David J. Press, Todd C. Sutherland and Belinda Heyne.
Antibiotic resistance is a serious threat endangering populations everywhere in the world. The misuse of antibiotic prescriptions to treat viral infections coupled with the inherent ability of pathogenic bacteria to form surface-attached communities, known as biofilms, are two factors contributing to the current antibiotic resistance crisis. Adding to the crisis is an alarmingly reduced production of new antimicrobial drugs. While new health policies are put in place to handle the current crisis, there is a critical need to develop efficient alternative methods to treat bacterial infections. An ideal method will see the eradication of microbes without risk for developing resistance. Due to a mode of action markedly different from typical antibiotic drug, photodynamic therapy (PDT) has been suggested as a potential treatment for bacterial infection. PDT involves the use of a photosensitizer, which upon activation with light, generates toxic reactive oxygen species, such as singlet oxygen. Singlet oxygen is an “energized form” of molecular oxygen, and is toxic to living organisms. This toxicity is due to singlet oxygen’s high reactivity towards biomolecules including proteins, DNA and lipids. Cellulose nanocrystals and their inherent biocompatibility and ease of chemical functionalization make them ideal candidates as templates for engineering new bionanomaterials for the PDT treatment of bacterial infections. To this end, we have attached successfully an FDA-approved photosensitizer on the surface of cellulose nanocrystals. The new bionanomaterial has been fully characterized by conventional spectroscopic techniques and its ability to generate singlet oxygen has been proven in vitro.