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201. Highly efficient and stable Ru nanoparticle electrocatalyst for the hydrogen evolution reaction in alkaline conditionsElectronic supplementary information (ESI) available: Experimental procedure; TEM images and particle size distributions; Rietveld refinements; STEM-EDS elemental mapping; XPS spectra of all three Ru samples; TGA analysis; HER testing protocol; comparison of HER activity in alkaline conditions; PXRD of Pt/C reference samples; modelling of EIS spectra; electrochemical active surface area (ECSA) determination and specific activities and references (PDF). See DOI: https://doi.org/10.1039/d2cy00177b

Author

Søndergaard-Pedersen, Frederik, Lakhotiya, Harish, Bøjesen, Espen Drath, Bondesgaard, Martin, Myekhlai, Munkhshur, Benedetti, Tania M., Gooding, J. Justin, Tilley, Richard D., and Iversen, Bo B.

Abstract

Developing alternatives to platinum-based electrocatalysts for the hydrogen evolution reaction (HER) is an important challenge for realizing the green transition. This is especially the case for alkaline conditions where Pt-based catalysts have very poor stability. Here, we demonstrate a new solvothermal synthesis method with facile allotropism control for selectively obtaining hexagonal-close-packed (hcp) and face-centered cubic (fcc) ruthenium nanoparticles. Both samples are highly active and durable HER catalysts in alkaline conditions outperforming state-of-the-art Pt/C. However, the samples show markedly different stabilities. The hcp sample shows exceptional stability for 12 hours constant operation at 10 mA cm−2with an overpotential that only increases 6 mV whereas the fcc sample increases 50 mV and the commercial Pt/C more than 350 mV. The significant variation in the stability of two Ru allotropes could be attributed to the difference in their crystal symmetries. Thus, this study underlines the importance of controlling the crystal structure of nanoparticle electrocatalysts and underlines the potential of using relatively cheaper Ru as an alternative to Pt for HER in alkaline conditions.

Published
2022
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202. Engineering regioselectivity in the hydrosilylation of alkynes using heterobimetallic dual-functional hybrid catalystsElectronic supplementary information (ESI) available Experimental details, spectral and catalysis data. See DOI: 10.1039/d1cy01804c

Author

Roemer, Max, Keaveney, Sinead T., Gonçales, Vinicius R., Lian, Jiaxin, Downes, James E., Gautam, Shreedhar, Gooding, J. Justin, and Messerle, Barbara A.

Abstract

The synthesis and characterization of carbon black supported rhodium and iridium heterobimetallic catalysts, termed hybrid catalysts, and their application in the hydrosilylation of alkynes is described. An aryl diazonium grafting procedure was applied to simultaneously immobilize Rh and Ir pyrazole–triazole complexes with tethers of varying lengths to carbon black, yielding the hybrid catalysts. The complexes differ in metal centre oxidation state and co-ligands, which are CO or Cp*Cl for the Rh complexes and Cp*Cl for the Ir complexes. The immobilization results in simultaneous surface binding and modification of the Rh complexes bearing CO-ligands. In this process, the CO ligands are removed and the overall structure of the catalytically active complex is altered. Analysis of the hybrid catalysts by XPS and SEM/EDX shows that the catalysts bear both surface bound Rh- and Ir-complexes. The Rh content is substantially higher than the Ir content. This is due to more efficient binding of the modified Rh complexes to the carbon black, as they feature two potential binding sites. Synchrotron based X-ray absorption spectroscopy (XAS) at the Rh K- and Ir L3edges further confirms the presence of the surface bound metal complexes. There is no indication that the presence of a secondary metal affects the electronic structure of the adjacent metal in the systems under investigation, for either the long or short tether derivatives. The performance of the different catalysts was assessed for promoting the hydrosilylation of alkynes, an important industrially relevant reaction. All catalysts are highly efficient. The modified Rh sites are α-selective in the product formation on activation of terminal alkynes, while the RhCp*Cl and IrCp*Cl sites are β(Z)-selective. When operating at mild conditions with high metal loadings, the surface bound Rh catalyst is the active species, while the Ir sites are inactive. At a lower overall surface coverage or higher temperature, the Ir sites become active, which allows engineering of the regioselectivity by adjusting surface coverages and metal loadings.

Published
2022
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203. A calibration-free approach to detecting microRNA with DNA-modified gold coated magnetic nanoparticles as dispersible electrodes

Author

Hoque, Sharmin, Gonçales, Vinicius R., Bakthavathsalam, Padmavathy, Tilley, Richard D., and Gooding, J. Justin

Abstract

Gold coated magnetic nanoparticles (Au@MNPs), modified with DNA sequences give dispersible electrodes that can detect ultralow amounts of microRNAs and other nucleic acids but, as with most other sensors, they require calibration. Herein we show how to adapt a calibration free approach for electrochemical aptamer-based sensors on bulk electrodes to microRNA (miR-21) detection with methylene blue terminated DNA modified Au@MNPs. The electrochemical square wave voltammetry signal from the DNA-Au@MNPs when collected at a bulk electrode under magnetic control, decreases upon capture of miR-21. We show that the square wave voltammogram has concentration dependent and independent frequencies that can be used to give a calibration free signal.

Published
2022
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204. A high-throughput 3D bioprinted cancer cell migration and invasion model with versatile and broad biological applicabilityElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d2bm00651k

Author

Jung, MoonSun, Skhinas, Joanna N., Du, Eric Y., Tolentino, M. A. Kristine, Utama, Robert H., Engel, Martin, Volkerling, Alexander, Sexton, Andrew, O'Mahony, Aidan P., Ribeiro, Julio C. C., Gooding, J. Justin, and Kavallaris, Maria

Abstract

Understanding the underlying mechanisms of migration and metastasis is a key focus of cancer research. There is an urgent need to develop in vitro3D tumor models that can mimic physiological cell–cell and cell–extracellular matrix interactions, with high reproducibility and that are suitable for high throughput (HTP) drug screening. Here, we developed a HTP 3D bioprinted migration model using a bespoke drop-on-demand bioprinting platform. This HTP platform coupled with tunable hydrogel systems enables (i) the rapid encapsulation of cancer cells within in vivotumor mimicking matrices, (ii) in situand real-time measurement of cell movement, (iii) detailed molecular analysis for the study of mechanisms underlying cell migration and invasion, and (iv) the identification of novel therapeutic options. This work demonstrates that this HTP 3D bioprinted cell migration platform has broad applications across quantitative cell and cancer biology as well as drug screening.

Published
2022
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208. Observing the Reversible Single Molecule Electrochemistry of Alexa Fluor 647 Dyes by Total Internal Reflection Fluorescence Microscopy

Author

Fan, Sanjun, primary, Webb, James E. A., additional, Yang, Ying, additional, Nieves, Daniel J., additional, Gonçales, Vinicius R., additional, Tran, Jason, additional, Hilzenrat, Geva, additional, Kahram, Mohaddeseh, additional, Tilley, Richard D., additional, Gaus, Katharina, additional, and Gooding, J. Justin, additional

Published
2019
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214. Understanding the performance of a paper‐based UV exposure sensor: The photodegradation mechanism of brilliant blue FCF in the presence of TiO 2 photocatalysts in both the solid state and solution

Author

Khiabani, Parisa S., primary, Soeriyadi, Alexander H., additional, Nam, Ekaterina V., additional, Peterson, Joshua R., additional, Webb, James E.A., additional, Thordarson, Pall, additional, Donald, William A., additional, and Gooding, J. Justin, additional

Published
2019
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218. Electrochemistry on Tribocharged Polymers Is Governed by the Stability of Surface Charges Rather than Charging Magnitude

Author

Zhang, Jinyang, primary, Rogers, Fergus J. M., additional, Darwish, Nadim, additional, Gonçales, Vinicius R., additional, Vogel, Yan B., additional, Wang, Fei, additional, Gooding, J. Justin, additional, Peiris, M. Chandramalika. R., additional, Jia, Guohua, additional, Veder, Jean-Pierre, additional, Coote, Michelle L., additional, and Ciampi, Simone, additional

Published
2019
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222. Microwave-assisted synthesis of black phosphorus quantum dots: efficient electrocatalyst for oxygen evolution reaction

Author

Batmunkh, Munkhbayar, primary, Myekhlai, Munkhshur, additional, Bati, Abdulaziz S. R., additional, Sahlos, Susanne, additional, Slattery, Ashley D., additional, Benedetti, Tania M., additional, Gonçales, Vinicius R., additional, Gibson, Christopher T., additional, Gooding, J. Justin, additional, Tilley, Richard D., additional, and Shapter, Joseph G., additional

Published
2019
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230. Simultaneous Functionalization of Carbon Surfaces with Rhodium and Iridium Organometallic Complexes: Hybrid Bimetallic Catalysts for Hydroamination

Author

Binding, Samantha C., primary, Pernik, Indrek, additional, Gonçales, Vinicius R., additional, Wong, Chin M., additional, Webster, Richard F., additional, Cheong, Soshan, additional, Tilley, Richard D., additional, Garcia-Bennett, Alfonso E., additional, Gooding, J. Justin, additional, and Messerle, Barbara A., additional

Published
2018
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246. Bioanalytical experiments for the undergraduate laboratory: monitoring glucose in sports drinks

Author

Gooding, J. Justin, Yang, Wenrong, and Situmorang, Manihar

Subjects
Biochemistry -- Study and teaching, Sugars -- Measurement, Isotonic beverages -- Analysis, Enzymes -- Usage, Chemistry, Education, Science and technology, University of New South Wales -- Curricula
Abstract

Two 3-hour bioanalytical experiments involving monitoring glucose in sports drinks have been developed for the undergraduate laboratory introducing students in the last year of university to biological emphasis in modern chemistry. Solution-based enzyme assay for the analysis of glucose concentrations in sports drinks is used and the same solutions are analyzed using an enzyme electrode. A bioanalytical chemistry course at the University of New South Wales in Australia and its purposes are discussed.

Published
2001

248. Pair Correlation Rnicroscopy Reveals The Role Of Nanoparticle Shape In Intracellular Transport And Site Of Drug Release

Author

Hinde, Elizabeth, Thammasiraphop, Kitiphume, Duong, Hien T. T., Yeow, Jonathan, Karagoz, Bunyamin, Boyer, Cyrille, Gooding, J. Justin, and Gaus, Katharina

Abstract

Nanoparticle size, surface charge and material composition are known to affect the uptake of nanoparticles by cells. However, whether nanoparticle shape affects transport across various barriers inside the cell remains unclear. Here we used pair correlation microscopy to show that polymeric nanoparticles with different shapes but identical surface chemistries moved across the various cellular barriers at different rates, ultimately defining the site of drug release. We measured how micelles, vesicles, rods and worms entered the cell and whether they escaped from the endosomal system and had access to the nucleus via the nuclear pore complex. Rods and worms, but not micelles and vesicles, entered the nucleus by passive diffusion. Improving nuclear access, for example with a nuclear localization signal, resulted in more doxorubicin release inside the nucleus and correlated with greater cytotoxicity. Our results therefore demonstrate that drug delivery across the major cellular barrier, the nuclear envelope, is important for doxorubicin efficiency and can be achieved with appropriately shaped nanoparticles.

Published
2017

249. Stochastic Electrochemical Measurement of a Biofouling Layer on Gold

Author

Jamali, Sina S., Somerville, Samuel V., Dief, Essam M., and Gooding, J. Justin

Abstract

Adsorption of a biofouling layer on the surface of biosensors decreases the electrochemical activity and hence shortens the service life of biosensors, particularly implantable and wearable biosensors. Real-time quantification of the loss of activity is important for in situassessment of performance while presenting an opportunity to compensate for the loss of activity and recalibrate the sensor to extend the service life. Here, we introduce an electrochemical noise measurement technique as a tool for the quantification of the formation of a biofouling layer on the surface of gold. The technique uniquely affords thermodynamic and kinetic information without applying an external bias (potential and/or current), hence allowing the system to be appraised in its innate state. The technique relies on the analysis of non-faradaic current and potential fluctuations that are intrinsically generated by the interaction of charged species at the electrode surface, i.e., gold. An analytical model is extended to explain the significance of parameters drawn from statistical analysis of the noise signal. This concept is then examined in buffered media in the presence of albumin, a common protein in the blood and a known source of a fouling layer in biological systems. Results indicate that the statistical analysis of the noise signal can quantify the loss of electrochemical activity, which is also corroborated by impedance spectroscopy as a complementary technique.

Published
2024
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