Development of a sensitive and specific 2-AA sensor for detecting Pseudomonas aeruginosa

Ravid Pollak Amoyal, Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Rehovot, Israel (ravid.pollak@mail.huji.ac.il)
Nofat Ovitz , Chemical Engineering, Sami Shamoon College Of Engineering, Be'er-sheva, Israel
Yael Helman, Plant Pathology And Microbiology, The Hebrew University Of Jerusalem, Rehovot, Israel
Dror Shamir, Nuclear Research Center, Be'er-sheva, Israel
Ariela Burg, Chemical Engineering, Sami Shamoon College Of Engineering, Be'er-sheva, Israel

Pseudomonas aeruginosa is an opportunistic human pathogen that accounts for a substantial proportion of all hospital-acquired infections, particularly those occurring in intensive care units. This bacterium is the most common cause of infections in burn-injuries and infections of the outer ear, as well as the most common respiratory pathogen in cystic fibrosis patients, leading to high rates of morbidity and mortality. Its ability to form persistent biofilms and antibiotic resistance makes infections difficult to treat, highlighting the importance of early detection. Studies have shown that 2-Aminoacetophenone (2-AA), a volatile molecule produced by P. aeruginosa, could serve as a valuable biomarker for detection of this pathogen. Previous studies in our lab demonstrated the efficient use of a bacterial whole-cell biosensor expressing a modified LuxR receptor for detection of 2-AA. The modified receptor designed in our lab could successfully detect P. aeruginosa in outer ear infections, however, for detection of P. aeruginosa infections in respiratory patients, a more sensitive sensor is required.

Utilizing electrochemistry holds a promise as a method for detecting the 2-AA molecule due to its oxidation properties. In order to improve the efficiency of the detection, an electrochemistry sensor was developed using dip pen nanolithographic (DPN) technique. By this technique, an ink including poly(styrenesulfonate) (PSS), ethylene glycol (EG) and copper nitrate were patterned on gold working electrodes as nanoclusters. The results indicated that 2-AA could be detected at very low concentrations of 1X10^-8 M. Notably, addition of copper nitrate to the nanoclusters patterned on the microelectrode raised the detection threshold of 2-AA even more. Besides the high detection efficiency, due to the controllable nanoclusters' large surface-to-volume ratio, which is a unique feature of DPN technique, the sensor requires small amounts of samples for detection. Thus, the described sensor may improve the identification of P. aeruginosa enabling timely detection and treatment.

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