Functionalized Plasmonic Nanostructures for Ultrasensitive Single Cell Analysis

Abstract

Ultrasensitive detection and quantification of soluble, secreted and cell surface-bound proteins is critical for advancing our understanding of cellular systems, enabling effective drug development, novel therapies, and bio-diagnostics. However, exiting technologies are largely limited by their sensitivity, making the detection and quantification of low-abundant proteins extremely challenging. This forms a major barrier in various fields of biology and biomedical sciences. In this work, we introduce novel cellular analysis methodologies based on plasmon-enhanced fluorescence for analyzing cell structure and probing surface and secreted proteins from cells. In the first part, we introduce plasmon-enhanced expansion microscopy and demonstrate the effectiveness of employing an ultrabright plasmonic nanolabel in probing hippocampal neurons and quantifying the morphological markers at high resolution. In the second part of this thesis, we introduce plasmon-enhanced FluoroDOT assay for ultrasensitive detection of cell secreted proteins. The plasmonic nanolabels enabled significantly improved signal-to-noise ratio compared to conventional fluorophores, therefore enabling detection and quantification of cell secreted proteins at extremely low concentrations of chemical or biological stimuli. In the third part, we establish plasmon-enhanced flow cytometry as a novel methodology to probe and analyze cellular surface proteins, enhancing the sensitivity of the approach in delineating cell populations with different protein levels. Overall, we establish the proof-of-concept for various plasmon-enhanced cellular analysis and biodetection methods that can be potentially useful in advancing the field of biological and biomedical sciences.