A new, efficient, and secure clinical approach is increasingly being sought for the treatment of cancer. Nanoemulsions (NE) are projected to have a profound effect on delivering improved healthcare services with significant implications on forthcoming healthcare policies. In contrast to other drug carriers, the key value of NEs is that they can be engineered to target tumor cells and overcome the major challenge of multi-drug resistance. Multifunctional NEs are being investigated by researchers in various fields of study, primarily in the treatment of different forms of cancer. The congruent presence of NEs with contrast agents or certain dyes increases the accuracy of cancer status identification by enhancing the responsiveness of the agents; thus, they are finding application as nanotheranostics. A summary of different NEs and their documented applications in cancer therapeutics, with emphasis on breast cancer, is presented in this chapter.
Top1. Introduction
Nanoemulsions (NEs) are kinetically-stable nanodroplet dispersions of two immiscible liquids, oil, and water, of size ranging from 20–200 nm (Gupta et al., 2016; McClements, 2012). They can be either oil-in-water (o/w) or water-in-oil (w/o) nanodroplet systems, with one being distributed in the other through a surfactant/ co-surfactant mixture (Mkandawire and Aryee, 2018). The inclusion of an emulsifier (surfactant/ co-surfactant) is essential to form the tiny droplets (Handa et al., 2021). It reduces the interfacial tension between the oil and water phases of the emulsion, i.e., it lowers the surface energy per unit area. The emulsifier also helps to stabilize nanoemulsions due to its effect on the repulsive electrostatic interactions and steric hindrance (Mason et al., 2006).
Nanoemulsions exhibit high surface area, enhanced stability, optical transparency, spontaneous emulsification, and tunable rheological properties. Furthermore, nanoemulsions can stabilize chemically unstable compounds by blocking their oxidative and light-induced degradation (Tayeb and Sainsbury, 2018; Chime et al., 2014). Thus, NEs are widely used in the food industry, pharmaceuticals, and cosmetics due to their enhanced functional properties.
In the field of pharmaceuticals, NEs are being used in marketed drugs, with many others in the clinical development stage. NE’s remarkable characteristics such as the ease of manufacture, increased loading capacities, high rate of drug solubility, long-term reliability, increased bioavailability, safety, and regulated cargo discharge, make them promising drug carriers (Kotta et al., 2012). NEs are usually formulated with surfactants considered to be GRAS (generally recognized as safe), and they can be consumed orally. As a result, nanoemulsions are typically used in oral drug delivery. In addition, they are widely exploited for ophthalmic, transdermal, pulmonary, and image-guided drug delivery. In recent years, NEs have been researched for parenteral drug delivery in cancer therapy (Ganta et al., 2014).
NEs are promising candidates for future diagnostics, medication therapies, dermatology, and biotechnology. NEs have many applications such as in cancer therapy, drug targeting, mucosal vaccines, transdermal drug delivery mediums, lipophilic drug delivery mechanisms, etc. If the Oswald-ripening process is constrained by highly insoluble oils, there is enormous scope for nano-emulsion applications (Sharma et al., 2013). In addition, they can be quickly targeted to the tumor sites specifically due to their size characteristics. Furthermore, the ability to surface functionalize with targeting molecules is advantageous for selective delivery of medications, proteins, photosensitizers, etc. to the tumor region. Perfluorochemical NEs have demonstrated positive effects in cancer therapy when combined with other treatment methods and delivered to the neovasculature (Shah et al., 2010).
Researchers must overcome material protection, scale-up, and quality management concerns to realize the promise of nanoemulsion dosage forms as anticancer therapeutics in clinical settings. Furthermore, before being used in therapeutic applications, the in-vivo delivery and metabolism of NEs of novel compounds must be thoroughly evaluated.
This Chapter will focus on applications of nanoemulsions in breast cancer, the most common tumor among women and commonly treated using chemotherapy. However, chemo-treatment efficacy is poor owing to side effects, multidrug resistance (MDR), and low specificity to tumor cells. Nanoemulsions are suitable alternatives for breast cancer treatment because of their unique functional properties. The objectives of the review are as follows:
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To explore the use of nanoemulsions in therapeutics
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To present the current role of nanoemulsions in cancer nanomedicine, and
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To outline the treatment procedures for breast cancer using nanoemulsions