The objective of this project was to develop a DNA hybridization sensor that can detect the presence of E. coli and reveal its resistance to the drug gentamicin. This probe will enable rapid and user-friendly diagnostics of E. coli infections and analysis of bacterial gentamicin-susceptibility profile by interrogation of a fragment of E. coli 16S rRNA bearing a substitution in the gentamicin-resistant cells. The sensor is promising for the point-of-care use to provide a timely UTI diagnostic solution. A quick diagnosis of E. coli infection and antibiotic resistance is crucial for treatment. To design a hybridization probe, we proposed a split approach for target interrogation and catalytic activity of a peroxidase-like deoxyribozyme (PDz) as a signal reporter. PDz contains a series of guanine residues in a strand and has been shown to form a parallel guanine-quadruplex (G4). This G4, with the addition of a hemin cofactor, catalyzes the reaction similar to that of horseradish peroxidase. If a colorless organic indicator is added to the G4-PDz-hemin containing solution and mixed H2O2, a colored oxidation product is formed (e.g., a dark blue/green). The color change reports the presence of the catalytically active G4, which occurs only when the nucleotide sequence of the target is a perfect match. When the target is not a perfect match, for example, in the case of the drug-causing nucleotide substitution, the G4 does not form, and there is no color change. The probes tested in this paper show promising results of such a sensor by being able to catalyze the described colorimetric reaction to generate a strong signal in the presence of a "gentamicin-susceptible" target and show selectivity against the "gentamicin-resistant" target.

Thesis Completion




Thesis Chair

Gerasimova, Yulia


Sui, Ning


Bachelor of Science (B.S.)


College of Medicine


Burnett School of Biomedical Sciences

Degree Program

Biomedical Sciences



Access Status

Campus Access

Length of Campus-only Access

1 year

Release Date