Comparison of Toxicity and Cellular Uptake of CdSe/ZnS and Carbon Quantum Dots for Molecular Tracking Using ISaccharomyces cerevisiae/I as a Fungal Model

• Published in: Nanomaterials (Basel, Switzerland) Vol. 14; no. 1
• Main Authors: Färkkilä, Sanni M. A, Mo, Jaaniso, Raivo, Kahru, Anne, Kiisk, Valter, Kikas, Arvo, Kozlova, Jekaterina, Kurvet, Imbi, Mäeorg, Uno, Otsus, Maarja, Kasemets, Kaja
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.12.2023
• Subjects: Analysis; Brewer's yeast; Chemical synthesis; Cysteine; Properties; Quantum dots; Selenides; Sulfides; Zinc compounds; Estonia
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano14010010

Plant resource sharing mediated by mycorrhizal fungi has been a subject of recent debate, largely owing to the limitations of previously used isotopic tracking methods. Although CdSe/ZnS quantum dots (QDs) have been successfully used for in situ tracking of essential nutrients in plant-fungal systems, the Cd-containing QDs, due to the intrinsic toxic nature of Cd, are not a viable system for larger-scale in situ studies. We synthesized amino acid-based carbon quantum dots (CQDs; average hydrodynamic size 6 ± 3 nm, zeta potential −19 ± 12 mV) and compared their toxicity and uptake with commercial CdSe/ZnS QDs that we conjugated with the amino acid cysteine (Cys) (average hydrodynamic size 308 ± 150 nm, zeta potential −65 ± 4 mV) using yeast Saccharomyces cerevisiae as a proxy for mycorrhizal fungi. We showed that the CQDs readily entered yeast cells and were non-toxic up to 100 mg/L. While the Cys-conjugated CdSe/ZnS QDs were also not toxic to yeast cells up to 100 mg/L, they were not taken up into the cells but remained on the cell surfaces. These findings suggest that CQDs may be a suitable tool for molecular tracking in fungi (incl. mychorrhizal fungi) due to their ability to enter fungal cells.