Real-time in-situ monitoring of air interface Pseudomonas aeruginosa biofilms growth and its antibiotic susceptibility using a novel dual-chamber microfluidic device

Ye Zhang1,2, Hanieh Gholizadeh1,2, Paul Young2,4, Daniela Traini2,3, Shaokoon Cheng1, Hui Xin Ong2,3

1 School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, NSW, Australia

2 Woolcock Institute of Medical Research, Sydney, NSW, Australia.

3 Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia

4 Department of Marketing, Macquarie Business School, Macquarie University, Sydney, NSW, Australia


Pseudomonas aeruginosa (P. aeruginosa) biofilm colonizing and growing in the human respiratory tract is a known cause of reduced antimicrobial response in several chronic respiratory diseases. Despite the plethora of research, most biofilm models are cultured on a solid-liquid interface, and conventional biofilm characterization methods are usually destructive, time-consuming, and cost-ineffective. In this study, we developed a novel dual-chamber microfluidic device integrated with advanced electrochemical microelectrodes consisting of conical carbon fibre electrodes for culturing biofilm at the air-liquid interface (ALI). Using our novel chamber real-time and in-situ monitoring of biofilm’s viability by detecting the excretion of pyocyanin (PYO) was also performed. Using this device, the growth of P. aeruginosa biofilms was monitored over 48 h, and its viability after 6 h exposure to 50, 400, and 1600 µg/mL of ciprofloxacin solutions via direct treatment (drug delivered into the apical chamber) and indirect treatment (drug delivered into the basal chamber) was measured and compared and electrochemical results verified with the colony-forming unit (CFU) count method.

Key Message

Our study showed that P. aeruginosa biofilm developed at the ALI constantly excretes PYO, with a strong correlation between the PYO electrical signal and the viable bacteria number. This highlights the benefit of this approach for rapid and low-cost ALI biofilm study and antimicrobial tests. We also found that biofilms were eradicated more effectively when treatment was applied directly on their surface.