2020 journal article

Carbon quantum dots: A bright future as photosensitizers for in vitro antibacterial photodynamic inactivation

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY, 206.

By: X. Nie*, C. Jiang n, S. Wu*, W. Chen*, P. Lv*, Q. Wang*, J. Liu*, C. Narh* ...

co-author countries: China 🇨🇳 United States of America 🇺🇸
author keywords: Antibacterial; Carbon quantum dots; Escherichia coli; Photodynamic inactivation; Staphylococcus aureus
Source: Web Of Science
Added: April 27, 2020

Carbon nanomaterials have increasingly gained the attention of the nano-, photo- and biomedical communities owing to their unique photophysical properties. Here, we facilely synthesized carbon quantum dots (CQDs) in a one-pot solvothermal reaction, and demonstrated their utility as photosensitizers for in vitro antibacterial photodynamic inactivation (aPDI). The bottom-up synthesis employed inexpensive and sustainable starting materials (citric acid), used ethanol as an environmentally-friendly solvent, was relatively energy efficient, produced minimal waste, and purification was accomplished simply by filtration. The CQDs were characterized by both physical (TEM, X-ray diffraction) and spectroscopic (UV–visible, fluorescence, and ATR-FTIR) methods, which together confirmed their nanoscale dimensions and photophysical properties. aPDI studies demonstrated detection limit inactivation (99.9999 + %) of Gram-negative Escherichia coli 8099 and Gram-positive Staphylococcus aureus ATCC-6538 upon visible light illumination (λ ≥ 420 nm, 65 ± 5 mW/cm2; 60 min). Post-illumination SEM images of the bacteria incubated with the CQDs showed perforated and fragmented cell membranes consistent with damage from reactive oxygen species (ROS), and mechanistic studies revealed that the bacteria were inactivated by singlet oxygen, with no discernable roles for other ROS (e.g., superoxide or hydroxyl radicals). These findings demonstrated that CQDs can be facilely prepared, operate via a Type II mechanism, and are effective photosensitizers for in vitro aPDI.