Nanobiotechnology and Microscale Transport
Our goal is to use the kinesin-microtubule system to transport, sense, and purify cargo in microfluidic channels, as shown in the schematic below. In this general sensor prototype, the sample (a cell lysate, a tissue biopsy, or a food sample, for instance) is introduced into the sample chamber. Microtubules are functionalized with oligonucles or a specific analyte of interest, which is then carried down microfluidic channels. The presence of target is detected fluorescently by a LED/photodiode integrated into the microfluidic channel, cargo-bound microtubules are sorted from empty ones at a bifurcation using electric fields, and the target is collected in the collection chamber for further analysis, sequencing, culturing, etc.
Towards this goal and in collaboration with Jackson Lab, we have constructed microfabricated channels in photoresist, functionalized them with kinesins (1,2), enclosed them (3,4), and used them to direct the movement of microtubules. We have also shown that microtubules can be moved by DC and AC electric fields (2,5), and we have shown that microtubules can be functionalized with molecular beacons and nucleotide targets complementary can be both detected and transport by microtubules moving over immobilized motors (6). Much of this work was carried out as part of the Motors Interdisciplinary Research Group in the Center for Nanoscale Science.
1. Moorjani, S.G., Jia, L., Jackson, T.N., and Hancock, W.O. (2003). Lithographically patterned channels spatially segregate kinesin motor activity and effectively guide microtubule movements. NanoLetters 3, 633-637.
2. Jia, L., Moorjani, S.G., Jackson, T.N., and Hancock, W.O. (2004). Microscale transport and sorting by kinesin molecular motors. Biomedical Microdevices 6, 67-74.
3. Platt, M., Muthukrishnan, G., Hancock, W.O., and Williams, M.E. (2005). Millimeter scale alignment of magnetic nanoparticle functionalized microtubules in magnetic fields. Journal of the American Chemical Society 127, 15686-15687.
4. Huang, Y.-M., Uppalapati, M., Hancock, W.O., and Jackson, T.N. (2007). Microtubule transport, concentration and alignment in enclosed microfluidic channels. Biomedical Microdevices 9, 175-184.
5. Hutchins, B.M., Platt, M., Hancock, W.O., and Williams, M.E. (2007). Directing transport of CoFe2O4-functionalized microtubules with magnetic fields. Small 3, 126-131.
6. Raab, M., and Hancock, W.O. (2008). Transport and detection of unlabeled nucleotide targets by microtubules functionalized with molecular beacons. Biotechnology and Bioengineering 99, 764-773.