Preparation of Nanoemulsions

Table 13.4 Various Methods of Preparation of Nanoemulsion (Debnath et al., 2011 Jain, 2011 Reza, 2011 Mason et al., 2006)...

Low energy techniques may be applied for preparation of nanoemulsions. Two methods can be applied (i) The emulsifier is dissolved in the oil phase and the aque-... 

Several experiments were carried out to investigate the methods of preparation of nanoemulsions and their stability. The first method applied the PIT principle for preparation of nanoemulsions. Experiments were carried out using hexadecane as the oil phase and Brij 30 (Cj2EO ) as the nonionic emulsifier [35]. The HLB temperature was determined using conductivity measurements, whereby 10 moldm NaQ was added to the aqueous phase (to increase the sensitivity of the conductibility measurements). 

Four methods may be applied for the preparation of nanoemulsions (covering the droplet radius size range 50-200 nm) use of high pressure homogenizers (aided by appropriate choice of surfactants and cosurfactants) application of the phase inversion composition method apphcation of the phase inversion temperature (PIT) concept dilution of a microemulsion. 

Formation of Nanoemulsions by Low-Energy Methods and Their Use as Templates for the Preparation of Polymeric Nanoparticles... 

The formation of ethylcellulose nanoemulsions by a low-energy method for nanoparticle preparation was reported recently. The nanoemulsions were obtained in a water-polyoxyethylene 4 sorbitan monolaurate-ethylcellulose solution system by the PIC method at 25 °C [54]. The solvent chosen for the preparation of the ethylcellulose solution was ethyl acetate, which is classed as a solvent with low toxic potential (Class 3) by ICH Guidelines [78]. Oil/water (O/W) nanoemulsions were formed at oil/ surfactant (O/S) ratios between 30 70 and 70 30 and water contents above 40 wt% (Figure 6.1). Compared with other nanoemulsions prepared by the same method, the O/S ratios at which they are formed are high, that is, the amount of surfactant needed for nanoemulsion preparation is rather low [14]. For further studies, compositions with volatile organic compound (VOC) contents below 7 wt% and surfactant concentrations between 3 and 5 wt% were chosen, that is, nanoemulsions with a constant water content of 90% and O/S ratios from 50 50 to 70 30. 

Emulsions are two-phase systems formed from oil and water by the dispersion of one liquid (the internal phase) into the other (the external phase) and stabilized by at least one surfactant. Microemulsion, contrary to submicron emulsion (SME) or nanoemulsion, is a term used for a thermodynamically stable system characterized by a droplet size in the low nanorange (generally less than 30 nm). Microemulsions are also two-phase systems prepared from water, oil, and surfactant, but a cosurfactant is usually needed. These systems are prepared by a spontaneous process of self-emulsification with no input of external energy. Microemulsions are better described by the bicontinuous model consisting of a system in which water and oil are separated by an interfacial layer with significantly increased interface area. Consequently, more surfactant is needed for the preparation of microemulsion (around 10% compared with 0.1% for emulsions). Therefore, the nonionic-surfactants are preferred over the more toxic ionic surfactants. Cosurfactants in microemulsions are required to achieve very low interfacial tensions that allow self-emulsification and thermodynamic stability. Moreover, cosurfactants are essential for lowering the rigidity and the viscosity of the interfacial film and are responsible for the optical transparency of microemulsions [136]. 

In principle, in the preparation of medicated nanoemulsions, the drug is initially solubilized or dispersed together with an emulsifier in suitable single oil or oil mixtures by means of slight... 

W/O microemulsions have been used in the preparation of nanopartides and for carrying out other reactions in highly confined geometries [234], As mentioned in Section 14.3 both nanoparticle suspensions and nanoemulsions have developed for use as drug-delivery agents. 

Several classes of formulations of disperse systems are encountered in the chemical industry, including suspensions, emulsions, suspoemulsions (mixtures of suspensions and emulsions), nanoemulsions, multiple emulsions, microemulsions, latexes, pigment formulations, and ceramics. For the rational preparation of these multiphase systems it is necessary to understand the interaction forces that occur between the particles or droplets. Control of the long-term physical stability of these formulations requires the application of various surfactants and dispersants. It is also necessary to assess and predict the stability of these systems, and this requires the application of various physical techniques. 

Preparation of a nanoemulsion of the substance by using a solvent in which it is soluble following emulsification of the solvent in another immiscible solvent ... 

The stability of nanoemulsions prepared using isohexadecane was assessed by following the droplet size as a function of time. Plots of versus time for four... 

HPH has emerged as a reliable and powerful technique for the preparation of SLN. HPH has been used for years for the production of nanoemulsions for parenteral nutrition. In contrast to other techniques, scaling up represents no or minor problems in most cases. High-pressure homogenizers push a liquid with high pressure (10 to... 

For styrene nanoemulsions prepared with 10 2 M sodium lauryl sulfate and a 1 1 molar ratio of ionic surfactant fatty alcohol, the order of decreasing stability with fatty alcohols of different chain length is Ci6 > Qg > CM > Ci2 > C10. For sodium lauryl sulfate-Ci6 alcohol mixtures, the order of decreasing stability with different sodium lauryl sulfate fatty alcohol ratios is 1 3 > 1 2 > 1 1 > 1 6 > 1 0.5. The 1 3 and 1 2 ratios produce emulsions with stabilities > 1 month. The presence of rodlike liquid-crystalline structures at 1 1 to 1 3 ionic surfactant fatty alcohol ratios is believed to be essential for the preparation of a stable nanoemulsion. (El-Aaser, 1984). 

Maali A and Hamed Mosavian MT. (2013). Preparation and application of nanoemulsions in the last decade (2000-2010). Journal of Dispersion Science and Technology, 34, 92-105. 

Chausson, M., Fluchere, A.S., Landreau, E., Aguni, Y., Chevalier, Y., Hamaide, T., Abdul-Malak, N., Bonnet, 1. (2008) Block copolymers of the type poly (caprolactone)-b-poly (ethylene oxide) for the preparation and stabilization of nanoemulsions. Int. J. Pharm.,362,153-162. 

---