Germicidal glowsticks: Side-emitting optical fibers inhibit Pseudomonas aeruginosa and Escherichia coli on surfaces

This paper investigates using UV-C side-emitting optical fibers (SEOFs) to prevent growth of pathogenic bacteria (Pseudomonas aeruginosa and Escherichia coli) on nutrient-rich surfaces. Attaching a SEOF to a single 265 nm light emitting diode (LED) increases irradiation area by >1000x and provides continuous low-irradiance of UV-C light to a large surface area. A zone-of-inhibition protocol was developed to quantify bacterial growth prevention on an agar plate around one SEOF. The inhibition zone increased linearly with irradiance time until achieving a maximum inhibition zone of 2.5 to 3 cm, which received ~ 4.3 mJ/cm² of 265 nm light in 2 hours. The surviving lawn edge bacterial colonies did not develop UV resistance after two generations of exposure. The agar plate remained bio-available after UV exposure, and bacteria could be grown on pre-illuminated area in the absence of UV-C light. Whereas we previously demonstrated SEOFs can inactivate planktonic bacteria, herein we show the ability of SEOFs to prevent bacteria growth on surfaces. This is the first step towards developing technologies with multiple SEOFs to inhibit biofilm growth on surfaces, which is a ubiquitous challenge across multiple applications from membrane surfaces to surfaces in pipes or water storage systems.