A microfluidic and Langmuir approach to unveil the interplay between hydroxypropyl methylcellulose and zein nanoparticles on the stability of Pickering emulsions

Utilizing microfluidic technology and Langmuir trough, the study investigated how hydroxypropyl methylcellulose (HPMC) interact with zein nanoparticles (ZNPs) at interfaces and their collective impact on emulsion stability. Herein, microchips were designed with varying adsorption channel lengths to study the effect of adsorption kinetics on the coalescence stability, while Langmuir assessments provided insights into particle adsorption kinetic and film properties of emulsion stabilization mechanisms. Results suggested that HPMC's incorporation expedited ZNPs' rearrangement rates at the interface, especially at low concentrations, resulting in a synergistic reduction in interfacial tension. However, at high HPMC concentration, a competitive adsorption scenario emerged between ZNPs and HPMC, leading to increased interfacial tension and instability. Microfluidic analyses of droplet coalescence, alongside Langmuir-derived interfacial rheology data, revealed that while a small amount of HPMC significantly bolstered emulsion stability by enhancing viscoelastic properties of interfacial film, an excess of HPMC inversely affected these parameters, diminishing film elasticity and thus, the emulsion's coalescence resistance. The adsorption kinetic and the interaction on interface of HPMC and zein particles were analyzed via microfluidic and LB technology in this study, which will not only expand our current strategies for interface engineering of emulsions, but also deepens our understanding of the interplay between mixed particle system adsorption properties, interfacial rheology, and Pickering composite emulsion stability.