Ramón Martínez-Mánez and co-workers, University of Valencia, Spain, detected finasteride, a steroid used in sports for doping. To do so, they use mesoporous silica nanoparticles that are functionalized with a finasteride derivative. They then load the nanoparticles with the fluorescent dye rhodamine B and cap the mesopores with an anti-finasteride antibody.

The dye is trapped inside the mesopores and is only released when surrounding finasteride in solution competes for binding to the antibodies. This then leads to decapping of the mesopores and release of the detectable fluorescent dye, which can then be detected.

• Antibody-Capped Mesoporous Nanoscopic Materials: Design of a Probe for the Selective Chromo-Fluorogenic Detection of Finasteride,
  Estela Climent, Ramón Martínez-Máñez, Ángel Maquieira, Félix Sancenón, M. Dolores Marcos, Eva M. Brun, Juan Soto, Pedro Amorós,
  ChemistryOpen 2012, 1(6), 251–259.
  DOI: 10.1002/open.201100008

ChemistryOpen – the first society-owned, open-access, chemistry journal – is a journal of ChemPubSoc Europe published by Wiley-VCH.