Zinc Oxide

Nanoformulated zinc oxide (ZnO) was one of the first nanoformulated materials to be discussed with a nano-safety angle. Nanoformulated titanium dioxide and ZnO available in sunscreens captured the attention of nongovernmental organizations (NGOs), among others, and raised significant questions.

ZnO exhibits semiconducting, piezoelectric, optoelectronic, and photochemical properties. ZnO applications range from pigments and protective coatings on metals to solar cells and transparent electrodes, to blue/ ultraviolet (UV) light-emitting devices.

Nanoformulated ZnO protects against UV-B and UV-A ultraviolet radiation emitted by the sun while being transparent in visible light. It is used in sunscreen because of this dual property, which gives sunscreen its sun protective ability, while at the same time being transparent, making it less visible on the skin. Nano-formulated ZnO is also used in cosmetics (e.g., moisturizers, lip products, foundations, face powders, hand creams, and so on) and in plastic, clear coating, electronics, ceramics, biosensors photonics, UV detectors, field emission display (FED—a flat panel display technology), and antistatic textile finishing.

Nanoformulated ZnO, sized at 15 to 30 nanometers (nm), has been found to be much more effective in curing neoprene rubber than non-nano ZnO. Initial studies indicate that nanoformulated zinc oxide dots might be effective in killing the foodborne pathogens Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes. P and n-type ZnO nanowires are ingredients for ZnO light-emitting diodes (LEDs) whereby materials and manufacturing costs for ZnO LEDs are far less expensive than the material currently used in LEDs. The Centre for Forensic Science at the University of Technology, Sydney (UTS), together with the Australian Federal Police, is testing 20 nm ZnO nanoparticles as fingerprint powder on surfaces such as glass, polyethylene, and aluminum. They have obtained clearer pictures of fingerprints with nano zinc powder as compared to conventional powders.

Fingerprints are illuminated using UV light that causes the zinc nanoparticles to fluoresce. Researchers from the Swiss Federal Institute of Technology in Zurich (ETH) have prepared nanostructured iron and zinc complexes with improved bioavailability that they believe could fortify food staples, such as wheat and rice, with iron and zinc, thereby combatting zinc and iron deficiencies, which affects about a third of the global population. ZnO nanopowder (30 nm) is used by itself or in blends with nanoparticles of titanium oxide, iron, aluminum, zirconium, silver, and manganese. It is used both in dispersions and in coated talc form.