title: Controlling mesopore size and processability of transparent enzyme-loaded silica films for biosensing applications.
abstract: Silica-based nanoporous thin films including large mesopores are relevant as enzyme supports for applications in biosensing. The diffusion and immobilization of large biomolecules such as enzymes in such porous films require the presence of large mesopores. Creating such morphologies based on a bottom-up synthesis using colloidal templates is a challenge in view of the combination of desired material properties and the robustness of the casting process for the fabrication of thin films. Here a strategy to reproducibly synthesize transparent porous silica thin films with submicrometer thickness and homogeneously distributed porosity is presented. For this purpose, polystyrene-poly-2-vinylpyridine (PS-P2VP) amphiphilic block copolymers are used as porogenic templates. Low-chain alcohols are employed as both selective solvents for the P2VP blocks and reaction media for silica synthesis. Rheology measurements reveal a strong influence of the block copolymer length on the behavior of PS-P2VP micelles in suspension. The pore distribution and accessibility into the film are controlled by adjusting the silica to block copolymer weight ratio. The solvent choice is shown to control not only the micelle size and the generated pore morphology but also the structural homogeneity of the films. Finally, the suitability of the synthesized films as supports for enzymes is tested using a model enzyme, horseradish peroxidase EC 1.11.1.7. Our approach is innovative, robust, and reproducible and provides a convenient alternative to synthesize large mesopores up to small macropores (20-100 nm) in nanostructured thin films with applications in biosensing and functional coatings.
authors.affiliation: Swiss Center for Electronics and Microtechnology (CSEM) , Jaquet-Droz 1, CH-2000 Neuchâtel, Switzerland.
authors.forename: Oswaldo
authors.initials: O
authors.lastname: Pérez-Anguiano
authors.forename: Bernard
authors.initials: B
authors.lastname: Wenger
authors.forename: Raphaël
authors.initials: R
authors.lastname: Pugin
authors.forename: Heinrich
authors.initials: H
authors.lastname: Hofmann
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Scolan
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004800:Enzymes, Immobilized / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry*; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D011137:Polystyrenes; D011145:Polyvinyls; D012822:Silicon Dioxide; D006735:Horseradish Peroxidase
keywords: PS-P2VP; amphiphilic block copolymers; biosensors; enzyme immobilization; large mesopores; thin films