(right side). Note that tpSil3-Dendra2, tpSil3-mEOS3.2 and tpSil3–Dronpa are shown in the outer region of the fultoportulae basal chamber instead of within the external tubes of the fultoportulae. The appearance of large circular non-fluorescent gaps correlates with the structural elements of fultoportulae observed in SEM images (insets of Figures 1.18d,e,f).
Figure 1.18 PALM analysis of tpSil3. (a) Comparison of epifluorescence image and reconstructed super-resolution image of tpSil3-Dendra2 with z-focus on the girdle band area of the diatom. The position of the line scan is highlighted. (b) Line scan through the silica cell wall showing the fluorescence intensity profiles obtained using the two imaging modalities. The FWHM of the PALM image is indicated. (c) Fourier ring correlation applied to super-resolution image in A revealing an effective resolution of 74.7nm. Comparison of epifluorescence images and reconstructed super-resolution image of Dendra2 (d), mEOS3.2 (e), and Dronpa (f) fused to tpSil3 with thew z-focus on the valve region of the diatom. Enlarged details of the fultoportulae to the right. For comparison, we also present an SEM image at the same scale corresponding to the enlarged details shown in the fluorescence image. Scale bars = 1μm and 100nm in the zoomed images. From [1.22] with permission of Springer Nature.
1.7 Conclusion
The structural, mechanical, and optoelectronic properties of diatoms make them ideal research subjects for biomedical research and other fields. Diatoms have been used in photonics to fabricate optical devices based on the micro-meter and nano-meter pores in silica skeletons. It is also possible to load the diatom structure with specific proteins, enzymes, or antibodies for use as biosensors in disease diagnosis and drug carriers, and their biocompatibility and non-toxicity make them an ideal bone implant material. Nano-patterned diatom frustules can even be used to differentiate cancer cells from normal cells. Nonetheless, further advancements will depend on a comprehensive understanding of diatom structure and morphology, which can only be achieved using non-intrusive methods, such as optical microscopy. Fluorescence-based microscopic methods can also be used to gain deeper insights into the application of diatoms in other fields, such as the monitoring of marine environments in vivo or ex vivo. The use of multidimensional imaging in conjunction with spectroscopic and dynamic information provides the sensitivity and selectivity sufficient to detect events at the molecular level.
Acknowledgement
This work was supported by the India-Taiwan International Cooperative Research Project of Ministry of Science and Technology, Taiwan (grant no. 110-2923-M-039-001-MY3).
References
[1.1] Allen, R.D., Allen, N.S. and Travis, J.L. (1981) Video-enhanced contrast, differential interference contrast (AVEC-DIC) microscopy: a new method capable of analyzing microtubule-related motility in the reticulopodial network of Allogromia laticollaris. Cell Motil 1(3), 291–302.
[1.2] Betzig, E., Patterson, G.H., Sougrat, R., Lindwasser, O.W., Olenych, S., Bonifacino, J.S., Davidson, M.W., Lippincott-Schwartz, J. and Hess, H.F. (2006) Imaging Intracellular Fluorescent Proteins at Nanometer Resolution. Science 313(5793), 1642–1645.
[1.3] Boyd, R.W. and Prato, D. (2008) Nonlinear Optics. Elsevier Science.
[1.4] Buhmann, M., Kroth, P.G. and Schleheck, D. (2012) Photoautotrophicheterotrophic biofilm communities: a laboratory incubator designed for growing axenic diatoms and bacteria in defined mixed-species biofilms. Environ Microbiol Rep 4(1), 133–140.
[1.5] Caputo, A., Nylander, J.A.A. and Foster, R.A. (2019) The genetic diversity and evolution of diatom-diazotroph associations highlights traits favoring symbiont integration. FEMS Microbiol Lett 366(2), fny297.
[1.6] Chauhan, D., Agrawal, G., Deshmukh, S., Roy, S.S. and Priyadarshini, R. (2018) Biofilm formation by Exiguobacterium sp. DR11 and DR14 alter polystyrene surface properties and initiate biodegradation. RSC Advances 8(66), 37590–37599.
[1.7] Débarre, D., Supatto, W., Pena, A.-M., Fabre, A., Tordjmann, T., Combettes, L., Schanne-Klein, M.-C. and Beaurepaire, E. (2006) Imaging lipid bodies in cells and tissues using third-harmonic generation microscopy. Nat Methods 3(1), 47–53.
[1.8] De Stefano, L., Maddalena, P., Moretti, L., Rea, I., Rendina, I., De Tommasi, E., Mocella, V. and De Stefano, M. (2009) Nano-biosilica from marine diatoms: A brand new material for photonic applications. Superlattices Microstruct. 46(1), 84–89.
[1.9] De Tommasi, E. (2016) Light Manipulation by Single Cells: The Case of Diatoms. J Spectrosc 2016, 2490128.
[1.10] Delalat, B., Sheppard, V.C., Rasi Ghaemi, S., Rao, S., Prestidge, C.A., McPhee, G., Rogers, M.-L., Donoghue, J.F., Pillay, V., Johns, T.G., Kröger, N. and Voelcker, N.H. (2015) Targeted drug delivery using genetically engineered diatom biosilica. Nat Commun 6(1), 8791.
[1.11] Delasoie, J., Rossier, J., Haeni, L., Rothen-Rutishauser, B. and Zobi, F. (2018) Slow-targeted release of a ruthenium anticancer agent from vitamin B12 functionalized marine diatom microalgae. Dalton Trans 47(48), 17221–17232.
[1.12] Denk, W., Strickler, J.H. and Webb, W.W. (1990) Two-photon laser scanning fluorescence microscopy. Science 248(4951), 73–76.
[1.13] Dertinger, T., Colyer, R., Iyer, G., Weiss, S. and Enderlein, J. (2009) Fast, background-free, 3D super-resolution optical fluctuation imaging (SOFI). Proc Natl Acad Sci USA 106(52), 22287–22292.
[1.14] Drum, R.W. and Gordon, R. (2003) Star Trek replicators and diatom nanotechnology. Trends Biotechnol 21(8), 325–328.
[1.15] Ewelina, S. and Boguslaw, S. (2009) The use of benthic diatoms in estimating water quality of variously polluted rivers. Oceanol Hydrobiol Stud 38(1), 17–26.
[1.16] Fabrega, J., Luoma, S.N., Tyler, C.R., Galloway, T.S. and Lead, J.R. (2011) Silver nanoparticles: Behaviour and effects in the aquatic environment. Environ Int 37(2), 517–531.
[1.17] Fan, X., Healy, J.J., O’Dwyer, K. and Hennelly, B.M. (2019) Label-free color staining of quantitative phase images of biological cells by simulated Rheinberg illumination. Appl Opt 58(12), 3104–3114.
[1.18] Fan, X., Healy, J.J., O’Dwyer, K. and Hennelly, B.M. (2020) Label-free color staining of quantitative phase images. Opt Lasers Eng 129, 106049.
[1.19] Fernández-Suárez, M. and Ting, A.Y. (2008) Fluorescent probes for super-resolution imaging in living cells. Nat Rev Mol Cell Biol 9(12), 929–943.
[1.20] Fu, W., Chaiboonchoe, A., Khraiwesh, B., Sultana, M., Jaiswal, A., Jijakli, K., Nelson, D.R., Al-Hrout, A.a., Baig, B., Amin, A. and Salehi-Ashtiani, K. (2017) Intracellular spectral recompositioning of light enhances algal photosynthetic efficiency. Sci Adv 3(9), e1603096.
[1.21] Ghobara, M.M., Ghobara, M.M., Mazumder, N., Vinayak, V., Reissig, L., Gebeshuber, I.C., Tiffany, M.A., Gordon, R. and Gordon, R. (2019) On Light and Diatoms: A Photonics and Photobiology Review. In: Diatoms: Fundamentals and Applications. 129–189.
[1.22] Gröger, P., Poulsen, N., Klemm, J., Kröger, N. and Schlierf, M. (2016) Establishing super-resolution imaging for proteins in diatom biosilica. Sci Rep 6(1), 36824.
[1.23] Hasle, G.R. and Fryxell, G.A. (1970) Diatoms: Cleaning and Mounting for Light and Electron Microscopy. Trans Am Microsc Soc 89(4), 469–474.
[1.24] Hell, S.W., Dyba, M. and Jakobs, S. (2004) Concepts for nanoscale resolution in fluorescence microscopy. Curr Opin Neurobiol 14(5), 599–609.
[1.25]