Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7755
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Article Citation - WoS: 5Citation - Scopus: 5Effect of Chain Topology on Plasmonic Properties of Pressure Sensor Films Based on Poly(acrylamide) and Au Nanoparticles(Elsevier Ltd., 2019) Topçu, Gökhan; Demir, Mustafa MuammerAu nanoparticles have been recognized as a colorimetric sensing element in polymeric systems because clustering shifts the red color of individual particles into saturated blue due to distinct plasmonic variation. The mechanism of pressure sensing is based on the disintegration of the particle clusters into the individual particles in polymers upon application of pressure. Polymers are usually composed of linear chains that provide a viscoelastic medium for their diffusion. Changing topology of polymer chains from linear to crosslinked under fixed pressure makes a clear change in spectral features of the particles probably due to the hindrance of particle diffusion by the crosslinking points. Therefore, the working range of the sensor films can be increased to higher-pressure values. In this work, polyacrylamide/Au nanoparticle films were prepared by various concentrations of formaldehyde as a crosslinking agent from 0.5 to 5.0 wt %. The initial absorption signal gradually shifts from 690 to 545 nm for linear chains upon application of pressure while shifting goes down to 571 nm for crosslinked ones. The colorimetric change is also examined under humid environments. Contrary to the crosslinking process, humid environment facilitates the diffusion of particles since the chains swell with water molecules that provide a convenient medium for particle diffusion.Master Thesis Green Synthesis of Metal Nanoparticles and Their Applications as Plasmonic Substrates(Izmir Institute of Technology, 2018) Elveren, Beste; Arslan Yıldız, Ahu; Yıldız, Ümit HakanGold nanoparticles (GNPs) have been widely used in diagnostic, tissue engineering, and drug delivery fields, in the last decades. Generally, reducing gold salts to zero valent gold has been accomplished by harsh chemicals and strong reducing agents, which cause toxicity and eventually limiting the bioapplications. Green synthesis is a newly developing methodology to synthesize GNPs. Especially natural products and plants extracts are commonly preferred for green synthesis based on their natural content. Biological molecule-capped GNPs, are more biofriendly and biocompatible nano-materials that can be used for varied applications.1-3 Sensor applications; varying from biosensing to environmental analysis, are an important field that GNPs were intensively utilized.4-5 Cyanide ion (CN-) has been considered as one of the main pollutants of water, because of its rapid discharge. CN- is currently being used in industry such as; polymer synthesis6, noble metal mining7, pest control8, plastics production etc., at large scale. However, there is an unmet need for CN- detection and monitoring. Colorimetric detection of CN- that utilizes GNPs has been done by several researchers.9-10 However, in all these studies reduction of GNPs were done by strong reducing agents. Green synthesis of GNPs eliminates the toxic side-products that can be harmful to both environment and human health. To overcome this problem green synthesized GNPs were used to establish the sensor platform, which can be further employed for CN- detection. Oxidation of GNPs in the presence of cyanide molecules is a direct-forward, colorimetric and optical method that requires no toxic chemicals; therefore it is a greener approach towards CN- detection in water resources.