Biosilica/polydopamine/silver nanoparticles composites: new hybrid multifunctional heterostructures obtained by chemical
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Research Letter
Biosilica/polydopamine/silver nanoparticles composites: new hybrid multifunctional heterostructures obtained by chemical modification of Thalassiosira weissflogii silica shells Danilo Vona, Università degli Studi di Bari «Aldo Moro», Via Orabona 4, 70126 Bari, Italy Stefania Roberta Cicco, CNR-ICCOM – Bari, Via Orabona 4, 70126 Bari, Italy Roberta Ragni, Università degli Studi di Bari «Aldo Moro», Via Orabona 4, 70126 Bari, Italy Gabriella Leone, Università degli Studi di Bari «Aldo Moro», Via Orabona 4, 70126 Bari, Italy; IIT-Center for Nano Science and Technology, Via Giovanni Pascoli, 70, 20133 Milano, Italy Marco Lo Presti, and Gianluca Maria Farinola, Università degli Studi di Bari «Aldo Moro», Via Orabona 4, 70126 Bari, Italy Address all correspondence to Gianluca Maria Farinola at [email protected] (Received 2 February 2018; accepted 29 May 2018)
Abstract Biosilica from living diatom microalgae has recently attracted the interest of the scientific community and found several applications in bionanotechnology. Among silica-maker organisms, diatom microalgae represent the most attractive marine microorganisms, featuring highly hierarchical, nanotextured and porous silica walls. These biologic structures, known as “frustules” are also chemically addressable via simple chemical synthesis. In this work, we propose new diatom-based hybrid materials consisting of biosilica extracted from living Thalassiosira weissflogii coated with polydopamine (PDA) films. The adhesion properties of the PDA were exploited to decorate the silica surface with silver nanoparticles. These multifunctional heterostructures can be useful for applications ranging from bioelectronics to biomedicine.
Introduction Living organisms such as diatoms, sponges, and grasses naturally build hierarchical biogenic silica structures at mild physiological conditions.[1] Nature uses smart and green routes to produce high-tech structures of nano- and micromaterials. Biosilicification, for example, is the most important process converting inorganic silicates into silicon oxide occurring in some living organisms.[2] It starts with the uptake of silicic acid from environments, which is then accumulated as silicatederived compounds, and finally deposited and aggregated as amorphous hydrated silica.[3] Natural SiOx biosynthesis occurs at low temperatures, low pressures, mild reaction conditions, and without any strong reagents.[4] Diatoms algae are wellknown organisms with active SiOx biosynthesis pathway. Diatoms are unicellular photosynthetic microalgae which populate all water environments. They range from 10 to 200 µm in diameter and they produce siliceous silica shells with both micro- and nanopatterning, called frustules.[5] Frustules have a pill-box-like structure composed of two planar porous valves connected by lateral rings called girdles. Other remarkable features like high surface area, mechanical properties, and simple chemical functionalization of their shells, make diatoms really appealing for applications in photonics,
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