Browsing by Author "Ceylan, A."
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Item Open Access Antifouling superhydrophobic surfaces with bactericidal and SERS activity(Elsevier BV, 2022-03-01) Şahin, F.; Çelik, N.; Ceylan, A.; Pekdemir, S.; Ruzi, M.; Önses, Mustafa SerdarFouling and contamination of surfaces are prevailing challenges humanities facing today in fields such as healthcare, hospitality, and food manufacturing. These challenges strongly motivate the development of multifunctional surfaces with antifouling and antimicrobial properties that are coupled with sensing capabilities. To address this challenge, we prepared a multifunctional superhydrophobic surface using eco-friendly materials: polydimethylsiloxane (PDMS) and carnauba wax. After deposition of a thin film of Ag, the surface gained surface-enhanced Raman scattering (SERS) activity and bactericidal property. The multifunctional superhydrophobic surface showed extreme liquid repellency towards water and common liquid food. The strong SERS activity enabled the detection of adulterant rhodamine B in a sausage down to a nanomolar level. Notably, the surface showed excellent bactericidal activity towards two common bacteria, E. coli, and S. aureus, significantly reducing their adhesion and killing. Additionally, the surface showed anti-fouling behavior against common liquid food, and even towards sticky foods such as yogurt, honey, and pomegranate sauce, reducing residual food by >97 %. Furthermore, the superhydrophobic surface showed excellent chemical stability in dynamic and static flow conditions and leaching of Ag in neutral and basic solutions was minimal.Item Open Access Co doping induced structural and optical properties of sol-gel prepared ZnO thin films(Elsevier BV, 2014-11) Gungor, E.; Gungor, T.; Caliskan, D.; Ceylan, A.; Özbay, EkmelThe preparation conditions for Co doping process into the ZnO structure were studied by the ultrasonic spray pyrolysis technique. Structural and optical properties of the Co:ZnO thin films as a function of Co concentrations were examined. It was observed that hexagonal wurtzite structure of ZnO is dominant up to the critical value, and after the value, the cubic structural phase of the cobalt oxide appears in the X-ray diffraction patterns. Every band-edge of Co:ZnO films shifts to the lower energies and all are confirmed with the PL measurements. Co substitution in ZnO lattice has been proved by the optical transmittance measurement which is observed as the loss of transmission appearing in specific region due to Co2+ characteristic transitions. © 2014 Elsevier B.V. All rights reserved.Item Open Access Disintegration and machine-learning-assisted identification of bacteria on antimicrobial and plasmonic Ag–CuxO nanostructures(American Chemical Society, 2023-03-08) Şahin, F.; Çamdal, A.; Şahin, G. D.; Ceylan, A.; Ruzi, M.; Önses, Mustafa SerdarBacteria cause many common infections and are the culprit of many outbreaks throughout history that have led to the loss of millions of lives. Contamination of inanimate surfaces in clinics, the food chain, and the environment poses a significant threat to humanity, with the increase in antimicrobial resistance exacerbating the issue. Two key strategies to address this issue are antibacterial coatings and effective detection of bacterial contamination. In this study, we present the formation of antimicrobial and plasmonic surfaces based on Ag–CuxO nanostructures using green synthesis methods and low-cost paper substrates. The fabricated nanostructured surfaces exhibit excellent bactericidal efficiency and high surface-enhanced Raman scattering (SERS) activity. The CuxO ensures outstanding and rapid antibacterial activity within 30 min, with a rate of >99.99% against typical Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. The plasmonic Ag nanoparticles facilitate the electromagnetic enhancement of Raman scattering and enables rapid, label-free, and sensitive identification of bacteria at a concentration as low as 103 cfu/mL. The detection of different strains at this low concentration is attributed to the leaching of the intracellular components of the bacteria caused by the nanostructures. Additionally, SERS is coupled with machine learning algorithms for the automated identification of bacteria with an accuracy that exceeds 96%. The proposed strategy achieves effective prevention of bacterial contamination and accurate identification of the bacteria on the same material platform by using sustainable and low-cost materials.Item Open Access Effects of rapid thermal annealing on the structural and local atomic properties of ZnO: Ge nanocomposite thin films(A I P Publishing LLC, 2015) Ceylan, A.; Rumaiz, A. K.; Caliskan, D.; Ozcan, S.; Özbay, Ekmel; Woicik, J. C.We have investigated the structural and local atomic properties of Ge nanocrystals (Ge-ncs) embedded ZnO (ZnO: Ge) thin films. The films were deposited by sequential sputtering of ZnO and Ge thin film layers on z-cut quartz substrates followed by an ex-situ rapid thermal annealing (RTA) at 600 °C for 30, 60, and 90 s under forming gas atmosphere. Effects of RTA time on the evolution of Ge-ncs were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), hard x-ray photoelectron spectroscopy (HAXPES), and extended x-ray absorption fine structure (EXAFS). XRD patterns have clearly shown that fcc diamond phase Ge-ncs of sizes ranging between 18 and 27 nm are formed upon RTA and no Ge-oxide peak has been detected. However, cross-section SEM images have clearly revealed that after RTA process, Ge layers form varying size nanoclusters composed of Ge-ncs regions. EXAFS performed at the Ge K-edge to probe the local atomic structure of the Ge-ncs has revealed that as prepared ZnO:Ge possesses Ge-oxide but subsequent RTA leads to crystalline Ge structure without the oxide layer. In order to study the occupied electronic structure, HAXPES has been utilized. The peak separation between the Zn 2p and Ge 3d shows no significant change due to RTA. This implies little change in the valence band offset due to RTA. © 2015 AIP Publishing LLC.Item Open Access Machine learning-assisted pesticide detection on a flexible surface-enhanced raman scattering substrate prepared by silver nanoparticles(American Chemical Society, 2022-09-12) Onses, M. Serdar; Ruzi, M.; Ceylan, A.; Sakir, M; Camdal, A.; Celik, N.; Sahin, F.Access to clean water is a pressing challenge affecting millions of lives and the aquatic body of the Earth. Sensitive detection of pollutants such as pesticides is particularly important to address this challenge. This study reports eco-friendly preparation of the surface-enhanced Raman scattering (SERS) substrate for machine learning-assisted detection of pesticides in water. The proposed SERS platform was prepared on a copy paper by reducing a silver salt using the extract of a natural plant, Cedrus libani. The fabricated SERS platform was characterized in detail using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The high-density formation of silver nanoparticles with an average diameter of 41 nm on the surface of the paper enabled detection of analytes with a nanomolar level sensitivity. This SERS capability was used to collect Raman signals of four different pesticides in water: myclobutanil, phosmet, thiram, and abamectin. Raman spectra of the pesticides are highly complex, challenging accurate determination of the pesticide type. To overcome this challenge and distinguish pesticides, machine learning (ML) approach was used. The ML-mediated detection of harmful pesticides on a versatile, green, and inexpensive SERS platform appears to be promising for environmental applications.Item Embargo Mechanochemical activation of siliconefor large-scale fabrication of anti-biofouling liquid-like surfaces(American Chemical Society, 2023-11-13) Celik, N.; Sahin, F.; Ruzi, M.; Ceylan, A.; Butt, H. J.; Önses, Mustafa SerdarLarge-scalepreparationof liquid-likecoatingswithperfecttransparencyvia solventlessand room-temperatureprocessesusinglow-costand biocompatiblematerialsis oftremendousinterestfor a broadrangeof applications.Here,wepresenta mechanochemicalactivationstrategyfor solventlessgraftingof poly(dimethylsiloxane)(PDMS)ontoglass,siliconwafers,and ceramics.Activationis achievedvia ball millingPDMSwithoutusingany solventsor additivespriorto application.Ballmillingresultsin chainscissionand generationof free radicals,allowingroom-temperaturegraftingat durations≤1 h. Thedepositionof ball-milledPDMScan be facilitatedby brushingordrop-casting,enablinglarge-scaleapplications.Theresultingsurfacesfacilitatethe slidingof dropletsat angles<20°for liquidswith surfacetensionrangingfrom 22 to 73 mN/m.An importantapplicationfor publichealthis generatinganti-biofoulingcoatingson sanitaryware.For example,PDMS-graftedsurfacespreparedon a regular-sizetoiletbowlexhibita 105-fold decreasein theattachmentof bacteriafrom urine.Thesefindingshighlightthe significantpotentialof mechanochemicalprocessesfor the practicalpreparationof liquid-likesurfaces.