Facultad de Ciencias

Plasmonic Hot-Electron Reactive Oxygen Species Generation: Fundamentals for Redox Biology

For decades, the possibility to generate Reactive Oxygen Species (ROS) in biological systems through the use of light was mainly restricted to the photodynamic effect:
the photoexcitation of molecules which then engage in charge- or energy-transfer to
molecular oxygen (O2) to initiate ROS production. However, the classical photodynamic
approach presents drawbacks, like per se chemical reactivity of the photosensitizing
agent or fast molecular photobleaching due to in situ ROS generation, to name a few.
Recently, a new approach, which promises many advantages, has entered the scene:
plasmon-driven hot-electron chemistry. The effect takes advantage of the photoexcitation
of plasmonic resonances inmetal nanoparticles to induce a new cohort of photochemical
and redox reactions. These metal photo-transducers are considered chemically inert and
can undergo billions of photoexcitation rounds without bleaching or suffering significant
oxidative alterations. Also, their optimal absorption band can be shape- and size-tailored
in order to match any of the near infrared (NIR) biological windows, where undesired
absorption/scattering areminimal. In thismini review, the basicmechanisms and principal
benefits of this light-driven approach to generate ROS will be discussed. Additionally,
some significant experiments in vitro and in vivo will be presented, and tentative new
avenues for further research will be advanced.

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