Abstract

From Model Membranes to Single Cells: Microfluidic Approaches to Sensing and Diagnostics

Stephen Evans, Professor, University of Leeds

This presentation will cover two aspects of our recent work.  The first will look at a novel biosensor based on phospholipid-coated nematic liquid crystal (LC) droplets and demonstrate the detection of a model antimicrobial peptide (AMP). Monodisperse lipid-coated LC droplets were generated and trapped in a bespoke microfluidic structure and were treated with AMP. The disruption of the lipid monolayer by the AMP was detected at concentrations well within its biologically active range, and was indicated by a dramatic change in the appearance of the droplets associated with the liquid crystal transition from a typical radial configuration to a bipolar configuration. This suggests the system has feasibility as a drug-discovery screening tool and for toxin detection.

The second area of research to be described is on the investigation of cell deformability and its importance for diagnostic applications. In particular we use cell deformability in both shear-dominant and inertia-dominant microfluidic flow regimes to probe different aspects of the cell structure. In the inertial regime, we follow cellular response from (visco-)elastic through plastic deformation to cell structural failure and show a significant drop in cell viability for shear stresses >11.8 kN/m². Comparatively, a shear-dominant regime requires lower applied stresses to achieve higher cell strains. From this regime, deformation traces as a function of time contain a rich source of information including maximal strain, elastic modulus, and cell relaxation times and thus provide a number of markers for distinguishing cell types and potential disease progression. These results emphasize the benefit of multiple parameter determination for improving detection and will ultimately lead to improved accuracy for diagnosis.