Diatoms Green Nanotechnology for Biosilica-Based Drug Delivery Systems

Abstract

Diatom microalgae are the most outstanding natural source of porous silica. Diatom cell is enclosed in 3-D ordered nanopatterned silica cell wall, called frustule. The unique properties of diatoms frustule, including high specific surface area, thermal stability, biocompatibility, tailorable surface chemistry, make them really promising for biomedical applications. Moreover, diatoms are easy to cultivate in artificial environment and there is a huge availability of diatom frustules as fossil material (diatomite) in several areas of the world. For all these reasons, diatoms are an intriguing alternative to synthetic materials for the development of low-cost drug delivery systems. This review article focuses on the possible use of diatoms derived silica as drug carrier systems. The functionalization strategies of diatom micro-/nanoparticles for improving their biophysical properties, such as cellular internalization and drug loading/release kinetics, are described. In addition, the realization of hybrid diatom-based devices with advanced properties for theranostics and targeted or augmented drug delivery applications, are also discussed.

Sinking of Four Species of Living Diatom Cells Directly Observed by a “Tumbled” Optical Microscope

“…Frustules are made of nanoporous silica (Nelson et al, 1995; Umemura et al, 2007, 2008, 2010; Jang et al, 2013; Maher et al, 2018; Terracciano et al, 2018) and are composed of 10–70% amorphous silica at a density of <2,600 kg/m 3 and the balance being sugars and proteins with a density of <1,300 kg/m 3 (Schmid et al, 1981; Csögör et al, 1999). With its unique 3D nanoporosity, the frustule optimizes diatom floating and sinking and diatom survival in water and helping to control photosynthesis, nutrient molecule selection, and antibacterial protection (Maher et al, 2018).…”

Mesoporous Silica-Bioglass Composite Pellets as Bone Drug Delivery System with Mineralization Potential

“…From a chemical point of view, amorphous silica is a silicon dioxide also known as colloidal, synthetic, or precipitated silica [ 8 ]. Presently, amorphous silica dedicated for medical applications is synthesized using a sol-gel process that is facile and effective [ 9 ]; however, production of amorphous silica from natural sources has been also explored [ 10 , 11 ]. The sol-gel process is based on two principal reactions: hydrolysis and polycondensation.…”