The area of healthcare needs new innovative methods and tools for improvisation and to impart better efficiencies. Nanoemulsions are pharmaceutical formulations containing nanometre-sized particles used for controlled and systemic delivery of bioactive pharmaceuticals. Various advantageous properties of nanoemulsions such as the presence of hydrophobic core region, higher stability, and smaller size have made them useful to a large extent in the biomedical field. They have been employed in transdermal drug delivery, intranasal drug delivery, pulmonary drug delivery, parenteral drug delivery, and improvised delivery of hydrophobic drugs. This chapter aims to discuss various applications of nanoemulsions in healthcare including cosmetics, antimicrobials, vaccine delivery, targeted drug delivery, gene delivery, cancer therapy, and many more in detail.
Top1. Introduction
Nanotechnology is a fast-growing field in the arena of science and technology. To date, nanotechnology has proven its advantages in various fields. One of the finest known products of nanotechnology are nanoemulsions (NEs). NEs, sometimes also referred to as mini emulsions, ultrafine emulsions, and submicron emulsions by some researchers, are the biphasic colloidal dispersions in which the oil droplets are dispersed in an aqueous phase (Solans & Solé, 2012; Ganta et al., 2014;McClements, D., 2011). These heterogeneous systems of particles are usually stabilized by an emulsifying agent and their internal phase droplets size generally lies below 1000 nm. On the basis of the dispersed and continuous phase, emulsions can be of four types: water-in-oil (w/o), oil-in-water (o/w), oil-in-water-in-oil (O/W/O), and water-in-oil-in-water (W/O/W) emulsions (Figure 1)(Tayeb & Sainsbury, 2018). The NEs particles can exist either in the form of W/O or O/W emulsions. In W/O NEs, the inner core of the particle is in an aqueous phase whereas, in O/W NEs, the inner core is composed of oil. O/W NEs have more applications in the healthcare industry because of the presence of a hydrophobic core region that aids in the delivery of water-insoluble drugs and bioactive compounds. Although the terms microemulsion and nanoemulsion look similar, there are pronounced differences between the two on the account of stability, particle size, etc. Microemulsions are thermodynamically stable whereas NEs are kinetically stable. Moreover, microemulsions are formed by the process of spontaneous thermodynamic self-assembly whereas NEs are formed by the applications of low or high external shear (McClements D., 2012).
Figure 1. Types of emulsions based on the dispersed and continuous phase.
In the healthcare care industry, there is a need for tools and technologies that improvise the existing process and innovate new processes having better efficiencies. Most of the current therapeutic agents show poor aqueous solubility and according to a study, about 40% of them have been eliminated from the drug development lines because of the limitation of having poor solubility in water (Ganta et al., 2014). For the delivery of hydrophobic bioactive compounds,NEs have evolved as effective carriers. Apart from having better solubility, NEs show other beneficial properties. NEs can be produced by easy methods. They have higher and long-term stability, high loading capacity, high biocompatibility, and increased bioavailability. Moreover, they can be used for the controlled release of bioactive compounds (Fryd & Mason, 2012). These all attractive properties make them advantageous tools to be used in the healthcare industry.
The current chapter attempts to address various applications of NEs in the healthcare industry including preparation of antimicrobials, non-toxic disinfectant cleaners, drug delivery agents, vaccine adjuvants, cancer therapeutics, and many more. Furthermore, the chapter aims to discuss the application of NEs in the cosmetic industry and the treatment of some other disease conditions.