Appl. Phys. Lett. 97, 043703 (2010)

The use of major crop plants such as maize (corn) in biofuel production is a source of contention, but there are other options; including photosynthetic algae, which can be grown in bioreactors. Radhakrishna Sureshkumar at Syracuse University in New York and his co-workers show that metallic nanoparticles in these reactors can boost algal growth by intensifying the light that the algae receive.

They designed silver nanoparticles of a size and shape that reflected or 'backscattered' only blue light — a wavelength at which the green microalga Chlamydomonas reinhardtii grows optimally. This reflection occurred as a result of interactions between the incoming light and oscillations of the electron charge at the nanoparticles' surface.

The researchers tested their particles in a mini bioreactor consisting of a Petri dish holding C. reinhardtii culture sitting atop another dish containing a suspension of the nanoparticles. When the authors shone light through the top of the algae dish, algal growth increased by more than 30%.