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nanotimes News in Brief

Sensors // Diatom Biosensor Could Shine Light on Future Nanomaterials

© Based on Material by PNNL F

luorescence is the key characteristic of a new biosensor developed by researchers at the

Department of Energy‘s Pacific Northwest National Laboratory (US). The biosensor includes fluorescent proteins embedded in a diatom shell that alter their glow when they are exposed to a particular sub- stance.

“Like tiny glass sculptures, the diverse silica shells of diatoms have long intrigued scientists,” said lead author and molecular biologist Kate Marshall, who works out of PNNL‘s Marine Sciences Laboratory in Sequim, Wash. “And the way our biosensor works could make diatoms even more attractive to scientists because it could pave the way for the development of novel, synthetic silica materials.”

Diatoms are perhaps best known as the tiny algae that make up the bulk of phytoplankton, the plant base of the marine food chain that feeds the ocean‘s creatures. But materials scientists are fascinated by diatoms for another reason: the intricate, highly-or- dered patterns that make up their microscopic shells, which are mostly made of silica. Researchers are loo- king at these minuscule glass cages to solve problems in a number of areas, including sensing, catalysis and environmental remediation.

A side and overhead view of the microsco- pic marine diatom Thalassiosira pseudo- nana. PNNL scien- tists used this species to develop a fluores-

cent biosensor that changes its glow in the presence of the sugar ribose. © Nils Kroeger, University of Regensburg.

12-03 :: March/April 2012

PNNL Laboratory Fellow and corresponding author Guri Roesijadi found inspiration for this biosensor in previous work by other researchers, who showed it‘s possible to insert proteins in diatom shells through genetic engineering. Using that work as a starting point, Roesijadi, Marshall and their PNNL colleagues aimed to use fluorescent proteins to turn diatoms into a biosensor. They specifically aimed to create a reagent-less biosensor, meaning one that detects a target substance on its own and without depending on another chemical or substance. As a test case, the PNNL team inserted genes for their biosensor into Thalassiosira pseudonana, a well-studied marine dia- tom whose shell resembles a hatbox. The new genes allowed the diatoms to produce a protein that is the biosensor.