Scientists developing nanotechnology—building innovative engineering and medical systems on a molecular scale—are finding that biology can offer great assistance. After all, living cells are essentially “nano-machines”, sustained by a complex array of molecular assemblies and their interactions. In the journal Materials Today Chemistry, Nasir Mahmood at RMIT University in Melbourne, Australia, with colleagues in Pakistan and China, reviews the use of biological systems as what he calls “chemical reactors” for making nanomaterials.

Building nanotechnology requires methods to make tiny metallic and magnetic clusters while controlling their surface properties. These nanoparticles serve as key components for such applications as micro optoelectronics, chemical sensing, catalysis, and interaction with body tissues to achieve diagnosis and therapy.

Plants, bacteria, fungi, and algae are proving to be great natural “technicians” to assist this task. Adding the appropriate starting materials can cause natural biochemistry to convert metal ions into useful metallic nanoparticles, and adjusting simple factors, such as temperature pH and chemical concentrations, can vary the properties of the resulting materials.

“We are finding that the synthesis of nanomaterials using biology can be far superior to other chemical methods in terms of cost and their eco-friendly nature,” says Mahmood.

The biological approach requires significantly less energy than alternative methods, since the organisms used generally work well at everyday temperatures and pressures. It also avoids using many toxic and expensive chemicals.

After reviewing the technical opportunities and advantages of what he calls “the biogenic approach,” Mahmood highlights some of the applications already being found for the nanomaterials produced. In medicine, they are helping to identify and treat diseases. For example, biologically-synthesized silver nanoparticles are used to inhibit cell growth and kill bacteria.

Biogenic zinc oxides and titanium oxides in sunscreens can block harmful ultra-violet rays. A range of metallic particles can help prevent drug resistance, by disrupting the process where bacteria form a biofilm. Some nanomaterials can enhance the texture and taste of foods. Others are proving useful as pesticides for agriculture or to help purify water.

Although many such examples of commercial applications already exist, Mahmood emphasizes that the field is still “at the beginning of a long journey.”

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