July 2013 Featured Paper

Abstract

Spherical gold nanoparticles (5-nm diameter) were modified with a small-molecule thiolated bisphenol A (BPA) ligand to achieve an estimated coverage of ~3.3 × 10^–10 mol cm^–2, or 180 ligands per particle. The modified particles were tested in an enzyme-linked immunosorbent assay (ELISA) format to measure functionality and were shown to bind specifically to anti-BPA antibody while resisting the non-specific adsorption of an antibody with no affinity for BPA. It was found that the use of 10 % ethanol as a co-solvent was required in the ELISA as aqueous buffers alone resulted in poor binding between anti-BPA antibody and the functionalised nanoparticles. This is likely due to the hydrophobic nature of the BPA ligand limiting its solubility, and therefore its availability for antibody interactions, in purely aqueous environments. To our knowledge, this is the first example of a nanoparticle modified with a small organic molecule being used in an ELISA assay..

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