Nanostructured Biosilica of Diatoms: From Water World to Biomedical Applications

Abstract

Diatoms—unicellular photosynthetic algae—are promising natural sources of nanostructured silica. These microorganisms produce in their membrane approximately a highly ordered porous cell wall called a frustule as protection from environmental stress. Diatom frustules consist of hydrated silica that show peculiar properties including biocompatibility, tailorable surface chemistry, chemical inertness, and thermal stability. Frustules harvested from aquatic ecosystems or diatomaceous fossil sediments represent an excellent cost-effective source of biosilica for a broad range of biomedical applications. The porous ultrastructure of the frustules displays a large surface area available for coating with various biomolecules through different functionalization methods. In this review article, we highlight the main features of diatom biosilica and present some of the most advantageous properties that support the employment of frustules in the field of drug delivery, biosensing, and regenerative medicine. In particular, it is offered an insight into the most common functionalization strategies through which diatom physicochemical properties can be modified and tailored according to the described field of application.

A Green Method for Synthesis of Silver-Nanoparticles-Diatomite (AgNPs-D) Composite from Pineapple (<i>Ananas comosus</i>) Leaf Extract

“…The material's physical properties are lightweight, low density, thermal conductivity, high porosity, and surface area, inertness, and high absorption capacity [3][4]. The composition and excellent physical properties make diatomite potential for application as a filler of composite material in industrial and biomedical applications [5].…”

Porous Silicon Optical Devices: Recent Advances in Biosensing Applications

“…The oxidized PSi can be readily modified via the silanization process ( Figure 2 A), based on the use of silane coupling agents (i.e., APTES, APDMES) characterized by different terminal motifs (i.e., NH 2 ; SH, COOH; CHO) that act as anchorage sites for proteins, antibody, DNA and others [ 60 ]. Silane-based chemistry is one of the most exploited modifications of porous silica-based synthetic or natural materials since it offers an effortless way to attach a biological or chemical molecule to the porous surface [ 61 , 62 , 63 ]. Silanization requires the availability of hydroxyl groups on the PSi surface in order to hydrolyze the alkoxy groups of the alkyl silane molecule, thus forming Si-O-Si bonds [ 64 ].…”

Recent Advances in the Fabrication and Functionalization of Flexible Optical Biosensors: Toward Smart Life-Sciences Applications

“…This necessity has stimulated the interest of many research groups toward novel SERS optical platforms based on natural materials. For example, natural biosilica-based SERS responsive devices have been recently reviewed by Tramontano et al [ 113 ]. In this context, natural polymers represent valid alternatives for flexible eco-friendly SERS platforms [ 114 ].…”