Recombinant maxi-K Recombinant maxi-K ChannelsChannels

on Transistor, A Prototype of on Transistor, A Prototype of Iono-electronic InterfacingIono-electronic Interfacing

Authors: B. Straub, E. Meyer, and P. Fromherz

Presenter: Todd Finkler

DisclaimerDisclaimerYou are about to enter the world of the unknown. The presenter’s background is in computer engineering, more specifically in networks. NOT in biological engineering or biology or medical or in any field that would make this topic easy. However, this topic is interesting to the presenter, so the presenter is wading forth into an area of unknown. If you chose to enter, you do so at your own risk. You may or may not get correct answers to your questions. You may or may not walk away from this talk more confused than when you entered the room. There are some really smart people who are examining this field and the presenter is not one of them. If you cannot read this, tough. If you can read this, I did not make this small enough. My bad. The presenter will not be held responsible for any misguided teachings from this presentation. If you cannot agree to this, you know where the door is since you came through the door to get here. This disclaimer is meant for entertainment purposes only, and is by no means intended to be serious. If, up to this point, you are still reading this and you still think this is serious, you need to take a break from school – especially since it is still so early in the semester. And if you are still reading this, you have a much longer attention span than I have. But that is good, because you will probably one of the few who actually pay attention to the whole presentation. Thanks for paying attention this long. Thanks also to those who have supported my efforts to this point, including Weiwei for asking a barrage of questions while I was developing these slides. Additionally, thanks to Koranan for her patience in getting this presentation at the last minute. And finally, thanks also to Professor Newcomb for hopefully giving me an “A” in this class for the semester. Enough with this nonsense and lets move on with the presentation. The following is a repeat of the above. You are about to enter the world of the unknown. The presenter’s background is in computer engineering, more specifically in networks. NOT in biological engineering or biology or medical or in any field that would make this topic easy. However, this topic is interesting to the presenter, so the presenter is wading forth into an area of unknown. If you chose to enter, you do so at your own risk. You may or may not get correct answers to your questions. You may or may not walk away from this talk more confused than when you entered the room. There are some really smart people who are examining this field and the presenter is not one of them. If you cannot read this, tough. If you can read this, I did not make this small enough. My bad. The presenter will not be held responsible for any misguided teachings from this presentation. If you cannot agree to this, you know where the door is since you came through the door to get here. This disclaimer is meant for entertainment purposes only, and is by no means intended to be serious. If, up to this point, you are still reading this and you still think this is serious, you need to take a break from school – especially since it is still so early in the semester. And if you are still reading this, you have a much longer attention span than I have. But that is good, because you will probably one of the few who actually pay attention to the whole presentation. Thanks for paying attention this long. Thanks also to those who have supported my efforts to this point, including Weiwei for asking a barrage of questions while I was developing these slides. Additionally, thanks to Koranan for her patience in getting this presentation at the last minute. And finally, thanks also to Professor Newcomb for hopefully giving me an “A” in this class for the semester. Enough with this nonsense and lets move on with the presentation. The following is a repeat of the above. You are about to enter the world of the unknown. The presenter’s background is in computer engineering, more specifically in networks. NOT in biological engineering or biology or medical or in any field that would make this topic easy. However, this topic is interesting to the presenter, so the presenter is wading forth into an area of unknown. If you chose to enter, you do so at your own risk. You may or may not get correct answers to your questions. You may or may not walk away from this talk more confused than when you entered the room. There are some really smart people who are examining this field and the presenter is not one of them. If you cannot read this, tough. If you can read this, I did not make this small enough. My bad. The presenter will not be held responsible for any misguided teachings from this presentation. If you cannot agree to this, you know where the door is since you came through the door to get here. This disclaimer is meant for entertainment purposes only, and is by no means intended to be serious. If, up to this point, you are still reading this and you still think this is serious, you need to take a break from school – especially since it is still so early in the semester. And if you are still reading this, you have a much longer attention span than I have. But that is good, because you will probably one of the few who actually pay attention to the whole presentation. Thanks for paying attention this long. Thanks also to those who have supported my efforts to this point, including Weiwei for asking a barrage of questions while I was developing these slides. Additionally, thanks to Koranan for her patience in getting this presentation at the last minute. And finally, thanks also to Professor Newcomb for hopefully giving me an “A” in this class for the semester. Enough with this nonsense and lets move on with the presentation. The following is a repeat of the above.

Joining Computer and Joining Computer and BrainBrainWhy Important?The challenge – different charge

carriers◦Computer – electrons in solid ion

lattice◦Brain – electrons in polar fluid

A Little Biology…A Little Biology…

How Cells Transmit How Cells Transmit Signals…Signals…

How Cells Transmit How Cells Transmit Signals Signals (cont.)(cont.)

Passing the SignalPassing the Signal

What Cell to Use?HEK293 – What?

◦Human Embryonic Kidney cell line with sheared adenovirus 5 DNA

HEK293 – Why?◦Conductance properties◦Well-defined ion channel

What Interface?

human slowpoke (hSlo) maxi-KCa channel◦ Perfectly controlled by

patch-clamp◦ Displays high single-

channel conductance yielding large membrane current.

◦ Is target for estradiol – potentially useful for biosensor

Neuron on TransistorNeuron on Transistor

Applying Voltage to the Applying Voltage to the CellCell

58 mV

53 mV

45 mV

40 mV

30 mV

-23 mV

-68 mV

Average Transistor SignalAverage Transistor Signal

VJ/IM = 73 V/nA

Relations

VJ = RJAJMgJM(VM – V0) where: VJ is the extracellular voltage in the gapRJ is the gap’s ohmic resistanceAJM is the area of the attached membranegJM is the average specific K+ conductance

IM = AMgM(VM – V0)

VJ / IM is constant experiementally, so…

gJM / gM must be constant for all VM

And…And…Boltzmann’s equation can describe their voltage-dependent gating

g/gbar = 1/(1 + e[z(V0.5 – VM)/Vth] ) where…

z is the gating charge

V0.5 is the half-maximum activation at a max specific gbar

Conductance Conductance MeasurementsMeasurements

QuestionsQuestions