineral medium with sunflower oil in the presence of marine *Bacillus* sp. and its hydrolytic enzyme and biosurfactants transform the oil into emulsion. Presence of Janus particle (amphiphilic compound nothing but the biosurfactant) stabilizes the emulsion and transform into stable colloidosomes. The presence of the particles at the water/oil interface minimizes the surface energy and therefore stabilizes the emulsion. The wettability and mobility of the particles will determine the stability of the emulsion and those factors are highly dependent on the hydrophobic/ hydrophilic character of the particles and transform into self-assembled supramolecular

The largest yield of colloidosomes is obtained when using a surfactant to stabilize the oil/water interface. This introduces an electrostatic driving force to take the latex particle to the emulsion interface. The hydrophobicity of the latex particles is the driving force in the surfactant free case but it is evident that the particles are held a short distance apart, presumably due to an electrostatic repulsion in the plane of the emulsion. This repulsion is well known and is thought to operate through the organic phase. The following figure demonstrates the morphological features of colloidosomes obtained from soybean oil (A)

Fig. 2. Multilamellar stable vesicles (MLSV) from soybean oil.

Further, most of the reports suggests only alkaline pH mediates the self-assembly processes (Wang et al., 2004). However, in the experiments concerned, we observed stable vesicle formation at acidic pH (>4.0). The formation of fused structures may also due to the counter ions exist in the growth media. According to Lei & MacDonald (2003), because of the counter ions, there is compression in the bilayer. More the compression more the packing, which reduces the entering of outer molecules to the inner core of the vesicle, increases the diameter of the vesicle to the maximum size and the additional bilayer will leads to fusion of vesicles. Though Singh et al. (2009) reported, presence of cationic surfactant increases the packing of lamellar structures, in our study the produced biosurfactants is a non-ionic and the complete packing of lamellar structure may be due to the accumulation effect. The molecular network formation between fatty acids and biosurfactants provides high thermal stability to the macroscopic structures observed.
