My current work focuses on trying to create biologically functional surfaces to allow for functional proteomics of the brain. These surfaces, once proven to be biologically specific, can be used as selection tools to select for aptamers, which may be used in an in vivo sensor for measuring neurotransmitter levels in real time at spatial and temporal resolutions orders of magnitude better than the state-of-the-art techniques are capable of. This represents a rather ambitious goal that may not be achieved in my graduate career here, but whose foundations I hope to build.
To clarify this a bit, a brief explanation seems appropriate. We are using a combination of self-assembly and chemical functionalization to create surfaces that will "fish out" specific molecules based on their biological function. For example, using a surface functionalized with the neurotransmitter serotonin, all proteins with a high affinity for serotonin would "stick" to the surface, while all other proteins would not. This allows for the separation of proteins, based on their functionality, from a heterogeneous solution. Once these surfaces are optimized, we can use them to pull down any molecule with an affinity for the functionality we impart to the surface.
This leads into the second project, creation of an
in vivo sensor. To create a sensor with the desired characteristics, a sensing element must first be created. For our application, we believe aptamers to be the best candidate. Aptamers are single strands of
DNA or
RNA that can be selected for specific targets, in this case neurotransmitters, using an "irrational" design method. This doesn't mean the method is not logical, it means that rather than "rationally" designing the desired final product, like with a computer chip, one tries many different variations and picks the one that works. Large libraries of aptamers are created via
PCR, which are then exposed to the intended target. Those strands that bind the target are separated out and cloned, and further steps allow the creation of aptamers with very high affinity for a target.
Once our functionalized surfaces are optimized, we can use them to select aptamers for our desired targets. It should be mentioned that while aptamers for larger molecules can be created, small molecules, such as neurotransmitters, present a problem because of the difficulty in separating out the bound and unbound aptamers. For large molecules, separation is usually done in solution using some form of
MS, where those aptamers that bind the target weigh more than those that do not and can, therefore, be separated based on the mass difference. With small molecules, however, the mass difference is too small, and separation is nearly impossible. Our surfaces, however, serve as ideal selection tools, since aptamers with an affinity to the target will bind to the surface, whereas those with a much lower affinity will stay in solution. Separation is then easy, and selection can be performed rapidly.
The next step would be to incorporate these sensors into a device capable of being used
in vivo to measure neurotransmitter levels. This is the rather more difficult step, whose details are likely to consume whatever time I have left working here. If you're deeply curious about our current thoughts on the matter, e-mail me at
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If you're still reading at this point, I commend you while being simultaneously appalled at your lack of taste.