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Superhydrophobic Surfaces as a Source of Airborne Singlet Oxygen through Free Space for Photodynamic Therapy
journal contribution
posted on 2020-03-31, 13:03 authored by David Aebisher, Dorota Bartusik-Aebisher, Sarah J. Belh, Goutam Ghosh, Andrés M. Durantini, Yang Liu, QianFeng Xu, Alan M. Lyons, Alexander GreerA superhydrophobic
(SH) sandwich system has been developed to enable
“contact-free” airborne singlet oxygen (1O2) delivery to a water droplet. The contact-free feature
means that the sensitizer is physically separated from the droplet,
which presents opportunities for photodynamic therapy (PDT). Trapping
of airborne 1O2 in a H2O droplet
residing on a lower SH surface was monitored with 9,10-anthracene
dipropionate dianion by varying distances to an upper 1O2-generating surface. Short distances of 20 μm
efficiently delivered airborne 1O2 to the droplet
in single-digit picomolar steady-state concentrations. Delivery decreases
linearly with distance, but 50% of the 1O2 steady-state
concentration is trapped at a distance of 300 μm from the generating
surface. The 1270 nm luminescence intensity was measured within the
SH sandwich system, confirming the presence of airborne 1O2. Physical quenching of 1O2 to
ground-state 3O2 by the water droplet itself
and both physical and chemical quenching of 1O2 by the water droplet containing the trap 9,10-anthracene dipropionate
dianion are observed. Unlike a majority of work in the field of PDT
with dissolved sensitizers, where 1O2 diffuses
short (hundreds of nanometers) distances, we show the delivery of
airborne 1O2 via a superhydrophobic surface
is effective through air in tenths of millimeters distances to oxidize
an organic compound in water. Our results provide not only potential
relevance to PDT but also surface bacterial inactivation processes.