Functional green nanoemulsions with biosurfactants: Synthesis, surface engineering and advanced food, cosmetic,...

Nanoemulsions are a distinct subclass of emulsions that have sparked increasing interest in pharmaceutical, cosmetic, and food sectors due to their increased specific surface area, high stability, tunable release profiles, and good oral bioavailability. Green nanoemulsions, with ingredients entirely from plant or microbial sources, are a conceptually new frontier for next generation nanoproducts. Engineering a kinetically stable green nanoemulsion system for tailored applications entails a systematic understanding of the critical properties of the biosurfactants. This review delivers a holistic and mechanistic exploration of green nanoemulsion systems, with greater focus on bio-derived surfactants and low-energy fabrication methods. We critically discuss how the interfacial behavior and physiochemical properties of surfactants can govern the stability of nanoemulsions. Particular emphasis is devoted to unveiling the untapped capacity of biosurfactants in modulating drug encapsulation, biodegradability, and controlled release across chemical, medical, food, cosmetic and agricultural industries. Emerging emulsion platforms, such as Pickering and stimuli-responsive nanoemulsions, that can respond to either a single stimulus or multiple stimuli, are also highlighted. By bridging interfacial science with translational medicine, this review can act as a roadmap to steer researchers toward the tailored design of green nanoemulsions for unforeseeable applications in bioimaging, drug delivery, and cancer therapy.