title: Confinement of a β-barrel protein in nanoperforated free-standing nanomembranes for ion transport.
abstract: Bioinspired free-standing nanomembranes (FSNMs) for selective ion transport have been tailored by immobilizing the Omp2a β-barrel membrane protein inside nanoperforations created in flexible poly(lactic acid) (PLA) nanomembranes. Perforated PLA FSNMs have been prepared by spin-coating a 99 : 1 PLA : poly(vinyl alcohol) mixture, and through a phase segregation process nanofeatures with dimensions similar to the entire nanomembrane thickness (∼110 nm) were induced. These nanofeatures have subsequently been transformed into nanoperforations (diameter: ∼51 nm) by selective solvent etching. The protein confined inside the nanopores of PLA FSNMs preserves the β-barrel structure and organizes in ovoid aggregates. The transport properties of Na+, K+, and Ca2+across non-perforated PLA, nanoperforated PLA, and Omp2a-filled nanoperforated PLA have been monitored by measuring the nanomembrane resistance with electrochemical impedance spectroscopy (EIS). The incorporation of nanoperforations enhances the transport of ions across PLA nanomembranes, whereas the functionality of immobilized Omp2a is essential to exhibit effects similar to those observed in biological nanomembranes. Indeed, Omp2a-filled nanoperforated PLA nanomembranes exhibit stronger affinity towards Na+and Ca2+ions than towards K+. In summary, this work provides a novel bioinspired strategy to develop mechanically stable and flexible FSNMs with channels for ion transport, which are precisely located inside artificial nanoperforations, thus holding great potential for applications in biofiltration and biosensing.
authors.affiliation: Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028, Spain. m.mar.perez@upc.edu carlos.aleman@upc.edu and Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C', C/Pasqual i Vila s/n, Barcelona E-08028, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Puiggalí-Jou
authors.affiliation: Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028, Spain. m.mar.perez@upc.edu carlos.aleman@upc.edu and Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C', C/Pasqual i Vila s/n, Barcelona E-08028, Spain.
authors.forename: Maria M
authors.initials: MM
authors.lastname: Pérez-Madrigal
authors.affiliation: Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028, Spain. m.mar.perez@upc.edu carlos.aleman@upc.edu and Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C', C/Pasqual i Vila s/n, Barcelona E-08028, Spain.
authors.forename: Luis J
authors.initials: LJ
authors.lastname: Del Valle
authors.affiliation: Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028, Spain. m.mar.perez@upc.edu carlos.aleman@upc.edu and Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C', C/Pasqual i Vila s/n, Barcelona E-08028, Spain.
authors.forename: Elaine
authors.initials: E
authors.lastname: Armelin
authors.affiliation: Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028, Spain. m.mar.perez@upc.edu carlos.aleman@upc.edu.
authors.forename: María T
authors.initials: MT
authors.lastname: Casas
authors.affiliation: Laboratoire de Chimie Physique des Biomolécules, Unité de Chimie Physique Théorique et Structurale (UCPTS), University of Namur, Rue de Bruxelles, 61, 5000 Namur, Belgium.
authors.forename: Catherine
authors.initials: C
authors.lastname: Michaux
authors.affiliation: Laboratoire de Chimie Physique des Biomolécules, Unité de Chimie Physique Théorique et Structurale (UCPTS), University of Namur, Rue de Bruxelles, 61, 5000 Namur, Belgium.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Perpète
authors.affiliation: Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C', C/Pasqual i Vila s/n, Barcelona E-08028, Spain and Departament d'Enginyeria Química, Escola Universitària d'Enginyeria Tècnica Industrial de Barcelona, Universitat Politècnica de Catalunya, Comte d'Urgell 187, 08036 Barcelona, Spain.
authors.forename: Francesc
authors.initials: F
authors.lastname: Estrany
authors.affiliation: Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028, Spain. m.mar.perez@upc.edu carlos.aleman@upc.edu and Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C', C/Pasqual i Vila s/n, Barcelona E-08028, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Alemán
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D002118:Calcium; D017136:Ion Transport; D007477:Ions; D058608:Nanopores; D011091:Polyesters; D018272:Porins / Q000737:chemistry*; D011188:Potassium; D012964:Sodium
chemical_list: D001426:Bacterial Proteins; D007477:Ions; C096735:Omp2a protein, Brucella; D011091:Polyesters; D018272:Porins; C033616:poly(lactide); D012964:Sodium; D011188:Potassium; D002118:Calcium