Diatom Biogenic Silica as a Felicitous Platform for Biochemical Engineering: Expanding Frontiers

Diatoms are a prolific class of single-celled photosynthetic microalgae, pervasive in aquatic habitats. More than 10 000 species of diatoms are widespread in the world and primarily sustain the food chain in marine ecosystems. An individual diatom has evolved with species-specific distinct microporous to nanoporous rigid siliceous cell walls or frustules. Exceptionally intricate pore patterns of frustules originate from the hierarchical arrangements of silica sheets. Astonishing intrinsic features of diatom frustules, such as chemical inertness, large surface area, mechanical strength, ordered 3D micropatterning to nanopatterning of pores, distinctive optical properties, biocompatibility, etc., have been tailored to utilize them in numerous applications including biomedicine, separation technology, sensing, photonics, energy conversion, and storage. The advantage of biosilica over synthetic nanoporous silica materials for their application in nanotechnology lies in its cost-effective production through in vivo biomineralization that circumvents the usage of hazardous chemicals. Various chemical and biological approaches have been implemented for surface modification, structure mimics, integration, and conversion of diatom silica shells without altering their structural attributes to manufacture nanostructured smart materials with a diverse heterogeneity. Diatom silica shells thus have gained prodigious attention as powerful tools in nanotechnology. We follow an insightful approach in this Review to deal with all different types of applications of diatom silica shells in diverse areas and associated strategies to improve their aptness to fabricate new materials or devices.