Disentangling the effects of carbon monoxide and singlet oxygen in photoCORM-based nanomaterials for antimicrobial therapeutics

Photochemically CO-releasing molecules (photoCORMs) have recently raised high hopes in the fight against antibiotic-resistant bacteria, but the underlying mechanisms are still badly known. It has been hypothesized that, in addition to a direct biochemical activity of the photoCORMs, the generation of both carbon monoxide (CO) and singlet oxygen (1O2) plays a key role in the phototherapeutic efficiency. To clarify this point, nanomaterials that produce only CO, only 1O2, or both, were prepared by associating various photoCORMs with cellulose nanocrystals, which act as biocompatible and hydrophilic carriers. The antibacterial efficiency of these nanomaterials, measured on Staphylococcus aureus and Pseudomonas aeruginosa, was compared. This study is one more step towards the development of original and efficient photoantimicrobials.