Neuroscience 2006 Posters: Neurochip

Single molecule placement of serotonin in self-assembled monolayers allows selective recognition by antibodies and native transmembrane receptors

P. S. Weiss1, M. J. Shuster2, A. U. Vaish3, A. M. Andrews4

1Dept Physics & Chemistry, Penn State Univ, University Park, PA, 2Dept Physics, Penn State Univ, University Park, PA, 3Huck Institutes of the Life Sciences, Penn State Univ, University Park, PA, 4Dept Veterinary & Biomedical Sci, Penn State Univ, University Park, PA.

We have developed neurotransmitter-functionalized self-assembled monolayers on gold surfaces that demonstrate selective molecular recognition to capture and identify (1) nucleic acid aptamers for in vivo nanobiosensor applications and (2) natively expressed brain proteins for proteomics applications. Spacing small molecule neurotransmitters so that they can be recognized on surfaces is critical for identifying larger biomolecule binding targets. “Like” molecules in monolayers tend to aggregate having deleterious effects on recognition. In addition, since large biomolecules cover a surface area of approximately 5 nm x 5 nm, or ca. 100 matrix molecules, having more than one tethered neurotransmitter molecule per 100-molecule area can interfere with specific binding. No nanolithographic methods have yet been identified to place single molecules on a 5 nm grid, however, we have shown that it is possible to prepare a self-assembled monolayer matrix into which single molecules can be inserted to achieve this type of spacing. In the present experiments, we inserted tether molecules and functionalized them with serotonin to ca. 0.5% surface coverage with near-optimal dilution in a matrix of oligoethyleneglycol-terminated alkanethiols. We have demonstrated selective molecular recognition of serotonin by both monoclonal and polyclonal antibodies directed against serotonin. These antibodies are known to recognize serotonin linked to large molecule congeners. Moreover, we have demonstrated molecular recognition of surface bound serotonin by native recombinant transmembrane serotonin receptors that recognize free solution serotonin. We are currently developing the coupling chemistry for dopamine. Ultimately, we envision that aptamers identified using these types of neurotransmitter-functionalized surfaces will be coupled to semiconductor nanowire or carbon nanotube platforms and will enable the creation of ultra small, multiplexed sensing devices having high sensitivity and fast response times, and this has the potential to revolutionize in vivo sensing.