Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 6Citation - Scopus: 8Enhanced Spontaneous Emission Rate in a Low-Q Hybrid Photonic-Plasmonic Nanoresonator(American Chemical Society, 2019) Gökbulut, Belkıs; İnanç, Arda; Topçu, Gökhan; Ünlütürk, Seçil Sevim; Özçelik, Serdar; Demir, Mustafa Muammer; İnci, Mehmet NaciIn this paper, CdTe quantum dots (QDs)-doped single electrospun polymer nanofibers are partially coated with gold nanoparticles to form distinct hybrid photonic-plasmonic nanoresonators to investigate the critical role of the cavity-confined hybrid mode on the modification of the spontaneous emission dynamics of the fluorescent emitters in low-Q photonic cavities. A total enhancement factor of 11.2 is measured via a time-resolved experimental technique, which shows that there is an increase of about three times in the spontaneous emission rate for the QDs-doped gold nanoparticle-decorated nanofibers as they are compared with those uncoated ones. The physical mechanism affecting the spontaneous emission rate of the encapsulated QDs in such a hybrid photonic-plasmonic nanoresonator is explained to be due to regeneration of the mode field in the nanofiber cavity upon the interaction of the dipoles with the surface plasmons of distinctive gold nanoparticles that surround the outer surface of the nanofiber.Article Citation - WoS: 45Citation - Scopus: 46Electrospun Polystyrene Fibers Knitted Around Imprinted Acrylate Microspheres as Sorbent for Paraben Derivatives(Elsevier, 2018) Demirkurt, Merve; Ölçer, Yekta Arya; Demir, Mustafa Muammer; Eroğlu, Ahmet EroğluParabens are used as antimicrobial preservatives in food, cosmetic products and pharmaceuticals regardless of their endocrine disrupting effect. In this study, highly selective molecular imprinted polymers (MIPs) were synthesized in submicron-sizes and converted to an SPME fiber coating through electrospinning process in order to determine parabens in water samples. Conversion of MIP to a fiber is achieved via creation of spacial knitting around MIP by polystyrene. The selectivity and extraction ability of the fibers were compared with the commercial fibers and the corresponding non-imprinted polymer (NIP) coated fiber. The coated fiber showed better extraction ability among them. Also, the results revealed that the fiber has better selectivity for benzyl paraben and the other structurally-related compounds, such as methyl and propyl paraben. Extraction efficiency of prepared fibers for three parabens has been tested by spiking bottled, tap and sea water samples. The recoveries changed between 92.2 ± 0.8 and 99.8 ± 0.1 for three different water types. This method could be used for selective and sensitive determination of parabens in aqueous samples.Conference Object Citation - Scopus: 2Fabrication of Polymer Nanofiber-Conducting Polymer Fabric and Noncontact Motion Sensing Platform(Trans Tech Publications, 2018) Mutlu, Mustafa Umut; Akın, Osman; Demir, Mustafa Muammer; Yıldız, Ümit HakanConductive polymer-electrospun polymer nanofiber network was combined to host iron oxide nanoparticles providing micrometer thick sensing interface. The sensor has fabricated as freestanding fabric exhibiting 10 to 100 KOhm base resistivity upon bias applied. The moving object has been sensed through the electrostatic interactions between fibers and object. The sensing range has been found to be 1-5 cm above the surface of fabric. By the controlled combination of conductive polymers electrospun polymer nanofibers effective device miniaturization has been provided without loss of performance. The noncontact motion sensor platform has unique flexibility and light weight holding a potential for wearable sensor technology.Article Citation - WoS: 44Citation - Scopus: 53Smart Phone Assisted Detection and Quantification of Cyanide in Drinking Water by Paper Based Sensing Platform(Elsevier Ltd., 2017) İncel, Anıl; Akın, Osman; Çağır, Ali; Yıldız, Ümit Hakan; Demir, Mustafa MuammerAn organometallic dye, europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) and gold nanoparticles (Au NPs) impregnated paper based sensor platform have been utilized for development of fluorescence turn-on cyanide assay in aqueous media. The ordinary filter paper with 6 μ m pore size were employed as solid support that facilitates impregnation of EuD4TEA and gold nanoparticles and provides durability. Detection mechanism relying on two processes (i) dissolution of gold nanoparticles causing fluorescence recovery and (ii) ligand exchange of triethyl amine with CN group stimulating cyanide specific fluorescence enhancement. The paper platform exhibit naked eye distinguishable color transition upon CN− addition from 10−2 to 10−12 M. To standardize the methodology a homemade image processing algorithm has been developed that enabling calibration of color change and quantify CN− concentration. The described algorithm is applicable to Android smart phones and facilitate transforming these devices into a quantitative cyanide detector. The overall methodology provides instrument free cyanide detection and therefore rapid control of water quality and safety at off-field conditions.Article Citation - WoS: 31Citation - Scopus: 36Integration of Triboluminescent Eud4tea Crystals To Transparent Polymers: Impact Sensor Application(American Chemical Society, 2017) İncel, Anıl; Eanes, Mehtap; McMillen, Colin D.; Demir, Mustafa MuammerLanthanide-based organometallic materials are well-known candidate triboluminescent (TL) materials that can show bright emission when a mechanical force is applied. These materials are usually in the form of crystalline powders, and it is often useful to integrate these samples into a polymer matrix in order to achieve processability, enabling coating from a solution/molten state or fabrication as a complex-shaped matrix. In this work, micrometer-sized europium tetrakis (dibenzoylmethide) triethylammonium (EuD4TEA) crystals were synthesized and integrated with various transparent polymers (PMMA, PS, PVDF, and PU) using two approaches: (i) blending and (ii) surface impregnation. In the former method, the crystalline particles were molecularly dissolved; therefore, a TL response cannot be achieved. More than 10 wt % TL crystals in the composite is needed to obtain TL signals. However, TL signal was achieved at 2.5 wt % when a composite was prepared by the latter approach. TL intensity shows exponential decay with consecutive mechanical action. The TL emission of PU-based surface impregnated composite expires with long-lived emission, and maximum TL response with respect to applied force was measured between 2.45 and 42.0 N.Article Citation - WoS: 55Citation - Scopus: 60Development of Molecularly Imprinted Polymers (mips) as a Solid Phase Extraction (spe) Sorbent for the Determination of Ibuprofen in Water(Royal Society of Chemistry, 2017) Ölçer, Yekta Arya; Demirkurt, Merve; Demir, Mustafa Muammer; Eroğlu, Ahmet EminIbuprofen is a well-known endocrine disrupter. In this study, highly selective molecularly imprinted polymers (MIPs) with different morphologies were synthesized via precipitation and bulk polymerization of methacrylic acid (MAA) and trimethylolpropane trimethacrylate (TRIM) in the presence of ibuprofen as a template. Non-imprinted polymers (NIPs) were also synthesized via the same procedure in the absence of ibuprofen. Spherical and monolithic MIPs were obtained using different experimental conditions, and the spherical MIP was shown to have better sorption towards ibuprofen. The optimum sample pH, sorbent amount, sample volume, and sorption time were determined to be 8.0, 25.0 mg, 10.0 mL, and 30.0 min, respectively. A methanol water mixture (MeOH:H2O, 80:20, pH 3.0) was employed as an eluent with >97% (±0.8, n = 3) desorption. The MIP demonstrated high selectivity towards ibuprofen in the presence of naproxen and ketoprofen. The validity of the proposed method was checked via spike recovery tests using drinking and tap water samples. The method worked efficiently for both water types, resulting in the recoveries of 97.2% (±0.3, n = 3) and 97.7% (±0.2, n = 3).Article Citation - Scopus: 2Enthalpy-Driven Selective Loading of Cdse0.75s0.25 Nanoalloys in Triblock Copolymer Polystyrene-B(Elsevier Ltd., 2016) Aşkın, Görkem; Çeçen, Volkan; Ünlütürk, Seçil Sevim; Özçelik, Serdar; Demir, Mustafa MuammerCdSe0.75S0.25 nanoalloys were blended with asymmetric triblock copolymer of polystyrene-b-polyisoprene-b-polystyrene(PS-SIS) in tetrahydrofuran. The fraction of styrene block varies from 14 to 22% with respect to isoprene by mass. The morphology of the copolymer cast film experiences a phase change from cylinder to lamella. CdSe0.75S0.25 nanoalloys were prepared by two-phase method. The surface of the nanoalloys was capped by either oleic acid (OA) or n-tri-octylphosphonic acid (TOPO) in situ. The mean diameter of the alloyed particles is around 12 nm in both systems. The chemical nature of the nanoalloy surface was found to influence the dispersion of the particles over polymer volume. The size of the nanoalloy domains in PS is 50 nm, on average, consisting of approximately 0.7 wt% nanoalloys. However, the size of the nanoalloy domains is smaller when they are loaded into PS-SIS. The structure formation is predominantly determined by enthalpic compatibilization. Atomic force microscopy results suggest that the nanoalloys capped with TOPO sequester into PS-rich domains and enlarge the domain. On the other hand, the ones capped with OA prefer to locate in polyisoprene domains. The increase of particles over 1.0 wt% distorts the lamella structure.Article Citation - WoS: 6Citation - Scopus: 7Utilization of Electrospun Polystyrene Membranes as a Preliminary Step for Rapid Diagnosis(John Wiley and Sons Inc., 2016) Işık, Tuğba; Horzum, Nesrin; Yıldız, Ümit Hakan; Liedberg, Bo; Demir, Mustafa MuammerRecent advances in clinical practice drive deoxyribonucleic acid (DNA) as an important class of biomarker. Monitoring the change in their concentration suggests the initiation and/or progression of various disorders. However, low quantity of DNA biomarkers in body fluids requires a delicate isolation methodology that provides efficient separation and easy handling. This study describes a newer-generation separation technology relying on electrospun fibers of sub-micrometer diameter of a commodity polymer for DNA biomarkers in simulative serum. Fibrous polystyrene membranes are prepared by electrospinning and they are subjected to post-modification with Au. The composite membranes may provide a convenient environment for the removal of bovine serum albumin (BSA) from BSA and DNA mixtures. The eluent can be used as an efficient tool for detection of DNA biomarkers associated with diagnosis of numerous life-threatening diseases.Conference Object Merkezi Laboratuvarların Araştırmadaki Önemi: İyte-mam Örneği(Yükseköğretim Kurulu, 2012) Güden, Mustafa; Akkurt, Sedat; Eroğlu, Ahmet Emin; Demir, Mustafa MuammerÜniversitelerin üç temel misyonu vardır: bilgiyi üretmek, bilgiyi yaymak ve topluma hizmet etmek. Bunlardan birincisi literatürü takip ederek edinilen bilgi ışığında planlanan deneylerle laboratuvarda güncel veri toplamak ile gerçekleştirilir. İkincisinde, elde edilen güncel veriyi yazılı veya sözlü olarak yayınlayarak bilgiyi yayar. Sonuncusunda ise toplumun bilgi ve birikim bakımından önünde olan üniversite topluma bazı sorunları çözmede katkıda bulunur. Bu çalışmada birinci konu olan veri üretimi ve bunun rasyonalize edilmesi konusunda İzmir Yüksek Teknoloji Enstitüsü (İYTE) Malzeme Araştırma Merkezi (İYTE-MAM) tecrübesi aktarılacaktır. Sanayi firmalarının katma değeri yüksek ürün üretebilmelerinin ön şartı öncelikle kendi ürünlerini geliştirmeleridir. Bunun için de üniversitelerde bulunan ve güncel cihazlarla donatılmış laboratuvarlar büyük önem taşımaktadır. Türk üniversiteleri son yıllarda araştırma makina teçhizat altyapısı bakımından gelişmiş batılı ülkelerin üniversite laboratuvarları ile boy ölçüşecek konuma gelmiştir. Ancak sağlıklı ve güncel veri toplamanın ön şartı deneyimli personel ve verimli bir işletme modeli ile çalıştırılan laboratuvarlarla gerçekleşebilir. Tek disiplinli ve içine kapanık bölüm yapısının dışında çok disiplinli ve farklı bölümlerden araştırmacıları bünyesinde bulunduran merkezler üniversiteden çevresine bilgi akışı köprüsü görevi görmektedir. Türk üniversitelerinde araştırma laboratuvarlarında sıkça rastlanan sorunlar deneyimli teknik personel eksikliği, cihaza erişimde zorluk, cihazın kalibre tutulmaması, teknik desteğin geç gelmesi gibi sıralanabilir. Bu sorunların aşılmasında üniversite çapında ve dışında herkesin kullanımına açık merkez laboratuvar modelinin en etkin çözüm olduğu İYTE-MAM örneğinde geçtiğimiz 10 yılda gözlenmiştir. Bu tür merkez laboratuvarlar randevu sistemiyle çalşarak sanayi firmalarından gelen taleplere hızla cevap verebilmektedir. 2001 yılında kurulan İYTE-MAM kampüste bulunan yüksek maliyetli makina teçhizatı bünyesinde toplayarak malzeme teknolojileri alanında kampüs içi ve kampüs dışında akademik veya sanayi kökenli araştırmacılara randevu sistemiyle hizmet vermektedir.Article Elektrodokuma Lifler Üzerine Konumlandırılmış: Yeni Nesil Metal Katalizörler(Bilim ve Ütopya Kooperatifi, 2008) Demir, Mustafa MuammerElektrodokuma liflerin oluşturduğu ağsı “nanoyapı”, birçok endüstriyel uygulama için vazgeçilmez bir özellik sunmaktadır. Son birkaç yıl içerisinde gerçekleştirilen akademik çalışlmalarda, bu lifsi yapıların yeni nesil katalitik ürünler için de umut vaat eden malzemeler arasında olduğu gösterilmektedir. Katalizörler, bir kimyasal tepkimenin gerçekleşmesini tetikleyen, kolaylaştıran maddeler olarak tanımlanırlar. Her ne kadar günlük hayatta katalizörlerle karşılaşmasak da, aslında çokça kullandığımız birçok ürünün katalizör kullanılmadan üretilmesi neredeyse imkânsızdır.