Diatoms Microalgae with Biosilca Shells as Living Materials for Biomedicine and Nanotechnology

Diatoms are microalgae which have their unique cell encased into a nanostructured silica shell called frustule. The silica shells can be envisioned as micro/nano structures suitable to chemical modification yielding smart functional nanomaterials [1, 2].<br/>Differently from the chemical production of silica, the biosynthesis of natural SiO₂ occurs in mild conditions and does not require the use of toxic precursors or reagents. Biosilica from diatoms features interesting properties such as high surface area, mechanical resistance<br/>and nanotexturization, which makes it appealing for applications in photonics, sensing, optoelectronics, biomaterial science and biomedicine. In addition, frustules’ biosilica can be easily chemically modified to add new functions by simple surface functionalization, and/or in vivo by adding specific molecules to the culture medium. We have shown applications of chemically modified frustules for bone cells growth [3] demonstrating that in vivo functionalization of diatom biosilica with sodium alendronate results in osteoactive material [4].<br/>We have also demonstrated the production of functional structures by coating living diatoms with biomimetic organic polymers, like polydopamine [5]. The resulting living heterostructures turn out to be intriguing platforms for additional chemical modifications,<br/>such as anchoring enzymes, affording multifunctional materials for biological applications.<br/>Finally, we have also shown that photonic microstructures can be produced by in vivo incorporation of tailored light emitting molecules in living <i>Thalassiosira weissflogii</i> diatoms [6, 7]. With a similar approach, biosilica has been doped with phosphorescent Ir complexes [8].<br/>Overall, our studies point out intriguing biotechnological routes to multifunctional nanomaterials for biomedicine and nanotechnology starting from unicellular algae.<br/><br/>[1] Ragni, R. , Cicco, S.R., Vona, D. and Farinola, G.M., Adv. Mater. 1704289,1-23 (2017)<br/>[2] Vona, D., Ragni, R., Altamura, E., Albanese, P., Giangregorio, M.M., Cicco, S.R., Farinola, G.M. Applied Sciences, 11 (8), 3327 (2021)<br/>[3] Cicco, S.R., Vona, D., De Giglio, E., Cometa, S., Mattioli Belmonte, M., Palumbo, F., Ragni, R. and Farinola, G.M., Chem Plus Chem, 80, 1104–1112 (2015)<br/>[4] Cicco, S.R., Vona, D., Leone, G., De Giglio, E, Bonifacio M., Cometa, S, Fiore, S. Palumbo, F, Ragni, R., Farinola, G.M., Materials Science & Engineering C 104 109897 (2019)<br/>[5] Vona, D., Cicco, S.R., Ragni, R., Vicente-Garcia, C., Leone, G., Giangregorio, M.M., Palumbo, F., Altamura, E., Farinola, G.M., Photochemical and Photobiological Sciences. 21, 949–958 (2022)<br/>[6] Ragni, R., Scotognella, F., Vona, D., Moretti, L., Altamura, E., Ceccone, G., Mehn, D., Cicco, S.R., Palumbo, F., Lanzani, G. and Farinola, G.M., Adv. Funct. Mater., 1706214, 1–9 (2018)<br/>[7] Leone, G., De la Cruz Valbuena, G., Cicco, S.R., Vona, D., Altamura, E., Ragni, R., Molotokaite, E., Cecchin, M., Cazzaniga, S., Ballottari, M., D’Andrea, C., Lanzani, G., Farinola, G.M., Scientific Reports, 11 (1), 5209 (2021)<br/>[8] Della Rosa, G., Vona, D., Aloisi, A. , Ragni, R., Di Corato, R., Lo Presti, M., Cicco, S.R., Altamura, E., Taurino, A., Catalano, M., Farinola, G.M., Rinaldi R., ACS Sustainable Chem. Eng., 7, 2207 (2019).