Optical Biosensors & Biophotonics

The Optical Biosensors and Biophotonics Group is led by Dr Tracy Melvin. The group's research is focused on the area of micro and nanofabricated devices for bioanalysis or for biomedical applications. These are either optical, microfluidic (Biological Micro Electro Mechanical Systems abbreviated as BioMEMS), or self-assembled devices.

Group webpage

PhD Projects:

Supervisor: Dr Tracy Melvin 

Optical/micorfluidic devices for the study
of stem cells

Embryonic stem cells, isolated from the inner cell mass of blastocyst stage embryos and adult stem cells, present in specific niches within tissues, are subjected to highly controlled microenvironments. The microenvironment of each cell - within each of the populations - in each tissue - is highly regulated as a result of cell-cell communication, chemical and physical signals. 

If we look to nature, then one has to question whether the present approaches to stem cell biology research are really appropriate for understanding and exploiting the potential of these remarkable cells. 

‘Bioinspired’ microfluidic structures, where molecules (growth factors or chemicals) are transported by streams (rather than conventional microfluidic channels), will be designed using advanced computational and numerical methods, and fabricated using microengineering approaches. 

Interrogation of stem cells within microfluidic devices will be achieved by optical methods. Optical\microfluidic devices are to be fabricated and applied for stem cell applications during the course of the project, which would be suitable for candidates with a background in physics, chemistry or an engineering topic with a strong interest in regenerative medicine. The project would also be suitable for candidates with an interest in pursuing a theoretical project, with a background in mathematics or a related subject. 

Optical sorting for regenerative medicine applications 

The application of optical tweezers as a means to evaluate molecular and cellular processes is at the forefront of interdisciplinary research. Specifically, optical tweezers have been employed to study cell mechanics and the interaction of the cell membrane with its surrounding environment. However there have been few studies investigating the physical processes that govern the orientation and behaviour of the cell in optical field gradients.

We have recently demonstrated that the response to an optical field gradient is cell-specific and depends on the main cellular constituents, namely the cytoplasm and nucleus. Experimental data obtained using a single beam optical trap fits remarkably well with our theoretical model appropriate to understand the interaction of optical tweezers on a mammalian cell. The model takes into account the heterogeneity of the cell with respect to refractive index. Employing this set of experimental and theoretical tools we are able to measure and predict the contribution of the main cellular components (cytoplasm and nucleus) to the dynamics of the cell as a whole in the optical field. 

These studies are to be extended for sorting cell populations for regenerative medicine applications. Optical\microfluidic devices are to be fabricated and applied for cell sorting applications during the course of the project, which would be suitable for candidates with a background in physics, chemistry or an engineering topic with a strong interest in regenerative medicine. 

Raman spectrocopy and associated techniques for the detection of protein assemblies associated in degenerative diseases, such as Alzheimer's

This project is a collaborative one between Tracy Melvin and Bill Brocklesby at the ORC and a pharmaceutical company. 

The project will involve the development of novel Raman imaging approaches suitable for the evaluation of the protein structure of the amyloid plaques and tau tangles, which are believed to be the species that initiate the disease cascade. Involving both fabrication and optical imaging technologies, the project would be suitable for candidates with a background in physics, chemistry or an engineering topic with a strong interest in protein structure and neurodegenerative diseases. 

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