Description General description Gold nanoparticles PEG 5000 biotin terminated. Application Biotin functionalized gold nanoparticles are suitable for binding of streptavidin labelled conjugates. The gold nanoparticle label allows for straightforward detection of streptavidin by measuring the increase in absorbance of the sample upon binding. The absorption maximum is gold nanoparticle size dependent, and ranges from 515-520 nm for a 5 nm particle to 572 nm for a 100 nm particle.