ABSTRACT
Nanoemulsions (NEs) are colloidal dispersions comprising of aqueous and oily phases with a surfactant and co-surfactant resulting in a thermodynamically stable system. NEs as a technology has been extensively consumed in pharmaceutical and food sectors as it presents numerous advantages in drug delivery and bioactive food product processing. The characterization of physiochemical properties of NEs is important as these parameters are known to influence the properties of drug and food products such as particle size, surface charge, viscosity, drug-phase compatibility, crystallinity affecting products final appearance, performance and stability. This chapter emphasizes consolidated information on various physical characterization techniques employed to evaluate NEs. Various characterization techniques include determination of droplet size, polydispersity index and zeta potential (ZP) by using a Zetasizer assessing the droplet size, surface charge and stability of NEs. Thermal analysis of NEs by using differential scanning calorimetry (DSC) provides a tool to determine the thermal stability of a drug product, melting temperatures, glass transition temperatures, crystallization and fusion events. Fourier transform infrared (FT-IR) analysis is a technique used to assess drug-components of NEs compatibility studies. X-ray diffraction (XRD) analysis is a tool to analyze crystallinity or amorphization of drug loaded in NEs. Similarly, the physical state of a compound (solid or liquid) is assessed by nuclear magnetic resonance (NMR). Small-angle X-ray scattering (SAXS) and sensory analysis are the characterization techniques used to evaluate shape, size, structure (nanostructure) and appearance of NEs.
