A simple optofluidic platform for label-free cell-surface marker screening

Current technologies for cell surface marker screening such as flow cytometry and florescence microscopy, though indispensable, are not well suited for deployment in low resource or point-ofcare settings. Recently, node-pore sensing (NPS) has emerged as a microfluidic platform for labelfree cell surface marker screening. In NPS the transit time of individual cells being flowed through an antibody-functionalized microchannel are measured. Cells that express surface markers corresponding to a functionalized region are delayed due to specific, transient interactions with the surface. In this manner, the presence or absence of a particular surface marker is determined with single cell resolution. Here we show that by measuring the transit time optically as opposed to electrically, the abilities of NPS can be extended. We demonstrate this approach through measurements on human breast cancer cells. The technology presented here could potentially be deployed in low-resource settings as a diagnostic tool.