(395c) Atomically-Thin Sensing Surfaces from 2D Materials for Detecting Cellular Gaps

Cellular layers play critical role as barriers, filters, and membranes in our bodies. The performance of cellular layers is often found to be determined by the properties of individual cellular gaps. Yet these gaps often fall below the diffraction limit, hampering their detection. Here, we develop a novel sensing modality called chemical tomography, where the diffusion of a harmless chemical tracer is used to reveal cellular gaps in human umbilical vein endothelial cellular (HUVEC) layers. For the readout, we employ atomically-thin and optically-active MoS2, whose two-dimensional form-factor enables it to serve as an array of 20,164 wireless sensors over 420x420 µm² area. A rigorous screening of 30 analytes identifies several tracer candidates with MoS2 dynamic range over five orders of magnitude in tracer concentration. In a single layer of HUVEC cells, we find local spots with 10^-8-10^-9 cm²/s diffusivities that are spatially correlated with immunofluorescence of vascular endothelial (VE)-cadherin proteins found on cell membrane. These spots correspond to cellular pores with effective sizes from 50 to 100 nm. This platform enables future studies on properties and dynamics of cellular gaps of various tissues.