| 1. |
- Carville, N. Craig, et al.
(författare)
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Influence of annealing on the photodeposition of silver on periodically poled lithium niobate
- 2016
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 119:5
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Tidskriftsartikel (refereegranskat)abstract
- The preferential deposition of metal nanoparticles onto periodically poled lithium niobate surfaces, whereby photogenerated electrons accumulate in accordance with local electric fields and reduce metal ions from solution, is known to depend on the intensity and wavelength of the illumination and the concentration of the solution used. Here, it is shown that for identical deposition conditions (wavelength, intensity, concentration), post-poling annealing for 10 h at 200 degrees C modifies the surface reactivity through the reorientation of internal defect fields. Whereas silver nanoparticles deposit preferentially on the +z domains on unannealed crystals, the deposition occurs preferentially along 180 degrees domain walls for annealed crystals. In neither case is the deposition selective; limited deposition occurs also on the unannealed -z domain surface and on both annealed domain surfaces. The observed behavior is attributed to a relaxation of the poling-induced defect frustration mediated by Li+ ion mobility during annealing, which affects the accumulation of electrons, thereby changing the surface reactivity. The evolution of the defect field with temperature is corroborated using Raman spectroscopy.
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| 2. |
- Balobaid, Laila, et al.
(författare)
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Direct shape control of photoreduced nanostructures on proton exchanged ferroelectric templates
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 102:4, s. 042908-
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Tidskriftsartikel (refereegranskat)abstract
- Photoreduction on a periodically proton exchanged ferroelectric crystal leads to the formation of periodic metallic nanostructures on the surface. By varying the depth of the proton exchange (PE) from 0.59 to 3.10 mu m in congruent lithium niobate crystals, the width of the lateral diffusion region formed by protons diffusing under the mask layer can be controlled. The resulting deposition occurs in the PE region with the shallowest PE depth and preferentially in the lateral diffusion region for greater PE depths. PE depth-control provides a route for the fabrication of complex metallic nanostructures with controlled dimensions on chemically patterned ferroelectric templates.
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| 3. |
- Balobaid, Laila, et al.
(författare)
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Photoreduction of metal nanostructures on periodically proton exchanged MgO-doped lithium niobate crystals
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:18, s. 182904-
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Tidskriftsartikel (refereegranskat)abstract
- Local reactivity on periodically proton exchanged lithium niobate (PPE: LN) surfaces is a promising route for the fabrication of regularly spaced nanostructures. Here, using MgO-doped PPE: LN templates, we investigate the influence of the doping on the nanostructure formation as a function of the proton exchange (PE) depth. The deposition is found to occur preferentially along the boundary between MgO-doped LN and the PE region when the PE depth is at least 1.73 mu m, however, for shallower depths, deposition occurs across the entire PE region. The results are found to be consistent with an increased photoconductivity of the MgO-doped LN.
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| 4. |
- Carville, N. Craig, et al.
(författare)
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Biocompatibility of ferroelectric lithium niobate and the influence of polarization charge on osteoblast proliferation and function
- 2015
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Ingår i: Journal of Biomedical Materials Research. Part A. - : John Wiley and Sons. - 1549-3296 .- 1552-4965. ; 103:8, s. 2540-2548
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the influence of substrate surface charge on in vitro osteoblast cell proliferation on ferroelectric lithium niobate (LN) crystal surfaces is investigated. LN has a spontaneous polarization along the z-axis and is thus characterized by positive and negative bound polarization charge at the +z and -z surfaces. Biocompatibility of LN was demonstrated via culturing and fluorescence imaging of MC3T3 osteoblast cells for up to 11 days. The cells showed enhanced proliferation rates and improved osteoblast function through mineral formation on the positively and negatively charged LN surfaces compared to electrostatically neutral x-cut LN and a glass cover slip control. These results highlight the potential of LN as a template for investigating the role of charge on cellular processes.
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| 5. |
- Carville, N. Craig, et al.
(författare)
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Biocompatible Gold Nanoparticle Arrays Photodeposited on Periodically Proton Exchanged Lithium Niobate
- 2016
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Ingår i: ACS Biomaterials Science & Engineering. - : American Chemical Society (ACS). - 2373-9878. ; 2:8, s. 1351-1356
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Tidskriftsartikel (refereegranskat)abstract
- Photodeposition of silver nanoparticles onto chemically patterned lithium niobate having alternating lithium niobate and proton exchanged regions has been previously investigated. Here, the spatially defined photodeposition of gold nanoparticles onto periodically proton exchanged lithium niobate is demonstrated. It is shown that the location where the gold nanoparticles form can be tailored by altering the concentration of HAuCl4. This enables the possibility to sequentially deposit gold and silver in different locations to create bimetallic arrays. The cytocompatibility of photodeposited gold, silver, and bimetallic ferroelectric templates to osteoblast-like cells is also investigated. Gold samples provide significantly greater cell biocompatibility than silver samples. These results highlight a potential route for using photodeposited gold on lithium niobate as a template for applications in cellular biosensing.
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| 6. |
- Carville, N. Craig, et al.
(författare)
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Photoreduction of SERS-Active Metallic Nanostructures on Chemically Patterned Ferroelectric Crystals
- 2012
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 6:8, s. 7373-7380
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Tidskriftsartikel (refereegranskat)abstract
- Photodeposition of metallic nanostructures onto ferroelectric surfaces is typically based on patterning local surface reactivity via electric field poling. Here, we demonstrate metal deposition onto substrates which have been chemically patterned via proton exchange (i.e., without polarization reversal). The chemical patterning provides the ability to tailor the electrostatic fields near the surface of lithium niobate crystals, and these engineered fields are used to fabricate metallic nanostructures. The effect of the proton exchange process on the piezoelectric and electrostatic properties of the surface is characterized using voltage-modulated atomic force microscopy techniques, which, combined with modeling of the electric fields at the surface of the crystal, reveal that the deposition occurs preferentially along the boundary between ferroelectric and proton-exchanged regions. The metallic nanostructures have been further functionalized with a target probe molecule, 4-aminothiophenol, from which surface-enhanced Raman scattering (SERS) signal is detected, demonstrating the suitability of chemically patterned ferroelectrics as SERS-active templates.
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| 7. |
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| 8. |
- Damm, Signe, et al.
(författare)
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Protein assemblies on ferroelectrically patterned microarrays of Ag nanoparticles
- 2017
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Ingår i: Ferroelectrics (Print). - : TAYLOR & FRANCIS LTD. - 0015-0193 .- 1563-5112. ; 515:1, s. 141-148
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Tidskriftsartikel (refereegranskat)abstract
- Nano-bio interfaces play a significant role in assay device design and performance, here we study the use of a combined plasmonic and ferroelectric active substrate design for protein assemblies on a plasmon active array. We demonstrate that biotinylation and protein assemblies can bemade onmetal nanoparticles patterned on ferroelectric substrates. These results inturndemonstratethat ferroelectric substrates combined with active plasmonics is potentially applicable as substrates for biological assays.
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| 9. |
- Damm, Signe, et al.
(författare)
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Surface enhanced luminescence and Raman scattering from ferroelectrically defined Ag nanopatterned arrays
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:8, s. 083105-
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Tidskriftsartikel (refereegranskat)abstract
- Ag nanopatterned arrays prepared using periodically proton exchanged templates have been demonstrated to support surface enhanced luminescence. Fluorescence lifetime imaging reveals that luminescence intensity is greatest on Ag and that the lifetime of the molecular probe is reduced, in line with a surface enhanced luminescence mechanism. Studies establish that the substrate simultaneously supports surface enhanced luminescence and Raman scattering. Spatial dependence along the nanopatterned arrays shows <7% variation in Raman scattering signal intensity, offering high reproducibility for practical applications. Fluorophores emitting near the plasmon absorption maxima are enhanced 4-fold.
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