## 8 Nanotechnological Tools for Nutraceuticals and Functional Foods
Co-encapsulation increased the chemical stability and in vitro bioavailability of nutraceuticals. A carotenoid antioxidant (astaxanthin) co-encapsulated with other natural antioxidants (tocotrienols, capsaicin and resveratrol) was shown to improve antioxidant activity synergistically, which was linked to molecular interactions between the nutraceuticals [228]. Lactobacillus acidophilus (probiotic) and inulin or polydextrose (prebiotics) have also been co-encapsulated into solid lipid microparticles, increasing their stability and survivability in simulated GIT conditions [229]. Other colloidal particles, such as alginate microgels [230], pea protein/alginate microgels [231] and alginate-chitosan microgels [232], have been utilized to encapsulate probiotics and prebiotics. Prebiotics within colloidal particles may boost probiotic viability by providing a source of nourishment. Multiple-particle encapsulation: In some cases, encapsulating different bioactive compounds inside other colloidal particles can be advantageous. There are several reasons why one may desire to do so. First, it is necessary to create a variety of bioactive-loaded colloidal dispersions that can be blended in various ratios if the aim is to carefully manage the balance of different bioactive substances in a meal or beverage. Second, if two or more bioactives interact physically or chemically, it may be better to keep them separated to avoid adverse interactions. Third, because different hydrophobic bioactive may have differing solubilities in non-polar settings, colloidal particles consisting of various hydrophobic materials may be beneficial (such as other oils or hydrophobic proteins) [233]. Fourth, some hydrophobic bioactives' chemical stability is impacted by their local molecular environment; for example, some may degrade faster in a lipid matrix than in a protein matrix. As a result, encapsulating various bioactives in separate colloidal particles with molecular environments tailored to each bioactive could be beneficial. Fifth, various bioactives may need to be released at different times or in other parts of the human body. For example, one bioactive may need to be released in the small intestine, whereas another requires release in the colon. Alternatively, one bioactive might require a burst release technique, while another might require a continuous release profile. The bioactive would be encased in colloidal particles with various release properties, such as nanodroplets for burst release and microgels for sustained release. Distinct bioactives could be contained within the same colloidal particle or across different types of colloidal particles [233]. A bioactive may be encapsulated in one emulsion, while a different kind of bioactive may be encapsulated in another. Another possibility is to encapsulate one type of bioactive in an emulsion and the other in a solid lipid nanoparticle. After that, the two colloidal delivery methods might be merged to generate a final formulation with various bioactive compounds. This technology could be particularly beneficial in personalized nutrition applications. To obtain the desired nutritional profile, a range of single bioactive-loaded delivery systems could be combined in varying doses and ratios. When combining different colloidal dispersions, it is vital to ensure that the particles are compatible; otherwise, the integrated system could be physically or chemically unstable. For example, one type of colloidal particle may promote the aggregation of a different kind of colloidal particle. If their surface charges are opposite, such as one positive and one negative, this can happen [234]. Furthermore, bioactive molecules can be prevented from migrating from one type of colloidal particle to another [235]. The entropy of mixing drives the exchange of bioactive chemicals between colloidal particles. Having all bioactive compounds randomly disseminated across all colloidal particles is better than having them concentrated in one type of particle from a thermodynamic standpoint.