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Translocation and fate of nanospheres in pheochromocytoma cells following exposure to synchrotron‐sourced terahertz radiation
(International Union of Crystallography, 2023-07-01) Perera, PGT; Vilagosh, Z; Linklater, D; Nguyen, THP; Appadoo, DRT; Vongsvivut, JP; Tobin, MJ; Dekiwadia, C; Croft, R; Ivanova, EP
The routes by which foreign objects enter cells is well studied; however, their fate following uptake has not been explored extensively. Following exposure to synchrotron-sourced (SS) terahertz (THz) radiation, reversible membrane permeability has been demonstrated in eukaryotic cells by the uptake of nanospheres; nonetheless, cellular localization of the nanospheres remained unclear. This study utilized silica core-shell gold nanospheres (AuSi NS) of diameter 50 ± 5 nm to investigate the fate of nanospheres inside pheochromocytoma (PC 12) cells following SS THz exposure. Fluorescence microscopy was used to confirm nanosphere internalization following 10 min of SS THz exposure in the range 0.5–20 THz. Transmission electron microscopy followed by scanning transmission electron microscopy energy-dispersive spectroscopic (STEM-EDS) analysis was used to confirm the presence of AuSi NS in the cytoplasm or membrane, as single NS or in clusters (22% and 52%, respectively), with the remainder (26%) sequestered in vacuoles. Cellular uptake of NS in response to SS THz radiation could have suitable applications in a vast number of biomedical applications, regenerative medicine, vaccines, cancer therapy, gene and drug delivery. © International Union of Crystallography. Open Access CC-BY 4.0
Coordination polymer electrocatalysts enable efficient CO‐to‐acetate conversion
(Wiley, 2023-12-30) Luo, MC; Ozden, A; Wang, ZY; Li, FW; Huang, JE; Hung, SF; Wang, YH; Li, J; Nam, DH; Li, Y; Xu, Y; Lu, RH; Zhang, SZ; Lum, YW; Ren, Y; Fan, LL; Wang, Fei; Li, HH; Appadoo, DRT; Dinh, CT; Liu, Y; Chen, B; Wicks, J; Chen, HJ; Sinton, D; Sargent, EH
Upgrading carbon dioxide/monoxide to multi‐carbon C2+ products using renewable electricity offers one route to more sustainable fuel and chemical production. One of the most appealing products is acetate, the profitable electrosynthesis of which demands a catalyst with higher efficiency. Here, a coordination polymer (CP) catalyst is reported that consists of Cu(I) and benzimidazole units linked via Cu(I)‐imidazole coordination bonds, which enables selective reduction of CO to acetate with a 61% Faradaic efficiency at −0.59 volts versus the reversible hydrogen electrode at a current density of 400 mA cm−2 in flow cells. The catalyst is integrated in a cation exchange membrane‐based membrane electrode assembly that enables stable acetate electrosynthesis for 190 h, while achieving direct collection of concentrated acetate (3.3 molar) from the cathodic liquid stream, an average single‐pass utilization of 50% toward CO‐to‐acetate conversion, and an average acetate full‐cell energy efficiency of 15% at a current density of 250 mA cm−2. © 2025 Advanced journals portfolio
Resolution of ferrocene and deuterated ferrocene conformations using dynamic vibrational spectroscopy: experiment and theory
(Elsevier, 2020-06-01) Trevorah, RM; Tran, NTT; Appadoo, DRT; Wang, F; Chantler, CT
The signature of molecular vibrations and distortions in dynamic molecules gives a complex fingerprint which is insightful and can substantiate (or otherwise) chemical hypotheses regarding molecular and conformer stability. Using high-accuracy experimental data of ferrocene (Fc) and deuterated ferrocene (dFc, Fc − d10) at temperatures from 7 K through to 388 K, we obtain complex spectral profiles which require an advanced reaction coordinate model to explain. We obtain compelling evidence that the single conformer model (staggered D5d or eclipsed D5h) used to interpret and explain many experimental results on ferrocene is invalid. However we also present compelling evidence that mixed conformer models are invalid, where ferrocene is represented by an effective dihedral angle between the cyclopentadienyl (Cp) rings; or by a mixture of Boltzmann populations of the two conformers. We find no evidence for single or mixed conformer models despite covering almost all conclusions from past literature for gas, solution or solid phase Fc. Some molecular dynamics computations have imputed free rotation at liquid helium temperatures or at room temperature – we find no evidence for either of these hypotheses. We measure and derive point-wise experimental uncertainty of the spectra, enabling quantitative assessment of specific chemical and physical models about the origin of the spectral line-shapes. A new principle based on the reaction coordinate is introduced. Advanced spectroscopy and modelling is introduced for hypothesis testing, to articulate the nature of the potential surface, the reaction coordinate and subtle conformational changes in dilute systems. Two expected spectral peaks appear inverted in the gas phase, but are explained by our Reaction Coordinate Method (RCM) model. The non-uniform broadening of the singlet and doublet peaks with increasing temperature is explained. Our experimental analysis shows that the lowest energy conformer is D5h for both Fc and dFc. We are able to represent the reduced mass ratios of the lowest vibrational modes for Fc and dFc of 1.11 for ν1 for Fc to Fc-d9 and of 1.10 for Fc to Fc-d10. The measured barrier height for rotation is 7.4 kJ mol−1 and 6.3 kJ mol−1 for Fc and dFc respectively, in comparison to numerous theoretical treatments and past experimental studies. For the first time, we obtain agreement of the model with the complex spectral evolution of profiles. These new techniques are sensitive discriminants of alternate models and chemical systems, which argues for wider application to other complex or impenetrable problems across fields arising for numerous other solutions, frozen or at room temperature. Crown Copyright © 2020 Published by Elsevier B.V
Characterisation of biological materials at THz frequencies by attenuated total reflection: lard
(MDPI, 2020-12-04) Vilagosh, Z; Lajevardipour, A; Appadoo, DRT; Ng, SH; Juodkazis, S; Wood, AW
The penetration depth of an evanescent wave in Attenuated Total Reflection (ATR) is dependent on the wavelength of the radiation utilised. At THz frequencies, the penetration depth into biological tissues is in the order of 0.1 to 0.5 mm; rendered pig lard was used as a model sample in this study. A method for the direct measurement of the evanescent wave penetration depth is presented which allows for the estimation of the dispersion of the complex refractive index by using the reflection of the evanescent wave from varying sample depths. The method employs frustrated total internal reflection, and has been demonstrated by using the THz/Far-IR beamline at the Australian synchrotron, and modelled using finite difference time domain (FDTD) simulations. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Terahertz and mid-infrared spectra of cold formic acid aerosol particles
(American Chemical Society, 2018-08-18) Ruzi, M; Auchettl, R; Ennis, C; Appadoo, DRT; Robertson, EG
Fourier transform infrared spectra of formic acid aerosol particles in situ generated in a collisional cooling cell at temperatures ranging between 90 and 210 K are recorded in the mid-infrared and THz/far-infrared regions. Infrared spectroscopic features are used to identify the formic acid dimer above 200 K, the crystalline β1 phase in the 110-200 K temperature range, and amorphous solid formic acid at ∼90 K. Density functional calculations of discrete clusters and the full periodic β1 crystalline structure help to assign the low wavenumber intermolecular modes by comparison with experimental far IR and Raman data from the literature. Refractive indices of the formic acid crystal in the mid-IR range are retrieved. These data are essential for radiative transfer modeling of solid formic acid condensed in the terrestrial atmosphere. THz/far IR spectra, in addition to the well documented mid-infrared spectra, may be useful for the identification of solid formic acid in astrophysical environments such as the young stellar object W33A. © 2025 American Chemical Society.

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