Chemistry - Conference Items

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    SMARTProbe -: An informative biopsy needle with bioimpedance sensing for real-time breast lesion screening
    (VDE Verlag, 2019-04) Ugwah, Justina A.; Bennett, Bill; O'Donnell, Brian; O'Sullivan, Martin; Moore, Eric
    Patients who present with a breast lesion require clinical and radiological examination for breast disease detection. For a definitive diagnosis, biopsy under ultrasound guidance is performed for histological assessment to determine if lesion is malignant or benign. The biopsy needle, currently a passive instrument, if integrated with impedance sensing, can give real time information for use as a tissue discriminating tool. Bio-impedance is a technique which enables the use of three variables (resistance, reactance and phase angle) as indices of structural and functional biological variables. The frequency dependent electrical impulse gives the physiology and pathological information about the conductive and dielectric properties of cells. The differences in electrical properties of malignant and healthy tissues are associated with increased water and mineral content within tumor cells, the changes in membrane permeability, altered packing density as well as orientation of cells. The prototype SMARTProbe, with bioimpedance sensing, is able to discriminate healthy tissue from malignant and benign lesions in ex-vivo clinical investigation. The fabrication process of sensors allows for defined and constant electrode distance, which enables small alternate current to be used, thus, decreasing variability as a result of tissue heterogeneity.
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    Ni, Pt, and Ti stanogermanide formation on Ge0.92Sn0.08
    (Institute of Electrical and Electronics Engineers (IEEE), 2019-04) Galluccio, Emmanuele; Petkov, Nikolay; Mirabelli, Gioele; Doherty, Jessica; Lin, Shih-Va; Lu, Fang-Liang; Liu, Chee Wee; Holmes, Justin D.; Duffy, Ray; Science Foundation Ireland
    The aim of this work is to provide a systematic and comparative study on the material characteristics and electrical contact performance for a germanium-tin (GeSn) alloy with a high percentage of Sn (8%). Thin metal films (10 nm) of Nickel (Ni), Titanium (Ti), or Platinum (Pt) were deposited on Ge 0.92 Sn 0.08 layers and subsequently annealed at different temperatures ranging from 300°C up to 500°C. Various experimental techniques were employed to characterize the metal morphology and the electrical contact behavior, with the intention of identifying the most promising metal candidate, in terms of low sheet resistance and low surface roughness, considering a low formation temperature. The investigations carried out show that for nano-electronic contact applications, nickel-stanogermanide (NiGeSn) turns out to be the most promising candidate among the three different metals analyzed. NiGeSn presents low sheet resistance combined with low formation temperatures, below 400°C; PtGeSn shows better thermal stability when compared to the other two options while, Ti was found to be unreactive below 500°C, resulting in incomplete TiGeSn formation.
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    Monolayer doping and other strategies in high surface-to-volume ratio silicon devices
    (Institute of Electrical and Electronics Engineers (IEEE), 2018-03) Duffy, Ray; Kennedy, Noel; Mirabelli, Gioele; Galluccio, Emmanuele; Hurley, Paul K.; Holmes, Justin D.; Long, Brenda; Enterprise Ireland; European Regional Development Fund
    To maintain electron device scaling, in recent years the semiconductor industry has been forced to move from planar to non-planar thin-body electron device architectures. This alone has created the need to develop a radically new, non-destructive, conformal method for doping. Doping alters the electrical properties of a semiconductor, related to the access resistance. Monolayer doping (MLD) is a promising surface-based technique, whereby organic molecules are covalently bound to the semiconductor surface at relatively low processing temperatures (room temperature - 160 °C). A thermal treatment is then applied which both frees the dopant atoms from the organic molecules, and provides the energy for diffusion into the semiconductor substrate and subsequent activation. Very promising results have been achieved, but mostly on planar unpatterned substrates. There is now a need to assess the suitability of MLD for thin-body semiconductor features with high surface-to-volume ratios and densely packed structures. It is the aim of this review paper to consider MLD from this perspective.
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    Branched PEI capped gold nanoparticles in water for siRNA delivery to cancer cells
    (TechConnect, 2017-05) Rahme, Kamil; Guo, Jianfeng; Biswas, Subhajit; O'Driscoll, Caitríona M.; Holmes, Justin D.; Science Foundation Ireland; Conseil National de la Recherche Scientifique
    Herein we describe a simple method for the synthesis of different sizes of polyethylenimine-capped gold nanoparticles (AuNPs-PEI) in water and assess their potential to deliver siRNA or other therapeutic agents to cancer cells. AuNP-PEI with diameters ranging between 25-150 nm have been synthesised in aqueous solutions using PEI (25 KD and 2KD) as capping ligands and using hydroxylamine-O-sulfonic acid or ascorbic acid as reducing agents. Different parameters were found to affect the final size of nanoparticles core (i.e. gold salt concentrations, PEI molecular weight/concentrations, and temperature). The obtained AuNP-PEIs were fully characterized using UV-visible spectroscopy, Electron Microscopy (EM), and Dynamic Light Scattering (DLS). UV-visible spectra clearly showed that the synthesized particles have size dependent optical properties with a plasmon band shift to longer wavelengths, as the size of the AuNP core was increased. In addition, DLS analysis indicated that all samples were nearly monodisperse with one size distribution and a polydispersity index (PDI) of about 0.15 (Std 0.03). EM analysis indicated that AuNPs-PEI were nearly spherical in shape. Zeta (ζ) potential measurements showed that all AuNPs-PEI samples were positively charged with a ζ-potential in the range of 38 (Std 5 mV), leading to a very high stability of the colloidal solution for several months when stocked at 4 C. Furthermore, the potential application of AuNP-PEIs in siRNA delivery to PC-3 prostate cancer cells was investigated. The ability of AuNP-PEIs to complex siRNA was analysed by gel electrophoresis. Results indicated that AuNP-PEI 2KD and AuNP-PEI 25KD could complex siRNA at MR0.5 and MR0.25 onwards, respectively, suggesting that AuNP-PEI 25KD has a better siRNA binding capacity than AuNP-PEI 2KD. Cellular uptakes were also performed using PC-3 cancer cells. Results following 24 h incubation indicated that AuNP-PEI 25KD achieved significantly higher fluorescein-positive cells (~ 98%) relative to that of AuNP-PEI 2KD (~ 5%), suggesting that AuNP-PEI 25KD, but not AuNP-PEI 2KD, could deliver siRNA into cells. Finally, we have also demonstrated that the surface of AuNPs-PEI can be further conjugated with thiolated polyethylene glycol (SH-PEG) onto AuNPs surface. Moreover, we have previously showed that covalently bonded targeting ligand (such as Anisic Acid or Folic acid) could be also chemically grafted on PEI, leading therefore to a multifunctional nanoparticle that may be promising in the field of Nanobiotechnology and Nanomedicine.
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    Nanochemistry in the new leaving certificate chemistry syllabus
    (Chemistry Education Research Group, University of Limerick, 2012) Holmes, Justin D.