Photoexcited Quantum Dots as Efficacious and Nontoxic Antibiotics in an Animal Model

Drug-resistant bacterial infections are a growing cause of illness and death globally. Current methods of treatment are not only proving less effective but also perpetuate evolution of new resistance. Here we propose, through an in vivo model, a new treatment for drug-resistant bacterial infection that uses semiconductor nanoparticles, called quantum dots (QDs), that can be activated by light to produce superoxide to specifically and effectively kill drug-resistant bacteria. We adapt this technology for in vivo assessment of toxicity and treatment of a subcutaneous infection in mice. As our cadmium telluride QDs with 2.4 eV band gap (CdTe-2.4 QDs) are activated by blue light, we engineered LED patches to adhere to the infection site on mice, thus providing the light necessary for the activity of injected QDs and treatment of the infection. We show, through assessment of body weight, histology, and inflammation and oxidative stress markers in serum, that the CdTe-2.4 QDs are nontoxic at concentrations that reduce drug-resistant bacterial viability in subcutaneous abscesses. Further, CdTe-2.4 QDs did not accumulate in the body and were safely excreted in urine via renal clearance. CdTe-2.4 QD treatment decreased abscess viability by as much as 7 orders of magnitude. We thus propose an alternative treatment approach for drug-resistant topical infections: the injection of a low concentration of QDs and the application of an adhesive patch comprising only an LED and a battery. This treatment could revolutionize last-resort treatments of burn wounds, cellulitis, and other skin infections.