Therapeutic Applications of Phytoplankton, with an Emphasis on Diatoms and Coccolithophores

Phytoplankton are complex living organisms that have attracted significant interest in the field of biomedicine. One subclass of phytoplankton, the diatoms, produce elegant self-assembled siliceous architectural features with a complex 3D porous structure. Diatoms are characterized by a distinct 3D architecture of silica cell walls called frustules with a highly ordered nano-/micropore structure and pattern. Another phytoplankton subclass of interest is the coccolithophore, which produces unique calcium carbonate plates with distinct architectural features called coccoliths. The unique morphological characteristics of coccoliths resembling the shape of a wagon wheel allows a higher surface area, thus an increased amount of immobilized therapeutic agent on their surface compared to a synthetic calcium carbonate microparticle. This review offers a summary of phytoplankton (microalgae) and their potential for application in drug delivery, diagnostics, drug discovery, as molecular factories, and as scaffolds for various therapeutic applications.