Diatoms as sensors and their applications

Diatoms are single-celled eukaryotic microalgae with silica-based cell walls of various shapes and sizes, and with a hierarchical pore structure leading to a very high surface area which can be useful in nanotechnology, drug delivery, biomimetics, molecular biology, and especially in biosensing. Diatom frustules are gaining popularity as biosensors because they do not require any specialized nano-fabrication step, are made of nanostructured amorphous silica, and their surface can be easily modified and functionalized with biomolecules. Thus, their biocompatibility, large surface area, and highly porous frustules enhance their speed of analysis, specificity, and sensitivity in biosensing. Diatoms are present in almost every water habitat, thus assuring low-cost, large availability, and eco-sustainability. Therefore, diatoms can be used as bio-derived transducers for label-free sensing, and based on their mechanisms they can be divided into various types like optical, plasmonic, electrochemical, immunosensors, etc. These diatom-based sensors can be used in agriculture, industry, and medicine especially in the detection of biomarkers and point-of-care biosensing.