Surface tension sensor meshes for rapid alcohol quantification

Falde, Eric J.; Wang, Julia; Grinstaff, Mark W.

doi:10.1039/c7ra09320a

Cited by 2 publications

(3 citation statements)

References 34 publications

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“…Instead, traditional designs detect and/or sort aqueous droplets solely based on their reliance on the differences in droplets’ surface tensions, which remain largely unchanged at amphiphile concentrations below CMC (see below for a detailed discussion). For example, nonlubricated nano-textured surfaces can be used to sense ethanol in droplets with a limit of resolution of ∼0.5% ethanol by volume, corresponding to ∼0.4 mN/m in terms of surface tension ( 42 ). Such a change in surface tension measured by contact angle goniometry will occur at SDS concentrations exceeding hundreds of micromolars—three orders of magnitude higher than with the presented approach.…”

Section: Resultsmentioning

confidence: 99%

Wettability-based ultrasensitive detection of amphiphiles through directed concentration at disordered regions in self-assembled monolayers

Yao

Bennett

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Various forms of ecological monitoring and disease diagnosis rely upon the detection of amphiphiles, including lipids, lipopolysaccharides, and lipoproteins, at ultralow concentrations in small droplets. Although assays based on droplets’ wettability provide promising options in some cases, their reliance on the measurements of surface and bulk properties of whole droplets (e.g., contact angles, surface tensions) makes it difficult to monitor trace amounts of these amphiphiles within small-volume samples. Here, we report a design principle in which self-assembled monolayer–functionalized microstructured surfaces coated with silicone oil create locally disordered regions within a droplet’s contact lines to effectively concentrate amphiphiles within the areas that dominate the droplet static friction. Remarkably, such surfaces enable the ultrasensitive, naked-eye detection of amphiphiles through changes in the droplets’ sliding angles, even when the concentration is four to five orders of magnitude below their critical micelle concentration. We develop a thermodynamic model to explain the partitioning of amphiphiles at the contact line by their cooperative association within the disordered, loosely packed regions of the self-assembled monolayer. Based on this local analyte concentrating effect, we showcase laboratory-on-a-chip surfaces with positionally dependent pinning forces capable of both detecting industrially and biologically relevant amphiphiles (e.g., bacterial endotoxins), as well as sorting aqueous droplets into discrete groups based on their amphiphile concentrations. Furthermore, we demonstrate that the sliding behavior of amphiphile-laden aqueous droplets provides insight into the amphiphile’s effective length, thereby allowing these surfaces to discriminate between analytes with highly disparate molecular sizes.

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Section: Resultsmentioning

confidence: 99%

Wettability-based ultrasensitive detection of amphiphiles through directed concentration at disordered regions in self-assembled monolayers

Yao

Bennett

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Additionally, some PLLA samples were selected and treated with 70% ethanol to decrease the surface tension of fibers and increase the amount of immobilized protein. 38 After ethanol evaporation, PLLA fibers were modified with laminin.…”

Section: Methodsmentioning

confidence: 99%

“…Additionally, some PLLA samples were selected and treated with 70% ethanol to decrease the surface tension of bers and increase the amount of immobilized protein. 38 Aer ethanol evaporation, PLLA bers were modied with laminin. All of the measurements were conducted with the use of Data Physics OCA 15EC (Germany) using the sessile drop method.…”

Section: Preparation Of Short Bers/hydrogel Systemmentioning

confidence: 99%