title: Antibody-capped mesoporous nanoscopic materials: design of a probe for the selective chromo-fluorogenic detection of finasteride.
abstract: The synthesis of capped mesoporous silica nanoparticles (MSN) conjugated with an antibody (AB) as a gatekeeper has been carried out in order to obtain a delivery system able to release an entrapped cargo (dye) in the presence of a target molecule (antigen) to which the conjugated antibody binds selectively. In particular, MSN loaded with rhodamine B and functionalized on the external surface with a suitable derivative of N-(t-butyl)-3-oxo-(5α,17β)-4-aza-androst-1-ene-17-carboxamide (finasteride) have been prepared (S1). The addition of polyclonal antibodies against finasteride induced capping of the pores due to the interaction with the anchored hapten-like finasteride derivative to give a MSN-hapten-AB nanoparticle S1-AB. It was found that the addition of capped material S1-AB to water solutions containing finasteride resulted in displacement of the antibody, pore uncapping and entrapped-dye release. The response of the gated material is highly selective, and only finasteride, among other steroids, was able to induce a significant uncapping process. Compared with finasteride, the finasteride metabolite was able to release 17 % of the dye, whereas the exogen steroids testosterone, metenolone and 16-β-hydroxystanozolol only induced very little release of rhodamine B (lower than 10 %) from aqueous suspensions containing sensing solid S1-AB. A detection limit as low as 20 ppb was found for the fluorimetric detection of finasteride. In order to evaluate a possible application of the material for label-free detection of finasteride, the capped material was isolated and stored to give final sensing solid S1-AB-i. It was found to display a similar behavior towards finasteride as to that shown by freshly prepared S1-AB; even after a period of two months, no significant loss of selectivity or sensitivity was noted. Moreover, to study the application for the detection of finasteride in biological samples, this "aged" material, S1-AB-i, was tested using commercially available blank urine as matrix. Samples containing 70 and 90 % blank urine were spiked with a defined amount of finasteride, and the concentration was determined using capped S1-AB-i. Recovery ranges from 94 % to 118 % were reached.
authors.affiliation: Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain) ; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Campus Rio Ebro 50018 Zaragoza (Spain).
authors.forename: Estela
authors.initials: E
authors.lastname: Climent
authors.affiliation: Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain) ; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Campus Rio Ebro 50018 Zaragoza (Spain).
authors.forename: Ramón
authors.initials: R
authors.lastname: Martínez-Máñez
authors.affiliation: Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain).
authors.forename: Angel
authors.initials: A
authors.lastname: Maquieira
authors.affiliation: Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain) ; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Campus Rio Ebro 50018 Zaragoza (Spain).
authors.forename: Félix
authors.initials: F
authors.lastname: Sancenón
authors.affiliation: Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain) ; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Campus Rio Ebro 50018 Zaragoza (Spain).
authors.forename: M Dolores
authors.initials: MD
authors.lastname: Marcos
authors.affiliation: Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain).
authors.forename: Eva M
authors.initials: EM
authors.lastname: Brun
authors.affiliation: Centro de Reconocimienro Molecular y Desarrollo Tecnológico (IDM), Unidad mixta Universidad Politécnica de Valencia Universidad de Valencia, Universidad Politécnica de Valencia, Departamento de Química Camino de Vera s/n, 46022 Valencia (Spain).
authors.forename: Juan
authors.initials: J
authors.lastname: Soto
authors.affiliation: Institut de Ciència dels Materials (ICMUV), Universidad de Valencia P.O. Box 2085, 46071 Valencia (Spain).
authors.forename: Pedro
authors.initials: P
authors.lastname: Amorós
keywords: MCM-41; antibodies; finasteride; hybrid materials; molecular gates