Label-free cell-substrate adhesion imaging on plasmonic nanocup arrays

Abstract

Abstract:Cell adhesion is a crucial biological and biomedical parameter defining cell differentiation, cell migration, cell survival, and state of disease. Because of its importance in cellular function, several tools have been developed in order to monitor cell adhesion in response to various biochemical and mechanical cues. However, there remains a need to monitor cell adhesion and cell-substrate separation with a method that allows real-time measurements on accessible equipment. In this article, we present a method to monitor cellsubstrate separation at the single cell level using a plasmonic extraordinary optical transmission substrate, which has a high sensitivity to refractive index changes at the metaldielectric interface. We show how refractive index changes can be detected using intensity peaks in color channel histograms from RGB images taken of the device surface with a brightfield microscope. This allows mapping of the nonuniform refractive index pattern of a single cell cultured on the plasmonic substrate and therefore high-throughput detection of cell-substrate adhesion with observations in real time.

Light-driven single-cell rotational adhesion frequency assay

“…Precise control of the interacting distance between cell and substrate is pivotal for measuring the adhesion strength in our scRAFA due to the strong dependence of the adhesion strength on the cell-substrate distance, which can be precisely controlled by moving the trapped cell up and down through optical tweezer. We conduct in situ optical transmission measurements to extract the cell-substrate distance during the cell rotation (Additional file 1 : Note 1) [ 29 ]. As an example, we collected the time-dependent transmission spectral shift for cell 1 and cell 2 during cell rotation (Fig.…”

Spectrometer-Free Plasmonic Biosensing with Metal–Insulator–Metal Nanocup Arrays

“…Plasmonic sensors are appealing for biosensing applications due to the high sensitivity of the generated evanescent fields to local refractive index (RI) changes. These sensors are currently based on surface plasmon resonance (SPR), extraordinary optical transmission (EOT), localized surface plasmon resonance (LSPR), or a combination of these mechanisms with applications including gas detection, cancer biomarker screening, and cell imaging . EOT plasmonic devices, which primarily rely on the generation of grating-coupled SPR on metallic nanohole arrays, are of particular interest for biosensing applications due to excitation and spectral detection in transmission mode at normal incidence, which simplifies the instrumentation requirements. − However, the performance of these devices in terms of the limit of detection (LOD) is significantly worse than SPR sensors in the Kretschmann configuration, which has a high angular sensitivity that can exceed 500°/RIU. , Current work in plasmonic biosensors seeks to match or outperform SPR sensors while simplifying the instrumentation requirements to lead to more widespread applications of these tools.…”