Seeing Red

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Science  25 Apr 2003:
Vol. 300, Issue 5619, pp. 553
DOI: 10.1126/science.300.5619.553b

Aggregation immunoassays can be used to detect molecules that present more than one antibody-binding site. In the presence of the target molecule, latex particles bearing anti-target immunoglobin G's (IgGs) will form aggregates that can be detected as changes in solution turbidity. However, such assays are not so useful for direct detection of molecules in blood, given its absorption in the visible regime. Hirsch et al. present a different approach for measuring aggregation: The latex particles are replaced by core-shell metal nanoparticles that can be detected in the near-infrared through their characteristic plasmon resonance. Aggregation diminishes the strength of the plasmon peak. They can quantitate rabbit IgG at the nanogram-per-milliliter level in whole blood in about 10 min.—PDS

Anal. Chem. 10.1021/ac0262210 (2003).

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