IGEM:IMPERIAL/2006/project/Bio elec interface

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(Enzymatic pH sensors: Email-correspondance with Anna)
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==Enzymatic pH sensors: Email-correspondance with Anna==
==Enzymatic pH sensors: Email-correspondance with Anna==
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From: Radomska, Anna  
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Sent: 01 August 2006 16:34
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From: Radomska, Anna <br>
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To: Vohra, Farah
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Sent: 01 August 2006 16:34 <br>
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Subject: RE: LB & M9
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To: Vohra, Farah <br>
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Subject: RE: LB & M9 <br>
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To read email click : __HIDER__
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Dear All,  
Dear All,  
   
   
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Anna
Anna
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Revision as of 12:06, 9 August 2006

Contents

Biological to Electrical Interface

System level diagram of biological to electrical interface
System level diagram of biological to electrical interface












Specifications

Bio Reporter Signal Transducer
Expressed by E.coli Detect Bio reporter
Degradation in medium afterwards. Time needed for degradation should be equal to/less than that of GFP Specific response to bio reporter only
No other interaction with E.coli processes Real-time readout
Sufficient expression and secretion of bio reporter in medium for detection by signal transducer Sufficient sensitivity to detect changes in bio reporter
Commercially available



Possible Implementation

  1. Signal transduction could involve (protein) redox-reactions
  2. Antigen/Antibody sensors?
  3. Protein sensors
  4. Hormone/Neurotransmitter sensors (e.g. serotonin)


Scenario 1:
  • E.coli is in a liquid medium
  • Some bioprocess triggers production of a bio reporter (protein) in E.coli
  • The bio reporter is expelled from the cell into the medium
  • A sensor will measure the level of bio reporter (protein) in the medium


Scenario 2:
  • E.coli is in a liquid medium
  • Some bioprocess triggers productio of a bioreporter (protein) in E.coli
  • The bio reporter is expelled from the cell into the medium
  • There, the bio reporter (protein/enzyme) breaks down a certain chemical present in the medium
  • A commercially available sensor then measures the
a) increase in concentration of the breakdown products or,
b) the decrease in concentratio of the initial chemical


Summary of meeting with Professor Tony Cass

Summary of meeting with Dr. Anna Radomska


Enzymatic pH sensors: Email-correspondance with Anna

<showhide> From: Radomska, Anna
Sent: 01 August 2006 16:34
To: Vohra, Farah
Subject: RE: LB & M9
To read email click : __HIDER__ <hide> Dear All,

Considering the media compositions that you have just sent to me I would presumed there is a chance for the biosensors I have described to work (with the polymeric membrane pH electrodes as a internal sensors for the enzyme sensor).

The diffusion models of enzymatic pH sensors are the following: model Carasa-Janaty model Moynihana_Wanga model Eddowes model Varanasiego I am sure you can fine in the literature their description and all necessarily equations. However I can provide you also some reference if you want to.

Anna

</hide></showhide>



From: Radomska, Anna Sent: 01 August 2006 18:30 To: Sander, Christin Y M Subject: RE: Models for enzymatic pH sensors


I am so sorry but probably some of names in the particular models were misspelled so therefore you could not find them in the literature. It is a crazy day today. Any way I am sending you some references to the models given earlier. Good luck.

1. model Carasa-Janaty

S.D. Caras at all, Anal. Chem., 57 (1985) 1920 S.D. Caras at all, Anal. Chem., 57 (1985) 1924 S.D. Caras at all, Anal. Chem., 57 (1985) 1917

2. model Moynihan-Wanga H.J. Moynihan, N.H.L. Wang, Biotechnol. Prog., 3 (1987) 90

3. model Eddowes M.J. Eddowes at all, Sens. Actuators, 7 (1985) 15 M.J. Eddowes, Sens. Actuators, 7 (1985) 97 M.J. Eddowes, Sens. Actuators, 11 (1987) 256 G.K. Chandler, M.J. Eddowes, Sens. Actuators, 13 (1988) 223

4. model Varanasi S. Varanasi at all, AIChE J., 33 (1987) 558 S. Varanasi at all, Biosens. Bioelectron., 3 (1988) 269 S.O. Ogundiran at all, Biotechnol. Bioeng., 37 (1991) 160


From: Radomska, Anna Sent: 08 August 2006 10:50 To: Sander, Christin Y M Subject: RE: Models for enzymatic pH sensors


Hi Christin,

To be honest I do not think so it is possible to reach the sensitivity range you want (nM). Potentiometric methods are known to have the detection limit around 10-6M (especially for the ion-selective electrodes). In some of the cases of ion-selective electrodes you could go up to 10-9M (look in the literature for Pretsch E or Sokalski T) but personally I do not think you can do that for pH-selective sensors. The only one thing that comes into my mind at the moment is e.g. tri-enzyme sensitive electrode. It would be amperometric set-up and so you could go much lower in the limit of detection. The path of determination would be e.g.

choline esterase converts butyryl choline into butyric acid and choline in presence of water. Then choline is transformed in the presence of oxygen and choline oxidase into betaine and hydrogen peroxide. Then H2O2 is converted using peroxidase into water. Of course H2O2 is a electrochemically detectable.

I send you an example of paper were researches used that pathway. You would have to adjust it to your own expectations. It is just of an idea but maybe it could be useful for your purpose.

Anna



From: Radomska, Anna Sent: 09 August 2006 17:08 To: Sander, Christin Y M Subject:


Hi Christin,

I am sorry for a late answer but I have been a bit busy. Any way back to our business...As far as I remember the way to obtain the tri-enzymatic sensor was not that complicated (it is doable). Of course there is a danger that procedure could not work as more enzyme incorporated into the biosensors means more complications to get all the enzymes working also sensitivity will be diminish comparing to single enzyme biosensors. You should be aware of these problems. However personally I think that if you strictly follow the procedure of getting tri-enzyme sensor which was presented in the paper I have sent to you have a great chance to obtain positive results. Of course 4 weeks time it is plenty of time to build that type of sensor (probably you can do that over couple of hours only). The enzymes you need should be ordered as soon as possible so you could get them by mail in few days time. As for enzymes ordering please be carefull and check for the references in the recommended paper as well as it is very important to order exactly what they were using in their research work.

Good luck

Anna

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