ORCID Profile
0000-0002-3276-8052
Current Organisation
University of Adelaide
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Publisher: American Chemical Society (ACS)
Date: 11-10-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6NR01068G
Abstract: Herein, we present a method for storing binary data within the spectral signature of nanoporous anodic alumina photonic crystals. A rationally designed multi-sinusoidal anodisation approach makes it possible to engineer the photonic stop band of nanoporous anodic alumina with precision. As a result, the transmission spectrum of these photonic nanostructures can be engineered to feature well-resolved and selectively positioned characteristic peaks across the UV-visible spectrum. Using this property, we implement an 8-bit binary code and assess the versatility and capability of this system by a series of experiments aiming to encode different information within the nanoporous anodic alumina photonic crystals. The obtained results reveal that the proposed nanosized platform is robust, chemically stable, versatile and has a set of unique properties for data storage, opening new opportunities for developing advanced nanophotonic tools for a wide range of applications, including sensing, photonic tagging, self-reporting drug releasing systems and secure encoding of information.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9TA08585H
Abstract: An extensive study on the structural engineering of titanium dioxide-functionalized nanoporous anodic alumina optical microcavities (TiO 2 -NAA-μQVs) for photocatalysis enhanced by light confinement is presented.
Publisher: American Chemical Society (ACS)
Date: 25-07-2018
DOI: 10.1021/ACS.ANALCHEM.8B02732
Abstract: This study reports on the real-time binding assessment between heavy metal ions and blood proteins immobilized onto nanoporous anodic alumina photonic crystals (NAA-PCs) by reflectometric interference spectroscopy (RIfS). The surface of NAA-PCs is chemically functionalized with γ-globulin (GG), transferrin (TFN), and serum albumin (HSA), the major proteins present in human blood plasma. Protein-modified NAA-PC platforms are exposed to analytical solutions of mercury ions of different concentrations. Dynamic changes in the effective optical thickness of protein-modified NAA-PCs in response to heavy metal ions are assessed in real time to evaluate the binding kinetics, affinity, and mechanism. Protein molecules undergo conformational changes upon exposure to mercury ions, with HSA exhibiting the strongest affinity. The combination of protein-modified NAA-PCs with RIfS allows real-time monitoring of protein-heavy metal ions interactions under dynamic flow conditions. This system is capable of detecting dynamic conformational changes in these proteins upon exposure to heavy metal ions. Our results provide new insights into these binding events, which could enable new methodologies to study the toxicity of heavy metal ions and other biomolecular interactions.
Publisher: OSA
Date: 2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9CY02561H
Abstract: A platform material composed of 2D gold (Au) nanodot plasmonic single-lattices (Au-nD-PSLs) featuring tailor-engineered geometric features for visible-NIR light-driven enhanced photocatalysis is presented.
Publisher: American Chemical Society (ACS)
Date: 16-02-2020
Abstract: Macrophage differentiation into M1 (inflammatory) and M2 (healing) phenotypes plays a vital role in determining the fate of biomaterials. The biophysical properties of the extracellular matrix are known to affect macrophage behavior. Mimicking these special biophysical properties of the extracellular matrix has led to increasing interest in biomaterial constructs with tailor-engineered surface nanotopographical and chemical properties. However, a significant gap of knowledge exists in the role played by the combinational effect of surface nanotopography and chemistry. To address this gap, we have fabricated nanoporous surfaces of controlled pore size (30, 65, and 200 nm) and lateral spacing with uniform outermost surface chemistry tailored with amines (NH
Publisher: American Chemical Society (ACS)
Date: 08-12-2020
Publisher: MDPI AG
Date: 25-11-2019
DOI: 10.3390/CATAL9120988
Abstract: Photocatalysis comprises a variety of light-driven processes in which solar energy is converted into green chemical energy to drive reactions such as water splitting for hydrogen energy generation, degradation of environmental pollutants, CO2 reduction and NH3 production. Electrochemically engineered nanoporous materials are attractive photocatalyst platforms for a plethora of applications due to their large effective surface area, highly controllable and tuneable light-harvesting capabilities, efficient charge carrier separation and enhanced diffusion of reactive species. Such tailor-made nanoporous substrates with rational chemical and structural designs provide new exciting opportunities to develop advanced optical semiconductor structures capable of performing precise and versatile control over light–matter interactions to harness electromagnetic waves with unprecedented high efficiency and selectivity for photocatalysis. This review introduces fundamental developments and recent advances of electrochemically engineered nanoporous materials and their application as platforms for photocatalysis, with a final prospective outlook about this dynamic field.
Publisher: American Chemical Society (ACS)
Date: 10-05-2016
DOI: 10.1021/ACS.ANALCHEM.6B00993
Abstract: In this study, we report an innovative approach aiming to assess the binding affinity between drug molecules and human serum albumin by combining nanoporous anodic alumina rugate filters (NAA-RFs) modified with human serum albumin (HSA) and reflectometric interference spectroscopy (RIfS). NAA-RFs are photonic crystal structures produced by sinusoidal pulse anodization of aluminum that present two characteristic optical parameters, the characteristic reflection peak (λPeak), and the effective optical thickness of the film (OTeff), which can be readily used as sensing parameters. A design of experiments strategy and an ANOVA analysis are used to establish the effect of the anodization parameters (i.e., anodization period and anodization offset) on the sensitivity of HSA-modified NAA-RFs toward indomethacin, a model drug. To this end, two sensing parameters are used, that is, shifts in the characteristic reflection peak (ΔλPeak) and changes in the effective optical thickness of the film (ΔOTeff). Subsequently, optimized NAA-RFs are used as sensing platforms to determine the binding affinity between a set of drugs (i.e., indomethacin, coumarin, sulfadymethoxine, warfarin, and salicylic acid) and HSA molecules. Our results verify that the combination of HSA-modified NAA-RFs with RIfS can be used as a portable, low-cost, and simple system for establishing the binding affinity between drugs and plasma proteins, which is a critical factor to develop efficient medicines for treating a broad range of diseases and medical conditions.
Publisher: SPIE
Date: 02-01-2018
DOI: 10.1117/12.2282248
Publisher: American Chemical Society (ACS)
Date: 31-03-0005
Publisher: American Chemical Society (ACS)
Date: 10-08-2022
Publisher: Springer Science and Business Media LLC
Date: 15-03-2018
DOI: 10.1038/S41598-018-22895-5
Abstract: This study presents a nanofabrication approach that enables the production of nanoporous anodic alumina distributed Bragg reflectors (NAA-DBRs) with finely engineered light filtering features across the spectral regions. The photonic stopband (PSB) of these NAA-based photonic crystal (PC) structures is precisely tuned by an apodization strategy applied during stepwise pulse anodization with the aim of engineering the effective medium of NAA-DBRs in depth. We systematically assess the effect of different fabrication parameters such as apodization function (i.e. linear positive, linear negative, logarithmic positive and logarithmic negative), litude difference (from 0.105 to 0.420 mA cm −2 ), current density offset (from 0.140 to 0.560 mA cm −2 ), anodization period (from 1100 to 1700 s), and pore widening time (from 0 to 6 min) on the quality and central wavelength of the PSB of NAA-DBRs. The PSB’s features these PC structures are demonstrated to be highly tunable with the fabrication parameters, where a logarithmic negative apodization is found to be the most effective function to produce NAA-DBRs with high quality PSBs across the UV-visible-NIR spectrum. Our study establishes that apodized NAA-DBRs are more sensitive to changes in their effective medium than non-apodized NAA-DBRs, making them more suitable sensing platforms to develop advanced optical sensing systems.
Publisher: American Chemical Society (ACS)
Date: 28-08-2018
Publisher: Wiley
Date: 09-08-2022
Abstract: Nanoporous anodic alumina (NAA) fabricated by anodization of aluminum is a versatile platform material with tailorable geometric, optical, and chemical features for specific light‐based technologies and applications. Recent advances in anodization technology have enabled a new generation of NAA‐based photonic crystals (PCs)—periodic dielectric nanoporous structures that selectively allow, forbid, and confine the flow of incoming electromagnetic waves of specific wavelengths across their structure. NAA–PCs provide exciting new opportunities to engineer light–matter interactions with versatility across the broad spectrum, from UV to IR. But despite these fundamental advances, demonstrations of sunlight‐harvesting technologies based on NAA–PCs are still limited. Herein, an up‐to‐date summary of recent advances in NAA–PC technology is provided, and proof‐of‐concept demonstrations and future pathways to propel this versatile platform material across sunlight‐harvesting technologies such as photocatalysis, photoelectrocatalysis, photothermal energy conversion, and solar cells are discussed.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8NR04263B
Abstract: A study about the structural engineering of high quality nanoporous anodic alumina optical microcavities (NAA-μCVs) fabricated by rationally designed anodisation strategies to enhance the light-confining capabilities of these photonic crystal (PC) structures is presented.
Publisher: AIP Publishing
Date: 02-2022
DOI: 10.1063/5.0078505
Abstract: To control and harness the intrinsic photoluminescence of solid-state, light-emitting materials produced by self-organization approaches remain challenging. This study demonstrates how the intrinsic broadband photoluminescence emission from nanoporous anodic alumina (NAA) produced by anodization of aluminum in oxalic acid electrolyte can be precisely tuned by engineering its structure in the form of photonic crystals (PCs). A combination of pulse and constant anodization in distinct acid electrolytes makes it possible to engineer a novel heterogeneous optical structure consisting of two layers: (i) a non-emitting, light-filtering layer in the form of multi-spectral nanoporous anodic alumina photonic crystals (MS–NAA–PCs) on its top (i.e., 58 µm thick and average pore diameter of 17 nm) and (ii) an intrinsically light-emitting layer of NAA at its bottom (i.e., 50 µm thick an average pore diameter of 40 nm). MS–NAA–PCs are engineered to feature three intense, well-resolved photonic stopbands (PSBs), the positions of which are spaced at specific regions of the visible spectrum from ∼380 to 560 nm. It is demonstrated that the PSBs of the non-emitting MS–NAA–PCs on top of the heterogeneous optical structure act as a light-filtering component, which makes it possible to narrow and tune the characteristically broad, Gaussian-like photoluminescence emission from the underlying light-emitting NAA layer. This structural design makes it possible to narrow the width of photoluminescence emission up to ∼50 nm and blue shift its position for ∼15 nm. Our advances pave the way for novel designs of intrinsic, light-emitting NAA-based PC structures, which could find broad applicability across light technologies, such as sensing and biosensing, photodetection, and solar light harvesting.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TC01735D
Abstract: An overview of structural, chemical, and iontronic properties of nanoporous anodic alumina (NAA) with proof-of-principle demonstrations of state-of-the-art iontronic applications such as ionic diodes, sensors, and osmotic energy generators.
Publisher: American Chemical Society (ACS)
Date: 22-02-2019
Publisher: American Chemical Society (ACS)
Date: 18-09-2023
Publisher: Elsevier BV
Date: 03-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7NR02115A
Abstract: We present the first realisation of linear variable bandpass filters in nanoporous anodic alumina (NAA-LVBPFs) photonic crystal structures. NAA gradient-index filters (NAA-GIFs) are produced by sinusoidal pulse anodisation and used as photonic crystal platforms to generate NAA-LVBPFs. The anodisation period of NAA-GIFs is modified from 650 to 850 s to systematically tune the characteristic photonic stopband of these photonic crystals across the UV-visible-NIR spectrum. Then, the nanoporous structure of NAA-GIFs is gradually widened along the surface under controlled conditions by wet chemical etching using a dip coating approach aiming to create NAA-LVBPFs with finely engineered optical properties. We demonstrate that the characteristic photonic stopband and the iridescent interferometric colour displayed by these photonic crystals can be tuned with precision across the surface of NAA-LVBPFs by adjusting the fabrication and etching conditions. Here, we envisage for the first time the combination of the anodisation period and etching conditions as a cost-competitive, facile, and versatile nanofabrication approach that enables the generation of a broad range of unique LVBPFs covering the spectral regions. These photonic crystal structures open new opportunities for multiple applications, including adaptive optics, hyperspectral imaging, fluorescence diagnostics, spectroscopy, and sensing.
Publisher: American Chemical Society (ACS)
Date: 20-05-2016
Abstract: This study presents a sawtooth-like pulse anodization approach aiming to create a new type of photonic crystal structure based on nanoporous anodic alumina. This nanofabrication approach enables the engineering of the effective medium of nanoporous anodic alumina in a sawtooth-like manner with precision. The manipulation of various anodization parameters such as anodization period, anodization litude, number of anodization pulses, r ratio and pore widening time allows a precise control and fine-tuning of the optical properties (i.e., characteristic transmission peaks and interferometric colors) exhibited by nanoporous anodic alumina photonic crystals (NAA-PCs). The effect of these anodization parameters on the photonic properties of NAA-PCs is systematically evaluated for the establishment of a fabrication methodology toward NAA-PCs with tunable optical properties. The effective medium of the resulting NAA-PCs is demonstrated to be optimal for the development of optical sensing platforms in combination with reflectometric interference spectroscopy (RIfS). This application is demonstrated by monitoring in real-time the formation of monolayers of thiol molecules (11-mercaptoundecanoic acid) on the surface of gold-coated NAA-PCs. The obtained results reveal that the adsorption mechanism between thiol molecules and gold-coated NAA-PCs follows a Langmuir isotherm model, indicating a monolayer sorption mechanism.
Publisher: American Chemical Society (ACS)
Date: 06-02-2015
DOI: 10.1021/AM5091963
Abstract: In this study, we present a nanoengineered therapeutic-releasing system based on aluminum wires featuring nanoporous anodic alumina layers and chitosan coatings. Nanoporous anodic alumina layers are produced on the surface of aluminum wires by electrochemical anodization. These nanoporous layers with precisely engineered nanopore geometry are used as nanocontainers for bovine serum albumin molecules labeled with fluorescein isothiocyanate (BSA-FITC), which is selected as a model drug. The surface of these therapeutic-releasing implants is coated with a biocompatible and biodegradable polymer, chitosan, in order to achieve a sustained release of protein over extended periods of time. The performance of this therapeutic-releasing device is systematically assessed through a series of experiments under static and dynamic flow conditions. In these experiments, the effect of such parameters as the number of layers of chitosan coating and the temperature and pH of the eluting medium is established. The obtained results reveal that the proposed therapeutic-releasing system based on nanoporous aluminum wires can be engineered with sustained release performance for up to 6.5 weeks, which is a critical factor for medical treatments using sensitive therapeutics such as proteins and genes when a localized delivery is desired.
Publisher: American Chemical Society (ACS)
Date: 18-03-2021
Publisher: SPIE
Date: 02-01-2018
DOI: 10.1117/12.2282250
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CY00627C
Abstract: This study explores the potential of gold-coated titania-functionalized nanoporous anodic alumina distributed Bragg reflectors (Au-TiO 2 -NAA-DBRs) as platforms to enhance photocatalytic reactions by integrating “slow photons” and surface plasmon resonance (SPR).
Publisher: American Chemical Society (ACS)
Date: 09-03-2022
Publisher: American Chemical Society (ACS)
Date: 25-06-2018
Abstract: In this study, we explore for the first time the capabilities of nanoporous anodic alumina gradient-index filters (NAA-GIFs) functionalized with titanium dioxide (TiO
Publisher: American Chemical Society (ACS)
Date: 08-01-2019
Publisher: MDPI AG
Date: 04-10-2018
DOI: 10.3390/NANO8100788
Abstract: Optical sensors are a class of devices that enable the identification and/or quantification of analyte molecules across multiple fields and disciplines such as environmental protection, medical diagnosis, security, food technology, biotechnology, and animal welfare. Nanoporous photonic crystal (PC) structures provide excellent platforms to develop such systems for a plethora of applications since these engineered materials enable precise and versatile control of light–matter interactions at the nanoscale. Nanoporous PCs provide both high sensitivity to monitor in real-time molecular binding events and a nanoporous matrix for selective immobilization of molecules of interest over increased surface areas. Nanoporous anodic alumina (NAA), a nanomaterial long envisaged as a PC, is an outstanding platform material to develop optical sensing systems in combination with multiple photonic technologies. Nanoporous anodic alumina photonic crystals (NAA-PCs) provide a versatile nanoporous structure that can be engineered in a multidimensional fashion to create unique PC sensing platforms such as Fabry–Pérot interferometers, distributed Bragg reflectors, gradient-index filters, optical microcavities, and others. The effective medium of NAA-PCs undergoes changes upon interactions with analyte molecules. These changes modify the NAA-PCs’ spectral fingerprints, which can be readily quantified to develop different sensing systems. This review introduces the fundamental development of NAA-PCs, compiling the most significant advances in the use of these optical materials for chemo- and biosensing applications, with a final prospective outlook about this exciting and dynamic field.
Publisher: American Chemical Society (ACS)
Date: 29-04-2022
Abstract: The hemispherical barrier oxide layer (BOL) closing the bottom tips of hexagonally distributed arrays of cylindrical nanochannels in nanoporous anodic alumina (NAA) membranes is structurally engineered by anodizing aluminum substrates in three distinct acid electrolytes at their corresponding self-ordering anodizing potentials. These nanochannels display a characteristic ionic current rectification (ICR) signal between high and low ionic conduction states, which is determined by the thickness and chemical composition of the BOL and the pH of the ionic electrolyte solution. The rectification efficiency of the ionic current associated with the flow of ions across the anodic BOL increases with its thickness, under optimal pH conditions. The inner surface of the nanopores in NAA membranes was chemically modified with thiol-terminated functional molecules. The resultant NAA-based iontronic system provides a model platform to selectively detect gold metal ions (Au
Publisher: Elsevier
Date: 2020
Publisher: Springer Science and Business Media LLC
Date: 21-06-2018
DOI: 10.1038/S41598-018-27775-6
Abstract: In this study, we present an advanced nanofabrication approach, so-called ‘heterogeneous pulse anodization’ (HPA), in which galvanostatic stepwise and apodized sinusoidal pulse anodizations are combined in a single process. This novel anodization method enables the precise optical engineering of the characteristic photonic stopbands (PSBs) of nanoporous anodic alumina photonic crystals (NAA-PCs). The resulting structures are hybrid PCs (Hy-NAA-PCs) composed of distributed Bragg reflectors (DBRs) and apodized gradient-index filters (APO-GIFs) embedded within the same PC structure. The modification of various anodization parameters such as anodization period, relative and total anodization time, structural arrangement of PCs within Hy-NAA-PCs, and pore widening time allows the fine-tuning of the PSBs’ features (i.e. number, position and bandwidth of central wavelength) across the spectral regions. The effects of these fabrication parameters are systematically assessed, revealing that the positions of the characteristic transmission bands of Hy-NAA-PCs are highly controllable. Our study provides a comprehensive rationale towards the development of unique Hy-NAA-PCs with controllable optical properties, which could open new opportunities for a plethora of applications.
Publisher: Elsevier BV
Date: 2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6NR06796D
Abstract: In this study, we present an advanced nanofabrication approach to produce gradient-index photonic crystal structures based on nanoporous anodic alumina. An apodization strategy is for the first time applied to a sinusoidal pulse anodisation process in order to engineer the photonic stop band of nanoporous anodic alumina (NAA) in depth. Four apodization functions are explored, including linear positive, linear negative, logarithmic positive and logarithmic negative, with the aim of finely tuning the characteristic photonic stop band of these photonic crystal structures. We systematically analyse the effect of the litude difference (from 0.105 to 0.840 mA cm
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6NR03490J
Abstract: Herein, we present a rationally designed advanced nanofabrication approach aiming at producing a new type of optical bandpass filters based on nanoporous anodic alumina photonic crystals. The photonic stop band of nanoporous anodic alumina (NAA) is engineered in depth by means of a pseudo-stepwise pulse anodisation (PSPA) approach consisting of pseudo-stepwise asymmetric current density pulses. This nanofabrication method makes it possible to tune the transmission bands of NAA at specific wavelengths and bandwidths, which can be broadly modified across the UV-visible-NIR spectrum through the anodisation period (i.e. time between consecutive pulses). First, we establish the effect of the anodisation period as a means of tuning the position and width of the transmission bands of NAA across the UV-visible-NIR spectrum. To this end, a set of nanoporous anodic alumina bandpass filters (NAA-BPFs) are produced with different anodisation periods, ranging from 500 to 1200 s, and their optical properties (i.e. characteristic transmission bands and interferometric colours) are systematically assessed. Then, we demonstrate that the rational combination of stacked NAA-BPFs consisting of layers of NAA produced with different PSPA periods can be readily used to create a set of unique and highly selective optical bandpass filters with characteristic transmission bands, the position, width and number of which can be precisely engineered by this rational anodisation approach. Finally, as a proof-of-concept, we demonstrate that the superposition of stacked NAA-BPFs produced with slight modifications of the anodisation period enables the fabrication of NAA-BPFs with unprecedented broad transmission bands across the UV-visible-NIR spectrum. The results obtained from our study constitute the first comprehensive rationale towards advanced NAA-BPFs with fully controllable photonic properties. These photonic crystal structures could become a promising alternative to traditional optical bandpass filters based on glass and plastic.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9NR10526C
Abstract: High-quality nanoporous anodic alumina gradient-index filters are realized by sinusoidal pulse anodization under optimized anodization conditions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9TC04438H
Abstract: We present a study on optical and surface chemistry engineering of nanoporous photonic crystals as sensing platforms for detection of ionic copper.
No related grants have been discovered for Cheryl Suwen Law.