Intracellular mapping of functional chemistry and nanoparticle theranostics with infrared nano-imaging
File(s)
Author(s)
Greaves, George
Type
Thesis
Abstract
Nanoscale imaging is key in studying cell function and pathology at the cellular level, but the diffraction limit (~250nm for visible light) poses a barrier. This necessitates the development of advanced imaging techniques such as electron and super-resolution microscopies, which generally require samples to be stained or labelled to operate at their full potential. In the handful of label-free techniques, it can be challenging to obtain chemical information at the nanoscale spatial resolutions required. At the same time, infrared spectroscopy and imaging is routinely used to obtain chemical information in a label-free way, but suffers from poor spatial resolution due to the diffraction limit (here ~3–5µm), rendering it of little value at the cellular level.
This thesis presents advancements in the cellular imaging capabilities of scattering-type scanning near-field optical microscopy (s-SNOM), a scanning probe microscopy technique that is here combined with infrared quantum cascade lasers to image cells with nanoscale (~30nm) spatial resolution and chemical sensitivity. In one of the key results of this thesis, multiple myeloma cells are imaged label-free at several wavelengths to isolate intracellular structures based on the infrared signatures of chemical groups occurring naturally in biomolecules. Several organelles such as mitochondria and endoplasmic reticulum are identified, having never been seen before at this spatial resolution in a directly optical way.
s-SNOM is also demonstrated as a tool to image interactions between cells and nanoparticles used in drug delivery. This has huge potential in nanomedicine, whereby the intracellular biochemical response of cells could be correlated with the uptake of such nanoparticles. Additionally, combining chemical mapping with the topographical information also obtained with s-SNOM is shown to provide a way of determining whether nanoparticles have internalised into cells, which is crucial in evaluating the efficacy of nanomedicines.
This thesis presents advancements in the cellular imaging capabilities of scattering-type scanning near-field optical microscopy (s-SNOM), a scanning probe microscopy technique that is here combined with infrared quantum cascade lasers to image cells with nanoscale (~30nm) spatial resolution and chemical sensitivity. In one of the key results of this thesis, multiple myeloma cells are imaged label-free at several wavelengths to isolate intracellular structures based on the infrared signatures of chemical groups occurring naturally in biomolecules. Several organelles such as mitochondria and endoplasmic reticulum are identified, having never been seen before at this spatial resolution in a directly optical way.
s-SNOM is also demonstrated as a tool to image interactions between cells and nanoparticles used in drug delivery. This has huge potential in nanomedicine, whereby the intracellular biochemical response of cells could be correlated with the uptake of such nanoparticles. Additionally, combining chemical mapping with the topographical information also obtained with s-SNOM is shown to provide a way of determining whether nanoparticles have internalised into cells, which is crucial in evaluating the efficacy of nanomedicines.
Version
Open Access
Date Issued
2023-08-25
Date Awarded
01/05/2024
License URL
Advisor
Phillips, Christopher
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/N509486/1
EP/R513052/1
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)