| The fabrication of multi-analyte biotransducers continues to be a major technical challenge when the length scales of the individual transducer elements are on the order of microns Generation-3 (Gen-3) biosensors and advanced enzyme biofuel cells will benefit from direct electron transfer to oxidoreductases facilitated by single-walled carbon nanotubes (SWNTs). Direct electron transfer helps to mitigate errors from the instability in oxygen tension, eliminate use of a mediator and produce a device with low operating potential close to the redox potential of the enzymes. Supramolecular conjugates of SWNT-glucose oxidase (GOx-SWNT) may be produced via ultrasonic processing. Using a Plackett-Burman experimental design to investigate the process of tip ultrasonication, conjugate formation was investigated as a function of ultrasonication times and functionalized SWNTs of various tube lengths. Supramolecular conjugates formed from shorter, -OH functionalized SWNTs using longer sonication times gave the most favored combination for forming bioactive conjugates.;There has also been growing interest in the fabrication of CNT-enzyme supramolecular constructs that control the placement of SWNTs within tunneling distance of co-factors for enhanced electron transfer efficiency in generation 3 biosensors and advanced biofuel cells. These conjugate systems raise a series of questions such as: Which peptide sequences within the enzymes have high affinity for the SWNTs? And, are these high affinity sequences likely to be in the vicinity of the redox-active co-factor to allow for direct electron transfer? Phage display has recently been used to identify specific peptide sequences that have high affinity for SWNTs. Molecular dynamics simulations were performed to study the interactions of five discrete peptides with (16,0) SWNT in explicit water as well as with graphene. The end residues appear to dominate the progression of adsorption regardless of character. Sequences identified by phage display share some homology with key enzymes (GOx, lactate oxidase and laccase) used in biosensors and enzyme-based biofuel cells.;Furthermore, the role of pyrrole electropolymerization as an additive technique for the biofabrication of side-by-side biotransducers for glucose and lactate with minimum cross-talk was investigated along with an electrodeposited layer of Fe/Ni hexacyanoferrate to serve as peroxide mediator, decorated with the electropolymerized PPy-Enzyme biorecognition layer, characterized in vitro, and implanted into the trapezius muscle of a piglet ( Sus scrofa) hemorrhage model. Internal calibration, response under controlled hemorrhage conditions, and post-resection re-characterization were used to evaluate biotransducer performance. |
