doi:10.1038/nindia.2013.13 Published online 29 January 2013
Researchers have used two photosynthetic microorganisms — cyanobacterium and microalgae — to synthesize gold nanoparticles of various shapes and sizes1. These nanoparticles could bind to DNA and are suitable for use in cell labelling and disease diagnosis.
Among the nanomaterials, gold nanoparticles are coveted for their wide range of applications, such as biomedical imaging, cancer therapy and chemical sensing. Researchers have utilized microorganisms such as fungi, algae, and bacteria to prepare gold nanoparticles in an eco-friendly way. However, no studies have compared the efficacy of two microorganisms in producing gold nanoparticles.
To compare the nanoparticle-yielding potential of microorganisms, the researchers cultured cyanobacterium (Phormidium willei) and microalgae (Coelastrella sp.) and added chloroauric acid separately to cultured cyanobacterium and microalgae.
After an hour, the reaction mixture containing the microalgae turned colourless, indicating synthesis of gold nanoparticles. The gold nanoparticles accumulated inside microalgal cells showing ruby-red colouration. Protein molecules present in the microalgae reduced gold ions to gold nanoparticles. The reaction mixture containing the cyanobacterium produced gold nanoparticles in the shape of nanotriangles.
The high reduction rate in acidic medium might have led to the synthesis of nanotriangles. In studies with herring sperm DNA, nanoparticles were able to bind to the DNA in the presence of interfering DNA binders such as ethidium bromide. In addition, the nanoparticles showed the ability to scavenge out diphenylpicrylhydrazyl, an organic radical, proving their antioxidant properties.
"The gold nanoparticles' potential to bind to DNA can be used for the diagnosis and treatment of various genetic diseases," says lead researcher N. Thajuddin.
The authors of this work are from: Bharathidasan University & Jamal Mohammed College, Tiruchirappalli, and Presidency College (Autonomous), Chennai, Tamil Nadu, India; and Institute of Botany and Microbiology, Belgium.