Diatoms are unicelluar organisms that synthesize two-part, amorphous silica shells (frustules) that display intricate nano-architecture and outstanding physical properties. Diatoms use these shells to protect their own cellular integrity but they also contain characteristic pores on their surfaces to permit the flow of material into and out of the cell. Diatoms accomplish the biomineralization of amorphous silica through polycondensation of silicic acid into silicate material with silica deposition vesicles. Silica nanoparticles are then deposited to form the base layer of the new frustule. Continued deposition based on this early template leads to complex 3D nano-architecture. The silica container maintains the microenvironment of the organism within. Inspired by this use of silica to protect delicate biomolecules, researchers have recently developed a variety of new biotechnology. One type involves the entrapment of enzymes and receptors within a silica matrix to produce a biosensor. A reporter group bound to the enzyme causes a measureable macroscopic effect when a specific molecule is detected. Becton, Dickinson and Company have recently patented a method of embedding glucose-binding proteins within an amorphous silica sol-gel matrix. The matrix is tailored to the size of the protein and restricts its ability to move or be denatured while permitting its activity. When glucose binds to the proteins it initiates a response in the attached reporter group that triggers a detectable change in an electrode.
Glucometers generate waste and often require drawing a small amount of blood. Silica-bound biosensor glucometers may be able to function with smaller sample volumes or may be the basis for implantable detectors.
Natural formation of amorphous silica materials in diatoms is directed by myriad organelles, enzymes, tubule scaffolds, and other elements curently beyond the capacity of science to reproduce. Mimicking the principle behind the use of amorphous silica to protect biomolecules is however within reach and will lead to the development of new kinds of pharmaceutical vectors and biotechnology.
Detecting blood glucose levels is crucial for diabetics and individuals suffering from certain other diseases. Entrapping glucose sensitive proteins in amorphous silica matrices could increase the lifespan and effectiveness of glucometers.Edit Summary