Modified Geobacter Pilus Conductivity Diameter
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Solution Overview
Problem
There is a need for improved organic electrical conductors and methods for making and using them, as existing microbial nanowires have limitations in conductivity and stability.
Innovation Solution
The development of genetically modified electrically conductive pilus produced by Geobacter sulfurreducens, where specific aromatic amino acids in the PilA protein are substituted, such as tryptophan at positions F51 and Y57, to enhance conductivity and reduce diameter, resulting in significantly increased conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aromatic amino acids are substituted in the PilA protein to enhance conductivity, then conductivity increases significantly, but the nanowire diameter decreases
Solution Approach 1:
The patent applies parameter changes by substituting specific aromatic amino acids (tryptophan at positions F51 and Y57) in the PilA protein sequence. This chemical modification changes the physical and electrical parameters of the nanowire, resulting in enhanced conductivity (up to one million-fold increase) and reduced diameter simultaneously, resolving the technical contradiction between these two properties.
2Reliability
If genetically modified pilus is produced to increase conductivity, then electrical performance improves, but the complexity of production increases
Solution Approach 1:
The patent applies local quality by making targeted, localized modifications to the PilA protein sequence at specific positions (F51 and Y57) rather than globally modifying the entire protein or production system. This focused approach achieves enhanced conductivity while minimizing the complexity increase, as only specific amino acid residues are altered in the genetic sequence.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified pilus demonstrates a substantial increase in conductivity, up to one million-fold compared to unmodified nanowires, with a corresponding reduction in diameter, making them more suitable for electronic applications.
Implementation Method 1
The modified pilus demonstrates a substantial increase in conductivity, up to one million-fold compared to unmodified nanowires
Data Source
AI summary
Improved electrically conductive pili were generated from a natural pilus protein from the microorganism Geobacter sulfurreducens. Substituting a tryptophan for the phenylalanine at position F51 and a tryptophan for the tyrosine at position Y57 of the pilus monomer substantially increased the conductivity of the pili and reduced their diameter to 1.5 nm. Substantial improvements in conductivity were also achieved by substituting an additional tyrosine, histidine, and phenylalanine in the pilus monomer to mimic the monomer of Geobacter metallireducens, but the pili retained the typical Geobacter sulfurreducens wild-type diameter of 3 nm.