Improving the sensitivity of immunoassays by tuning gold nanoparticles to the tipping point

Conventional lateral flow immunoassays are based on labeled antibodies. In this paper we describe an alternative design based on gold nanoparticles labeled with haptens. The haptens are conjugated to gold nanoparticles by a method that allows the number per particle to be tuned to the point of maximum sensitivity. This leads to improvements compared with conventional lateral flow devices without relinquishing any of their advantages. In parallel assays for the environmental pollutant 2,4-dinitrophenol the alternative devices were 50% more sensitive.