Digital Imaging‐based Colourimetry for Enzymatic Processes in Transparent Liquid Marbles

Abstract

Liquid marbles are a promising microreactor platform that recently attracts significant research interest owing to their ability to accommodate a wide range of micro reactions. However, the use of destructive and ex‐situ methods to monitor reactions impairs the potential of liquid‐marble‐based microreactors. This paper proposes a non‐destructive, in situ, and cost‐effective digital‐imaging‐based colourimetric monitoring method for transparent liquid marbles, using the enzymatic hydrolysis of starch as an illustrative example. The colourimetric reaction between starch and iodine produces a complex that exhibits a dark blue colour. We found that the absorbance of red channel of digital images showed a linear relationship with starch concentration with high sensitivity and repeatability. This digital‐imaging‐based colourimetric method was used to study the hydrolysis of starch by α‐amylase. The results show high accuracy and applicability of first‐order kinetics for this reaction. The demonstration of digital‐imaging‐based colourimetry indicates the potential of liquid marble‐based microreactors.

Interfacial Crystallization within Janus Saline Marbles

“…Liquid marbles are gas-permeable multi-phase entities. , Mass transfer between the liquid confined by hydrophobic powders and the surrounding gas phase is possible. , Thus, liquid marbles may be easily converted into micro-reactors. − In our recent paper, we reported the use of liquid marbles for the controlled interfacial crystallization . Now, we demonstrate the controlled interfacial crystallization observed within the Janus marbles built of different hemispheres. ,, In addition to its fundamental importance, interfacial crystallization has major significance in cutting edge applications such as improvement of efficiency of photovoltaic devices and DNA-controlled self-assembly …”

“…25 Liquid marbles are gas-permeable multi-phase entities. 26,27 Mass transfer between the liquid confined by hydrophobic powders and the surrounding gas phase is possible. 26,27 Thus, liquid marbles may be easily converted into microreactors.…”

“…26,27 Mass transfer between the liquid confined by hydrophobic powders and the surrounding gas phase is possible. 26,27 Thus, liquid marbles may be easily converted into microreactors. 26−31 In our recent paper, we reported the use of liquid marbles for the controlled interfacial crystallization.…”

Investigation of liquid marble shell using X‐ray: shell thickness and effective surface tension

“…Liquid marble is a non‐wetting droplet coated with micro‐ or nano‐sized hydrophobic particles [1] . Attractive features of a liquid marble such as low evaporation rate, high robustness, tuneable porosity, and ease of manipulation enable it to be an efficient tool for microfluidic applications [2–11] . These features depend on the properties and structure of the liquid marble shell [12–14] .…”

Modelling Sessile Droplet Profile Using Asymmetrical Ellipses

“…Besides measuring conventional liquid droplets, these tools have been used to analyse liquid marbles, which are liquid droplets coated with micro-or nanoparticles [21][22][23][24][25][26][27]. Thanks to their unique features such as high elasticity, self-propulsion, and ability to coalesce, liquid marbles are present in applications such as micro-or nanoscale chemical reaction control, microfluidics, or cosmetics [28][29][30][31][32][33][34][35][36][37][38][39][40][41]. When liquid marbles rest on a flat and smooth surface, they are analogous to a sessile droplet on a non-wetting solid surface [42].…”