Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/112058
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Type: Journal article
Title: Fabrication and optimization of bilayered nanoporous anodic alumina structures as multi-point interferometric sensing platform
Author: Nemati, M.
Santos, A.
Losic, D.
Citation: Sensors, 2018; 18(2):470-1-470-18
Publisher: MDPI
Issue Date: 2018
ISSN: 1424-2818
1424-8220
Statement of
Responsibility: 
Mahdieh Nemati, Abel Santos and Dusan Losic
Abstract: Herein, we present an innovative strategy for optimizing hierarchical structures of nanoporous anodic alumina (NAA) to advance their optical sensing performance toward multi-analyte biosensing. This approach is based on the fabrication of multilayered NAA and the formation of differential effective medium of their structure by controlling three fabrication parameters (i.e., anodization steps, anodization time, and pore widening time). The rationale of the proposed concept is that interferometric bilayered NAA (BL-NAA), which features two layers of different pore diameters, can provide distinct reflectometric interference spectroscopy (RIfS) signatures for each layer within the NAA structure and can therefore potentially be used for multi-point biosensing. This paper presents the structural fabrication of layered NAA structures, and the optimization and evaluation of their RIfS optical sensing performance through changes in the effective optical thickness (EOT) using quercetin as a model molecule. The bilayered or funnel-like NAA structures were designed with the aim of characterizing the sensitivity of both layers of quercetin molecules using RIfS and exploring the potential of these photonic structures, featuring different pore diameters, for simultaneous size-exclusion and multi-analyte optical biosensing. The sensing performance of the prepared NAA platforms was examined by real-time screening of binding reactions between human serum albumin (HSA)-modified NAA (i.e., sensing element) and quercetin (i.e., analyte). BL-NAAs display a complex optical interference spectrum, which can be resolved by fast Fourier transform (FFT) to monitor the EOT changes, where three distinctive peaks were revealed corresponding to the top, bottom, and total layer within the BL-NAA structures. The spectral shifts of these three characteristic peaks were used as sensing signals to monitor the binding events in each NAA pore in real-time upon exposure to different concentrations of quercetin. The multi-point sensing performance of BL-NAAs was determined for each pore layer, with an average sensitivity and low limit of detection of 600 nm (mg mL-1)-1 and 0.14 mg mL-1, respectively. BL-NAAs photonic structures have the capability to be used as platforms for multi-point RIfS sensing of biomolecules that can be further extended for simultaneous size-exclusion separation and multi-analyte sensing using these bilayered nanostructures.
Keywords: biomolecule detection; nanoporous anodic alumina; optical sensors; reflectometric interference spectroscopy; structural fabrication
Rights: © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
RMID: 0030081842
DOI: 10.3390/s18020470
Grant ID: http://purl.org/au-research/grants/arc/FT110100711
http://purl.org/au-research/grants/arc/DE140100549
Appears in Collections:IPAS publications
Chemical Engineering publications

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