Eunice Shing Mei Goh

Singapore Eye Research Institute, Tumasik, Singapore

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Publications (10)30.54 Total impact

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    ABSTRACT: Taking advantage of the cluster effect observed in multivalent peptides, this work describes antifungal activity and possible mechanism of action of tetravalent peptide (B4010) which carries 4 copies of the sequence RGRKVVRR through a branched lysine core. B4010 displayed better antifungal properties than natamycin and amphotericin B. The peptide retained significant activity in the presence of monovalent/divalent cations, trypsin and serum and tear fluid. Moreover, B4010 is non-haemolytic and non-toxic to mice by intraperitoneal (200 mg/kg) or intravenous (100 mg/kg) routes. S. cerevisiae mutant strains with altered membrane sterol structures and composition showed hyper senstivity to B4010. The peptide had no affinity for cell wall polysaccharides and caused rapid dissipation of membrane potential and release of vital ions and ATP when treated with C. albicans. We demonstrate that additives which alter the membrane potential or membrane rigidity protect C. albicans from B4010-induced lethality. Calcein release assay and molecular dynamics simulations showed that the peptide preferentially binds to mixed bilayer containing ergosterol over phophotidylcholine-cholesterol bilayers. The studies further suggested that the first arginine is important for mediating peptide-bilayer interactions. Replacing the first arginine led to a 2-4 fold decrease in antifungal activities and reduced membrane disruption properties. The combined in silico and in vitro approach should facilitate rational design of new tetravalent antifungal peptides.
    PLoS ONE 02/2014; 9(2):e87730. DOI:10.1371/journal.pone.0087730 · 3.23 Impact Factor
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    ABSTRACT: A series of optically transparent ZnS-poly(vinylpyrrolidone) (PVP) nanocomposite films with high refractive indices and high Abbe numbers have been prepared. Mercaptoethanol (ME) capped ZnS nanoparticles (NPs) were introduced into the PVP polymer matrix via simple blending with high nanophase contents. ME-ZnS NPs of around 3 nm were prepared from zinc acetate and thiourea precursors in N,N-dimethylformamide using ME as a capping agent. Transparent nanocomposite films with high refractive indices and high Abbe numbers can be easily prepared by a conventional film casting method. TGA results indicated that the ZnS/PVP nanocomposite films exhibit good thermal stability and the measured contents of ZnS NPs in the films agree well with the theoretical values. The refractive indices and the Abbe numbers of the ZnS/PVP nanocomposite films range from 1.5061 to 1.7523 and 55.6 to 20.4 with the content of ME-ZnS NPs varied between 0 and 80 wt %, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
    Journal of Applied Polymer Science 08/2013; 129(4). DOI:10.1002/app.38883 · 1.64 Impact Factor
  • E. S. M. Goh · H. Y. Yang · Z. J. Han · T. P. Chen · K. Ostrikov
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    ABSTRACT: Effective control of room-temperature electroluminescence of n-ZnMgO/p-GaN light-emitting diodes (LEDs) over both emission intensity and wavelength is demonstrated. With varied Mg concentration, the intensity of LEDs in the near-ultraviolet region is increased due to the effective radiative recombination in the ZnMgO layer. Furthermore, the emission wavelength is shifted to the green/yellow spectral region by employing an indium-tin-oxide thin film as the dopant source, where thermally activated indium diffusion creates extra deep defect levels for carrier recombination. These results clearly demonstrate the effectiveness of controlled metal incorporation in achieving high energy efficiency and spectral tunability of the n-ZnMgO/p-GaN LED devices.
    Applied Physics Letters 12/2012; 101(26). DOI:10.1063/1.4773367 · 3.52 Impact Factor
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    ABSTRACT: Functionalization of material surfaces can improve their biointegration and bactericidal effect. To expand the biomedical applications of titanium in artificial cornea implantation surgery, titanium alloy substrates were coated with polydopamine and dual bound with recombinant vascular endothelial growth factor (VEGF) and anti-microbial peptide (AMP), SESB2V. Successful chemical binding was assessed with attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Coating thickness was assessed by atomic force microscopy. Cellular studies revealed that the functionalized substrates displayed the abilities to enhance primary human corneal fibroblast adhesion, proliferation, and viability. Angiogenesis assay with human mesenchymal stem cells was used to verify the biological functions of immobilized VEGF while bactericidal assay was evaluated for the anti-microbial activities of immobilized SESB2V peptide. We found that the titanium surface that was sequentially functionalized with VEGF and SESB2V had enhanced fibroblast proliferation and anti-microbial properties. The incorporation of such peptides into an artificial cornea implant is important for implant-tissue integration and wound healing. This may improve implant integration and reduce the risk of device infection following artificial cornea implantation. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
    Journal of Biomedical Materials Research Part B Applied Biomaterials 11/2012; 100(8):2090-100. DOI:10.1002/jbm.b.32774 · 2.33 Impact Factor
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    Eunice S M Goh · T P Chen · H Y Yang · Y Liu · C Q Sun
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    ABSTRACT: Although the dielectric behavior of nanostructured semiconductors has been intensively investigated, the physics behind observations remains disputed with possible mechanisms such as quantum confinement and dangling bond polarization. Here we show that theoretical reproduction of the measured dielectric suppression of Ge nanocrystals asserts that the dielectric suppression originates from the shorter and stronger bonds at the skin-deep surface, the associated local densification and quantum entrapment of energy. Coordination-imperfection induced local quantum entrapment perturbs the Hamiltonian that determines the band gap and hence, the process of electron polarization consequently.
    Nanoscale 02/2012; 4(4):1308-11. DOI:10.1039/c2nr11154c · 7.39 Impact Factor
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    Eunice S. M. Goh · T. P. Chen · S. F. Huang · Y. C. Liu · C. Q. Sun
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    ABSTRACT: The bandgap and optical properties (dielectric functions and optical constants) of dome-shaped Ge nanocrystals (nc-Ge) with average sizes of ∼6 nm in height and ∼13 nm in diameter have been investigated using spectroscopic ellipsometry based on the Forouhi-Bloomer optical dispersion model. As compared to bulk crystalline Ge, the nc-Ge exhibited a bandgap expansion of ∼0.2 eV and a significant reduction in the dielectric function. The bandgap expansion and dielectric suppression are discussed in terms of the quantum confinement effect as well as the bond contraction model.
    Journal of Applied Physics 03/2011; 109(6):064307-064307-4. DOI:10.1063/1.3554833 · 2.19 Impact Factor
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    S Zhu · T P Chen · Z H Cen · E S M Goh · S F Yu · Y C Liu
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    ABSTRACT: The split of surface plasmon resonance of self-assembled gold nanoparticles on Si substrate is observed from the dielectric functions of the nanoparticles. The split plasmon resonances are modeled with two Lorentz oscillators: one oscillator at ~1 eV models the polarization parallel to the substrate while the other at ~2 eV represents the polarization perpendicular to the substrate. Both parallel and perpendicular resonances are red-shifted when the nanoparticle size increases. The red shifts in both resonances are explained by the image charge effect of the Si substrate.
    Optics Express 10/2010; 18(21):21926-31. DOI:10.1364/OE.18.021926 · 3.49 Impact Factor
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    Eunice S. M. Goh · T. P. Chen · C. Q. Sun · Y. C. Liu
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    ABSTRACT: The band gap and optical properties (dielectric functions and optical constants) of Ge thin films with various thicknesses below 50 nm, which were synthesized with electron beam evaporation technique, have been determined using spectroscopic ellipsometry and UV-visible spectrophotometry. The optical properties are well described with the Forouhi–Bloomer model. Both the band gap and optical properties show a strong dependence on the film thickness. For film thickness smaller than ∼10 nm , a band gap expansion is observed as compared to bulk crystalline Ge, which is attributed to the one-dimensional quantum confinement effect. However, a band gap reduction was observed for thickness larger than ∼10 nm , which is explained in terms of the amorphous effect in the Ge layers.
    Journal of Applied Physics 02/2010; 107(2-107):024305 - 024305-5. DOI:10.1063/1.3291103 · 2.19 Impact Factor
  • R. Ang · T. P. Chen · Z. Liu · J. I. Wong · M. D. Yi · M. Yang · Z. H. Cen · S. Zhu · W. Zhu · E. S. M. Goh
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    ABSTRACT: In this letter, Ni-rich NiO thin film is deposited on p-type Si substrate by dc magnetron sputtering to form a metal-insulator-semiconductor structure. The charge trapping in the Ni nanocrystals (nc-Ni) embedded in NiO matrix induces a flatband voltage shift and capacitance modulation, which could be used for memory applications. The charging of nc-Ni depends on the voltage polarity, as well as the charging time and magnitude of gate voltage. The capacitance modulation can be described by an equivalent circuit model.
    Applied Physics Letters 07/2009; 95(1):012104-012104-3. DOI:10.1063/1.3170353 · 3.52 Impact Factor
  • Eunice Shing Mei Goh · Tu Pei Chen · Chang Qing Sun · Liang Ding · Yang Liu
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    ABSTRACT: An anti reflective layer for Si photodetectors working at various wavelengths is designed based on a SiO2 film containing Si nanocrystals (nc-Si). It is shown that with a proper amount of nc-Si distributed in the oxide and at the right thickness of the film, a single layer of nc-Si/SiO2 film can serve as a perfect anti reflection coating with very low or insignificant light loss. For example, for a 110 nm layer with an nc-Si volume fraction of 34%, the reflectance and the transmittance at the wavelength of 850 nm can reach 0.008 and 99.99%, respectively.
    Japanese Journal of Applied Physics 06/2009; 48(6). DOI:10.1143/JJAP.48.060206 · 1.06 Impact Factor