1
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Jara Fornerod M, Alvarez-Fernandez A, Michalska M, Papakonstantinou I, Guldin S. Glucose Oxidase Loading in Ordered Porous Aluminosilicates: Exploring the Potential of Surface Modification for Electrochemical Glucose Sensing. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:7577-7587. [PMID: 37780408 PMCID: PMC10536975 DOI: 10.1021/acs.chemmater.3c01202] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/22/2023] [Indexed: 10/03/2023]
Abstract
Enzymatic electrochemical sensors have become the leading glucose detection technology due to their rapid response, affordability, portability, selectivity, and sensitivity. However, the performance of these sensors is highly dependent on the surface properties of the electrode material used to store glucose oxidase and its ability to retain enzymatic activity under variable environmental conditions. Mesoporous thin films have recently attracted considerable attention as promising candidates for enzyme storage and activity preservation due to their well-defined nanoarchitecture and tunable surface properties. Herein, we systematically compare pathways for the immobilization of glucose oxidase (GOx) and their effectiveness in electrochemical glucose sensing, following modification protocols that lead to the electrostatic attraction (amino functionalization), covalent bonding (aldehyde functionalization), and electrostatic repulsion (oxygen plasma treatment) of the ordered porous aluminosilicate-coated electrodes. By direct comparison using a quartz crystal microbalance, we demonstrate that glucose oxidase can be loaded in a nanoarchitecture with a pore size of ∼50 nm and pore interconnections of ∼35 nm using the native aluminosilicate surface, as well as after amino or aldehyde surface modification, while oxygen plasma exposure of the native surface inhibits glucose oxidase loading. Despite a variety of routes for enzyme loading, quantitative electrochemical glucose sensing between 0 and 20 mM was only possible when the porous surface was functionalized with amino groups, which we relate to the role of surface chemistry in accessing the underlying substrate. Our results highlight the impact of rational surface modification on electrochemical biosensing performance and demonstrate the potential of tailoring porous nanoarchitecture surfaces for biosensing applications.
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Affiliation(s)
| | - Alberto Alvarez-Fernandez
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
| | - Martyna Michalska
- Department
of Electronic & Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K.
| | - Ioannis Papakonstantinou
- Department
of Electronic & Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K.
| | - Stefan Guldin
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
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2
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Jara Fornerod M, Alvarez-Fernandez A, Williams ER, Skoda MWA, Prieto-Simon B, Voelcker NH, Stefik M, Coppens MO, Guldin S. Enhanced Structural Control of Soft-Templated Mesoporous Inorganic Thin Films by Inert Processing Conditions. ACS APPLIED MATERIALS & INTERFACES 2022; 14:56143-56155. [PMID: 36503231 PMCID: PMC9782354 DOI: 10.1021/acsami.2c18090] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Mesoporous thin films are widely used for applications in need of high surface area and efficient mass and charge transport properties. A well-established fabrication process involves the supramolecular assembly of organic molecules (e.g., block copolymers and surfactants) with inorganic materials obtained by sol-gel chemistry. Typically, subsequent calcination in air removes the organic template and reveals the porous inorganic network. A significant challenge for such coatings is the anisotropic shrinkage due to the volume contraction related to solvent evaporation, inorganic condensation, and template removal, affecting the final porosity as well as pore shape, size, arrangement, and accessibility. Here, we show that a two-step calcination process, composed of high-temperature treatment in argon followed by air calcination, is an effective fabrication strategy to reduce film contraction and enhance structural control of mesoporous thin films. Crucially, the formation of a transient carbonaceous scaffold enables the inorganic matrix to fully condense before template removal. The resulting mesoporous films retain a higher porosity as well as bigger pores with extended porous order. Such films present favorable characteristics for mass transport of large molecules. This is demonstrated for lysozyme adsorption into the mesoporous thin films as an example of enzyme storage.
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Affiliation(s)
| | - Alberto Alvarez-Fernandez
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
| | - Eric R. Williams
- Department
of Chemistry and Biochemistry, University
of South Carolina, Columbia, South Carolina 29208, United States
| | - Maximilian W. A. Skoda
- ISIS
Pulsed Neutron and Muon Source, Rutherford
Appleton Laboratory, Harwell, Oxfordshire OX11 OQX, U.K.
| | - Beatriz Prieto-Simon
- Department
of Electronic Engineering, Universitat Rovira
i Virgili, 43007 Tarragona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Nicolas H. Voelcker
- Monash Institute
of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
- Melbourne
Centre for Nanofabrication, Victorian Node
of the Australian National Fabrication Facility, Clayton, Victoria 3168, Australia
| | - Morgan Stefik
- Department
of Chemistry and Biochemistry, University
of South Carolina, Columbia, South Carolina 29208, United States
| | - Marc-Olivier Coppens
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
- Centre
for Nature Inspired Engineering, University
College London, Torrington
Place, London WC1E 7JE, U.K.
| | - Stefan Guldin
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
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3
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Suthar J, Alvarez-Fernandez A, Taylor A, Fornerod MJ, Williams GR, Guldin S. Silica Inverse Opal Nanostructured Sensors for Enhanced Immunodetection of Extracellular Vesicles by Quartz Crystal Microbalance with Dissipation Monitoring. ACS APPLIED NANO MATERIALS 2022; 5:12951-12961. [PMID: 36185167 PMCID: PMC9513796 DOI: 10.1021/acsanm.2c02775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 08/05/2022] [Indexed: 05/02/2023]
Abstract
Extracellular vesicles (EVs) are nanosized circulating assemblies that contain biomarkers considered promising for early diagnosis within neurology, cardiology, and oncology. Recently, acoustic wave biosensors, in particular based on quartz crystal microbalance with dissipation monitoring (QCM-D), have emerged as a sensitive, label-free, and selective EV characterization platform. A rational approach to further improving sensing detection limits relies on the nanostructuration of the sensor surfaces. To this end, inorganic inverse opals (IOs) derived from colloidal self-assembly present a highly tunable and scalable nanoarchitecture of suitable feature sizes and surface chemistry. This work systematically investigates their use in two-dimensional (2D) and three-dimensional (3D) for enhanced QCM-D EV detection. Precise tuning of the architecture parameters delivered improvements in detection performance to sensitivities as low as 6.24 × 107 particles/mL. Our findings emphasize that attempts to enhance acoustic immunosensing via increasing the surface area by 3D nanostructuration need to be carefully analyzed in order to exclude solvent and artifact entrapment effects. Moreover, the use of 2D nanostructured electrodes to compartmentalize analyte anchoring presents a particularly promising design principle.
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Affiliation(s)
- Jugal Suthar
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
- UCL
School of Pharmacy, University College London,
Bloomsbury, 29-39 Brunswick
Square, London WC1N 1AX, U.K.
| | - Alberto Alvarez-Fernandez
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
| | - Alaric Taylor
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
| | - Maximiliano J. Fornerod
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
| | - Gareth R. Williams
- UCL
School of Pharmacy, University College London,
Bloomsbury, 29-39 Brunswick
Square, London WC1N 1AX, U.K.
| | - Stefan Guldin
- Department
of Chemical Engineering, University College
London, Torrington Place, London WC1E 7JE, U.K.
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4
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Augurio A, Alvarez-Fernandez A, Panchal V, Pittenger B, De Wolf P, Guldin S, Briscoe J. Controlled Porosity in Ferroelectric BaTiO 3 Photoanodes. ACS APPLIED MATERIALS & INTERFACES 2022; 14:13147-13157. [PMID: 35271773 PMCID: PMC8949718 DOI: 10.1021/acsami.1c17419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 01/14/2022] [Indexed: 05/17/2023]
Abstract
The use of ferroelectric polarization to promote electron-hole separation has emerged as a promising strategy to improve photocatalytic activity. Although ferroelectric thin films with planar geometry have been largely studied, nanostructured and porous ferroelectric thin films have not been commonly used in photo-electrocatalysis. The inclusion of porosity in ferroelectric thin films would enhance the surface area and reactivity, leading to a potential improvement of the photoelectrochemical (PEC) performance. Herein, the preparation of porous barium titanate (pBTO) thin films by a soft template-assisted sol-gel method is reported, and the control of porosity using different organic/inorganic ratios is verified by the combination of scanning electron microscopy and ellipsometry techniques. Using piezoresponse force microscopy, the switching of ferroelectric domains in pBTO thin films is observed, confirming that the ferroelectric polarization is still retained in the porous structures. In addition, the presence of porosity in pBTO thin films leads to a clear improvement of the PEC response. By electrochemical poling, we also demonstrated the tuning of the PEC performance of pBTO thin films via ferroelectric polarization. Our work offers a simple and low-cost approach to control the morphology optimization of ferroelectric thin films, which could open up the development of materials with great potential for PEC applications.
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Affiliation(s)
- Adriana Augurio
- School
of Engineering and Material Science and Materials Research Institute, Queen Mary University of London, E1 4NS London, U.K.
| | - Alberto Alvarez-Fernandez
- Department
of Chemical Engineering, University College
London, Torrington Place, WC1E 7JE London, U.K.
| | | | - Bede Pittenger
- AFM
Unit, Bruker Nano Surfaces, 93117 Santa Barbara, California, United States
| | - Peter De Wolf
- AFM
Unit, Bruker Nano Surfaces, 93117 Santa Barbara, California, United States
| | - Stefan Guldin
- Department
of Chemical Engineering, University College
London, Torrington Place, WC1E 7JE London, U.K.
| | - Joe Briscoe
- School
of Engineering and Material Science and Materials Research Institute, Queen Mary University of London, E1 4NS London, U.K.
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5
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Alvarez-Fernandez A, Fornerod MJ, Reid B, Guldin S. Solvent Vapor Annealing for Controlled Pore Expansion of Block Copolymer-Assembled Inorganic Mesoporous Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:3297-3304. [PMID: 35235337 PMCID: PMC9097528 DOI: 10.1021/acs.langmuir.2c00074] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/23/2022] [Indexed: 05/18/2023]
Abstract
Mesoporous inorganic thin films are promising materials architectures for a variety of high-value applications, ranging from optical coatings and purification membranes to sensing and energy storage devices. Having precise control over the structural parameters of the porous network is crucial for broadening their applicability. To this end, the use of block copolymers (BCP) as sacrificial structure-directing agents via micelle coassembly is a particularly attractive route, since the resultant pore size is directly related to scaling laws for the radius of gyration of the pore-forming macromolecule. However, tailoring the molecular weight of the BCP via bespoke synthesis is an elaborate process that requires precise control over highly sensitive reactions conditions. Alternative methods have emerged, based on supramolecular assembly or the addition of different swelling agents. Nevertheleses, to date, these present a negative impact on the structural order and pore size dispersity of the final inorganic mesoporous films. In this work, we propose a novel and effective method for control over pore size, porosity, and structural order, which relies on a synergistic combination of BCP selective swelling via solvent vapor annealing (SVA) and locking of the structure by condensation of the inorganic sol-gel precursors. The results obtained in this work for TiO2 establish SVA as a new, straightforward, simple, and powerful route for the fabrication of mesoporous thin-film materials with controllable structural characteristics.
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6
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Alvarez-Fernandez A, Reid B, Suthar J, Choy SY, Jara Fornerod M, Mac Fhionnlaoich N, Yang L, Schmidt-Hansberg B, Guldin S. Fractionation of block copolymers for pore size control and reduced dispersity in mesoporous inorganic thin films. NANOSCALE 2020; 12:18455-18462. [PMID: 32941587 DOI: 10.1039/d0nr05132b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Mesoporous inorganic thin films are promising materials architectures for a variety of applications, including sensing, catalysis, protective coatings, energy generation and storage. In many cases, precise control over a bicontinuous porous network on the 10 nm length scale is crucial for their operation. A particularly promising route for structure formation utilizes block copolymer (BCP) micelles in solution as sacrificial structure-directing agents for the co-assembly of inorganic precursors. This method offers pore size control via the molecular weight of the pore forming block and is compatible with a broad materials library. On the other hand, the molecular weight dependence impedes continuous pore tuning and the intrinsic polymer dispersity presents challenges to the pore size homogeneity. To this end, we demonstrate how chromatographic fractionation of BCPs provides a powerful method to control the pore size and dispersity of the resulting mesoporous thin films. We apply a semi-preparative size exclusion chromatographic fractionation to a polydisperse poly(isobutylene)-block-poly(ethylene oxide) (PIB-b-PEO) BCP obtained from scaled-up synthesis. The isolation of BCP fractions with distinct molecular weight and narrowed dispersity allowed us to not only tune the characteristic pore size from 9.1 ± 1.5 to 14.1 ± 2.1 nm with the identical BCP source material, but also significantly reduce the pore size dispersity compared to the non-fractionated BCP. Our findings offer a route to obtain a library of monodisperse BCPs from a polydisperse feedstock and provide important insights on the direct relationship between macromolecular characteristics and the resulting structure-directed mesopores, in particular related to dispersity.
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Affiliation(s)
- Alberto Alvarez-Fernandez
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
| | - Barry Reid
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
| | - Jugal Suthar
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK. and UCL School of Pharmacy, University College London, 29-39 Brunswick Square, Bloomsbury, London, WC1N 1AX, UK
| | - Swan Yia Choy
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
| | - Maximiliano Jara Fornerod
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
| | - Niamh Mac Fhionnlaoich
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
| | - Lixu Yang
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
| | - Benjamin Schmidt-Hansberg
- BASF SE, Process Research & Chemical Engineering, Coating & Film Processing, Carl-Bosch-Strasse 38, 67056 Ludwigshafen am Rhein, Germany
| | - Stefan Guldin
- Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK.
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7
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Alvarez-Fernandez A, Reid B, Fornerod MJ, Taylor A, Divitini G, Guldin S. Structural Characterization of Mesoporous Thin Film Architectures: A Tutorial Overview. ACS APPLIED MATERIALS & INTERFACES 2020; 12:5195-5208. [PMID: 31961128 DOI: 10.1021/acsami.9b17899] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Mesoporous thin film architectures are an important class of materials that exhibit unique properties, which include high surface area, versatile surface functionalization, and bicontinuous percolation paths through a broad library of pore arrangements on the 10 nm length scale. Although porosimetry of bulk materials via sorption techniques is common practice, the characterization of thin mesoporous films with small sample volumes remains a challenge. A range of techniques are geared toward providing information over pore morphology, pore size distribution, surface area and overall porosity, but none of them offers a holistic evaluation and results are at times inconsistent. In this work, we present a tutorial overview for the reliable structural characterization of mesoporous films. Three model samples with variable pore size and porosity prepared by block copolymer (BCP) coassembly serve for a rational comparison. Various techniques are assessed side-by-side, including scanning electron microscopy (SEM), atomic force microscopy (AFM), grazing incidence small-angle X-ray scattering (GISAXS), and ellipsometric porosimetry (EP). We critically discuss advantages and limitations of each technique and provide guidelines for reliable implementation.
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Affiliation(s)
- Alberto Alvarez-Fernandez
- Department of Chemical Engineering , University College London , Torrington Place , London WC1E 7JE , United Kingdom
| | - Barry Reid
- Department of Chemical Engineering , University College London , Torrington Place , London WC1E 7JE , United Kingdom
| | - Maximiliano J Fornerod
- Department of Chemical Engineering , University College London , Torrington Place , London WC1E 7JE , United Kingdom
| | - Alaric Taylor
- Department of Chemical Engineering , University College London , Torrington Place , London WC1E 7JE , United Kingdom
| | - Giorgio Divitini
- Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , United Kingdom
| | - Stefan Guldin
- Department of Chemical Engineering , University College London , Torrington Place , London WC1E 7JE , United Kingdom
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