Cardiogenesis of embryonic stem cells with liquid marble micro-bioreactor.

A liquid marble micro-bioreactor is prepared by placing a drop of murine embryonic stem cell (ESC) (Oct4B2-ESC) suspension onto a polytetrafluoroethylene (PTFE) particle bed. The Oct4B2-ESC aggregates to form embryoid bodies (EBs) with relatively uniform size and shape in a liquid marble within 3 d. For the first time, the feasibility of differentiating ESC into cardiac lineages within liquid marbles is being investigated. Without the addition of growth factors, suspended EBs from liquid marbles express various precardiac mesoderm markers including Flk-1, Gata4, and Nkx2.5. Some of the suspended EBs exhibit spontaneous contraction. These results indicate that the liquid marble provides a suitable microenvironment to induce EB formation and spontaneous cardiac mesoderm differentiation. Some of the EBs are subsequently plated onto gelatin-coated tissue culture dishes. Plated EBs express mature cardiac markers atrial myosin light chain 2a (MLC2a) and ventricular myosin light chain (MLC2v), and the cardiac structural marker α-actinin. More than 60% of the plated EBs exhibit spontaneous contraction and express mature cardiomyocyte marker cardiac troponin T (cTnT), indicating that these EBs have differentiated into functional cardiomyocytes. Together, these results demonstrate that the liquid-marble technique is an easily employed, cost effective, and efficient approach to generate EBs and facilitating their cardiogenesis.

Liquid marbles as micro-bioreactors for rapid blood typing.

A liquid marble micro- bioreactor is used to conduct blood typing as a typical biological assay. This study portrays the potential of using such microreactors for biochemical and biological analysis.

Tumor inside a pearl drop.

The confined internal space of a liquid marble, as well as its porous and non-adhesive shell, offers an attractive application possibility - accommodating living cells inside liquid marbles. Cancer cells in suspension may aggregate to form three dimensional structures, also known as cancer cell spheroids (CCS). In this study, CCS formation inside liquid marble is investigated. This liquid marble application opens significant and novel avenues for biomedical applications and cancer research.

Measurement of the surface tension of liquid marbles.

The capillary rise and Wilhelmy plate methods have been used to study the "surface tension" of water marbles encapsulated with polytetrafluoroethylene (PTFE) powders of 1-, 35-, and 100-µm particle size. With the capillary rise technique, a glass capillary tube was inserted into a water marble to measure the capillary rise of the water. The Laplace pressure exerted by the water marble was directly measured by comparing the heights of the capillary rise from the marble and from a flat water surface in a beaker. An equation based on Marmur's model was proposed to calculate the water marble surface tension. This method does not require the water contact angle with the supporting solid surface to be considered; it is therefore a simple but efficient method for determining liquid marble surface tension. The Wilhelmy method was used to measure the surface tension of a flat water surface covered by PTFE powder. This method offers a new angle for investigating liquid marble shell properties. A discussion on the nature and the realistic magnitude of liquid marble surface tension is offered.

Liquid marble for gas sensing.

The porous and superhydrophobic shell of a liquid marble prevents contact of its liquid core with outside surfaces, but allows gas transport. Liquid marble can therefore be used to sense gas or emit gas. Liquid marbles loaded with different indicators can simultaneously sense different gases via different mechanisms.