Magnetothermal Miniature Reactors Based on Fe₃ O₄ Nanocube-Coated Liquid Marbles

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 (Fe₃ O₄ ) 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 Fe₃ O₄ 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.