Browsing Chemistry - Book Chapters by Title
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- ItemBioconjugated gold nanoparticles enhance siRNA delivery in prostate cancer cells(Springer, 2019-05-17) Rahme, Kamil; Guo, Jianfeng; Holmes, Justin D.; Dinesh Kumar, Lekha; Science Foundation Ireland; Irish Research Council; Department of Science and Technology of Jilin Province; National Council for Scientific ResearchHere we describe a simple way to create a gold nanoparticle (AuNP)-based non-viral delivery system to deliver siRNA into prostate cancer cells. Therefore, positively charged polyethylenimine (PEI)-capped AuNPs were synthesized in water and further conjugated with the targeting ligand (folic acid) for folate receptors (AuNPs-PEI-FA). The AuNPs-PEI-FA could effectively complex small interfering RNA (siRNA) through electrostatic interaction. Flow cytometry displayed that AuNPs-PEI-FA could specifically deliver siRNA into LNCaP cells, a prostate cancer cell line overexpressing prostate-specific membrane antigen (PSMA) that exhibits a hydrolase enzymatic activity with a folate substrate. In contrast, internalization of siRNA into PC-3 cells, a prostate cancer cell line not expressing PSMA or folate receptors, was not achieved using AuNPs-PEI-FA.siRNA. Following endolysosomal escape, the AuNPs-PEI-FA-.siRNA formulation resulted in significant endogenous gene silencing when compared to the nontargeted formulation, suggesting the potential of AuNPs-PEI-FA for targeted delivery of therapeutic siRNAs in the treatment of prostate cancer.
- ItemFIB patterning of stainless steel for the development of nano-structured stent surfaces for cardiovascular applications(Springer International Publishing, 2013-12-06) Schmidt, Michael; Nazneen, F.; Galvin, Paul; Petkov, Nikolay; Holmes, Justin D.; Wang, M. Z.; Higher Education Authority; Science Foundation Ireland; National Biophotonics and Imaging Platform IrelandStent implantation is a percutaneous interventional procedure that mitigates vessel stenosis, providing mechanical support within the artery and as such a very valuable tool in the fight against coronary artery disease. However, stenting causes physical damage to the arterial wall. It is well accepted that a valuable route to reduce in-stent re-stenosis can be based on promoting cell response to nano-structured stainless steel (SS) surfaces such as by patterning nano-pits in SS. In this regard patterning by focused ion beam (FIB) milling offers several advantages for flexible prototyping. On the other hand FIB patterning of polycrystalline metals is greatly influenced by channelling effects and redeposition. Correlative microscopy methods present an opportunity to study such effects comprehensively and derive structure–property understanding that is important for developing improved patterning. In this chapter we present a FIB patterning protocol for nano-structuring features (concaves) ordered in rectangular arrays on pre-polished 316L stainless steel surfaces. An investigation based on correlative microscopy approach of the size, shape and depth of the developed arrays in relation to the crystal orientation of the underlying SS domains is presented. The correlative microscopy protocol is based on cross-correlation of top-view scanning electron microscopy, electron backscattering diffraction, atomic force microscopy and cross-sectional (serial) sectioning. Various FIB tests were performed, aiming at improved productivity by preserving nano-size accuracy of the patterned process. The optimal FIB patterning conditions for achieving reasonably high throughput (patterned rate of about 0.03 mm2/h) and nano-size accuracy in dimensions and shapes of the features are discussed as well.
- ItemGold nanoparticles: synthesis, characterization, and bioconjugation(CRC Press, Taylor & Francis, 2015-09) Rahme, Kamil; Holmes, Justin D.; Lyshevski, Sergey E.Gold nanoparticles (Au NPs) with diameters ranging between 4-150 nm have been synthesized in water. The strong reducing agent sodium borohydride (NaBH4) was used to produce small Au NPs with diameter about 4 +_1 nm. 15 and 30 nm Au NPs were obtained by a slightly modified Turkevich and Frens method using sodium citrate as both reducing and stabilizing agent at high temperature. The attempt to produce Au NPs with diameter larger than 30-40 nm by the Turkevich method resulted in an increase in the polydispersity and the shape diversity of the final Au NPs, indicating the importance of the trial of new reducing agents in the production of Au NPs especially for diameters above 40 nm. Therefore, hydroxylamine-o-sulfonic acid (NH2SO4H) (HOS) was used here for the first time as a new reducing agent for HAuCl4 at room temperature to produce Au NPs with diameter of about 60, 90 and 150 nm. This new method using HOS is an extension of the approaches described to produce Au NPs with diameter above 40 nm by direct reduction. The obtained nanoparticles were characterized using uv-visible spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). Further biocojuguation on 15, 30 and 90 nm Au NPs were performed by grafting covalently Apolipoprotein E (ApoE) and Bovine Serum Albumin (BSA) through an ethylene glycol-N-hydroxysuccinimide linker (NHS-PEG-S-S-PEG-NHS) making them very attractive for drug delivery and cell targeting. Finally, functionalized polyethylene glycol-based thiol polymers were also used to stabilize the pre-synthesized Au NPs-PEG-Protein.
- ItemImpurity exclusion and retention during crystallisation and recrystallisation - the phenacetin by ethylation of paracetamol process(InTech, 2015-05-06) Horgan, Danielle E.; Crowley, Lorraine M.; Stokes, Stephen P.; Lawrence, Simon E.; Moynihan, Humphrey A.; Irish Research Council for Science Engineering and Technology; Science Foundation Ireland
- ItemMesoporous materials as templates for semiconductor nanowires assembly(IOS Press, 2003) Holmes, Justin D.; Morris, Michael A.; Ryan, Kevin M.; European Commission; Intel Corporation; Intel Ireland Ltd.In this chapter is described a novel approach for synthesizing mesoporous silicas with tunable pore diameters, wall thickness and pore spacings that can be used as templates for the assembly of semiconductor nanowire arrays. Silicon and germanium nanowires, with size monodisperse diameters, can readily be formed within the mesoporous silica matrix using a supercritical fluid inclusion technique. These nano-composite materials display unique optical properties such as intense room temperature ultraviolet and visible photoluminescence. The implication of these mesoporous nanowire materials for future electronic and opto-electronic devices is discussed.
- ItemNanohaiku and nanohaiga: nanotechnologies meet art(изток-запад [East-West], 2017-11) Georgiev, Yordan M.; Panova, Nedyalka; Gangnaik, Anushka S.; Ghoshal, Tandra; Nikolova, Antoaneta; Holmes, Justin D.The present work combines science and arts in an innovative and intriguing way. Using Electron Beam Lithography (EBL) and Directed Self-Assembly (DSA) of Block Co-Polymers (BCP) in conjunction with the shortest poetic form, haiku, the paper attractively demonstrate the capabilities of these nanofabrication techniques and explores the interaction between the top-down EBL process and the bottom-up DSA approach. Silicon (Si) substrates and EBL with the hydrogen silsesquioxane (HSQ) negative tone resist were used for capturing examples of the tiniest haiku poems written and translated into six languages having four different character styles. Subsequently, the haiku nanostructures (“nanohaiku”) were used as guiding features between which the poly(styrene)-blockpoly(ethylene oxide) (PS-b-PEO) diblock copolymer is spin coated to create self-organised nanopatterns. The annealing was done in toluene solvent vapours at 50°C for 1.5 hours and then the samples were immersed in ethanol for 15 hours at 40°C to dissolve the PEO copolymer. In areas within and in-between the individual characters and syllables of the poems, unusual patterns were observed. We interpret them as self-assembled “nanohaiga” directed by the morphology and the linguistic geometry of the nanohaiku. Moreover, we demonstrate how the BCP pattern changes when interacting with the same verse translated into different languages. Thus we add to the haiku poem's own nanostructure and meaning a new visual identity, nanohaiga, combining for the first time poetry, visual art and advanced nanofabrication technologies.
- ItemNovel approaches for genuine single phase room temperature magnetoelectric multiferroics(Wiley, 2016-05) Keeney, Lynette; Schmidt, Michael; Amann, Andreas; Maity, Tuhin; Deepak, Nitin; Faraz, Ahmad; Petkov, Nikolay; Roy, Saibal; Pemble, Martyn E.; Whatmore, Roger W.; Alguero, Miguel; Gregg, J. Marty; Mitoseriu, Liliana; Science Foundation IrelandThis chapter reviews approaches currently under investigation for the fabrication of single‐phase magnetoelectric multiferroics, from bulk ceramics to those in thin‐film form. It presents an approach of inserting magnetic ions into the Aurivillius phase, layer‐structured ferroelectric materials, whereby thin films of average composition Bi6Ti2.8Fe1.52Mn0.68O18 (B6TFMO) demonstrate room temperature ferroelectricity, ferromagnetism, and magnetoelectric coupling. The chapter also discusses the importance of careful microstructural analysis of the materials and the application of a statistical model to determine a confidence level that the observed effects are from genuine single‐phase magnetoelectric multiferroics. It reviews how careful phase analysis and statistical treatment of the data confirmed that the B6TFMO phase is a single‐phase multiferroic to a confidence level of 99.5%. Finally, it summarizes how direct evidence of magnetoelectric coupling in the B6TFMO thin films was obtained. This review demonstrates that with materials development and design, the development of room temperature multiferroic materials can be achieved.
- ItemOrganometallic-metallic-cyclotriphosphazene mixtures: solid state method for metallic nanoparticle growth(Nova Science Publishers, 2013-04) Díaz, Carlos; Valenzuela, María Luisa; O'Dwyer, Colm; Roger Dong; Fondo Nacional de Desarrollo Científico, Tecnológico y de Innovación TecnológicaWe review a recent general solid state method to obtain metallic, metal oxide and phosphate nanoparticles and crystals by pyrolysis at 800°C using organometallic derivatives of cyclo and polyphosphazene precursors containing diverse organometallic fragments linked to polymeric or oligomeric phosphazenes. When the preparation of the molecular precursor is not possible or results in low yield, an alternative method using solid state mixtures of the type MLn/N3P3[O2C12H8]n, where MLn can be a single metallic salt, and a coordination compound or an organometallic, is possible. For AuCl(PPh3)/[NP(O2C12H8)]n mixtures, single crystal cubic Au nanoparticles form, whose morphology, crystal shape, size and distribution strongly depends on deposition quantity and the mixture molar ratio. Nanoparticles as small as 3.5 nm are observed if the mixture is prepared in a crucible and varied geometries of microcrystals found when the mixture was deposited on Si or SiO2 wafers, including single-crystal gold fullerene structures. Extension to Ag, Pd and Re-containing precursor mixtures such as Ag(PPh3)(CF3SO3)/ [NP(O2C12H8)]3, PdCl2/N3P3[O2C12H8]3, and KReO4/N3P3[O2C12H8]3 allows microcrystal formation during pyrolysis. A thermally induced phase demixing mechanism describes the evolution of the crystal growth, aided microphase separation of the polymer mixture. This microphase demixing is shown to be an overarching mechanism involved in the nano to micro scale growth of crystals. A probable mechanism of the atomic and molecular-level chemistry is also proposed based on decomposition of the macromolecular polymeric, trimer and oligomeric precursors for the initial stages.
- ItemProbing of nanocontacts inside a transmission electron microscope(Springer-Verlag Berlin Heidelberg, 2007) Erts, Donats; Lohmus, Ants; Holmes, Justin D.; Olin, HakanIn the past twenty years, powerful tools such as atomic force microscopy have made it possible to accurately investigate the phenomena of friction and wear, down to the nanometer scale. Readers of this book will become familiar with the concepts and techniques of nanotribology, explained by an international team of scientists and engineers, actively involved and with long experience in this field. Edited by two pioneers in the field, 'Fundamentals of Frictions and Wear at the Nanoscale' is suitable both as first introduction to this fascinating subject, and also as a reference for researchers wishing to improve their knowledge of nanotribology and to keep up with the latest results in this field.