HYBRID EVENT: You can participate in person at Orlando, USA or Virtually from your home or work.

6th edition of World Nanotechnology Conference

April 24-25, 2023

April 24 -26, 2023 | Orlando, USA
World Nano 2022

Cadmium Selenide Zinc Sulfide Quantum Dots on Saccharomyces cerevisiae: Their traffic routes and impact on endocytosis and exocytosis as well as on actin dynamics

Kyoungtae Kim, Speaker at Nanotechnology conferences
Missouri State University, United States
Title : Cadmium Selenide Zinc Sulfide Quantum Dots on Saccharomyces cerevisiae: Their traffic routes and impact on endocytosis and exocytosis as well as on actin dynamics


Quantum dots (QDs) are nano-sized semiconductor crystals that are highly utilized for research and medical purposes. Although recent studies have hinted at the toxicity of QDs, their impact on fungal cells remains unclear. Instead of relying on each biochemical assay to assess the harmful effects mediated by QDs, we have used RNAseq to create altered transcriptome profiles in response to QD treatment. We found that cadmium-based QDs leads to an alteration in the quantity of mRNA transcripts implicated in endocytosis, membrane fusion, sorting at the endosome, and endosome maturation. We then examined the trafficking route of red Cadmium Selenide Zinc Sulfide Quantum Dots (CdSe/ZnS QDs) as well as the phenotypic changes it induces in budding yeast cells. We tracked CdSe/ZnS QDs’ subcellular location by using yeast strains expressing different reference markers, including: plasma membrane reference marker GFP-2PH; early endocytosis vesicle reference marker Abp1- GFP; late Golgi/trans Golgi network reference marker FAPPI(PH)-GFP; and late endosome reference marker Vps10-GFP. We found that immediately after treating, CdSe/ZnS QDs interacted with yeast cells. However, CdSe/ZnS QD only co-localized with the plasma membrane reference marker after 3 hours of treatment, suggesting that CdSe/ZnS requires at least 3hrs to arrive at the plasma membrane. Around 6 hours after treatment, CdSe/ZnS was found at the plasma membrane, the early endocytosis vesicle, and the late Golgi/ trans Golgi network. QDs was never found co-localizing with the late endosome, suggesting that this is not a destination for CdSe/ZnS QDs intracellular trafficking. The rest of QDs’ intracellular trafficking route is in need of further investigation. We also treated yeast with different concentrations of CdSe/ZnS QDs (4µg/mL, 12µg/mL, 50µg/mL) and studied the integrity of actin cable upon QDs exposure. After 6 hours, a higher percentage of cells showed actin cable fragmentation in 12µg/mL and 50µg/mL of QDs treatment. Furthermore, we performed a recovery assay by removing QDs from the culture media. After 3 hours of incubation in QDs- free media, partial actin cable recovery was observed, hinting that the effect of QDs toxicity is reversible. Additionally, our viability assay data reveals that 6hrs of QDs exposure led to a significant decrease in the yeast sample’s optical density for all treatment concentrations. Interestingly, there was no significant difference in optical density between the treated samples and the control samples after 24 hours of treatment, indicating that QDs exposure only causes an inhibitory effect on yeast growth. We are currently assessing if QDs affect the membrane cargo Snc1 trafficking. Altogether, our research will provide new insights into the understanding of QD-mediated impacts on endocytosis and exocytosis.

Audience take-away:

  • Quantum dot chemical and physical properties, Quantum-dot impacts on the alteration of transcriptome, Transcriptome data-based hypothesis would be tested for more investigation on physiological impacts mediated by QDs.
  • Over the last five years, we have characterized the toxicity of several Engineered Nanomaterials (ENMs) that are not strictly regulated by the FDA or EPA in the United States. ENMs, being nano- sized particles (1-100 nm in diameter), have a significant number of applications and are currently used in healthcare as fluorescent probes and drug delivery vehicles.
  • They are also used in consumer products including textiles, cosmetics, and food. According to the EPA’s Information Gathering Rule, companies must report on the chemical identity, manufacturing methods, and exposure of any nanoscale materials they incorporate into their products. We provided gene expression data in yeast and mammalian cells exposed to nanoparticles, including carbon nanotubes, silver nanoparticles, metal oxide nanoparticles (ZnO and CuO), and quantum dots (CdSe/ZnS and InP/ZnS). With our results, we have identified thousands of genes and many cellular functions that were negatively impacted by ENM exposure.
  • Notably, our contributions provided novel insights into the field of ENM-toxicity by implementing state-of-the-art transcriptomic techniques (RNA- seq). Although these agencies have attempted to manage the risks of ENM exposure, there are legal frameworks preventing their regulation because of their poorly understood toxicity. Currently, we have a poor understanding of ENM-toxicity, however, we continue to use them.
  • These reasons are precisely why new government regulations and oversight are needed to responsibly use them. A big step in updating the current ENM government regulations is conducting a thorough investigation of their toxicity. Our findings on ENMs have ultimately helped us to understand how they are toxic through identifying changes in gene expression and what functions those genes are implicated in. Eventually, when we better understand how these extremely small materials behave, we can improve upon current regulation policies that will more efficiently protect public health and the environment.


Dr. Kyoungtae Kim is a professor at Missouri State University in Springfield, MO. He received his B.A. and M.A. in Biological Science at Kyungpook National University in Taegu, Korea. He went on to obtain his Ph.D. in Biology at Florida State University in Tallahassee, Florida, and completed his post-doc at Washington University in St. Louis, MO, where he studied cell biology and physiology. He is now located at Missouri State University where his research focuses on cellular trafficking and nanomaterial-based nanotoxicology.

His work has been published in the following international peer-reviewed journals: European Polymer Journal (quartile 1 in material chemistry), FEMS Yeast Research (quartile 1 in medicine), Cell Biology International (quartile 2 in medicine), Journal of Bioscience (quartile 2 in biological science), Biology of the Cell (quartile 1 in medicine), European Journal of Cell Biology (quartile 1 in medicine), Genes (quartile 1 in genetics, 5-year average), Nanomaterials (quartile 1 in material science), and Biomolecules (quartile 1 in biochemistry, 5-year average). All these journals are categorized into either Quartile 1 or Quartile 2, with Quartile 1 being the highest values and impacts in each field. It is noteworthy that his publication was cited by many top-tier journals including Nature, Science, and Current Opinion in Cell Biology.

Overall, his research results were disseminated in 227 presentations at internal and external scientific meetings, including 15 invited and 2 keynote presentations. Since 2015, 151 presentations co-authored with Missouri State University students have been made, and 10 invited talks including two keynote talks were made. Since 2015, 67% of his work has been at National/International and regional (state) conferences. Most of the remainder were at the institutional level meetings.

It is noteworthy that he was invited to several international conferences to present the results of his research as a keynote speaker or main presenter. For example, at the sixteenth International Conference on the Science and Application of Nanotube held in Japan in 2015, he presented his results with the theme of "Carbon Nanomaterials Negatively Affect Cell Viability and Gene Expression". In 2018 two other topics "Membrane Trafficking" and "Quantum dot-mediated Cell Toxicity" were presented by him as a keynote speaker in Montreal, Canada. He also served as a conference session moderator at the American Society for Cell Biology and was invited to serve as the World Yeast Congress Organizing Committee and Worlds Yeast Congress Session Chair. In 2019, his research was presented at the German-American Science Slam held in St. Louis, MO with the title “What doesn't kill you makes you...develop acute health problems down the road”. In 2020, he was invited to give his research talk at the EFIGIE Talks held virtually in Brazil with the title “Study of Intracellular Traffics and assessment of anticancer therapeutics and engineered nanoparticles on cells”. His research also has been covered by internal publications (2017, Mind’s Eye, MSU Alumni Magazine), local media (KSMU Ozark Public Radio STEM spots, 2017), and many news articles in the College of Natural and Applied Sciences NewsWatch articles.