title: Chemical stabilization of porous silicon for enhanced biofunctionalization with immunoglobulin.
abstract: Porous silicon (PSi) is widely used in biological experiments, owing to its biocompatibility and well-established fabrication methods that allow tailoring its surface. Nevertheless, there are some unresolved issues such as deciding whether the stabilization of PSi is necessary for its biological applications and evaluating the effects of PSi stabilization on the surface biofunctionalization with proteins. In this work we demonstrate that non-stabilized PSi is prone to detachment owing to the stress induced upon biomolecular adsorption. Biofunctionalized non-stabilized PSi loses the interference properties characteristic of a thin film, and groove-like structures resulting from a final layer collapse were observed by scanning electron microscopy. Likewise, direct PSi derivatization with 3-aminopropyl-triethoxysilane (APTS) does not stabilize PSi against immunoglobulin biofunctionalization. To overcome this problem, we developed a simple chemical process of stabilizing PSi (CoxPSi) for biological applications, which has several advantages over thermal stabilization (ToxPSi). The process consists of chemical oxidation in H2O2, surface derivatization with APTS and a curing step at 120 °C. This process offers integral homogeneous PSi morphology, hydrophilic surface termination (contact angleθ= 26°) and highly efficient derivatized and biofunctionalized PSi surfaces (six times more efficient than ToxPSi). All these features are highly desirable for biological applications, such as biosensing, where our results can be used for the design and optimization of the biomolecular immobilization cascade on PSi surfaces.
authors.affiliation: Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain.
authors.forename: Nelson
authors.initials: N
authors.lastname: Naveas
authors.affiliation: Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain.
authors.forename: Vicente Torres
authors.initials: VT
authors.lastname: Costa
authors.affiliation: Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain.
authors.forename: Dario
authors.initials: D
authors.lastname: Gallach
authors.affiliation: Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain.
authors.forename: Jacobo
authors.initials: J
authors.lastname: Hernandez-Montelongo
authors.affiliation: Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain.
authors.forename: Raul Jose Martín
authors.initials: RJ
authors.lastname: Palma
authors.affiliation: Molecular Biology Department, Universidad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain.
authors.forename: Josefa Predenstinacion
authors.initials: JP
authors.lastname: Garcia-Ruiz
authors.affiliation: Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Manso-Silván
keywords: biofunctionalization; biomaterial; material stability; nanostructured materials; porous silicon; protein adsorption