Light and Magnetic Dual-Responsive Pickering Emulsion Micro-Reactors

Abstract

Emulsion droplets can serve as ideal compartments for reactions. In fact, in many cases, the chemical reactions are supposed to be triggered at a desired position and time without change of the system environment. Here, we present a type of light and magnetic dual-responsive Pickering emulsion microreactor by coadsorption of light-sensitive titania (TiO) and super paramagnetic iron oxide (FeO) nanoparticles at the oil-water interface of emulsion droplets. The droplets encapsulating different reactants in advance can be driven close to each other by an external magnetic field, and then the chemical reaction is triggered by UV illumination due to the contact of the isolated reactants as a result of droplet coalescence. An insight into the incorporation of hydrophobic TiO and hydrophilic FeO nanoparticles simultaneously at the emulsion interface is achieved. On the basis of that, an account is given of the coalescence mechanism of the Pickering emulsion microreactors. Our work not only provides a novel Pickering emulsion microreactor platform for triggering chemical reactions in a nonintrusive and well-controlled way but also opens a promising avenue to construct multifunctional Pickering emulsions by assembly of versatile building block nanoparticles at the interface of emulsion droplets.

Enzyme-Loaded Mesoporous Silica Particles with Tuning Wettability as a Pickering Catalyst for Enhancing Biocatalysis

“…Surface wettability of particles is thought to be crucial in stabilizing Pickering emulsions. In our previous studies, the most stable Pickering emulsion with the relatively large interfacial area is formed when the three-phase contact angle (TCA) of particles is close to 90 • [37,38]. To get the optimum condition, silylating agents with different carbon chain length (C0, C3, C6, C8, C10, C12) is used to modify the LMSPs.…”

Recent developments in Pickering emulsions for biomedical applications

“…[99,100] Though promising, only a handful are directly applicable to or have been demonstrated for biomedical applications. [53,101] A range of stimulus combinations have been investigated, such as CO2 and light, [99] pH and light, [100] CO2 and redox environments, [102] temperature and ionic strength, [103] pH and temperature, [104][105][106] pH and magnetic fields, [101,[107][108][109] and magnetic fields and temperature. [23,110] Many systems employ emulsifiers composed of a single amphiphilic polymer with multi-functionality or co-polymer systems bearing different stimuli-sensitive groups (often based on poly(N-isopropylacrylamide) or poly(methyl methacrylate) species), either as a polymeric emulsifier or via modification of an inorganic particle.…”

Surfactant-Free Cellulose Filaments Stabilized Oil in Water Emulsions

“…Previously, several types of solid particles have been applied as stabilizers for Pickering emulsions, including (i) inorganic particles such as silica (Xue et al 2017;Björkegren et al 2020), metal oxide particles (Xie et al 2017;Fessi et al 2019), graphene (He et al 2013), calcium carbonate (Zhu et al 2013), etc. ;(ii) polymeric particles such as polystyrene (Jiang et al 2019;Li et al 2019); and (iii) food-grade particles such as starch (Zhu 2019), chitin (Jiménez-Saelices et al 2020, whey (Lee et al 2020), etc. With the growing demand for sustainable materials with reduced environmental footprints and with green and energy-efficient production routes, the application of natural materials has attracted increasing attention.…”