Research                                

Nanoscale Optics and Spectroscopy

Tip enhanced Raman spectroscopy

New probes for tip enhanced Raman spectroscopy (TERS): single Ag nanoparticle attached at the apex of an AFM tip.

silver nanoparticles
silver nanorods Raman

Optical properties of metal nanoparticles can be optimised by tuning their size and shape

A wide range of biological nanomaterials have been recently developed for biotechnology applications, such as drug delivery, tissue engineering, biosensing, etc. To achieve ultimate functionality for such materials, a better understanding of the relationship between their chemical/physical properties iand molecular structure is important.

 

Atomic force microscopy (AFM) is a powerful technique that can measure  topographical images and mechanical properties of materials with nanoscale spatial resolution. On the other hand, Raman spectroscopy can provide detailed information on molecular conformation together with orientation of the molecular bonds in a sample. Our aim is to integrate these two powerful techniques to obtain simultaneously topographical, mechanical and molecular information with spatial resolution beyond the optical diffraction limit. 

 

One area of research is the investigations of biological nanomaterials obtained by molecular self-assembly by AFM and polarised Raman microscopy. Self-assembly exploits molecular recognition patterns based on a balance between thermodynamic and kinetic processes. Biological molecules, such as peptides, are ideal building blocks for designing nanostructures by self-assembly because of their specific molecular recognition patterns and the opportunities to manipulate them for specific functions.

 

At the same time, we are developing new methods for tip-enhanced Raman microscopy (TERS), a technique that allows Raman spectral measurements with nanoscale spatial resolution. Currently, our efforts are focused on developing simple and reproducible methods for fabrication of TERS tips.  


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Molecular imaging of live cells by Raman micro-spectroscopy

Raman cell imaging microscopy

Label-free imaging of nucleic acids (DNA, RNA) in neuro-progenitor stem cells.

stem cells Raman Notingher

Imaging Raman spectral markers in live heart cells obtained from human embryonic stem cells. 

Optical spectroscopy has the potential to underpin fundamental advances in our understanding of molecular and cellular processes. All biological events are dynamic processes, which involving highly orchestrated, complex time-dependent molecular interactions. However, extracting quantitative spatial and temporal information at a sub-cellular organelle level without disturbing the cell remains a key challenge when imaging individual living cells. Most molecular techniques currently available require labelling, fixation, or other procedures that kill the cells. Thus, these techniques provide only single time-shots and cannot provide insight into discrete and dynamic molecular events in living cells.

Confocal Raman microscopy (CRM) is based on the interaction of light with vibrating molecules in cells and can measure the physical and chemical properties of cells without requiring labelling or killing the cells. Molecular images of live cells in-vitro can be recorded while the  cells are maintained physiological buffers. CRM uses lasers in the visible and near-infrared regions, therefore the  high spatial resolution is typically 400-700nm.

 

One area of research is the development of Raman microscopy for tissue engineering and regenerative medicine applications.  Raman spectroscopy can be used to measure time-dependent biochemical changes in live embryonic stem cells, providing lineage-specific spectral markers that can be used to identify cell types. Phenotypic identification of stem cells progeny at early stages of differentiation helps refinement of protocols to induce the efficient differentiation of cells with a mature phenotype. The spectral markers can also be used for purification of cell populations by Raman activated cell sorting.


Our group is interested in developing molecular imaging tools to study interactions between host cells and pathogens (viruses, parasites).  The aim of these studies is to chronicle crucial landmarks of disease initiation and progression. The molecular changes will be related to understand the invasive infection as well as host cell system components necessary to maintain protective strategies against the invading pathogens, information which will direct therapeutic approaches for these invasive infections.


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