Status of the three-phase line tension: a review

() A nonmechanical pumping mechanism, thermocapillary pumping TCP , is de- scribed for moing nanoliter- and picoliter-sized drops of liquid within microfabricated flow channels. In TCP, one end of a single drop is heated to create a surface tension difference between the ends of the drop. The induced surface tension difference causes a capillary pressure difference between the two drop ends and results in drop motion. TCP ¤elocities of up to 20 mmrmin were measured for seeral liquids at temperature differ- ences between 10 and 708C. An expression deeloped for TCPelocity yields predictions that agree with experimentalelocities within corresponding uncertainty limits. Seeral techniques for assisting TCP are also suggested when contact angle hysteresis, the major factor limiting TCPelocities, is too large. These techniques include using surface treat- ments to reduce the contact angle hysteresis, conerging channels to offset hysteresis, or an applied pressure to assist in moement.

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Thermocapillary Pumping of Discrete Drops in Microfabricated Analysis Devices

Nanobubbles and the Nanobubble Bridging Capillary Force

The debate on the dependence of apparent contact angles on drop contact area or three-phase contact line: A review

The significance and magnitude of the line tension in three-phase (solid-liquid-fluid) systems

We report contact angle measurements of five n-alkanes, dodecane through hexadecane, on Teflon (FEP) as a function of drop size. In all cases the contact angles decreased by approximately 5° when the drop size was increased from approximately 1 to 4 mm contact radius. A complete solution to the problem of mechanical equilibrium of a sessile drop on a solid surface indicates that the dependence of the contact angle on drop size may be explained by including the effect of line tension in the Young equation. The observed drop size dependence of the contact angle yields a line tension of (2.5 ± 0.5) × 10−6 J/m. Over the range of n-alkanes studied it was not possible to discern any dependence of the line tension on liquid surface tension.

The dependence of contact angles on drop size and line tension

Glioblastoma (GBM) remains the most frequently diagnosed primary malignant brain cancer in adults. Despite recent progress in understanding the biology of GBM, the clinical outcome for patients remains poor, with a median survival of approximately one year after diagnosis. One factor contributing to failure in clinical trials is the fact that traditional models used in GBM drug discovery poorly recapitulate patient tumors. Previous studies have shown that monensin (MON) analogs, namely esters and amides on C-26 were potent towards various types of cancer cell lines. In the present study we have investigated the activity of these molecules in GBM organoids, as well as in a host:tumor organoid model. Using a mini-ring cell viability assay we have identified seven analogs (IC50 = 91.5 ± 54.4-291.7 ± 68.8 nM) more potent than parent MON (IC50 = 612.6 ± 184.4 nM). Five of these compounds induced substantial DNA fragmentation in GBM organoids, suggestive of apoptotic cell death. The most active analog, compound 1, significantly reduced GBM cell migration, induced PARP degradation, diminished phosphorylation of STAT3, Akt and GSK3β, increased ɣH2AX signaling and upregulated expression of the autophagy associated marker LC3-II. To investigate the activity of MON and compound 1 in a tumor microenvironment, we developed human cerebral organoids (COs) from human induced pluripotent stem cells (iPSCs). The COs showed features of early developing brain such as multiple neural rosettes with a proliferative zone of neural stem cells (Nestin+), neurons (TUJ1 +), primitive ventricular system (SOX2 +/Ki67 +), intermediate zone (TBR2 +) and cortical plate (MAP2 +). In order to generate host:tumor organoids, we co-cultured RFP-labeled U87MG cells with fully formed COs. Compound 1 and MON reduced U87MG tumor size in the COs after four days of treatment and induced a significant reduction of PARP expression. These findings highlight the therapeutic potential of MON analogs towards GBM and support the application of organoid models in anti-cancer drug discovery. 

https://doi.org/10.1016/j.biopha.2022.113440

Anti-glioblastoma activity of monensin and its analogs in an organoid model of cancer

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults. Despite numerous clinical trials, the standard of care therapy has remained unchanged for the last decade. One of the main problems contributing to the limited effective treatment options and poor overall survival is the lack of models which can reliably recapitulate tumor heterogeneity. Organoids are 3D self‐organized structures which mimic tumor architecture, microenvironment, and cellular interactions which makes them an improved model for anti‐cancer drug discovery.

J Gaydos

Papers

The dependence of contact angles on drop size and line tension

Anti-glioblastoma activity of monensin and its analogs in an organoid model of cancer

Monensin and its analogues show anti‐glioblastoma activity in an organoid model of cancer