A method for biomanufacturing large amounts of zinc sulfide nanoparticles inexpensively could lead to their wider availability and use in applications such as light-emitting displays, sensors and solar panels. A research team from Oak Ridge National Laboratory (ORNL) used bacteria fed by sugar at a temperature of 150 °F in 25- and 250-gallon reactors to produce about three-fourths of a pound of zinc sulfide quantum dots (QDs). This was achieved without using process optimization, indicating that even higher yields of QDs may be possible using this method. The ORNL biomanufacturing technique for producing QDs is based on a platform technology that can produce nanometer-size semiconducting materials as well as magnetic, photovoltaic, catalytic and phosphor materials. Using this 250-gallon reactor, ORNL researchers produced three-fourths of a pound of zinc sulfide quantum dots, shown in the inset. Courtesy of ORNL. Unlike many biological synthesis technologies, ORNL's biomanufactured QD synthesis occurred outside of the cells. As a result, the nanomaterials were produced as loose particles, making them easy to separate through washing and centrifuging. Successful biomanufacturing of light-emitting or semiconducting nanoparticles requires the ability to control material synthesis at the nanometer scale with sufficiently high reliability, reproducibility and yield to be cost-effective. ORNL research team leader Ji-Won Moon said that goal had been achieved, noting that the ORNL approach reduces production costs by approximately 90 percent compared to other methods. ORNL researchers envision their QDs being used initially in buffer layers of photovoltaic cells and other thin-film-based devices that can benefit from their electro-optical properties as light-emitting materials. "Since biomanufacturing can control the QD diameter, it is possible to produce a wide range of specifically tuned semiconducting nanomaterials, making them attractive for a variety of applications that include electronics, displays, solar cells, computer memory, energy storage, printed electronics and bioimaging," said Moon. The research was published in Applied Microbiology and Biotechnology (doi: 10.1007/s00253-016-7556-y). A method to produce significant amounts of semiconducting nanoparticles for light-emitting displays, sensors, solar panels and biomedical applications has gained momentum with a demonstration by researchers at Oak Ridge National Laboratory. Courtesy of Jenny Woodbery/ORNL.