State-of-the-art developments in carbon quantum dots (CQDs): Photo-catalysis, bio-imaging, and bio-sensing applications

Carbon quantum dots (CQDs), the intensifying nanostructured form of carbon material, have exhibited incredible impetus in several research fields such as bio-imaging, bio-sensing, drug delivery systems, optoelectronics, photovoltaics, and photocatalysis, thanks to their exceptional properties. The CQDs show extensive photonic and electronic properties, as well as their light-collecting, tunable photoluminescence, remarkable up-converted photoluminescence, and photo-induced transfer of electrons were widely studied. These properties have great advantages in a variety of visible-light-induced catalytic applications for the purpose of fully utilizing the energy from the solar spectrum. The major purpose of this review is to validate current improvements in the fabrication of CQDs, characteristics, and visible-light-induced catalytic applications, with a focus on CQDs multiple functions in photo-redox processes. We also examine the problems and future directions of CQD-based nanostructured materials in this growing research field, with an eye toward establishing a decisive role for CQDs in photocatalysis, bio-imaging, and bio-sensing applications that are enormously effective and stable over time. In the end, a look forward to future developments is presented, with a view to overcoming challenges and encouraging further research into this promising field.

TEMED Enhanced Photoluminescent Imaging of Human Serum Proteins by Quantum Dots After PAGE

Polyacrylamide gel electrophoresis (PAGE) has become one of the most powerful and widely used separation techniques for complex biological samples, whose traditional detection methods include organic dye or silver staining. For simple, convenient, and ultrasensitive detection of proteins after PAGE, a novel enhanced photoluminescent (PL) imaging method was developed. Thioglycolic acid (TGA)-capped CdTe quantum dots (QDs) and the enhancer reagent tetramethylethylenediamine (TEMED) were introduced, achieving the direct detection of various proteins in native 1-DE, 2-DE and SDS-PAGE. Here we describe the general protocol of TEMED enhanced PL imaging by QDs, including materials, practical procedures, and some notes.

The advanced role of carbon quantum dots in nanomedical applications

Carbon quantum dots (CQDs) have emerged as a potential material in the diverse fields of biomedical applications due to their numerous advantageous properties including fluorescence, water solubility, biocompatibility, low toxicity, small size and ease of modification, inexpensive scale-up production, and versatile conjugation with other nanoparticles. Thus, CQDs became a preferable choice in various biomedical applications such as nanocarriers for drugs, therapeutic genes, photosensitizers, and antibacterial molecules. Further, their potentials have also been verified in multifunctional diagnostic platforms, cellular and bacterial bio-imaging, development of theranostics nanomedicine, etc. This review provides a concise insight into the progress and evolution in the field of CQD research with respect to methods/materials available in bio-imaging, theranostics, cancer/gene therapy, diagnostics, etc. Further, our discussion is extended to explore the role of CQDs in nanomedicine which is considered to be the future of biomedicine. This study will thus help biomedical researchers in tapping the potential of CQDs to overcome various existing technological challenges.

Strongly tricolor-emitting carbon dots synthesized by a combined aging–annealing route and their bio-application

A novel way has been established to make the FCDs with a very high QY, high stability, low cell cytotoxicity, and outstanding performance as a fluorescence probe.

Rapid synthesis of nitrogen doped carbon dots and their application as a label free sensor array for simultaneous discrimination of multiple proteins

A label free sensor array for discriminating various proteins and distinguishing serums from rectal cancer patients, Alzheimer's disease patients and healthy people was developed by utilizing novel nitrogen doped carbon dots.

Large-scale synthesis of N-doped carbon quantum dots and their phosphorescence properties in a polyurethane matrix

An easy, large-scale synthesis of N-doped carbon quantum dots (CQDs) was developed by using isophorone diisocyanate (IPDI) as a single carbon source under microwave irradiation. The yield of raw N-doped CQDs was about 83%, which is suitable for industrial-scale production. A detailed formation mechanism for N-doped CQDs involving self-polymerization and condensation of IPDI was demonstrated. Moreover, the obtained N-doped CQDs can be homogeneously dispersed in various organic monomers and do not need toxic organic solvents as dispersing agents. This advantage expands the range of applications of CQDs in composites. The N-doped CQDs dispersed in polyurethane (PU) matrixes emit not only fluorescence but also phosphorescence and delayed fluorescence at room temperature upon excitation with ultraviolet (UV) light. Furthermore, the phosphorescence of CQD/PU composites is sensitive to oxygen and therefore, the obtained-CQDs could be exploited in the development of novel oxygen sensors.

One-pot microwave-assisted in situ reduction of Ag+and Au3+ions by Citrus limon extract and their carbon-dots based nanohybrids: a potential nano-bioprobe for cancer cellular imaging

In situreduction and microwave-assisted synthesis of Ag/C-dot and Au/C-dot nanohybrids using natural lemon extract for cancer cellular imaging applications.

Recent advances in carbon nanodots: synthesis, properties and biomedical applications

Herein, a mini review is presented concerning the most recent research progress of carbon nanodots, which have emerged as one of the most attractive photoluminescent materials. Different synthetic methodologies to achieve advanced functions and better photoluminescence performances are summarized, which are mainly divided into two classes: top-down and bottom-up. The inspiring properties, including photoluminescence emission, chemiluminescence, electrochemical luminescence, peroxidase-like activity and toxicity, are discussed. Moreover, the biomedical applications in biosensing, bioimaging and drug delivery are reviewed.

Carbon quantum dots and their applications

This review covers the progress in the research and development of carbon quantum dots and their applications in chemical sensing, biosensing, bioimaging, nanomedicine, photocatalysis and electrocatalysis.

Using metal nanoparticles as a visual sensor for the discrimination of proteins

The fluorescence of metal NPs is changed differently upon binding to a protein-in gel, forming a visual sensor for protein discrimination.