Carbon Dots for Targeted Bioimaging and Sensing

Carbon dots are quasi-spherical carbon nanoparticles, typically below 10 nm in diameter, endowed with strong, tunable photoluminescence and excellent chemical stability. Their abundant surface functional groups enable facile conjugation of targeting ligands—such as folic acid, aptamers or polysaccharides—while heteroatom doping and controlled synthesis yield high quantum yields and photostability. Owing to their small size, low toxicity and aqueous dispersibility, carbon dots have emerged as versatile tools for fluorescence-guided imaging of cancer cells, cellular organelles and live tissues, as well as for the ultrasensitive detection of biomolecules, metal ions and pathogens. Integration into hybrid systems—combining magnetic or plasmonic components—extends their functionality to magnetic separation and multimodal sensing. Current challenges focus on scalable, reproducible synthesis, comprehensive understanding of in vivo fate and long-term biocompatibility, and the translation of laboratory prototypes into point-of-care diagnostic and theranostic platforms.

Research from Nature Portfolio

High-quantum-yield carbon dots synthesised from folic acid via a one-step hydrothermal route exhibit quantum yields above 90% and exploit inherent folate residues for receptor-mediated uptake by cancer cells, producing bright, stable fluorescence for targeted tumour imaging. A DNA aptamer (AS1411) wrapped around water-soluble carbon dots forms a ‘signal-on’ spectrofluorometric probe: upon binding nucleolin on cancer cells, the aptamer releases the dots, triggering a fluorescence increase that enables detection down to a few cells. Separately, fluorescent polydopamine nanoparticles prepared by ethylenediamine-induced degradation selectively label neuromast hair cells in live zebrafish, providing a minimally toxic in vivo indicator for sensory cell imaging and viability assays.

Carbon Dots for Targeted Bioimaging and Sensing publication trend

The graph below shows the total number of articles in carbon dots for targeted bioimaging and sensing across all publications each year (not limited to Nature Index journals).

Technical terms

Carbon dots (CDs): Fluorescent carbon nanoparticles (<10 nm) with diverse surface functionalities.

Quantum yield: Ratio of emitted to absorbed photons, measuring fluorescence efficiency.

Hydrothermal synthesis: High-temperature, high-pressure aqueous method for nanoparticle fabrication.

Aptamer: Short, single-stranded nucleic acid that binds selectively to a molecular target.

Photoluminescence: Light emission following photon absorption, central to fluorescence imaging.

Bioconjugation: Chemical linkage of biomolecules (e.g. ligands) to nanoparticles for targeted delivery.

Biocompatibility: Compatibility with living systems, minimising toxicity and immune response.

References

1. Carbon Nanomaterial Fluorescent Probes and Their Biological Applications. Chemical Reviews (2024).
2. Synthesis of Luminescent Carbon Dots with Ultrahigh Quantum Yield and Inherent Folate Receptor-Positive Cancer Cell Targetability. Scientific Reports (2018).
3. Bacterial detection with amphiphilic carbon dots. Analyst (2015).
4. Hyaluronan-Conjugated Carbon Quantum Dots for Bioimaging Use. ACS Applied Materials & Interfaces (2020).
5. Carbon Dots-AS1411 Aptamer Nanoconjugate for Ultrasensitive Spectrofluorometric Detection of Cancer Cells. Scientific Reports (2017).
6. Fluorescent polydopamine nanoparticles as a probe for zebrafish sensory hair cells targeted in vivo imaging. Scientific Reports (2018).
7. Green sonochemistry assisted synthesis of hollow magnetic and photoluminescent MgFe 2 O 4 –carbon dot nanocomposite as a sensor for toxic Ni( ii ), Cd( ii ) and Hg( ii ) ions and bacteria. RSC Advances (2021).