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

Abstract

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.

Photoactivated Indium Phosphide Quantum Dots Treat Multidrug-Resistant Bacterial Abscesses In Vivo

“…However, deeper red light of longer than 700 nm wavelength could be used for treatment of infections that require greater tissue penetration. These InP QDs also represent a marked improvement from previously studied superoxide-generating CdTe QDs, , which are activated by blue to green light, a range of wavelengths with poor transmission through skin. , QDs activated by NIR light are therefore well suited for in vivo application.…”

“…We have previously shown that superoxide-generating QDs are nontoxic and efficacious in a murine abscess infection model using drug-resistant bacteria . These studies were conducted using cadmium telluride (CdTe) QDs ,− and thus were limited by both the risk of material toxicity due to presence of cadmium and limitations in photoactivation due to the necessity for high-energy light wavelengths.…”

“…These studies were conducted using cadmium telluride (CdTe) QDs ,− and thus were limited by both the risk of material toxicity due to presence of cadmium and limitations in photoactivation due to the necessity for high-energy light wavelengths. Despite that, doses of 600 nM CdTe QDs were able to reduce bacterial viability by as much as 7 orders of magnitude without causing a toxicity response in mice . Here, we use InP QDs to develop a light-activated treatment against MDR bacteria.…”

Special Issue: Nanomedicine Advances in Infectious Disease

“…Next, Chatterjee et al 8 literally shed light on the use of quantum dots (QDs) as an alternative to traditional small molecule antibiotics for treating drug-resistant bacterial infections. The authors developed cadmium telluride QDs with a 2.4 eV band gap that could be activated by blue light from LEDs to produce superoxide that kills drug-resistant bacteria.…”

Light-activated quantum dot potentiation of antibiotics to treat drug-resistant bacterial biofilms

“…[15][16][17][18][19] The cadmium telluride (CdTe) QDs characterized by Courtney et al and used in these experiments are approximately 2-4 nm in diameter with a 2.4 eV bandgap and conduction band aligned with the reduction potential of dissolved oxygen. 11,12,20 These features make CdTe-2.4 eV QDs excitable by #517 nm light to produce only localized superoxide which specically targets bacteria. 11,13,21 Only nanomolar concentration of CdTe-2.4 eV QDs are necessary to kill bacteria, making them safe and nontoxic to mammalian cells.…”