Team:UC Davis/Electrochemistry

From 2014.igem.org

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<p> Once the electrode type was chosen on the basis of its sensitivity, the analytical solution components were optimized to maintain maximum selectivity for NADH. Any solution component introduced in the original Olive Oil Sample, aldehyde extraction processes, or the enzyme purification step could have theoretically impacted the electrode’s sensitivity for NADH. Collaboration with the protein engineering team led to the development of a solution mix that enabled selective detection of enzyme generated NADH in a solution with a large background  of  various solution components.  
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Once the electrode type was chosen on the basis of its sensitivity, the analytical solution components were optimized to maintain maximum selectivity for NADH. Electrochemical systems are inherently sensitive to the addition of electroactive compounds to the solution being analyzed. In our biosensor, we needed to be able to combine an olive oil extraction solution containing aldehydes, purified protein, and buffer for our system to function properly. All of these system components had the potential to introduce electroactive solution components that would increase noise, or inhibit our system’s ability to see a signal related to NADH generation. Thus, it was necessary to optimize the protein purification as well as extraction buffers to allow unhindered electrode function. Additionally, we optimized the system to maintain a proper NADH signal to system noise ratio so as to allow for effective NADH detection and system function.  
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These interference is often shown in our graph as “NOISE”. In order to examine each and individual noise factor, we have divided our experiment into two parts:
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<u>Optimizing solution</u><br><br>
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Optimizing solution includes: <br><br>
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1) Testing how each and every chemical in the testing solution affects the signals collected from electrode.<br>
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2) Deciding on concentration of each chemical which would minimizing the noise level.<br><br>
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<p>To find more about our system optimization,  
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<u>Optimizing system</u><br><br>
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<a href="https://2014.igem.org/Team:UC_Davis/Electrochemistry_System_Optimization">
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This part of experiment deals with many internal and external possibilities that may or may not created the “noise” in our system. Some of our solutions has not shown any consistent improvement of decreasing these noise; however,few displays some improvement in getting rid of these noise.  <br><br>
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click here
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</a>.  
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To find more about our system optimization, <a href="https://2014.igem.org/Team:UC_Davis/Electrochemistry_System_Optimization">click here</a>.  
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Revision as of 23:14, 16 October 2014

UC Davis iGEM 2014

Electrode Choice

Electrode Choice

System Optimization

System Optimization

Coupling Enzymes

Coupling Enzymes

Having settled on NAD+ dependent Aldehyde Dehydrogenases as our method of differentiating between aldehydes, we needed to develop an efficient electrode system to detect enzyme activity via NADH. We acquired, selected, and optimized an electrode setup for the detection of NADH at low concentrations in a complex solution. Additionally, we demonstrated the ability of the electrode setup to detect enzyme generated NADH over time, and thereby functionally deconvolute aldehyde profiles within a sample.

Electrode Choice

We developed our Electrode System to be:

  • Sensitive: have a low limit of detection for NADH
  • Reactive: Detect NADH with high linear range
  • Selective: Be robust to any possible solution components
  • Affordable: Cost accessible to the average consumer
  • Efficient: Use a low sample volume
  • Compatible: Be compatible with our, as well as other potentiostats
  • Portable


We tested three screen printed base electrode types, and five different working electrode modification schemes in order to achieve the requisite sensitivity for our system. We settled on Dropsens screen printed #610 Electrodes, depicted above. To find out more about our electrode selection process, click here.

System Optimization

Once the electrode type was chosen on the basis of its sensitivity, the analytical solution components were optimized to maintain maximum selectivity for NADH. Electrochemical systems are inherently sensitive to the addition of electroactive compounds to the solution being analyzed. In our biosensor, we needed to be able to combine an olive oil extraction solution containing aldehydes, purified protein, and buffer for our system to function properly. All of these system components had the potential to introduce electroactive solution components that would increase noise, or inhibit our system’s ability to see a signal related to NADH generation. Thus, it was necessary to optimize the protein purification as well as extraction buffers to allow unhindered electrode function. Additionally, we optimized the system to maintain a proper NADH signal to system noise ratio so as to allow for effective NADH detection and system function.

To find more about our system optimization, click here .

Coupling Enzymes

Once enzymes have been engineered and successfully displayed their specificity, our mission is to come up with the most suitable solution and enzyme ratio to get the most clear signals from our electrode. This includes:

Measuring enzyme activity in our system:

Searching for satisfactory range of concentration for enzyme to be added to our solution in order to demonstrate the signals that are coherent to the enzyme kinetics data.

Demonstrate enzyme specificity measured from our system device:

Prove that our system and device display the same specificity of each enzyme as we previously seen on the enzyme kinetics data.

To find out more about our enzyme testing, click here.

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