Additive manufacture of three dimensional metal-polymer nanocomposites through two-photon fabrication

Two-photon fabrication is an attractive additive manufacturing (AM) technique that allows the production of 3D objects with high resolution down to 100 nm. It has been applied to fabricate nano-photonics, microelectromechanical systems (MEMS), microelectronics, microfluidic devices and biochips. In this thesis, complex 2D and 3D gold-, silver- and copper-polymer nanocomposites were additive manufactured for the first time through two-photon polymerisation (TPP) and two-photon reduction (TPR) in a single step. The research aims to investigate the printability of using simultaneous photopolymerisation and photoreduction to produce 3D metal-polymer nanocomposites that could be potentially applied to microelectronics, metamaterials and SERS (surface-enhanced Raman spectroscopy). A series of formulations were developed and prepared to assess the printability. The relationship between materials composition or processing parameter and final structures were characterised and investigated. The potential applications of fabricated structures were evaluated and discussed. 3D gold-polymer nanostructures were fabricated through the two-photon based manufacturing method. Two kinds of triacrylate based monomers of similar structure were compared and chosen to fabricate gold-polymer nanocomposites. Irgacure 369 was used as a photoinitiator. When gold salt was added, additional photoinitiator was required to provide more free radicals for photoreduction because there was a competition between TPP and TPR. The adding of two-photon sensitive dye, tris(2,2’-2 bipyridyl) dichlororuthenium (II) hexahydrate, can stabilise the fabrication process, allowing for the fabrication of 3D gold-polymer nanocomposite structures. Silver-polymer nanocomposites were developed through simultaneous photopolymerisation and photoreduction for the first time. A series of materials were assessed to produce silver-polymer nanocomposites. A phase-transfer protocol that transferred silver ions from the water phase to toluene phase enabled good mixing of PETA (pentaerythritol triacrylate) as a monomer, Irgacure 369 as a photoinitiator and coumarin 30 as a photosensitive dye. 2D and 3D complex silver-polymer nanostructures were fabricated by TPL (Two-photon lithography). By adding coumarin 30 photosensitive dye, better light interaction, higher resolution of line width and more uniform size and distribution of silver NPs (nanoparticles) were observed. The average size of silver particles well distributed in the fabricated structures was 5.8 ± 1.5 nm. An initial investigation on the fabrication of copper-containing nanostructures through two-photon fabrication was conducted. 3D copper-polymer nanocomposites were successfully obtained. The phase transfer method used in this research could be applied in the synthesis of a variety of metal-polymer functional materials through simultaneous photopolymerisation. The successful additive manufacture of complex 2D (twodimensional) and 3D (three-dimensional) metal-polymer nanocomposite structures provides potential to be used in photonics, metamaterials, plasmonics, electronics, catalysis and bio-sensing

Additive manufacture of three dimensional nanocomposite based objects through multiphoton fabrication

Three dimensional structures prepared from a gold-polymer composite formulation have been fabricated using multiphoton lithography. In this process, gold nanoparticles were simultaneously formed through photoreduction whilst polymerisation of two possible monomers was promoted. The monomers, trimethylopropane triacrylate (TMPTA) and pentaerythritol triacrylate (PETA) were mixed with a gold salt, but it was found that the addition of a Ruthenium (II) complex enhanced both the geometrical uniformity and integrity of the polymerized / reduced material, enabling the first production of 3D gold-polymer structures by single step multiphoton lithography

Author Correction: Additive manufacture of complex 3D Au-containing nanocomposites by simultaneous two-photon polymerisation and photoreduction

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Strategies for Integrating Metal Nanoparticles with Two-Photon Polymerization Process: Toward High Resolution Functional Additive Manufacturing

This study reports the successful fabrication of complex 3D metal nanoparticle–polymer nanocomposites using two-photon polymerization (2PP). Three complementary strategies are detailed: in situ formation of metal nanoparticles (MeNPs) through a single-step photoreduction process, integration of pre-formed MeNPs into 2PP resin, and site-selective MeNPs decoration of 3D 2PP structures. In the in situ formation strategy, a phase-transfer method is applied to transfer silver and copper ions from an aqueous phase into a toluene solvent to disperse them in photoreactive monomers.The addition of a photosensitive dye, coumarin 30, facilitated the reduction of silver ions and improved the distribution of silver nanoparticles (AgNPs). This strategy is successfully used to produce other MeNPs, such as Cu and Au. The integration of pre-formed MeNPs enabled highly controlled NP size distribution within the 2PP 3D structures with high-fidelity To enable selective decoration of 2PP 3D surfaces with MeNPs, a multimaterial strategy is developed, with one of the resins designed for thiol-ene reaction, which demonstrated selective binding to AuNPs. The successful development of complementary strategies for integration of MeNPs into 2PP resins offers exciting opportunities for fabrication of MeNP composites with sub-micron resolution for applications fromphotonics to metamaterials and drug delivery

Additive manufacture of complex 3D Au-containing nanocomposites by simultaneous two-photon polymerisation and photoreduction

The fabrication of complex three-dimensional gold-containing nanocomposite structures by simultaneous two-photon polymerisation and photoreduction is demonstrated. Increased salt delivers reduced feature sizes down to line widths as small as 78nm, a level of structural intricacy that represents a significant advance in fabrication complexity. The development of a general methodology to efficiently mix pentaerythritol triacrylate (PETA) with gold chloride hydrate (HAuCl4∙3H2O) is reported, where the gold salt concentration is adjustable on demand from zero to 20wt%. For the frst-time 7-Diethylamino-3-thenoylcoumarin (DETC) is used as the photoinitiator. Only 0.5wt% of DETC was required to promote both polymerisation and photoreduction of up to 20wt% of gold salt. This efficiency is the highest reported for Au-containing composite fabrication by two-photon lithography. Transmission Electron Microscopy (TEM) analysis confirmed the presence of small metallic nanoparticles (5.4±1.4nm for long axis / 3.7±0.9nm for short axis) embedded within the polymer matrix, whilst X-ray Photoelectron Spectroscopy (XPS) confirmed that they exist in the zero valent oxidation state. UV-vis spectroscopy defined that they exhibit the property of localised surface plasmon resonance (LSPR). The capability demonstrated in this study opens up new avenues for a range of applications, including plasmonics, metamaterials, flexible electronics and biosensors

A common variant near TGFBR3 is associated with primary open angle glaucoma

Primary open angle glaucoma (POAG), a major cause of blindness worldwide, is a complex disease with a significant genetic contribution. We performed Exome Array (Illumina) analysis on 3504 POAG cases and 9746 controls with replication of the most significant findings in 9173 POAG cases and 26 780 controls across 18 collections of Asian, African and European descent. Apart from confirming strong evidence of association at CDKN2B-AS1 (rs2157719 [G], odds ratio [OR] = 0.71, P = 2.81 × 10−33), we observed one SNP showing significant association to POAG (CDC7–TGFBR3 rs1192415, ORG-allele = 1.13, Pmeta = 1.60 × 10−8). This particular SNP has previously been shown to be strongly associated with optic disc area and vertical cup-to-disc ratio, which are regarded as glaucoma-related quantitative traits. Our study now extends this by directly implicating it in POAG disease pathogenesis

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Abstract Primary open angle glaucoma (POAG), a major cause of blindness worldwide, is a complex disease with a significant genetic contribution. We performed Exome Array ), we observed one SNP showing significant association to POAG (CDC7-TGFBR3 rs1192415, OR G-allele = 1.13, P meta = 1.60 × 10 −8 ). This particular SNP has previously been shown to be strongly associated with optic disc area and vertical cup-to-disc ratio, which are regarded as glaucoma-related quantitative traits. Our study now extends this by directly implicating it in POAG disease pathogenesis

Additive manufacture of three dimensional metal-polymer nanocomposites through two-photon fabrication

Two-photon fabrication is an attractive additive manufacturing (AM) technique that allows the production of 3D objects with high resolution down to 100 nm. It has been applied to fabricate nano-photonics, microelectromechanical systems (MEMS), microelectronics, microfluidic devices and biochips. In this thesis, complex 2D and 3D gold-, silver- and copper-polymer nanocomposites were additive manufactured for the first time through two-photon polymerisation (TPP) and two-photon reduction (TPR) in a single step. The research aims to investigate the printability of using simultaneous photopolymerisation and photoreduction to produce 3D metal-polymer nanocomposites that could be potentially applied to microelectronics, metamaterials and SERS (surface-enhanced Raman spectroscopy). A series of formulations were developed and prepared to assess the printability. The relationship between materials composition or processing parameter and final structures were characterised and investigated. The potential applications of fabricated structures were evaluated and discussed. 3D gold-polymer nanostructures were fabricated through the two-photon based manufacturing method. Two kinds of triacrylate based monomers of similar structure were compared and chosen to fabricate gold-polymer nanocomposites. Irgacure 369 was used as a photoinitiator. When gold salt was added, additional photoinitiator was required to provide more free radicals for photoreduction because there was a competition between TPP and TPR. The adding of two-photon sensitive dye, tris(2,2’-2 bipyridyl) dichlororuthenium (II) hexahydrate, can stabilise the fabrication process, allowing for the fabrication of 3D gold-polymer nanocomposite structures. Silver-polymer nanocomposites were developed through simultaneous photopolymerisation and photoreduction for the first time. A series of materials were assessed to produce silver-polymer nanocomposites. A phase-transfer protocol that transferred silver ions from the water phase to toluene phase enabled good mixing of PETA (pentaerythritol triacrylate) as a monomer, Irgacure 369 as a photoinitiator and coumarin 30 as a photosensitive dye. 2D and 3D complex silver-polymer nanostructures were fabricated by TPL (Two-photon lithography). By adding coumarin 30 photosensitive dye, better light interaction, higher resolution of line width and more uniform size and distribution of silver NPs (nanoparticles) were observed. The average size of silver particles well distributed in the fabricated structures was 5.8 ± 1.5 nm. An initial investigation on the fabrication of copper-containing nanostructures through two-photon fabrication was conducted. 3D copper-polymer nanocomposites were successfully obtained. The phase transfer method used in this research could be applied in the synthesis of a variety of metal-polymer functional materials through simultaneous photopolymerisation. The successful additive manufacture of complex 2D (twodimensional) and 3D (three-dimensional) metal-polymer nanocomposite structures provides potential to be used in photonics, metamaterials, plasmonics, electronics, catalysis and bio-sensing

Risk Analysis and Optimization of Water Surface Deviation from Shafts in the Filling–Emptying System of a Mega-Scale Hydro-Floating Ship Lift

Hydro-floating ship lifts are a milestone in the field of high dam navigation. In order to ensure the running safety of a hydro-floating ship lift, the effective integration of a numerical simulation method and cloud model theory was carried out to deal with the hydrodynamic risks presented by water surface deviations from the shafts in the filling–emptying system such as a lock. In this study, the average values of water surface deviation from the shafts were 0.2, 0.22 and 0.24 m, through numerical simulation on a similar hydro-floating ship lift at the lifting heights of 80, 100 and 120 m, respectively. An increase in the lifting height causes the water surface deviation from the shafts to increase, and the hydrodynamic risk is greatly increased in the equal inertial pipeline filling–emptying system. In addition, the water surface deviations from the shafts of the equal inertial pipeline and longitudinal culvert filling–emptying system like a lock were compared. The longitudinal culvert was better at optimizing running safety in the filling–emptying system and dealing with the uncertainty of water surface deviation from the shafts. The results show that the numerical simulation method and cloud model theory can effectively control the risk of water surface deviation from the shafts and can be used to aid in decision-making for risk prevention in relation to hydro-floating ship lifts

Neuroprotective Effects of TRPM7 Deletion in Parvalbumin GABAergic vs. Glutamatergic Neurons following Ischemia

Oxidative stress induced by brain ischemia upregulates transient receptor potential melastatin-like-7 (TRPM7) expression and currents, which could contribute to neurotoxicity and cell death. Accordingly, suppression of TRPM7 reduces neuronal death, tissue damage and motor deficits. However, the neuroprotective effects of TRPM7 suppression in different cell types have not been investigated. Here, we found that induction of ischemia resulted in loss of parvalbumin (PV) gamma-aminobutyric acid (GABAergic) neurons more than Ca2+/calmodulin-kinase II (CaMKII) glutamatergic neurons in the mouse cortex. Furthermore, brain ischemia increased TRPM7 expression in PV neurons more than that in CaMKII neurons. We generated two lines of conditional knockout mice of TRPM7 in GABAergic PV neurons (PV-TRPM7−/−) and in glutamatergic neurons (CaMKII-TRPM7−/−). Following exposure to brain ischemia, we found that deleting TRPM7 reduced the infarct volume in both lines of transgenic mice. However, the volume in PV-TRPM7−/− mice was more significantly lower than that in the control group. Neuronal survival of both GABAergic and glutamatergic neurons was increased in PV-TRPM7−/− mice; meanwhile, only glutamatergic neurons were protected in CaMKII-TRPM7−/−. At the behavioral level, only PV-TRPM7−/− mice exhibited significant reductions in neurological and motor deficits. Inflammatory mediators such as GFAP, Iba1 and TNF-α were suppressed in PV-TRPM7−/− more than in CaMKII-TRPM7−/−. Mechanistically, p53 and cleaved caspase-3 were reduced in both groups, but the reduction in PV-TRPM7−/− mice was more than that in CaMKII-TRPM7−/− following ischemia. Upstream from these signaling molecules, the Akt anti-oxidative stress signaling was activated only in PV-TRPM7−/− mice. Therefore, deleting TRPM7 in GABAergic PV neurons might have stronger neuroprotective effects against ischemia pathologies than doing so in glutamatergic neurons