Carbon Dots: An Emerging Smart Material for Analytical Applications

Abstract

Carbon dots (CDs) are optically active carbon-based nanomaterials. These nanomaterials can change their light emission properties in response to various external stimuli such as pH, temperature, pressure, and light. The CD’s remarkable stimuli-responsive smart material properties have recently stimulated massive research interest for their exploitation to develop various sensor platforms. Herein, an effort has been made to review the major advances made on CDs, focusing mainly on its smart material attributes and linked applications. Since the CD’s material properties are largely linked to their synthesis approaches, various synthesis methods, including surface passivation and functionalization of CDs and the mechanisms reported so far in their photophysical properties, are also delineated in this review. Finally, the challenges of using CDs and the scope for their further improvement as an optical signal transducer to expand their application horizon for developing analytical platforms have been discussed.

Effects of Heteroatom Doping of Carbon Dots from Sugar on Optical Properties, Phenolic Content, Antioxidant Activity, Photostability, and Cytotoxicity

“…The enhancement in QY is possibly because nitrogen‐containing groups are good electron donors and can introduce electronic states that are more favorable for radiative decay [54–55] . Furthermore, it was previously found that the nitrogen‐containing groups could act as surface passivating agents, which trapped surface electrons for more efficient radiative recombination, thus considerably enhancing the photoluminescence in N‐CDs [56–60] …”

“…[54][55] Furthermore, it was previously found that the nitrogen-containing groups could act as surface passivating agents, which trapped surface electrons for more efficient radiative recombination, thus considerably enhancing the photoluminescence in N-CDs. [56][57][58][59][60] From these results, we can conclude that photoluminescence of CDs from table sugar can be tuned by heteroatom doping. All CDs exhibited excitation-dependence photoluminescence (Figure S2).…”

State of Art Technology: Synthesis of Carbon Dots and Their Potential Applications in Biomedical, Research and Environmental Remediation

“…The chemical property of CQD is highly important among all the properties due to their photoluminescence phenomenon, chirality and UV-absorption [122]. Typically, CDs can act as both electron acceptors and donors [123]. All these properties are discussed below in detail by citing relevant literature.…”

“…Although using excellent properties such as low toxicity [140] and good biocompatibility makes CQDs ideal materials for bioimaging, biosensors and drug delivery applications, CQDs can, however, offer advantages in catalysis, sensors and optronics based on their excellent optical and electronic properties [123].…”

“…Bioimaging is a technique for imaging and direct observation of biological methods in real-time which is often used to obtain the information from the 3D morphology of the observed specimen from the outside, i.e., without physical interference [123]. Because of its fluorescence emissions and biocompatibility, CQDs are being used for bioimaging.…”