Towards Single Particle Tracking in Simulated Microgravity-Grown Biofilms 73 Materials and Methods Three commercially available QDs were purchased for characterization: Thermo Fisher QdotTM605 ITKTMAmino (PEG) Quantum Dots (Q21501MP), Ocean NanoTech PEG Quantum Dots 620 nm (QMG620-02), and Strem 620 nm CdSe/ZnS core/shell quantum dots with carboxylic acid (48-1640). TEM images of the QDs were taken on a Talos F200X TEM (Fig. 2). The concentration of particles in the images is arbitrary. Diluted samples were prepared on lacey carbon-supported 300 mesh copper TEM grids. QD Feret diameters (maximum caliper length) of representative samples were measured with ImageJ. Preliminary Size Characterization Results Thermo Fisher QDs had an average Feret diameter ±standard deviation of 10.3 ±1.4 nm. Ocean NanoTech QDs had an average Feret diameter ±standard deviation of 12.4 ±3.8 nm. Strem QDs had an average Feret diameter ±standard deviation of 8.6±2.1 nm. Observational analysis of the TEM images (Fig. 2), confirmed by measured values, shows that the Thermo Fisher QDs are highly uniform in size and shape but are triangular, while the Ocean Nanotech QDs are nonuniform in both size and shape. The Strem QDs are uniform in both size and shape and are the most spherical of the three samples, potentially making them the most desirable for tracking and subsequent analysis. Acknowledgements and Funding Sources The authors are grateful for the TEM images taken by experts in the University of Kentucky Electron Microscopy Core and to the National Science Foundation Graduate Research Fellowship Award No. 2239063 and National Science Foundation CAREER Award Grant No. 2045853 for providing funding. References 1. H. C. Flemming, T. R. Neu, and D. J. Wozniak, “The EPS matrix: the “house of biofilm cells”,” (in eng), J Bacteriol, vol. 189, no. 22, pp. 7945-7, Nov 2007, doi: 10.1128/jb.00858-07. 2. R. Mirghani et al., “Biofilms: Formation, drug resistance and alternatives to conventional approaches,” (in eng), AIMS Microbiol, vol. 8, no. 3, pp. 239-277, 2022, doi: 10.3934/microbiol.2022019. 3. B. Kowalska-Krochmal and R. Dudek-Wicher, “The Minimum Inhibitory Concentration of Antibiotics: Methods, Interpretation, Clinical Relevance,” (in eng), Pathogens, vol. 10, no. 2, Feb 4 2021, doi: 10.3390/pathogens10020165. 4. A. Checinska Sielaff et al., “Characterization of the total and viable bacterial and fungal communities associated with the International Space Station surfaces,” Microbiome, vol. 7, no. 1, p. 50, 2019/04/08 2019, doi: 10.1186/s40168-019-0666-x. 5. S. Xiao, K. J. Venkateswaran, and S. C. Jiang, “The risk of Staphylococcus skin infection during space travel and mitigation strategies,” Microbial Risk Analysis, vol. 11, pp. 23-30, 2019/04/01/ 2019, doi: https://doi.org/10.1016/j.mran.2018.08.001. 6. H. Jang, S. Y. Choi, and R. J. Mitchell, “Staphylococcus aureus Sensitivity to Membrane Disrupting Antibacterials Is Increased under Microgravity,” (in eng), Cells, vol. 12, no. 14, Jul 21 2023, doi: 10.3390/cells12141907. 7. “Human Research Program Integrated Research Plan,” NASA, 07/2023 2023. 8. P. Flores, J. Luo, D. W. Mueller, F. Muecklich, and L. Zea, “Space biofilms - An overview of the morphology of Pseudomonas aeruginosa biofilms grown on silicone and cellulose membranes on board the international space station,” (in eng), Biofilm, vol. 7, p. 100182, Jun 2024, doi: 10.1016/j.bioflm.2024.100182. 9. L. Zea et al., “Design of a spaceflight biofilm experiment,” Acta Astronaut, vol. 148, pp. 294-300, Jul 2018, doi: 10.1016/j.actaastro.2018.04.039. 10. B. H. Pyle, G.A. McFeters, S.C. Broadaway, C.K. Johnsrud, R.T. Storga, and J. Borkowski, “Bacterial Growth on surfaces and in suspensions. In Biorack on Spacehab,” Biological Experiments on Shuttle to Mir Missions 03, 05, and 06. European Space Agency SP-1222, 1999. 11. R. J. McLean, J. M. Cassanto, M. B. Barnes, and J. H. Koo, “Bacterial biofilm formation under microgravity conditions,” (in eng), FEMS Microbiol Lett, vol. 195, no. 2, pp. 115-9, Feb 20 2001, doi: 10.1111/j.1574-6968.2001.tb10507.x. 12. W. Kim et al., “Spaceflight promotes biofilm formation by Pseudomonas aeruginosa,” (in eng), PLoS One, vol. 8, no. 4, p. e62437, 2013, doi: 10.1371/journal.pone.0062437. 13. P. Flores et al., “Preparation for and performance of a Pseudomonas aeruginosa biofilm experiment on board the International Space Station,” Acta Astronautica, vol. 199, pp. 386-400, 2022/10/01/ 2022, doi: https://doi.org/10.1016/j.actaastro.2022.07.015. 14. L. C. Powell et al., “Quantifying the effects of antibiotic treatment on the extracellular polymer network of antimicrobial resistant and sensitive biofilms using multiple particle tracking,” npj Biofilms and Microbiomes, vol. 7, no. 1, p. 13, 2021/02/05 2021, doi: 10.1038/s41522-02000172-6. 15. K. Forier et al., “Transport of nanoparticles in cystic fibrosis sputum and bacterial biofilms by single-particle tracking microscopy,” (in eng), Nanomedicine (Lond), vol. 8, no. 6, pp. 935-49, Jun 2013, doi: 10.2217/nnm.12.129. 16. A. Birjiniuk, N. Billings, E. Nance, J. Hanes, K. Ribbeck, and P. S. Doyle, “Single particle tracking reveals spatial and dynamic organization of the E. coli biofilm matrix,” (in eng), New J Phys, vol. 16, no. 8, p. 085014, Aug 27 2014, doi: 10.1088/1367-2630/16/8/085014. 17. M. E. Grady, E. Parrish, M. A. Caporizzo, S. C. Seeger, R. J. Composto, and D. M. Eckmann, “Intracellular nanoparticle dynamics affected by cytoskeletal integrity,” (in eng), Soft Matter, vol. 13, no. 9, pp. 1873-1880, Mar 1 2017, doi: 10.1039/c6sm02464e.
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