title: Engineering of Surface Chemistry for Enhanced Sensitivity in Nanoporous Interferometric Sensing Platforms.
abstract: We explore new approaches to engineering the surface chemistry of interferometric sensing platforms based on nanoporous anodic alumina (NAA) and reflectometric interference spectroscopy (RIfS). Two surface engineering strategies are presented, namely (i) selective chemical functionalization of the inner surface of NAA pores with amine-terminated thiol molecules and (ii) selective chemical functionalization of the top surface of NAA with dithiol molecules. The strong molecular interaction of Au3+ions with thiol-containing functional molecules of alkane chain or peptide character provides a model sensing system with which to assess the sensitivity of these NAA platforms by both molecular feature and surface engineering. Changes in the effective optical thickness of the functionalized NAA photonic films (i.e., sensing principle), in response to gold ions, are monitored in real-time by RIfS. 6-Amino-1-hexanethiol (inner surface) and 1,6-hexanedithiol (top surface), the most sensitive functional molecules from approaches i and ii, respectively, were combined into a third sensing strategy whereby the NAA platforms are functionalized on both the top and inner surfaces concurrently. Engineering of the surface according to this approach resulted in an additive enhancement in sensitivity of up to 5-fold compared to previously reported systems. This study advances the rational engineering of surface chemistry for interferometric sensing on nanoporous platforms with potential applications for real-time monitoring of multiple analytes in dynamic environments.
authors.affiliation: School of Chemical Engineering, ‡Department of Chemistry, §Institute for Photonics and Advanced Sensing (IPAS), and ∥ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), The University of Adelaide , Adelaide, SA 5005, Australia.
authors.forename: Cheryl Suwen
authors.initials: CS
authors.lastname: Law
authors.affiliation: School of Chemical Engineering, ‡Department of Chemistry, §Institute for Photonics and Advanced Sensing (IPAS), and ∥ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), The University of Adelaide , Adelaide, SA 5005, Australia.
authors.forename: Georgina M
authors.initials: GM
authors.lastname: Sylvia
authors.affiliation: School of Chemical Engineering, ‡Department of Chemistry, §Institute for Photonics and Advanced Sensing (IPAS), and ∥ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), The University of Adelaide , Adelaide, SA 5005, Australia.
authors.forename: Madieh
authors.initials: M
authors.lastname: Nemati
authors.affiliation: School of Chemical Engineering, ‡Department of Chemistry, §Institute for Photonics and Advanced Sensing (IPAS), and ∥ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), The University of Adelaide , Adelaide, SA 5005, Australia.
authors.forename: Jingxian
authors.initials: J
authors.lastname: Yu
authors.affiliation: School of Chemical Engineering, ‡Department of Chemistry, §Institute for Photonics and Advanced Sensing (IPAS), and ∥ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), The University of Adelaide , Adelaide, SA 5005, Australia.
authors.forename: Dusan
authors.identifier: http://orcid.org/0000-0002-1930-072X
authors.initials: D
authors.lastname: Losic
authors.affiliation: School of Chemical Engineering, ‡Department of Chemistry, §Institute for Photonics and Advanced Sensing (IPAS), and ∥ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), The University of Adelaide , Adelaide, SA 5005, Australia.
authors.forename: Andrew D
authors.identifier: http://orcid.org/0000-0002-0604-2629
authors.initials: AD
authors.lastname: Abell
authors.affiliation: School of Chemical Engineering, ‡Department of Chemistry, §Institute for Photonics and Advanced Sensing (IPAS), and ∥ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), The University of Adelaide , Adelaide, SA 5005, Australia.
authors.forename: Abel
authors.identifier: http://orcid.org/0000-0002-5081-5684
authors.initials: A
authors.lastname: Santos
keywords: nanoporous anodic alumina; optical sensing; reflectometric interference spectroscopy; sensing performance; surface chemistry engineering