Graphene Nanoplatelet-Embedded Acrylic Paint for Low Cost Waterproof Paintable Capacitive Sensors and Free Standing Supercapacitors
Modern capacitive touch input and proximity sensing technologies are rigid and limited to flat substrates making it impossible to apply them onto objects with irregular geometries like textiles or car handles. Furthermore, the high cost restricts the applications to small surfaces and cannot be scaled up to be applied on large surfaces such as walls. Therefore, a paint-on scheme would broaden the applications of capacitive touch input and proximity sensing devices. Paintable capacitive sensors are an emerging technology hindered by the high cost and lackluster properties of conductive paints. Existing conductive paints utilize expensive filler materials such as silver and gold to achieve high conductivity but suffer from low surface area. High surface area is critical for capacitive proximity sensors to detect objects from far distances and for overall sensitivity. Carbonaceous alternatives using micronized graphite exhibit low conductivity, require high loadings and most disintegrate when in contact with water. Multilayer graphene nanoplatelets are investigated for their high conductivity, high surface area, low cost, flexibility and eco friendliness. A waterproof acrylic latex is combined with multilayer graphene and dispersed via bath sonication. The optimal time of sonication and optimal graphene loading is determined through systematic testing. An Arduino Uno is loaded with a CapSense library and the graphene based paint is utilized as the interface to sense both touch and proximity.
Investigation of the Role of Mammalian Siderophore 2,5-DHBA in Neurodegeneration
Lipocalin 2 (LCN2), a 25-kDa secreted protein that belongs to the lipocalin family, is known to bind to a class of bacterial Fe-binding molecules known as siderophores. Iron is essential for bacterial growth. To obtain iron from host cells, bacteria produce siderophores, such as Enterochelin (Ent), to bind and transport host iron into the bacterial cell. In response, the host produces LCN2 to bind the iron-laden enterochelin, forming the tricomplex, LCN2: Ent: Fe3+. This inhibits bacterial growth as iron has been sequestered by LCN2. Devireddy et.al. 2005, proposed the binding of the tricomplex, LCN2: Ent: Fe3+ with the LCN2 receptor (LCN2R). This resulted in the internalisation of the complex, releasing the bound iron into the cell. The increase of intracellular iron was reported to cause cell mortality. Recent publications postulated 2,5-dihydroxybenzoic acid (2,5-DHBA) to be an endogenous mammalian siderophore homologue in mouse in vivo and in vitro studies, which could sequester LCN2 and iron. High iron concentrations in the brain have been consistently observed in Alzheimer's disease and Parkinson's disease. Accumulation of intracellular iron is known to be toxic to neurons, resulting in neurodegeneration. Hence, this study aims to determine the role of 2,5-DHBA as the mammalian siderophore in a cell culture model of neurodegeneration. We hypothesise that addition of 2,5-DHBA to cells exposed to LCN2 will result in increased iron uptake into neuronal cells, reducing cell viability. SH-SY5Y (human neuroblastoma) cell line was used in our study. To determine if SH-SY5Y is a suitable cell line, endogenous levels of LCN2 and LCN2R mRNA and protein expression were determined using reverse transcription-polymerase chain reaction (RT-PCR) and Western Blot analysis respectively. Preliminary results showed presence of both the LCN2R mRNA and protein but absence of LCN2 mRNA. This could be due to the low expression of LCN2 when not exposed to stress. Hence, to simulate conditions of neurodegeneration (by inducing high expression of LCN2), SH-SY5Y was treated with Kainic Acid (KA). After KA, LCN2 mRNA and protein expression levels will be detected again. With the successful upregulation of LCN2 gene expression, SH-SY5Y will be treated with 2,5-DHBA with KA treatment to determine cell viability using the MTS cell proliferation assay. A decreased cell viability or increased expression of pro-apoptotic genes would support the function of 2,5-DHBA as a mammalian siderophore in the brain. Furthermore, KA treatment can also be applied to microglial or astrocyte cell lines, which are known to secrete high levels of LCN2 when treated with KA. Co-culturing these cells with SH-SY5Y can allow us to study the downstream effects of secreted LCN2 from glial cells binding to the LCN2R receptors on SH-SY5Y neuronal cells. This study will help to further understanding of the relationship between 2,5-DHBA and cellular iron transport. If 2,5-DHBA is able to bind LCN2 and iron to increase intracellular iron levels in the neuronal cells, the formation of the tricomplex, LCN2: 2,5-DHBA: Fe3+, could be targeted for therapeutic interventions in neurodegenerative diseases by reducing intracellular iron levels to help ameliorate the progression of neurodegenerative diseases.
New approach to the synthesis of functionalized fluoroalkenes
Fluorine has a big influence on physical, chemical and biological properties of organic structures. Organofluorine compounds are widely used in modern medical chemistry to develop new drugs. Insertion of fluorine atom into organic molecules can improve their reactivity in biological systems, increase their metabolic stability, lipophilicity and permeability through membranes. As a consequence, in recent years, the percentage of drugs containing one or more fluorine atoms has increased rapidly up to 40%. The fluoroallylic fragment is also able to change properties of bioactive molecules. Its introduction into such structures as inhibitors of histonedeacetylase, inhibitors of matrix metalloproteinase, asparagine, glutamine, etc. increases their biological activity and electronic properties. We propose a new method for the synthesis of functionalized fluoroalkenes, based on the generation of fluoroallyl nucleophiles from silyl- and boronyl-substituted fluorocyclopropanes and their further usage in the allylation of carbonyl compounds or their derivatives. Due to the fact that the cyclopropanation of alkenyl boronates is not possible under conditions of alkaline dehydrohalogenation of dibromofluoromethane, we have developed a new method for the preparation of silyl- and boronyl-substituted cyclopropanes, which consist of carbene cyclopropanation of multiple C=C bonds by sodium dibromofluoroacetate catalyzed by (IPr)AgCl. The new method is effective for the cyclopropanation of not only boronyl- and silyl-substituted olefins, but also for low-reactivity alkenes, such as monoalkyl substituted alkenes, allyl alcohol ethers and α,β-unsaturated carbonyl compounds. The conditions for isomerization of silyl- and boronyl-substituted fluorohalocyclopropanes in the presence of catalytic amounts of copper (I) bromide in acetonitrile was selected. It was shown that the regioselectivity of the process is determined by the thermodynamic control. Thus, the formation of fluorovinylsilanes or fluorovinylboranes in the isomerization of α-silyl- or α-boronyl-gem-bromofluorophenylcyclopropanes and fluoroallylsilanes upon isomerization of β-silyl-gem-bromofluorophenylcyclopropanes was observed. Thus, new types of fluorinated reagents were obtained that are not previously described in the literature (...)