1. Tutorial 10 Derek Wright Wednesday, March 30 th, 2005

2. Nano-BioSystems Neuro-Electronic Interfacing Biomaterials DNA Microarrays

3. Neuro-Electronic Interfaces Focuses on interfacing between neurons and electronic circuits –Circuits use electrons and holes –Neurons use ions in fluid Circuits have high carrier mobility relative to neurons Both use electricity, but differently

4. Neurons Typically 20  m in diameter Surrounded by an electrically insulating membrane –Lipid = fat Ionic current can flow through the membrane using special proteins

5. Neurons

6. Neuron-Chip Interfaces a) Neuron potential acts as a gate voltage in a FET b) Voltage of the silicon induces E- field, which opens up ion channels c) Current through cell membrane creates a potential between the cell and the chip, again acting as a gate voltage in a FET d) Voltage of the silicon induces potential between the cell and the chip, which opens up ion channels

7. Neuron Immobilization When neurons are placed on a chip they grow connections to surrounding neurons –Like ropes tying neurons together These connections pull neurons together The neurons move away from where they were placed Pegs can be used to hold the neuron in place –Like a fence

8. Neuron Immobilization

9. Biomaterials Biological materials can be considered nanotechnology –We can use them to engineer new things! –http://www.pbs.org/wgbh/aso/tryit/dna/shockw ave.html Amino Acid: 0.6 nm Polypeptide: 4 – 50 nm Proteins: Made up of polypeptides DNA is the ultimate nanotechnology

10. DNA Microarrays DNA is double stranded It can be split into single strands If two single strands meet and are matching, they will bind A “gene chip” uses an array of different single stranded DNA segments fastened in a grid

11. DNA Microarrays A solution containing unknown DNA fragments is “tagged” with fluorescent molecules The solution is poured over the gene chip Any matching pairs will bind The chip is illuminated with UV light The fluorescent molecules illuminate, indicating their presence http://www.bio.davidson.edu/courses/genomics/c hip/chip.html

12. DNA Microarrays The hard part is making the array with single stranded genes How do you make so many different gene segments and attach them to specific locations? Many methods developed: –Lithography –Ink jet printing –Direct writing

13. Thank You! This presentation will be available on the web.