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Electrochemical Peptide-Based Environmental Sensors for the Detection of Uranium
ELECTROCHEMICAL PEPTIDE-BASED ENVIRONMENTAL SENSORS FOR THE DETECTION OF URANIUM Channing C. Stellato, Ph.D. University of Nebraska, 2020 Advisor: Rebecca Y. Lai Despite uranium’s importance in worldwide energy production, it is an emerging heavy metal contaminant due to its potential chemical and radioactive toxicity. Biosensors have demonstrated to be a sensitive, trace detecting and portable in-field method to detecting heavy metals such as uranium. In Chapter 2, we designed and employed a uranyl ion-specific peptide in the fabrication of an electrochemical peptide-based (E-PB) sensor. The peptide sequence originates from calmodulin, a Ca(II)-binding protein, modified with a phosphothreonine that enhances the sequence’s affinity for U(VI) over Ca(II), the native target. This study places emphasis on strategic utilization of non-standard amino acids in the design of metal ion-chelating peptides, which will further diversify the types of peptide recognition elements available for metal ion sensing applications. In Chapter 3, we discuss three uranyl-chelating peptides designed modeling after the uranyl binding pocket found in a mutated Ni(II)-dependent transcriptional repressor (NikR). All three thiolated and methylene blue (MB)-modified peptides, NikR-5, NikR-11, and NikR-15, contain only the five core amino acids responsible for target recognition, but the two longer peptides have either one or two additional glycine amino acids in between the five core amino acids. The goal of this study was to elucidate the effects of the additional glycine on probe flexibility on target recognition. This simple yet versatile approach to recreating binding pockets on electrode surfaces can potentially be employed in the design of other E-PB and surface-based metal ion sensors. Chapter 4 combines the results from the previous chapters, and we engineered four novel uranyl-chelating peptides for E-PB uranium sensors. Two of the four short (five amino acids) peptides integrated alternating phosphoserine and either aspartic acid or glycine amino acids in the sequence, while the other two peptides were the control peptides with serine instead of phosphoserine. This approach of designing a metal-chelating peptide recognition element demonstrated the that we can engineer the binding pocket on an electrode while incorporating non-standard amino acids to further enhance target recognition. To conclude, in Chapter 5 the phosphoserine peptide probe from Chapter 4 was shown to demonstrate dual sensing for an improved U(VI) E-PB sensor.
Stellato, Channing C, "Electrochemical Peptide-Based Environmental Sensors for the Detection of Uranium" (2020). ETD collection for University of Nebraska - Lincoln. AAI27955896.