Magnetothermal Miniature Reactors Based on Fe₃O₄ Nanocube‐Coated Liquid Marbles

Abstract

Liquid marbles have recently attracted much interest in various scientific fields because of their isolated environment and robustness. However, conventional liquid marbles lack a reliable heating mechanism, which is critical in many potential applications. Here, the development of iron oxide (Fe3O4) nanocube‐coated liquid marbles (iNLMs), which can be homogeneously heated with an alternating magnetic field (AMF) to as high as 86 °C, is reported. Through tuning the power of the AMF, the iNLMs canbe heated to desired temperatures in controllable patterns. Furthermore, multicenter and selective heating is realized based on the unique magnetothermal properties of iNLMs. As heatable miniature reactors, the iNLMs are further demonstrated to facilitate the kinetic study of temperature‐dependent chemical reactions. DNA amplification is successfully performed in liquid marbles, achieving a 25% superior amplification rate compared with that in a common thermal cycler. These results confirm the feasibility of coating liquid marbles with Fe3O4 nanocubes to form delicate magnetothermal miniature reactors, which provides a reliable method of applying liquid marbles in areas such as biosensor technology, point‐of‐care testing, and theranostics.

Liquid marbles: review of recent progress in physical properties, formation techniques, and lab-in-a-marble applications in microreactors and biosensors

“…Fe 3 O 4 nanocube-coated LMs have been fabricated as heatable miniature reactors because their internal liquid phase can be uniformly heated when exposed to an alternating magnetic field (AMF). 144 Furthermore, because Fe 3 O 4 nanocube-coated LMs allowed the desired temperature and heating/cooling program by the power and on/off switching of the AMF, they were applied as a miniature reactor for DNA amplification and achieved 25% better amplification compared to commercially available thermal cycling methods (Fig. 7B).…”

“…143 (B) DNA amplification using Fe 3 O 4 nanocube-coated LMs as an alternative magnetic field (AMF)-triggered heatable miniature reactors. 144 (C) Isoelectric focusing (IEF)-based protein analysis using fluid channels composed of deformable LM, termed liquid plasticine. 145 (D) Cryopreservation of cells using gelatine-based LMs and its mechanism.…”

“…(A) In situ detection of noncovalent intermolecular interactions between MBA and the target analyte using plasmonic LMs 143. (B) DNA amplification using Fe 3 O 4 nanocube-coated LMs as an alternative magnetic field (AMF)-triggered heatable miniature reactors 144. (C) Isoelectric focusing (IEF)-based protein analysis using fluid channels composed of deformable LM, termed liquid plasticine 145.…”

Magneto Twister: Magneto Deformation of the Water–Air Interface by a Superhydrophobic Magnetic Nanoparticle Layer

“… 14 Moreover, by varying the intensity of the MF, the shell of the liquid marble can be reversibly opened and closed, enabling the removal and insertion of liquids. 13 More recently, these magnetic marbles were used for liquid transportation, 13 miniaturized microreactors, 14 , 15 magneto-thermal reactors, 16 and as digital microfluidics, 17 , 18 among others. It is worth mentioning here that superhydrophobic magnetic NPs were used to clean oil spills or organic contaminants on water surfaces, 19 − 21 wherein the superhydrophobic particles made a colloidal suspension with the oil spills due to the non-polar attraction between the oil and the outer shell of the particles but not with the water.…”