The antibacterial efficacy of aluminum oxide nanostructures by hot water treatment for HVAC systems

A review of the current literature suggests that heating, ventilating, and air conditioning (HVAC) systems increase the risk of nosocomial infections if not properly maintained and frequently scrutinized via quality checks. Herein, we present a novel hot water treatment (HWT) to produce aluminum oxide (Al 2 O 2 ) nanostructures on the surface of aluminum (Al) sheets which are used as ductwork for HVAC systems. These aluminum oxide nanostructures, because of morphological changes undergone during hot water treatment, have the unique ability to inhibit bacteria growth using both physical and chemical mechanisms of action, i.e., contact cell membrane damage and reactive oxygen species (ROS). Air and surface analysis was done with an untreated ventilation system and the HWT ventilation system with Al 2 O 2 nanostructures. We observed ~ 460 Escherichia coli colonies on agar plates in untreated control samples, while almost no bacteria growth was observed on the agar plates placed in the nanostructured aluminum sheets. This research clearly demonstrates the effectiveness of this novel, inexpensive, and chemical-free method of producing aluminum oxide nanostructures to decrease bacteria growth in HVAC systems and in turn significantly improving the air quality. Graphic abstract