"We looked to areas like nanotechnology, biotechnology and energy simply because they fulfil pressing needs," said Blaise Zerega, editor of Red Herring. "We believe these companies are bent on overcoming scientific limits and building sound business models around their developments."

The list contains 50 private and 50 public companies that Red Herring staff say will excel despite current economic conditions. Besides nanotechnology, the businesses are active in biotechnology, communications hardware, communications services, computer hardware, consumer electronics, data storage, energy, media, semiconductors, software and wireless.

Nanomaterials specialist NTera was spun out from University College Dublin in April 1997. The company is developing nanomaterials for flat-panel displays, medical diagnostic sensors, drug delivery, batteries and solar cells.

US start-up Nanosphere is focusing on "biodiagnostic nanoparticle probes and biomolecular detection systems for nucleic acid and protein identification". Founded by two professors at Northwestern University, the company's technology is based on gold nanoparticle probes. Nanosphere says that it is developing a hand-held device that can detect almost any viral, bacterial and genetic agent with a known DNA sequence. The company plans to start beta testing its disease-detection systems later this year.

Fellow US company Quantum Dot, meanwhile, is developing quantum dot particles for use as detectors for nucleic acids and proteins. The semiconductor nanocrystals, dubbed Qdots, have interesting optical properties and applications in drug discovery and development. Quantum Dot says that the crystals were developed at Lawrence Berkeley National Laboratory, the Massachusetts Institute of Technology, the University of Melbourne and Indiana University.