Gold Nanoparticles: A Novel Dye for Synthetic Fabrics

<p>Fabric has always been prominent throughout history. In the last 70 years new synthetic fabrics have been developed which mimic the natural fibres but have increased strength, durability and stretchability. Common fibres include Polyester, Nylon and Lycra(R). These fibres can be blended to incorporate the properties of both the individual fibre types. Gold nanoparticles have been found to give the stable deep red colour found in stained glass but the science was not understood until the quantum mechanical work of Mie in 1908 on the interaction of electromagnetic radiation (visible light) with fine particles of matter. It is proposed that gold nanoparticles can be used as stable colourants bound to synthetic fibres and other textiles due to its chemical unreactivity. The most common formation method is the use of a reductant such as poly(ethylene imine), sodium citrate or tannic acid. This thesis reports the research and development of new, novel hybrid materials created by combining the interesting properties of both the synthetic fabrics and gold nanoparticles. Twenty five different methods (broken down into four general categories - pre-made colloids, in-situ reduction, use of external reductant after uptake of gold solution and growth of seed particles) were attempted resulting in fabrics that were a variety of shades and colours including pink, purple, tan and gold. The synthetic fabric-gold nanoparticle hybrid samples were analysed by scanning electron microscopy, energy dispersive spectroscopy, infrared spectroscopy, ultraviolet/visible reflectance spectroscopy, x-ray photoelectron spectroscopy, fluorescence spectroscopy and ColourQuest measurements. A sample was also subjected to industry standard "abrasion" and colourfastness tests in which it gained the highest mark possible, showing no staining of other fabrics under dry rub conditions. Atomic absorption measurements were performed on solutions after the fabric was removed in order to confirm the amount of gold uptake by the fabric samples. Analysis showed that a range of nanoparticle sizes and shapes were produced which influenced the visual colour of the fabric. The purple samples produced are caused by small particles (<100nm) that have aggregated together. Samples that appear tan or gold in colour have mainly large particles (>500nm) that are either made up of small spheres fused together or are large plates (trigonal, hexagonal); therefore, Mie's laws do not appear to apply. Light coloured samples generally have a few small particles (<100nm) that are spaced out over the fibre surface.</p>

Gold Nanoparticles: A Novel Dye for Synthetic Fabrics

<p>Fabric has always been prominent throughout history. In the last 70 years new synthetic fabrics have been developed which mimic the natural fibres but have increased strength, durability and stretchability. Common fibres include Polyester, Nylon and Lycra(R). These fibres can be blended to incorporate the properties of both the individual fibre types. Gold nanoparticles have been found to give the stable deep red colour found in stained glass but the science was not understood until the quantum mechanical work of Mie in 1908 on the interaction of electromagnetic radiation (visible light) with fine particles of matter. It is proposed that gold nanoparticles can be used as stable colourants bound to synthetic fibres and other textiles due to its chemical unreactivity. The most common formation method is the use of a reductant such as poly(ethylene imine), sodium citrate or tannic acid. This thesis reports the research and development of new, novel hybrid materials created by combining the interesting properties of both the synthetic fabrics and gold nanoparticles. Twenty five different methods (broken down into four general categories - pre-made colloids, in-situ reduction, use of external reductant after uptake of gold solution and growth of seed particles) were attempted resulting in fabrics that were a variety of shades and colours including pink, purple, tan and gold. The synthetic fabric-gold nanoparticle hybrid samples were analysed by scanning electron microscopy, energy dispersive spectroscopy, infrared spectroscopy, ultraviolet/visible reflectance spectroscopy, x-ray photoelectron spectroscopy, fluorescence spectroscopy and ColourQuest measurements. A sample was also subjected to industry standard "abrasion" and colourfastness tests in which it gained the highest mark possible, showing no staining of other fabrics under dry rub conditions. Atomic absorption measurements were performed on solutions after the fabric was removed in order to confirm the amount of gold uptake by the fabric samples. Analysis showed that a range of nanoparticle sizes and shapes were produced which influenced the visual colour of the fabric. The purple samples produced are caused by small particles (<100nm) that have aggregated together. Samples that appear tan or gold in colour have mainly large particles (>500nm) that are either made up of small spheres fused together or are large plates (trigonal, hexagonal); therefore, Mie's laws do not appear to apply. Light coloured samples generally have a few small particles (<100nm) that are spaced out over the fibre surface.</p>

Design of High-Relaxivity Polyelectrolyte Nanocapsules Based on Citrate Complexes of Gadolinium(III) of Unusual Composition

Through nuclear magnetic relaxation and pH-metry, the details of the complexation of gadolinium(III) ions with citric acid (H4L) in water and aqueous solutions of cationic polyelectrolytes are established. It is shown that the presence of poly(ethylene imine) (PEI) in solution affects magnetic relaxation behavior of gadolinium(III) complexes with citric acid (Cit) to a greater extent than polydiallyldimethylammonium chloride (PDDC). A large increase in relaxivity (up to 50 mM−1s−1) in the broad pH range (4–8) is revealed for the gadolinium(III)–citric acid–PEI system, which is particularly strong in the case of PEI with the molecular weight of 25 and 60 kDa. In weakly acidic medium (pH 3–7), the presence of PEI results in the formation of two tris-ligand associates [Gd(H2L)3]3− and [Gd(H2L)2(HL)]4−, which do not exist in aqueous medium. In weakly alkaline medium (pH 7–10), formation of ternary complexes Gd(III)–Cit–PEI with the Gd(III)–to–Cit ratio of 1:2 is evidenced. Using transmission electron microscopy (TEM) and dynamic light scattering techniques (DLS), the formation of the particles with the size of 50–100 nm possessing narrow molecular-mass distribution (PDI 0.08) is determined in the solution containing associate of PEI with tris-ligand complex [Gd(H2L)2(HL)]4−.

Effect of Phenolic Acids on Temperature-sensitive Property of Self-assembly of Ionic Pair of Poly(ethylene imine)/(phenylthio)Acetic Acid

The ionic pair self-assembly (IPSAM) composed of poly(ethyleneimine) (PEI) and (phenylthio)acetic acid (PTA) was prepared and the effect of phenolic acids (PAs) (e.g. cinnamic acid (CA), hydroxycinnamic acid (HCA), and dihydroxycinnamic acid (DHCA)) on the upper critical solution temperature (UCST) and the temperature-responsive releasing property of IPSAM were investigated. PEI/PTA ionic pair showed a UCST behavior and the PAs decreased the UCST effective in the order of DHCA > HCA > CA. The PAs were thought to attach to the PEI chain of PEI/PTA ionic pair as pendants. According to the interfacial tensiometry, PEI/PTA(3/7) ionic pair was found to be air/water interface-active due to their amphiphilic property. CA had little effect on the interfacial activity of the ionic pair. HCA and HDCA significantly decreased the interfacial activity possibly because they are more polar than CA thus the hydrophilic and lipophilic balance of PEI/PTA ionic pair could be broken by their attachment to PEI chains. IPSAM was found as nanoparticles whose diameter was tens of nanometer and PAs had little effect on the shape and the size of IPSAM, once the UCST of PEI/PTA/PA ionic pair was above room temperature where the TEM micrographs were taken. If the UCST of PEI/PTA/PA ionic pair was below room temperature, no particulate matters were found on the TEM micrographs. The release degree of cargo loaded in IPSAM increased slowly with time lapse below UCST. Whereas, the release degree increased rapidly with time lapse above UCST, possibly because of the thermally-induced disintegration of IPSAM.

Adhesion of monocytes and endothelial cells isolated from the human aorta suppresses by miRNA-PEI particles

Background Knowledge of stenosis in coronary arteries requires an understanding of the cellular and molecular processes that occur throughout the leukocyte rolling process. In this study, the roles of miR-125a-5p and miR-495-3p were investigated on the adhesion of endothelial cells (ECs) isolated from the human aorta. Methods Human primary endothelial cells were obtained from the aorta of people who had died of brain death. Whole blood was used to isolate the monocytes. The miR-125 and miR-495 were predicted and transfected into ECs using Poly Ethylene Imine (PEI). The expression levels of adhesion molecules and monocyte recruitment were identified by the RT-qPCR technique and Leukocyte-Endothelial Adhesion Assay kit, respectively. Results The ICAM-1, ICAM-2 and VCAM-1 expression levels decreased significantly in the miR-495/PEI-transfected ECs (P < 0.05) while in the miR-125/PEI-transfected ECs only the ICAM-2 and ITGB-2 expression levels decreased significantly (P < 0.05) as compared to the miR-synthetic/PEI-transfected ECs. Furthermore, the monocyte adhesion was decreased in the miR-125 and miR-mix/PEI-transfected ECs as compared to the miR-synthetic/PEI-transfected ECs (P = 0.01 and P = 0.04, respectively). Conclusion According to the findings, the efficient relations between miR-125 and adhesion molecules may be responsible for the inhibition of monocyte rolling.

Preparation of Poly(ethylene glycol)@Polyurea Microcapsules Using Oil/Oil Emulsions and Their Application as Microreactors

The development process of catalytic core/shell microreactors, possessing a poly(ethylene glycol) (PEG) core and a polyurea (PU) shell, by implementing an emulsion-templated non-aqueous encapsulation method, is presented. The microreactors’ fabrication process begins with an emulsification process utilizing an oil-in-oil (o/o) emulsion of PEG-in-heptane, stabilized by a polymeric surfactant. Next, a reaction between a poly(ethylene imine) (PEI) and a toluene-2,4-diisocyanate (TDI) takes place at the boundary of the emulsion droplets, resulting in the creation of a PU shell through an interfacial polymerization (IFP) process. The microreactors were loaded with palladium nanoparticles (NPs) and were utilized for the hydrogenation of alkenes and alkynes. Importantly, it was found that PEG has a positive effect on the catalytic performance of the developed microreactors. Interestingly, besides being an efficient green reaction medium, PEG plays two crucial roles: first, it reduces the palladium ions to palladium NPs; thus, it avoids the unnecessary use of additional reducing agents. Second, it stabilizes the palladium NPs and prevents their aggregation, allowing the formation of highly reactive palladium NPs. Strikingly, in one sense, the suggested system affords highly reactive semi-homogeneous catalysis, whereas in another sense, it enables the facile, rapid, and inexpensive recovery of the catalytic microreactor by simple centrifugation. The durable microreactors exhibit excellent activity and were recycled nine times without any loss in their reactivity.

A Trimethylguanosine Synthase1-like (TGS1) homologue is implicated in vernalisation and flowering time control

Key message A plant-specificTrimethylguanosine Synthase1-likehomologue was identified as a candidate gene for theeflmutation in narrow-leafed lupin, which alters phenology by reducing vernalisation requirement. Abstract The vernalisation pathway is a key component of flowering time control in plants from temperate regions but is not well understood in the legume family. Here we examined vernalisation control in the temperate grain legume species, narrow-leafed lupin (Lupinus angustifolius L.), and discovered a candidate gene for an ethylene imine mutation (efl). The efl mutation changes phenology from late to mid-season flowering and additionally causes transformation from obligate to facultative vernalisation requirement. The efl locus was mapped to pseudochromosome NLL-10 in a recombinant inbred line (RIL) mapping population developed by accelerated single seed descent. Candidate genes were identified in the reference genome, and a diverse panel of narrow-leafed lupins was screened to validate mutations specific to accessions with efl. A non-synonymous SNP mutation within an S-adenosyl-L-methionine-dependent methyltransferase protein domain of a Trimethylguanosine Synthase1-like (TGS1) orthologue was identified as the candidate mutation giving rise to efl. This mutation caused substitution of an amino acid within an established motif at a position that is otherwise highly conserved in several plant families and was perfectly correlated with the efl phenotype in F2 and F6 genetic population and a panel of diverse accessions, including the original efl mutant. Expression of the TGS1 homologue did not differ between wild-type and efl genotypes, supporting altered functional activity of the gene product. This is the first time a TGS1 orthologue has been associated with vernalisation response and flowering time control in any plant species.