An overview of nanoemulsion characterization via atomic force microscopy

Abstract

Nanoemulsion-based systems are widely applied in food industries for protecting active ingredients against oxidation and degradation and controlling the release rate of active core ingredients under particular conditions. Visualizing the interface morphology and measuring the interfacial interaction forces of nanoemulsion droplets are essential to tailor and design intelligent nanoemulsion-based systems. Atomic force microscopy (AFM) is being established as an important technique for interface characterization, due to its unique advantages over traditional imaging and surface force-determining approaches. However, there is a gap in knowledge about the applicability of AFM in characterizing the droplet interface properties of nanoemulsions. This review aims to describe the fundamentals of the AFM technique and nanoemulsions, mainly focusing on the recent use of AFM to investigate nanoemulsion properties. In addition, by reviewing interfacial studies on emulsions in general, perspectives for the further development of AFM to study nanoemulsions are also discussed.

Enzymatic and Nonenzymatic Conjugates of Lactoferrin and (−)-Epigallocatechin Gallate: Formation, Structure, Functionality, and Allergenicity

“…AFM was used to provide insights into the morphology of the protein–polyphenol samples due to its ability to observe structures at the molecular level under near-natural conditions. , The morphologies of LF, LF–EGCG complexes, and LF–EGCG conjugates determined using this method are shown in Figure . The bright colors in the images indicate high peaks, while the dark colors indicate deep troughs.…”

CO2-Switchable Phase Separation of Nonaqueous Surfactant-Free Ionic Liquid-Based Microemulsions

“…These results are in agreement with those of DLS, confirming the CO 2 -switchable phase separation. Atomic force microscopy (AFM) is established as an important technique for interface characterizations, 46,47 which can provide information on the imaging of micro/nanostructured surface topography under different circumstances (air"dry mode," aqueous"wet mode," and vacuum). To further demonstrate the CO 2 -switchable phase separation behavior of the [C n DMEA][Im] (n = 2, 4, and 6)/DMSO/ EA microemulsions, AFM was performed to identify their micro/nanostructures before and after bubbling with CO 2 , and the results are shown in Figure 6 and Figures S14 and S15.…”

Potential of Wood Hemicelluloses and Their Derivates as Food Ingredients

“…150,151 Hence, it may be intriguing in the future to apply direct characterization methods for emulsion interfaces, such as neutron scattering 152 and atomic force microscopy. 153…”