Researchers at Penn State University and SurroMed, Inc., in the 5 October issue of the journal Science report on the fabrication, optical properties, and initial application of microscopic metallic barcodes. When coated with biomolecules, these patterned metallic particles enable the simultaneous monitoring of multiple biological reactions in very small volumes of fluid.
The researchers prepare these barcoded particles by sequentially electroplating different metals within narrow channels to form metallic rods having complex striping patterns.
To read out the striping pattern, scientists take advantage of the fact that metals such as gold and silver reflect colored light differently. For example, silver looks much brighter under blue light than does gold, thus a gold-silver multistriped particle gives a pattern of light and dark stripes reminiscent of conventional barcodes of the sort used in the retail industry.
The researchers have prepared particles with stripes from 50 nanometers to 5 micrometers in length, with up to 13 different segments or 5 different metals. This flexibility means that it should be possible to create thousands of different distinguishable barcode patterns.
The scientists have coated particles of a given pattern such that they bind molecules of interest from solution. Thus, the particle striping pattern encodes the identity of the molecule to be detected on that particle.
The scientists then use a standard laboratory technique to determine the presence or absence of the specific molecules of interest. The researchers anticipate that barcoded particles will enable them to track and identify multiple biological components in clinical samples in a manner analogous to barcodes used in tracking inventory.
As a proof of principle for the use of these particles in bioanalysis, the scientists demonstrated their utility in two types of bioassays employing DNA and antibodies. Using an immunoass
Contact: Barbara K. Kennedy