David is a Senior Lecturer and an ARC DECRA Fellow in the School of Mathematical and Physical Sciences, and is a core member of the Elemental Bio-imaging Facility. David was a Fulbright Postdoctoral Scholar which he undertook at UCLA to develop new methods to determine the efficacy of drug treatments for Duchenne muscular dystrophy. The success of this project led to the awarding of a DECRA to investigate quantitative 3-dimensional imaging of membrane proteins.
David specialises in hyphenation to ICP-MS, including HPLC and laser ablation, as well as LC-MS and GC-MS applications. His major areas of research include development and application of novel analytical techniques and spectroscopic techniques to biological research.
David teaches Analytical Chemistry 1 to 2nd year students. It is a subject that he developed and introduced to provide fundamental theoretical knowledge and laboratory skills in a discipline that underpins and meet the needs of industry and research.
Can supervise: YES
- Environmental and biological speciation of elements using HPLC-ICP-MS, including using novel, microfluidic devices.
- Elemental bio-imaging and immuno-mass spectrometry imaging using LA-ICP-MS.
- Analytical Chemistry 1
Clases, D, de Vega, RG, Bishop, D & Doble, P 2019, 'SEC-ICP-MS and on-line isotope dilution analysis for characterisation and quantification of immunochemical assays', ANALYTICAL AND BIOANALYTICAL CHEMISTRY, vol. 411, no. 16, pp. 3553-3560.View/Download from: UTS OPUS or Publisher's site
Lockwood, TE, Talebi, M, Minett, A, Mills, S, Doble, PA & Bishop, DP 2019, 'Micro solid-phase extraction for the analysis of per- and polyfluoroalkyl substances in environmental waters.', Journal of chromatography. A, vol. 1604.View/Download from: UTS OPUS or Publisher's site
Growing concern over the environmental and health impacts of per- and polyfluoroalkyl substances (PFASs) has led to the development of increasingly stringent regulatory guidelines. To meet these guidelines for the determination of PFASs in surface-water, solid-phase extraction (SPE) is commonly implemented for clean-up and pre-concentration of samples. In this paper a micro-SPE method for the clean-up and pre-concentration of PFASs from surface-water was developed. A micro-SPE packing phase was created to retain 13 long and short chain PFAS after examining combinations of four 3 µm particle size sorbents, with the optimal phase consisting of a 50:50 mixture of C18 and aminopropyl silica. Micro-SPE achieved similar results to conventional SPE methods while reducing sample preparation time to 5 min and using only 2 mL of sample. The method was validated using spiked recoveries (100 ng L-1) from PFAS contaminated surface-water samples with recoveries ranging from 86% to 111% and relative standard deviations below 18%. Concentrations of the PFASs in the samples ranged from below the limit of quantification to 898 ± 15 ng L-1. Automation of sample preparation, including the micro-SPE extraction, was also demonstrated. These results show the potential for automated micro-SPE to replace conventional SPE, with the decreases in sample preparation time, sample and solvent volumes crucial for incorporation into routine analyses in commercial laboratories.
Meyer, S, Clarke, C, dos Santos, RO, Bishop, D, Krieger, MA & Blanes, L 2019, 'Developing self-generated calibration curves using a capillary-driven wax-polyester lab on a chip device and thermal gates', Microchemical Journal, vol. 146, pp. 708-712.View/Download from: UTS OPUS or Publisher's site
© 2019 Elsevier B.V. Here we describe the development of a capillary-driven wax-polyester lab on a chip device and the concept of thermal gates to create self-generated calibration curves. The devices were fabricated by printing a wax pattern on a polyester film, and laminating two mirrored layers together. Victoria Blue R and a diluent of methanol/water (1:1) were placed in separate wells, and capillary forces drove the reagents through three additional mixing wells, resulting in respective dilutions of 50%, 25% and 12.5% of the original dye concentration (100%). A photo was taken after the capillary action ceased, and the color brightness of the four different concentrations was used for the creation of a calibration curve, resulting in a coefficient of determination of 0.99. The chip was readily adapted to include an additional channel to perform chemical reactions with KOH to increase the available detection options. The chip designs required up to three reagents to be simultaneously added, with any discrepancies in the synchronization of reagent addition leading to irreproducible results. To overcome these synchronization discrepancies, thermal gates were added by printing 0.15 mm wax barriers across the channel inlets to prevent liquid movement. These gates were simultaneously opened to allow the solutions to flow by applying heat, controlled by an Arduino-based instrument controller, through bent copper filaments positioned adjacent to the barriers for 380 milliseconds.
Pamphlett, R, Kum Jew, S, Doble, PA & Bishop, DP 2019, 'Elemental Analysis of Aging Human Pituitary Glands Implicates Mercury as a Contributor to the Somatopause.', Frontiers in Endocrinology, vol. 10, no. JUN.View/Download from: UTS OPUS or Publisher's site
Background: Growth hormone levels often decline on aging, and this "somatopause" is associated with muscle and bone loss, visceral adiposity and impaired cardiovascular function. Mercury has been detected in human pituitary glands, so to see if mercury could play a part in the somatopause we measured the proportion of people at different ages who had mercury in their anterior pituitary cells. Materials and methods: Paraffin sections of pituitary glands taken at autopsy from 94 people between the ages of 2 and 99 years were stained for inorganic mercury using autometallography. Pituitary mercury content was classified as none, low (<30% of cells) or high (>30% of cells) in increasing two-decade age groups. Autometallography combined with immunohistochemistry determined which hormone-producing cells contained mercury. Laser ablation-inductively coupled plasma-mass spectrometry was used to confirm the presence of mercury. Results: The proportion of people with low-content pituitary mercury remained between 33 and 42% at all ages. The proportion of people with high-content mercury increased with increasing age, from 0% of people in the 2-20 year group to a peak of 50% of people in the 61-80 years group, followed by a fall to 35% of people in the 81-99 years group. Mercury, when present, was found always in somatotrophs, occasionally in corticotrophs, rarely in thyrotrophs and gonadotrophs, and never in lactotrophs. Laser ablation-inductively coupled plasma-mass spectrometry detected mercury in regions of pituitaries that stained with autometallography. Conclusions: The proportion of people with mercury in their anterior pituitary cells, mostly somatotrophs, increases with aging, suggesting that mercury toxicity could be one factor contributing to the decline in growth hormone levels found in advancing age.
Taudte, RV, Roux, C, Bishop, DP, Fouracre, C & Beavis, A 2019, 'High-throughput screening for target compounds in smokeless powders using online-SPE tandem mass spectrometry', AUSTRALIAN JOURNAL OF FORENSIC SCIENCES.View/Download from: UTS OPUS or Publisher's site
Bishop, DP, Cole, N, Zhang, T, Doble, PA & Hare, DJ 2018, 'A guide to integrating immunohistochemistry and chemical imaging.', Chemical Society reviews, vol. 47, no. 11, pp. 3770-3787.View/Download from: UTS OPUS or Publisher's site
Chemical imaging provides new insight into the fundamental atomic, molecular, and biochemical composition of tissue and how they are interrelated in normal physiology. Visualising and quantifying products of pathogenic reactions long before structural changes become apparent also adds a new dimension to understanding disease pathogenesis. While chemical imaging in isolation is somewhat limited by the nature of information it can provide (e.g. peptides, metals, lipids, or functional groups), integrating immunohistochemistry allows simultaneous, targeted imaging of biomolecules while also mapping tissue composition. Together, this approach can provide invaluable information on the inner workings of the cell and the molecular basis of diseases.
Bishop, DP, Grossgarten, M, Dietrich, D, Vennemann, A, Cole, N, Sperling, M, Wiemann, M, Doble, PA & Karst, U 2018, 'Correction: Quantitative imaging of translocated silver following nanoparticle exposure by laser ablation-inductively coupled plasma-mass spectrometry (Analytical Methods (2018) DOI: 10.1039/c7ay02294h)', Analytical Methods, vol. 10, no. 8.View/Download from: UTS OPUS or Publisher's site
© 2018 The Royal Society of Chemistry. The authors regret that the incorrect affiliation was shown initially for Nerida Cole. The corrected list of author affiliations for this paper is as shown above. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.
Bishop, DP, Grossgarten, M, Dietrich, D, Vennemann, A, Cole, N, Sperling, M, Wiemann, M, Doble, PA & Karst, U 2018, 'Quantitative imaging of translocated silver following nanoparticle exposure by laser ablation-inductively coupled plasma-mass spectrometry', Analytical Methods, vol. 10, no. 8, pp. 836-840.View/Download from: UTS OPUS or Publisher's site
© 2018 The Royal Society of Chemistry. The likelihood of exposure to antimicrobial silver nanoparticles continues to grow with their increasing ubiquity in various medical and consumer products. While translocation of silver nanoparticles to major organs has been examined, the in situ location and concentration in the organs is not well characterised. Here we have used laser ablation-inductively coupled plasma-mass spectrometry to quantitatively image serial sections to construct a three-dimensional representation of the distribution of silver in rat spleen following respiratory tract exposure via intratracheal instillation of silver nanoparticles. Silver was distributed predominantly in the white pulp of the spleen at concentrations greater than 300 ng g-1. Imaging tissue sections via laser-ablation-inductively coupled plasma-mass spectrometry is an excellent tool for the visualisation and quantification of metals attributed to nanoparticles in organs allowing investigation of silver nanoparticle exposure in vivo.
Bishop, DP, Hare, DJ, Clases, D & Doble, PA 2018, 'Applications of liquid chromatography-inductively coupled plasma-mass spectrometry in the biosciences: A tutorial review and recent developments', TrAC - Trends in Analytical Chemistry, vol. 104.View/Download from: UTS OPUS or Publisher's site
© 2017. The biological function of minor and trace elements is ordinarily determined by their association with specific proteins, peptides and other biomolecules. Therefore, measuring the total elemental content of a biological sample provides limited information, particularly when a specific effect is due to an individual metal-protein complex. Speciation of metalloproteins, heteroatom-containing molecules or other compounds tagged with an exogenous metal can be used to overcome this limitation. A range of chromatographic separation techniques with on-line elemental detection using inductively coupled plasma-mass spectrometry (ICP-MS) have been applied to the biosciences, and each technique has intrinsic features that must be considered when designing speciation experiments. This tutorial review provides an overview of speciation in the biosciences, highlighting the unique abilities and limitations encountered. A selection of recent technical advances and new applications, the challenges of sample preparation and implementation of new technical developments are discussed, as well as the future directions of technology that is rapidly gaining a foothold in the contemporary biochemistry laboratory.
Chen, H, Ng, JPM, Bishop, DP, Milthorpe, BK & Valenzuela, SM 2018, 'Gold nanoparticles as cell regulators: beneficial effects of gold nanoparticles on the metabolic profile of mice with pre-existing obesity', JOURNAL OF NANOBIOTECHNOLOGY, vol. 16.View/Download from: UTS OPUS or Publisher's site
Main, BJ, Bowling, LC, Padula, MP, Bishop, DP, Mitrovic, SM, Guillemin, GJ & Rodgers, KJ 2018, 'Detection of the suspected neurotoxin β-methylamino-l-alanine (BMAA) in cyanobacterial blooms from multiple water bodies in Eastern Australia.', Harmful algae, vol. 74, pp. 10-18.View/Download from: UTS OPUS or Publisher's site
The emerging toxin β-methylamino-l-alanine (BMAA) has been linked to the development of a number of neurodegenerative diseases in humans including amyotrophic lateral sclerosis (ALS), Alzheimer's disease, and Parkinson's disease. BMAA has been found to be produced by a range of cyanobacteria, diatoms, and dinoflagellates worldwide, and is present in freshwater, saltwater, and terrestrial ecosystems. Surface scum samples were collected from waterways in rural and urban New South Wales, Australia and algal species identified. Reverse phase liquid chromatography-tandem mass spectrometry was used to analyse sixteen cyanobacterial scum for the presence of BMAA as well as its toxic structural isomer 2,4-diaminobutyric acid (2,4-DAB). BMAA was detected in ten of the samples analysed, and 2,4-DAB in all sixteen. The presence of these toxins in water used for agriculture raises concerns for public health and food security in Australia.
Maixner, F, Turaev, D, Cazenave-Gassiot, A, Janko, M, Krause-Kyora, B, Hoopmann, MR, Kusebauch, U, Sartain, M, Guerriero, G, O´Sullivan, N, Teasdale, M, Cipollini, G, Paladin, A, Mattiangeli, V, Samadelli, M, Tecchiati, U, Putzer, A, Palazoglu, M, Meissen, J, Lösch, S, Rausch, P, Baines, JF, Kim, BJ, An, H, Gostner, P, Egarter-Vigl, E, Malfertheiner, P, Keller, A, Stark, RW, Wenk, M, Bishop, D, Bradley, DG, Fiehn, O, Engstrand, L, Moritz, RL, Doble, P, Franke, A, Nebel, A, Oeggl, K, Rattei, T, Grimm, R & Zink, A 2018, 'The Iceman´s last meal consisted of fat, wild meat and cereals', Current Biology, vol. 28, no. 14, pp. 2348-2355.View/Download from: Publisher's site
The history of humankind is marked by the constant adoption of new dietary habits affecting human physiology, metabolism, and even the development of nutrition-related disorders. Despite clear archaeological evidence for the shift from hunter-gatherer lifestyle to agriculture in Neolithic Europe , very little information exists on the daily dietary habits of our ancestors. By undertaking a complementary -omics approach combined with microscopy, we analyzed the stomach content of the Iceman, a 5,300-year-old European glacier mummy [2, 3]. He seems to have had a remarkably high proportion of fat in his diet, supplemented with fresh or dried wild meat, cereals, and traces of toxic bracken. Our multipronged approach provides unprecedented analytical depth, deciphering the nutritional habit, meal composition, and food-processing methods of this Copper Age individual.
Miles, NG, Butler, GL, Diamond, SL, Bishop, DP, van der Meulen, DE, Reinfelds, I & Walsh, CT 2018, 'Combining otolith chemistry and telemetry to assess diadromous migration in pinkeye mullet, Trachystoma petardi (Actinopterygii, Mugiliformes)', Hydrobiologia, vol. 808, no. 1, pp. 265-281.View/Download from: UTS OPUS or Publisher's site
© 2017, Springer International Publishing AG, part of Springer Nature. This study examines the complex diadromous movements in pinkeye mullet (Trachystoma petardi) of south-eastern Australia. The techniques used to study these movements included LA-ICP-MS single line ablation transects and microchemical imaging as well as preliminary acoustic telemetry results which were used to aid in interpretation of chemical signatures related to complex movement patterns across salinity gradients. Ba:Ca and Sr:Ca from single ablation transects and microchemical images revealed differences between the otolith core and outer regions. Otolith Ba:Ca and Sr:Ca patterns were more easily distinguished in images compared to transects and these revealed that T. petardi spend their early life in saline waters. Movement patterns for adults varied, with a range of movements identified between fresh and saline waters. Telemetry data assisted in explaining the likely cause of the ambiguity in otolith microchemistry data, including identification of multiple rapid movements across salinity gradients. However, many movements through salinity gradients appear too brief to result in any clear Sr:Ca or Ba:Ca saline or mesohaline signature within the chemistry of the otolith. The combination of otolith chemistry and telemetry proved useful in providing information on this poorly understood species suggesting that T. petardi display a catadromous life history.
Pamphlett, R, Bishop, DP, Kum Jew, S & Doble, PA 2018, 'Age-related accumulation of toxic metals in the human locus ceruleus.', PloS one, vol. 13, no. 9, pp. e0203627-e0203627.View/Download from: UTS OPUS or Publisher's site
Damage to the locus ceruleus has been implicated in the pathogenesis of a number of neurological conditions. Locus ceruleus neurons accumulate toxic metals such as mercury selectively, however, the presence of toxic metals in locus ceruleus neurons of people of different ages, and with a variety of disorders, is not known. To demonstrate at what age toxic metals are first detectable in the locus ceruleus, and to evaluate whether their presence is more common in certain clinicopathological conditions, we looked for these metals in 228 locus ceruleus samples. Samples were taken at coronial autopsies from individuals with a wide range of ages, pre-existing conditions and causes of death. Paraffin sections of pons containing the locus ceruleus were stained with silver nitrate autometallography, which indicates inorganic mercury, silver and bismuth within cells (termed autometallography-detected toxic metals, or AMG™). No locus ceruleus AMG neurons were seen in 38 individuals aged under 20 years. 47% of the 190 adults (ie, aged 20 years and over) had AMG locus ceruleus neurons. The proportion of adults with locus ceruleus AMG neurons increased during aging, except for a decreased proportion in the 90-plus years age group. No differences were found in the proportions of locus ceruleus AMG neurons between groups with different neurological, psychiatric, or other clinicopathological conditions, or among various causes of death. Elemental analysis with laser ablation-inductively coupled plasma-mass spectrometry was used to cross-validate the metals detected by AMG, by looking for silver, gold, bismuth, cadmium, chromium, iron, mercury, nickel, and lead in the locus ceruleus of ten individuals. This confirmed the presence of mercury in locus ceruleus samples containing AMG neurons, and showed cadmium, silver, lead, iron, and nickel in the locus ceruleus of some individuals. In conclusion, toxic metals stained by AMG (most likely inorganic mercury) appear in locus ceruleus ...
Portbury, SD, Hare, DJ, Bishop, DP, Finkelstein, DI, Doble, PA & Adlard, PA 2018, 'Trehalose elevates brain zinc levels following controlled cortical impact in a mouse model of traumatic brain injury', METALLOMICS, vol. 10, no. 6, pp. 846-853.View/Download from: Publisher's site
Bishop, DP, Blanes, L, Wilson, AB, Wilbanks, T, Killeen, K, Grimm, R, Wenzel, R, Major, D, Macka, M, Clarke, D, Schmid, R, Cole, N & Doble, PA 2017, 'Microfluidic high performance liquid chromatography-chip hyphenation to inductively coupled plasma-mass spectrometry', Journal of Chromatography A, vol. 149, pp. 64-69.View/Download from: UTS OPUS or Publisher's site
© 2017 Elsevier B.V.The Agilent Chip Cube Interface is a microfluidic chip-based technology originally designed for nanospray molecular mass spectrometry in which the sample enrichment, nano-column, tubing, connectors and spray tip were integrated into a single biocompatible chip. Here we describe the hyphenation of the Chip Cube Interface to ICP-MS via modification of the standard HPLC chip design and a new total consumption nebuliser suitable for flow rates as low as 300nLmin-1. The potential of the instrument to eliminate common nanoLC - ICP-MS shortcomings such as leaks, blockages and band-broadening was demonstrated via analysis of cyanocobalamin in equine plasma. The method was linear over three orders of magnitude with an r2 of 0.9999, the peak area repeatability was 1.9% (n=7), and the detection limit was 14ngmL-1. This novel configuration of the Chip Cube Interface coupled to ICP-MS is a suitable platform for the analysis of biomolecules associated with trace metals and speciation applications.
O'Neill, ES, Kaur, A, Bishop, DP, Shishmarev, D, Kuchel, PW, Grieve, SM, Figtree, GA, Renfrew, AK, Bonnitcha, PD & New, EJ 2017, 'Hypoxia-Responsive Cobalt Complexes in Tumor Spheroids: Laser Ablation Inductively Coupled Plasma Mass Spectrometry and Magnetic Resonance Imaging Studies.', Inorganic Chemistry, vol. 56, no. 16, pp. 9860-9868.View/Download from: UTS OPUS or Publisher's site
Dense tumors are resistant to conventional chemotherapies due to the unique tumor microenvironment characterized by hypoxic regions that promote cellular dormancy. Bioreductive drugs that are activated in response to this hypoxic environment are an attractive strategy for therapy with anticipated lower harmful side effects in normoxic healthy tissue. Cobalt bioreductive pro-drugs that selectively release toxic payloads upon reduction in hypoxic cells have shown great promise as anticancer agents. However, the bioreductive response in the tumor microenvironment must be better understood, as current techniques for monitoring bioreduction to Co(II) such as X-ray absorption near-edge structure and extended X-ray absorption fine structure provide limited information on speciation and require synchrotron radiation sources. Here, we present magnetic resonance imaging (MRI) as an accessible and powerful technique to monitor bioreduction by treating the cobalt complex as an MRI contrast agent and monitoring the change in water signal induced by reduction from diamagnetic Co(III) to paramagnetic Co(II). Cobalt pro-drugs built upon the tris(2-pyridylmethyl)amine ligand scaffold with varying charge were investigated for distribution and activity in a 3D tumor spheroid model by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and MRI. In addition, paramagnetic 1H NMR spectroscopy of spheroids enabled determination of the speciation of activated Co(II)TPAx complexes. This study demonstrates the utility of MRI and associated spectroscopy techniques for understanding bioreductive cobalt pro-drugs in the tumor microenvironment and has broader implications for monitoring paramagnetic metal-based therapies.
Portbury, SD, Hare, DJ, Sgambelloni, CJ, Bishop, DP, Finkelstein, DI, Doble, PA & Adlard, PA 2017, 'Age modulates the injury-induced metallomic profile in the brain.', Metallomics, vol. 9, no. 4, pp. 402-410.View/Download from: UTS OPUS or Publisher's site
The biological transition metals iron (Fe), copper (Cu) and zinc (Zn) are thought to contribute to the neuronal pathologies that occur following traumatic brain injury (TBI), and indeed our previously published work in young (3 month-old) mice clearly demonstrates a significant spatiotemporal modulation of metals following TBI. Of note, however, is the literature observation that there is both an apparent detrimental effect of aging on TBI outcomes and an alteration in metals and their various transporters with normal advancing age. Therefore, to determine whether there was an interaction between aging, metals and TBI, we have utilised laser ablation-inductively coupled plasma-mass spectrometry to examine the spatial and temporal distribution of Fe, Zn and Cu following an acute controlled cortical impact brain injury in aged (24 months) rodents. The relative abundance of metals in corresponding regions within the ipsilateral and contralateral hemispheres as well as the hippocampus was assessed. Substantial region and time point specific alterations in Fe, Zn and Cu were identified immediately and up to 28 days post-TBI. The data from this follow-up study has also been compared to our previous data from young animals, and aged mice exhibit an appreciably enhanced and persistent elevation of all metals in every region surveyed, with individual metal disparities at various time points observed post-injury. This may potentially contribute to the acceleration in the onset of cognitive decline and neurological disease that has been observed in the aged population following head trauma.
Lao, W, Jin, X, Tan, Y, Xiao, L, Padula, M, Bishop, D, Reedy, B, Ong, M, Kamal, M & Qu, X 2016, 'Characterisation of Bone Beneficial Components from Australian Wallaby Bone', Medicines, vol. 3, pp. 1-13.View/Download from: UTS OPUS or Publisher's site
Background: Osteoporosis is a condition in which the bones become brittle, increasing the risk of fractures. Complementary medicines have traditionally used animal bones for managing bone disorders, such as osteoporosis. This study aimed to discover new natural products for these types of conditions by determining mineral and protein content of bone extracts derived from the Australian wallaby. Methods: Inductively coupled plasma-mass spectrometry and Fourier transform infrared spectroscopic analysis were used for mineral tests, proteome analysis was using LC/MS/MS and the effects of wallaby bone extracts (WBE)s on calcium deposition and alkaline phosphatase activity were evaluated in osteogenic cells derived from adipose tissue-derived stem cells (ADSCs). Results: Concentrations of calcium and phosphorus were 26.21% and 14.72% in WBE respectively. Additionally, minerals found were wide in variety and high in concentration, while heavy metal concentrations of aluminium, iron, zinc and other elements were at safe levels for human consumption. Proteome analysis showed that extracts contained high amounts of bone remodelling proteins, such as osteomodulin, osteopontin and osteoglycin. Furthermore, in vitro evaluation of WBEs showed increased deposition of calcium in osteoblasts with enhanced alkaline phosphatase activity in differentiated adipose-derived stem cells. Conclusion: Our results demonstrate that wallaby bone extracts possess proteins and minerals beneficial for bone metabolism. WBEs may therefore be used for developing natural products for conditions such as osteoporosis and further investigation to understand biomolecular mechanism by which WBEs prevent osteoporosis is warranted.
Bishop, DP, Clases, D, Fryer, F, Williams, E, Wilkins, S, Hare, DJ, Cole, N, Karst, U & Doble, PA 2016, 'Elemental bio-imaging using laser ablation-triple quadrupole-ICP-MS', JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, vol. 31, no. 1, pp. 197-202.View/Download from: UTS OPUS or Publisher's site
Callahan, DL, Hare, DJ, Bishop, DP, Doble, PA & Roessner, U 2016, 'Elemental imaging of leaves from the metal hyperaccumulating plant Noccaea caerulescens shows different spatial distribution of Ni, Zn and Cd', RSC ADVANCES, vol. 6, no. 3, pp. 2337-2344.View/Download from: UTS OPUS or Publisher's site
Hare, DJ, Fryer, F, Paul, B, Bishop, DP & Doble, PA 2016, 'Characterisation of matrix-based polyatomic interference formation in laser ablation-inductively coupled plasma-mass spectrometry using dried micro-droplet ablation and its relevance for bioimaging', ANALYTICAL METHODS, vol. 8, no. 41, pp. 7552-7556.View/Download from: Publisher's site
Paul, B, Hare, DJ, Bishop, DP, Paton, C, Van, TN, Cole, N, Niedwiecki, MM, Andreozzi, E, Vais, A, Billings, JL, Bray, L, Bush, AI, McColl, G, Roberts, BR, Adlard, PA, Finkelstein, DI, Hellstrom, J, Hergt, JM, Woodhead, JD & Doble, PA 2016, 'Visualising mouse neuroanatomy and function by metal distribution using laser ablation-inductively coupled plasma-mass spectrometry imaging (vol 6, pg 5383, 2015)', CHEMICAL SCIENCE, vol. 7, no. 10, pp. 6576-6576.View/Download from: UTS OPUS or Publisher's site
Fowler, AM, Macreadie, PI, Bishop, DP & Booth, DJ 2015, 'Using otolith microchemistry and shape to assess the habitat value of oil structures for reef fish', MARINE ENVIRONMENTAL RESEARCH, vol. 106, pp. 103-113.View/Download from: UTS OPUS or Publisher's site
Bishop, DP, Hare, DJ, de Grazia, A, Fryer, F & Doble, PA 2015, 'Speciation and quantification of organotin compounds in sediment and drinking water by isotope dilution liquid chromatography-inductively coupled plasma-mass spectrometry', ANALYTICAL METHODS, vol. 7, no. 12, pp. 5012-5018.View/Download from: UTS OPUS or Publisher's site
Bishop, DP, Hare, DJ, Fryer, F, Taudte, RV, Cardoso, BR, Cole, N & Doble, PA 2015, 'Determination of selenium in serum in the presence of gadolinium with ICP-QQQ-MS', ANALYST, vol. 140, no. 8, pp. 2842-2846.View/Download from: UTS OPUS or Publisher's site
Cho, HR, Lee, Y, Doble, P, Bishop, D, Hare, D, Kim, Y-J, Kim, KG, Jung, HS, Park, KS, Choi, SH & Moon, WK 2015, 'Magnetic resonance imaging of the pancreas in streptozotocin-induced diabetic rats: Gadofluorine P and Gd-DOTA', WORLD JOURNAL OF GASTROENTEROLOGY, vol. 21, no. 19, pp. 5831-5842.View/Download from: Publisher's site
Kim, SY, Naskar, D, Kundu, SC, Bishop, DP, Doble, PA, Boddy, AV, Chan, H-K, Wall, IB & Chrzanowski, W 2015, 'Formulation of Biologically-Inspired Silk-Based Drug Carriers for Pulmonary Delivery Targeted for Lung Cancer', SCIENTIFIC REPORTS, vol. 5.View/Download from: UTS OPUS or Publisher's site
Lee, S, Kim, J-E, Hong, S-H, Lee, A-Y, Park, E-J, Seo, HW, Chae, C, Doble, P, Bishop, D & Cho, M-H 2015, 'High Inorganic Phosphate Intake Promotes Tumorigenesis at Early Stages in a Mouse Model of Lung Cancer', PLOS ONE, vol. 10, no. 8.View/Download from: Publisher's site
Paul, B, Hare, DJ, Bishop, DP, Paton, C, Nguyen, VT, Cole, N, Niedwiecki, MM, Andreozzi, E, Vais, A, Billings, JL, Bray, L, Bush, AI, McColl, G, Roberts, BR, Adlard, PA, Finkelstein, DI, Hellstrom, J, Hergt, JM, Woodhead, JD & Doble, PA 2015, 'Visualising mouse neuroanatomy and function by metal distribution using laser ablation-inductively coupled plasma-mass spectrometry imaging', Chemical Science, vol. 6, no. 10, pp. 5383-5393.View/Download from: UTS OPUS or Publisher's site
Paul, B, Hare, DJ, Bishop, DP, Paton, C, Van, TN, Cole, N, Niedzwiecki, MM, Andreozzi, E, Vais, A, Billings, JL, Bray, L, Bush, AI, McColl, G, Roberts, BR, Adlard, PA, Finkelstein, DI, Hellstrom, J, Hergt, JM, Woodhead, JD & Doble, PA 2015, 'Visualising mouse neuroanatomy and function by metal distribution using laser ablation-inductively coupled plasma-mass spectrometry imaging (vol 6, pg 5383, 2015)', CHEMICAL SCIENCE, vol. 6, no. 11, pp. 6677-6677.View/Download from: UTS OPUS or Publisher's site
Taudte, RV, Roux, C, Bishop, D, Blanes, L, Doble, P & Beavis, A 2015, 'Development of a UHPLC method for the detection of organic gunshot residues using artificial neural networks', Analytical Methods, vol. 7, no. 18, pp. 7447-7454.View/Download from: UTS OPUS or Publisher's site
The introduction of lead and heavy-metal free ammunition to the market challenges the current protocol for gunshot residue (GSR) investigations, which focuses on the inorganic components. Future proofing GSR analysis requires the development and implementation of new methods for the collection and analysis of organic GSR (OGSR) into operational protocols. This paper describes the development and optimisation of an ultra high performance liquid chromatography method for the analysis of 32 compounds potentially present in OGSR. An artificial neural network was applied to predict the retention times of the target analytes for various gradients for rapid determination of optimum separation conditions. The final separation and analysis time for the 32 target analytes was 27 minutes with limits of detection ranging from 0.03 to 0.21 ng. The method was applied to the analysis of smokeless powder and samples collected from the hands of a shooter following the discharge of a firearm. The results demonstrate that the method has the potential for use in cases involving GSR.
McGowan, N, Fowler, A, Parkinson, K, Bishop, D, Ganio, K, Doble, PA, Booth, DJ & Hare, DJ 2014, 'Beyond the transect: An alternative microchemical imaging method for fine scale analysis of trace elements in fish otoliths during early life', The Science of the Total Environment, vol. 494-495, pp. 177-186.View/Download from: UTS OPUS or Publisher's site
Microchemical analysis of otolith (calcified `ear stones used for balance and orientation) of fishes is an important tool for studying their environmental history and management. However, the spatial resolution achieved is often too coarse to examine short-termevents occurring in early life. Current methods rely on single points or transects across the otolith surface, which may provide a limited viewof elemental distributions, a matter that has not previously been investigated. Imaging by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) permits microchemical analyses of short-term events in early life with high (b10 ìm) resolution, twodimensional (2D) visualization of elemental distributions. To demonstrate the potential of this method, we mapped the concentrations of Sr and Ba, two key trace elements, in a small number of juvenile otoliths of neon damselfish (Pomacentrus coelestis) using an 8 ìm beam diameter (laser fluence of 13.8 ± 3.5 J cm.2). Quantification was performed using the established method by Longerich et al. (1996), which is applied to 2D imaging of a biological matrix here for the first time. Accuracy of N97% was achieved using a multi-point non matrix-matched calibration of National Institute of Standards and Technology (NIST) 610 and 612 (trace elements in glass) using Longerich's calculation method against the matrix-matched standard FEBS-1 (powdered red snapper [Lutjanus campechanus] otolith). The spatial resolution achieved in the otolith corresponded to a time period of 2 ± 1 days during the larval phase, and 4 ± 1 days during the post-settlement juvenile phase. This method has the potential to improve interpretations of early life-history events at scales corresponding to specific events. While the images showed gradients in Sr and Ba across the larval settlement zone more clearly.
Canning, J, Huyang, G, Ma, M, Beavis, A, Bishop, D, Cook, K, McDonagh, A, Shi, D, Peng, G-D & Crossley, MJ 2014, 'Percolation diffusion into self-assembled mesoporous silica microfibres', Nanomaterials, vol. 4, no. 1, pp. 157-174.View/Download from: UTS OPUS or Publisher's site
Percolation diffusion into long (11.5 cm) self-assembled, ordered mesoporous
microfibres is studied using optical transmission and laser ablation inductive
coupled mass spectrometry (LA-ICP-MS). Optical transmission based diffusion
studies reveal rapid penetration (< 5 s, D > 80 um2.s-1) of Rhodamine B with
very little percolation of larger molecules such as zinc tetraphenylporphyrin
(ZnTPP) observed under similar loading conditions. The failure of ZnTPP to
enter the microfibre was confirmed, in higher resolution, using LA-ICP-MS. In
the latter case, LA-ICP-MS was used to determine the diffusion of zinc acetate
dihydrate, D ~ 3 x 10-4 nm2.s-1. The large differences between the molecules
are accounted for by proposing ordered solvent and structure assisted
accelerated diffusion of the Rhodamine B based on its hydrophilicity relative
to the zinc compounds. The broader implications and applications for
filtration, molecular sieves and a range of devices and uses are described.
cho, H, kim, D, Kim, D, Doble, PA, Bishop, D, Hare, DJ, Park, C, Moon, WK, Han, MH & Choi, SH 2014, 'Malignant Glioma: MR imaging by using 5-Aminolevulinic acid in an animal model', Radiology, vol. 272, no. 3, pp. 720-730.View/Download from: UTS OPUS or Publisher's site
Chou, J, Valenzuela, SM, Santos, J, Bishop, D, Milthorpe, B, Green, DW, Otsuka, M & Ben-Nissan, B 2014, 'Strontium- and magnesium-enriched biomimetic beta-TCP macrospheres with potential for bone tissue morphogenesis', JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, vol. 8, no. 10, pp. 771-778.View/Download from: Publisher's site
Hare, DJ, Lei, P, Ayton, S, Roberts, B, Grimm, R, George, J, Bishop, D, Beavis, AB, Donovan, S, McColl, G, Volitakis, I, Masters, C, Adlard, P, Cherny, R, Bush, A, Finkelstein, D & Doble, PA 2014, 'An iron-dopamine index predicts risk of parkinsonian neurodegeneration in the substantia nigra pars compacta', Chemical Science, vol. 5, pp. 2160-2169.View/Download from: UTS OPUS or Publisher's site
The co-localization of iron and dopamine raises the risk of a potentially toxic reaction. Disturbance of the balance in this unique chemical environment makes neurons in the substantia nigra pars compacta (SNc) particularly vulnerable to parkinsonian neurodegeneration in the aging brain. In Parkinson's disease, these neurons degenerate coincident with an elevation in brain iron levels, yet relatively little is known about specific regional iron distribution with respect to dopamine. To directly appraise the irondopamine redox couple, we applied immuno-assisted laser ablation-inductively coupled plasma-mass spectrometry imaging to co-localize iron with the dopamine-producing enzyme tyrosine hydroxylase at the coronal level of the substantia nigra. We found that in the healthy brain the SNc does not contain the greatest concentration of iron within the midbrain, while the dopamine-rich environment in this region reflects an increased oxidative load. The product of iron and dopamine was significantly greater in the SNc than the adjacent ventral tegmental area, which is less susceptible to neuron loss in Parkinson's disease. Accordingly, this `risk factor was elevated further following 6-hydroxydopamine (6-OHDA) lesioning. Considering mounting evidence that brain iron increases with age, this measurable irondopamine index provides direct experimental evidence of a relationship between these two redox-active chemicals in degenerating dopaminergic neurons.
Austin, CE, Smith, TM, Bradman, A, Hinde, K, Joannes-Boyau, R, Bishop, DP, Hare, DJ, Doble, PA, Eskenazi, B & Arora, M 2013, 'Barium distributions in teeth reveal early-life dietary transitions in primates', Nature, vol. 498, pp. 216-219.View/Download from: UTS OPUS or Publisher's site
Early-life dietary transitions reflect fundamental aspects of primate evolution and are important determinants of health in contemporary human populations1, 2. Weaning is critical to developmental and reproductive rates; early weaning can have detrimental health effects but enables shorter inter-birth intervals, which influences population growth3. Uncovering early-life dietary history in fossils is hampered by the absence of prospectively validated biomarkers that are not modified during fossilization4. Here we show that large dietary shifts in early life manifest as compositional variations in dental tissues. Teeth from human children and captive macaques, with prospectively recorded diet histories, demonstrate that barium (Ba) distributions accurately reflect dietary transitions from the introduction of mothers milk through the weaning process. We also document dietary transitions in a Middle Palaeolithic juvenile Neanderthal, which shows a pattern of exclusive breastfeeding for seven months, followed by seven months of supplementation.
Chou, J, Hao, J, Kuroda, S, Bishop, DP, Ben-Nissan, B, Milthorpe, BK & Otsuka, M 2013, 'Bone regeneration of rat tibial defect by zinc-tricalcium phosphate (Zn-TCP) from porous Foraminifera carbonate macrospheres', Marine Drugs, vol. 11, no. 12, pp. 5148-5158.View/Download from: UTS OPUS or Publisher's site
Foraminifera carbonate exoskeleton was hydrothermally converted to biocompatible and biodegradable zinc-tricalcium phosphate (Zn-TCP) as an alternative biomimetic material for bone fracture repair. Zn-TCP samples implanted in a rat tibial defect model for eight weeks were compared with unfilled defect and beta-tricalcium phosphate showing accelerated bone regeneration compared with the control groups, with statistically significant bone mineral density and bone mineral content growth. CT images of the defect showed restoration of cancellous bone in Zn-TCP and only minimal growth in control group. Histological slices reveal bone in-growth within the pores and porous chamber of the material detailing good bone-material integration with the presence of blood vessels. These results exhibit the future potential of biomimetic Zn-TCP as bone grafts for bone fracture repair.
Chou, J, Ito, T, Bishop, D, Otsuka, M, Ben-Nissan, B & Milthorpe, B 2013, 'Controlled release of simvastatin from biomimetic β-TCP drug delivery system.', PLoS ONE, vol. 8, no. 1, pp. 1-6.View/Download from: UTS OPUS or Publisher's site
Simvastatin have been shown to induce bone formation and there is currently a urgent need to develop an appropriate delivery system to sustain the release of the drug to increase therapeutic efficacy whilst reducing side effects. In this study, a novel drug delivery system for simvastatin by means of hydrothermally converting marine exoskeletons to biocompatible beta-tricalcium phosphate was investigated. Furthermore, the release of simvastatin was controlled by the addition of an outer apatite coating layer. The samples were characterized by x-ray diffraction analysis, fourier transform infrared spectroscopy, scanning electron microscopy and mass spectroscopy confirming the conversion process. The in-vitro dissolution of key chemical compositional elements and the release of simvastatin were measured in simulated body fluid solution showing controlled release with reduction of approximately 25% compared with un-coated samples. This study shows the potential applications of marine structures as a drug delivery system for simvastatin.
Hare, DJ, Lear, J, Bishop, DP, Beavis, AB & Doble, PA 2013, 'Protocol for production of matrix-matched brain tissue standards for imaging by laser ablation-inductively coupled plasma-mass spectrometry', Analytical Methods, vol. 5, no. 8, pp. 1915-1921.View/Download from: UTS OPUS or Publisher's site
Calibration with matrix-matched standards remains the most practical means for producing quantitative images of trace metal distribution in tissue sections by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). A general guide for producing matrix-matched standards for assay of trace metals in brain tissue is presented. Cortical tissue was taken from pooled sheep brains and spiked with varying approximate concentrations of standard solutions of Co, Cu, Fe, Mg, Mn, Sr, Se and Zn. The tissue was homogenised and the total analyte amount accurately determined by solution nebulisation ICP-MS. The analytical ?gures of merit for LA-ICP-MS imaging were determined from these tissue standards cryosectioned at 30 mm. Repeated 8-point calibration curves were reproducibly linear, with correlation coe?cients ranging from 0.9874 (Mg) to 0.9991 (Sr). Limits of analysis were suitable for quantifying most analytes in a sample mouse brain, with the exception of Co and Se
Huyang, G, Canning, J, Petermann, I, Bishop, DP, McDonagh, AM & Crossley, MJ 2013, 'Room Temperature Sol-Gel Fabrication and Functionalization for Sensor Applications', Photonic Sensors, vol. 3, no. 2, pp. 168-177.View/Download from: UTS OPUS or Publisher's site
The structure and physical properties of a thin titania sol-gel layer prepared on silicon and silica surfaces were examined. Spectroscopic (FTIR, UV-VIS spectroscopy), refractive index (ellipsometry) and microscopic (light microscopy and SEM/EDS) tools were used to examine both chemical uniformity and physical uniformity of the sol-gel glass layers. The conditions for the fabrication of uniform layers were established, and room temperature dopant incorporation was examined. The absorption bands of porphyrin-containing titania sol-gel layers were characterized. By addition of a metal salt to the titania layer, it was possible to metallate the free-base porphyrin within and change the UV-VIS absorbance of the porphyrin, the basis of metal detection using porphyrins. The metalloporphyrins were detected by localized laser ablation inductive coupled mass spectroscopy (LA-ICP-MS), indicating fairly uniform distribution of metals across the titania surface.
Wang, Y, Sharma, N, Su, D, Bishop, DP, Ahn, H & Wang, G 2013, 'High capacity spherical Li[Li0.24Mn0.55Co0.14Ni0.07]O2 cathode material for lithium ion batteries', Solid State Ionics, vol. 233, pp. 12-19.View/Download from: UTS OPUS or Publisher's site
Li[Li0.24Mn0.55Co0.14Ni0.07]O2 cathode materials with controlled spherical morphology and particle size in the range of 5â10 Î¼m were synthesized by a modified co-precipitation method. The crystal structure of Li[Li0.24Mn0.55Co0.14Ni0.07]O2 was investigated by Rietveld analysis of structural models using X-ray and neutron powder diffraction data, indicating the presence of Li2MnO3 in the final product. Li[Li0.24Mn0.55Co0.14Ni0.07]O2 shows low initial irreversible capacity loss (47.2 mAh/g), high reversible capacity (264.6 mAh/g), good capacity retention (90.4% over 50 cycles) and satisfactory rate capability when used as the cathode material in lithium ion batteries. X-ray photoelectron spectroscopy analysis of the pristine, charged and discharged electrodes of Li[Li0.24Mn0.55Co0.14Ni0.07]O2 reveals that the Mn4 +/Mn3 + redox couple participates in the delithiation/lithiation process. Overall, the improved electrochemical performance of the Li[Li0.24Mn0.55Co0.14Ni0.07]O2 electrode can be ascribed to the controlled and specially designed morphology and the composition of the sample that is produced by the co-precipitation method.
Hemtasin, C, Ung, AT, Kanokmedhakul, S, Kanokmedhakul, K, Bishop, R, Sastraruji, T & Bishop, D 2012, 'Synthesis of alkaloid-like compounds via the bridging Ritter Reaction', Monatshefte fÃ¼r Chemie, vol. 143, no. 6, pp. 955-963.View/Download from: UTS OPUS or Publisher's site
Alkaloid-like compounds containing a benzo[c]azepine core structure were successfully prepared in three steps from H-dibenzo[a,d]cyclohepten-5-ol via the bridging Ritter reaction. Biological studies of these compounds revealed that some of them are AChE inhibitors and antimalarial agents.
Austin, CE, Fryer, FI, Lear, J, Bishop, DP, Hare, DJ, Rawling, T, Kirkup, L, McDonagh, AM & Doble, PA 2011, 'Factors Affecting Internal Standard Selection For Quantitative Elemental Bio-Imaging Of Soft Tissues By LA-ICP-MS', Journal of Analytical Atomic Spectrometry, vol. 26, no. 7, pp. 1494-1501.View/Download from: UTS OPUS or Publisher's site
Element response variations under different laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) operating conditions were investigated to identify important factors for selecting an internal standard (IS) for quantitative elemental bi
Hare, DJ, Tolmachev, S, James, A, Bishop, DP, Austin, CE, Fryer, FI & Doble, PA 2010, 'Elemental bio-imaging of thorium, uranium, and plutonium in tissues from occupationally exposed former nuclear workers', Analytical Chemistry, vol. 82, no. 8, pp. 3176-3182.View/Download from: UTS OPUS or Publisher's site
Internal exposure from naturally occurring radionuclides (including the inhaled long-lived actinides 232Th and 238U) is a component of the ubiquitous background radiation dose (National Council on Radiation Protection and Measurements. Ionizing radiation exposure of the population of the United States; NCRP Report No. 160; NCRP: Bethesda, MD, 2009). It is of interest to compare the concentration distribution of these natural ?-emitters in the lungs and respiratory lymph nodes with those resulting from occupational exposure, including exposure to anthropogenic plutonium and depleted and enriched uranium. This study examines the application of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) to quantifying and visualizing the mass distribution of uranium and thorium isotopes from both occupational and natural background exposure in human respiratory tissues and, for the first time, extends this application to the direct imaging of plutonium isotopes. Sections of lymphatic and lung tissues taken from deceased former nuclear workers with a known history of occupational exposure to specific actinide elements (uranium, plutonium, or americium) were analyzed by LA-ICPMS.
Trace elements play a key role in a wide range of biological processes. A full understanding of those processes requires a knowledge not only of the genomics and proteomics of the organism, but also the distribution and concentration of trace elements. A new application of inductively coupled plasma mass spectrometry (ICP-MS) provides the capability to directly visualize trace elements in soft tissue, offering the promise of improved diagnosis and monitoring of disease. © 2009 The Biochemical Society.
Canning, J, Ma, M, Gibson, B, Huyang, G, Beavis, A, Bishop, D, Cook, K, McDonagh, A, Shi, J, Shi, D, Peng, GD & Crossley, M 2013, 'The nanostructure of silica microfibers fabricated by microfluidic selfassembly', Proceedings of SPIE - The International Society for Optical Engineering, Asia Pacific Optical Sensors Conference (APOS), SPIE.View/Download from: Publisher's site
The porous properties of self-assembled waveguides made up of nanoparticles are characterised. Atomic force microscopy (AFM) reveals predominantly hcp or fcc packing suggesting a remarkably well ordered and distributed porous structure. N2 adsorption studies estimate a surface area SA ∼ 101 m2/g, a total interstitial volume Vi ∼ 1.7 mL/g and a pore size distribution of r ∼ (2 - 6) nm. This distribution is in excellent agreement with the idealised values for identically sized particles obtained for the octahedral and tetrahedral pores of the hcp and fcc lattices, estimated to lie within and rtet ∼ (2.2 - 3.3) nm and roct ∼ (4.2 - 6.2) nm for particles varying in size over 20 to 30 nm. Optical transmission based percolation studies reveal rapid penetration of Rhodamine dye ( < 5 s) with very little percolation of larger molecules such as ZnTPP observed under similar loading conditions. In the latter case, laser ablation was used to determine the transport of hydrated Zn2+ to be D ∼ 3 x 10-4 nm2s-1. By comparison, ZnTPP was not able to percolate into the wire over the time of exposure, t = 10 mins, effectively demonstrating the self-assembled structure acting as a molecular sieve. We discuss the potential of such structures more broadly and conclude that the controllable distribution of such nano-chambers offers the possibility of amplifying, or up-scaling, an otherwise local interaction or nanoreactions to make detection and diagnostics much simpler; it als o opens up a new approach to material engineering making new composites with periodic nanoscale variability. These and other unique aspects of these structures are embodied in an overall concept of lab-in-wire, or similar self-assembled structures, extending our previous concept of lab-in-fibre from the micro domain into the nano domain. © 2013 SPIE.
Huyang, G, Canning, J, Bishop, D, McDonagh, A & Crossley, MJ 2012, 'An evaluation of the distribution of metal ions in otherwise uniform titania sol-gel layers designed for optical sensing using laser ablation inductive coupled plasma mass spectroscopy', Proceedings of SPIE - The International Society for Optical Engineering, International Conference on Optical Fibre Sensors, SPIE, Beijing, China.View/Download from: UTS OPUS or Publisher's site
Free-base porphyrins are bound to titania sol-gel layers deposited on glass slides. The porphyrin-containing titania layers show the UV-VIS spectra of the porphyrin and are found to be uniformly and evenly distributed. By addition of a metal salt to the titania layer, it was possible to metallate the free-base porphyrin within and change the UV-VIS absorbance of the porphyrin. The metalloporphyrins based on Cu and Zn ions could be detected by laser ablation inductive coupled plasma mass spectroscopy (LA-ICP-MS). Aggregation of metals is observed indicating that metal ions are also attaching directly to the titania. In samples where already metalized porphyrins are used little or no aggregation is observed, indicating that the titania sol gel is non-uniform in its affinity for metal ions. © 2012 SPIE.