Carbon Quantum Dots Derived from Different Carbon Sources for Antibacterial Applications

Abstract

Nanoparticles possess unique features due to their small size and can be composed of different surface chemistries. Carbon quantum dots possess several unique physico-chemical and antibacterial activities. This review provides an overview of different methods to prepare carbon quantum dots from different carbon sources in order to provide guidelines for choosing methods and carbon sources that yield carbon quantum dots with optimal antibacterial efficacy. Antibacterial activities of carbon quantum dots predominantly involve cell wall damage and disruption of the matrix of infectious biofilms through reactive oxygen species (ROS) generation to cause dispersal of infecting pathogens that enhance their susceptibility to antibiotics. Quaternized carbon quantum dots from organic carbon sources have been found to be equally efficacious for controlling wound infection and pneumonia in rodents as antibiotics. Carbon quantum dots derived through heating of natural carbon sources can inherit properties that resemble those of the carbon sources they are derived from. This makes antibiotics, medicinal herbs and plants or probiotic bacteria ideal sources for the synthesis of antibacterial carbon quantum dots. Importantly, carbon quantum dots have been suggested to yield a lower chance of inducing bacterial resistance than antibiotics, making carbon quantum dots attractive for large scale clinical use.

Carbon Dots Synthesized from Cinchona Pubescens Vahl. An Efficient Antibacterial Nanomaterial and Bacterial Detector.

“…This effect could be attributed to Gram‐negative bacteria's inner and outer lipid membranes that have difficult intracellular access to CDs. Here, the antibacterial mechanism was associated with the ability of CDs to activate oxygen species on their surface and the electrostatic interactions between CDs and bacteria, where the microorganisms lost their ability to multiply and stop being metabolically active [12] …”

“…In particular, the bactericidal behavior of CDs can be attributed to two main mechanisms: the physicochemical characteristics associated with their inherent functional groups and the photoactivation produced after light irradiation [7] . In the first one, the antimicrobial mechanism is commonly associated with electrostatic interactions between CDs and bacterial surfaces and the ability of CDs to reactivate oxygen species (ROS) on the surface of the bacteria [1,12] …”

“…Considering that the method applied and the carbon source used are determinant factors for the CDs final physical, chemical, and functional properties, including their biocompatibility and antibacterial efficacy, [12] here, was used the hydrothermal method to synthesize CDs that are useful as an antibacterial nanomaterial and bacterial detector. Cinchona pubescens Vahl, [16] or red quinine, was used as a natural carbon source.…”

Recent advances of carbon dots as new antimicrobial agents

“…Thus, antibiotics, medicinal, and some biomass become the ideal precursors for synthesizing antibacterial CDs. 78 Table 1 summarizes the antibacterial activity, bacteriostatic species, and antibacterial conditions of different precursor synthetic CDs. The precursors are mainly natural biomass, antibiotic drugs, and chemicals.…”

“…CDs could preserve some carbon source characteristics during the carbonization process. Thus, antibiotics, medicinal, and some biomass become the ideal precursors for synthesizing antibacterial CDs 78 . Table 1 summarizes the antibacterial activity, bacteriostatic species, and antibacterial conditions of different precursor synthetic CDs.…”