Carbon quantum dots (CQDs; luminescent carbon nanoparticles, size < 10 nm) have attracted much attention with respect to their eco-friendliness and multi-functionality.
Carbon dots (or carbon quantum dots) are small (less than 10 nm) and luminescent carbon nanoparticles with some form of surface passivation. As an emerging class of nanomaterials, carbon dots have found wide applications in medicine, bioimaging, sensing, electronic devices, and catalysis. In this review, we focus on the recent advancements of carbon dots for sensing and killing microorganisms, including bacteria, fungi, and viruses. Synthesis, functionalization, and a toxicity profile of these carbon dots are presented. We also discuss the underlying mechanisms of carbon dot-based sensing and killing of microorganisms.
Carbon dots were originally found and reported as surface-passivated small carbon nanoparticles, where the effective surface passivation was the chemical functionalization of the carbon nanoparticles with organic molecules. Understandably, the...
The commercially acquired aqueous solution of “carbon quantum dots” sample was evaluated by optical absorption and fluorescence emission methods; in reference to aqueous dispersed small carbon nanoparticles and representative carbon dots prepared from chemical functionalization of the carbon nanoparticles. The results suggest a very low content of carbon that is associated with nanoscale carbon particles/domains in the as-supplied sample; and likely significant contamination by dye-like species/mixtures. In the absence of any information on the synthesis and history of the commercial sample, the possible cause of the contamination was illustrated by an example on similar dye formation in the one-pot carbonization synthesis of “red carbon dots” from citric acid–formamide precursor mixtures under too mild processing conditions that were insufficient for the intended carbonization. The negative impacts to the carbon dots research field by the apparent proliferation and now commercial availability of carbon-deficient or even largely carbon-less “carbon quantum dots”, which are more susceptible to dye contamination or dominance, are discussed.
Carbon nanoparticles are a class of materials with extraordinary properties. In the past three decades, four major types of carbon nanoparticles were synthesized and investigated: fullerenes, carbon nanotubes, graphene and carbon quantum dots. One of the main properties of such materials is their hydrophobic nature. At the same time, Langmuir?Blodgett (LB) method the for deposition of thin films of hydrophobic materials provides the possibility to design thin films of different carbon-based nanoparticles with special architectures and features enabling their usage in various fields, particularly in electronics and biomedicine. In this review, the state of art of LB thin films of four types of carbon-based nanoparticles and their application in electronics and biomedicine are presented. The breakthrough in this field was finally achieved by application of carbon quantum dots soluble in solvents optimized for LB deposition.
Carbon quantum dots (CDs) are a novel class of fluorescent carbon nanoparticles and nanomaterials with fascinating properties, which have attracted worldwide attention and have been applied in different fields during the last decade.
The photoluminescence of carbon quantum dots synthesized from natural honey and mixtures of honey and sugar has been studied. An increase in the sugar content leads to a decrease in the photoluminescence intensity without changing the shape of the luminescence spectrum of these quantum dots aqueous solutions, which is associated with a decrease in the yield of their synthesis in the sugar presence. The discovered effect can be used to detect sugar in honey. When examining five different market samples of flower honey using this method, two of them showed a significant decrease in the photoluminescence intensity. A laboratory test for compliance with GOST 19792-2017 Standard requirements established an excess of the sucrose content in these samples. Luminescent determination of sugar in honey does not require complicated equipment and can be used to develop a new analytical method for determining the sugar content in counterfeit natural honey.
Role of alkan-1-ol solvents in the synthesis of yellow luminescent carbon quantum dots (CQDs): van der Waals force-caused aggregation and agglomeration