Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands.
Department of Food Science, College of Agriculture and Veterinary Medicine, United Arab Emirates University, Al Ain, United Arab Emirates.
Adv Colloid Interface Sci. 2022 Jul;305:102688. doi: 10.1016/j.cis.2022.102688. Epub 2022 Apr 30.
Antibubbles are unusual physical objects consisting of a liquid core(s) surrounded by a thin air film/shell while in a bulk liquid. Antibubbles carry two air-liquid interfaces, i.e., one with the inner liquid and the other with the outer liquid. The distinct structure of antibubbles makes them quite attractive for drug and therapeutic delivery, although their potential applications have not been realized so far. The major challenge in this regard is a short-lived span of antibubbles, which is usually in the order of a few minutes to a few hours based on the stabilization mechanism used. We present a critical overview of different techniques that can be used to generate antibubbles. This includes a more commonly applied conventional approach in which the air-film is created through surface entrapment when a liquid jet/drop falls on a bulk liquid. The other available options rely on entirely different mechanisms for antibubble formation, for instance, through drop encapsulation by a submerged air bubble, or through evaporation/sublimation of volatile oil from a W/O/W double emulsion. Furthermore, the mechanisms of antibubble formation and collapse, and the factors affecting their stability have been discussed explicitly; and wherever required, the concept is correlated to other allied physical objects such as bubbles, liquid marbles, etc. Finally, the potential applications, research gaps in the existing knowledge, and some directions for future research are provided towards the end of this article.
抗气泡是一种不寻常的物理物体，由一个液体核心（多个）被一层薄的空气膜/壳包围，而处于主体液体中。抗气泡具有两个气-液界面，即一个与内部液体相接，另一个与外部液体相接。抗气泡的独特结构使它们在药物和治疗输送方面非常有吸引力，尽管它们的潜在应用尚未实现。在这方面的主要挑战是抗气泡的短暂寿命，这通常根据所使用的稳定机制，在几分钟到几个小时的范围内。我们对可以产生抗气泡的不同技术进行了批判性的综述。这包括一种更常用的常规方法，其中通过液体射流/液滴落在主体液体上时的表面捕获来形成气膜。其他可用的选择则依赖于完全不同的抗气泡形成机制，例如通过被淹没的气泡包裹液滴，或通过 W/O/W 型双重乳液中挥发性油的蒸发/升华。此外，明确讨论了抗气泡的形成和崩溃的机制，以及影响其稳定性的因素；并且在需要的地方，将该概念与其他相关物理物体（如气泡、液滴等）相关联。最后，在本文的结尾处提供了抗气泡的潜在应用、现有知识中的研究差距以及未来研究的一些方向。
