Sialic Acid-Functionalized Gold Nanoparticles for Sensitive and Selective Colorimetric Determination of Serotonin Begüm Avcı, Yeliz Akpınar, Gülay Ertaş, Mürvet Volkan ACS Omega, 2024 We present a novel colorimetric method inspired by nature's complex mechanisms, capable of selectively determining serotonin with high sensitivity. This method exploits the inherent binding affinity of serotonin with sialic acid (SA) molecules anchored to gold nanoparticles (SA-AuNPs). Upon serotonin binding, SA-AuNPs aggregate, and a characteristic red shift in the absorbance of SA-AuNPs accompanied by a dramatic color change (red to blue) occurs, readily observable even without instrumentation. The proposed method effectively eliminates interventions from potential interfering species such as dopamine, epinephrine, l-tyrosine, glucosamine, galactose, mannose, and oxalic acid. The absence of a color change with l-tryptophan, a structurally related precursor of serotonin, further confirms the high selectivity of this approach for serotonin detection. The colorimetric method has a wide linear dynamic range (0.05-1.0 μM), low limit of detection (0.02 μM), and fast response time (5 min). The limit of detection of the method is lower than other colorimetric serotonin sensors reported so far. The possible use of the proposed method in biological sample analysis was evaluated by employing a serotonin recovery assay in processed human plasma. The recoveries ranged from 90.5 to 104.2%, showing promising potential for clinical applications.
In vitro study on the competitive reactions between arsenite and selenite with glutathione Canan Höçük Özkan, Mehmet Atakay, Bekir Salih, Gülay Ertaş Journal of Mass Spectrometry, 2024 Exposure to arsenic can cause various biological effects by increasing the production of reactive oxygen species (ROS). Selenium acts as a beneficial element by regulating ROS and limiting heavy metal uptake and translocation. There are studies on the interactive effects of As and Se in plants, but the antagonistic and synergistic effects of these elements based on their binding to glutathione (GSH) molecules have not been studied yet. In this study, we aimed to investigate the antagonistic or synergistic effects of As and Se on the binding mechanism of Se and As with GSH at pH 3.0, 5.0, or 6.5. The interaction of As and Se in Se(SG)2 + As(III) or As(SG)3 + Se(IV) binary systems and As(III) + Se(IV) + GSH ternary system were examined depending on their ratios via liquid chromatography diode array detector/electrospray mass spectrometry (LC‐DAD/MS) and liquid chromatography–electrospray ionization–tandem mass spectrometry (LC‐ESI‐MS/MS). The results showed that the formation of As(GS)3 was not detected in the As(III) + Se(SG)2 binary system, indicating that As(III) did not affect the stability of Se(SG)2 complex antagonistically. However, in the Se(IV) + As(SG)3 binary system, the addition of Se(IV) to As(SG)3 affected the stability of As(SG)3 antagonistically. Se(IV) reacted with GSH, disrupting the As(SG)3 complex, and consequently, Se(SG)2 formation was measured using LC‐MS/DAD. In the Se(IV) + GSH + As(III) ternary system, Se(SG)2 formation was detected upon mixing As(III), Se(IV), and GSH. The increase in the concentration of As(III) did not influence the stability of the Se(SG)2 complex. Additionally, Se(IV) has a higher affinity than As(III) to the GSH, regardless of the pH of the solution. In both binary and ternary systems, the formation of the by‐product glutathione trisulfide (GSSSG) was detected using LC‐ESI‐MS/MS.
Evaluation of colloidal platinum on cytotoxicity, oxidative stress and barrier permeability across the gut epithelium Sinem Tunçer, Melis Çolakoğlu, Sinem Ulusan, Gülay Ertaş, Çimen Karasu, Sreeparna Banerjee Heliyon, 2019 induced oxidative stress, protected from oxidative stress related death of intestinal epithelial cells and could pass a model gut barrier easily. Colloidal Pt can therefore be consumed orally for its anti-oxidant and other health promoting benefits.
Mixed-monolayer of N-hydroxysuccinimide-terminated cross-linker and short alkanethiol to improve the efficiency of biomolecule binding for biosensing Demet Ataman Sadık, Haslet Eksi-Kocak, Gülay Ertaş, İsmail Hakkı Boyacı, Mehmet Mutlu Surface and Interface Analysis, 2018 The goal of this study was to use a novel surface chemistry for modifying gold surfaces to decrease the steric hindrance, minimize the nonspecific bindings while providing directed immobilization of proteins for advancing the transducer property and to provide a biosensing platform for surface plasmon resonance (SPR) applications. Mixed self‐assembled monolayers (mSAMs) were prepared using 3,3′‐Dithiodipropionic acid di (N‐hydroxysuccinimide ester) (DSP) and 6‐mercapto‐1‐hexanol (MCH) and the selected model proteins bovine serum albumin (BSA) and lysozyme were tested for binding efficiency. First, binding of these two proteins at constant concentration to different DSP:MCH mSAMs were compared to deduce the best molar ratio for forming mSAM using a continuous flow system coupled to SPR. Coincidently the maximum protein binding DSP:MCH mSAM were the same for both proteins. The change in Response Unit (∆RU) signal due to protein binding between DSP SAM and maximum protein binding DSP:MCH mSAM for lysozyme binding was more in comparison to BSA binding. Second, the effect of BSA and lysozyme concentration on binding efficiency to maximum protein binding DSP:MCH mSAM were compared and discussed. Lysozyme and BSA were shown to reach saturations on the same monolayer at concentrations of 5.7x10−5 and 8.96x10−6 [M] respectively, hence the molar ratio for limit concentrations is 6:1. The DSP SAM, MCH SAM, and DSP:MCH mSAMs where maximum and minimum protein binding occurs were also characterized with XPS and Attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy. Blank gold surface, maximum protein binding DSP:MCH mSAM and BSA immobilized DSP:MCH mSAM on gold surface were also investigated utilizing tapping mode AFM.
Sludge disintegration methods, their impact on additives leaching from microplastics and change in plastic properties N Cemalgil, İ Ayça, O Karakurt, İE Göktepe, G Ertaş, FD Sanin Journal of Environmental Chemical Engineering, 122979 , 2026 2026
Mesophilic or Thermophilic Anaerobic Digestion: The case of additive release from polypropylene microplastics” O Altuntaş, İ Erel Göktepe, G Ertaş, FD Sanin 2025
Synthesis of M-rGO and M-rGO-sand coated reactive media for contaminant remediation S Sevinc Sengor, S Çelebi, A Şenol, OAIM Elkawefi, G Ertaş, K Ünlü EGU General Assembly Conference Abstracts, EGU25-14731 , 2025 2025
A Comparative Study of Arsenic Removal from Drinking Water Using Zero-Valent Iron (ZVI) and Magnetite/Reduced Graphene Oxide (MrGO) Coated Sand in Column Systems A Şenol, S Çelebi, OAIM Elkawefi, S Sevinç Şengör, G Ertaş, K Ünlü EGU General Assembly Conference Abstracts, EGU25-10696 , 2025 2025
Arsenic removal from drinking water with magnetite (Fe3O4) reduced graphene oxide (MRGO) nanocomposite material: Evaluations on process chemistry, system design and engineering … S Çelebi, OAIM Elkawefi, A Şenol, S Sevinç Şengör, G Ertaş, K Ünlü EGU General Assembly Conference Abstracts, EGU25-9942 , 2025 2025
A Comparative Evaluation of Magnetite Reduced Graphene Oxide Composite and Zero-Valent Iron for Arsenic Removal from Water OAIM Elkawefi, S Çelebi, A Şenol, S Sevinç Şengör, G Ertaş, K Ünlü EGU General Assembly Conference Abstracts, EGU25-10076 , 2025 2025
Sialic acid-functionalized gold nanoparticles for sensitive and selective colorimetric determination of serotonin B Avcı, Y Akpınar, G Ertas, M Volkan ACS omega 9 (22), 23832-23842 , 2024 2024 Citations: 12
In vitro study on the competitive reactions between arsenite and selenite with glutathione CH Özkan, M Atakay, B Salih, G Ertaş Journal of Mass Spectrometry 59 (5), e5020 , 2024 2024 Citations: 1
Mikroplastiklerden Nanoplastiklere PLASTİK KİRLETİCİLER MA Bhat, FNUR ERASLAN, G Ertaş, EE GAGA Mikroplastiklerden Nanoplastiklere PLASTİK KİRLETİCİLER , 2023 2023
A benzimidazole-based turn-off fluorescent sensor for selective detection of mercury (II) EGC Ergun, G Ertas, D Eroglu Journal of Photochemistry and Photobiology A: Chemistry 394, 112469 , 2020 2020 Citations: 30
Gülay Ertaş G Ertaş 2020
In vitro study on the reactions between Arsenic and Selenium with glutathione C Höçük, M ATAKAY, B SALİH, G Ertaş 2019
Evaluation of colloidal platinum on cytotoxicity, oxidative stress and barrier permeability across the gut epithelium S Tunçer, M Çolakoğlu, S Ulusan, G Ertaş, Ç Karasu, S Banerjee Heliyon 5 (3) , 2019 2019 Citations: 17
LangmuirMetotuKullanılarak CdSe Kuantum Noktalarının Ince Filmlerinin Hazırlanması M Volkan, A Gökmen, G Ertaş 2018
Mixed-Monolayer of N-Hydroxysuccinimide Cross-Linker and Short Alkanethiol To Improve the Efficiency of Biomolecule Binding for Biosensing D Ataman Sadık, H Eksi-Koçak, G Ertaş, İH Boyacı, M Mutlu Surface and Interface Analysis , 2018 2018
Mixed‐monolayer of N‐hydroxysuccinimide‐terminated cross‐linker and short alkanethiol to improve the efficiency of biomolecule binding for biosensing D Ataman Sadık, H Eksi‐Kocak, G Ertaş, İH Boyacı, M Mutlu Surface and Interface Analysis 50 (9), 866-878 , 2018 2018 Citations: 18
UÇUCU BİLEŞİK OLUŞTURARAK BOR ELEMENTİNİN ATOMİK SPEKTROMETRİ İLE TAYİNI G Ertaş 2017
Maya Hücrelerinde Bor ve Arsenik Elementlerinin Sinerjik ve Antagonistik Etkileri G Ertaş, Gİ Gökmen, M Volkan, A Gökmen 2017
MAYA HÜCRELERİNDE BOR VE ARSENİK TÜRLENDİRMESİ G Ertaş 2017
FOTOKİMYASAL BUHAR OLUŞTURMA İLE SELENYUM TAYİNİ ÇALIŞMALARI G Ertaş 2017
MOST CITED SCHOLAR PUBLICATIONS
X-ray-Induced Production of Gold Nanoparticles on a SiO 2 /Si System and in a Poly(methyl methacrylate) Matrix F Karadas, G Ertas, E Ozkaraoglu, S Suzer Langmuir 21 (1), 437-442 , 2005 2005 Citations: 89
Differential Charging in SiO 2 /Si System As Determined by XPS F Karadas, G Ertas, S Suzer The Journal of Physical Chemistry B 108 (4), 1515-1518 , 2004 2004 Citations: 84
Tunable surface plasmon resonance on an elastomeric substrate S Olcum, A Kocabas, G Ertas, A Atalar, A Aydinli Optics express 17 (10), 8542-8547 , 2009 2009 Citations: 79
Plasmonic band gap structures for surface-enhanced Raman scattering A Kocabas, G Ertas, SS Senlik, A Aydinli Optics Express 16 (17), 12469-12477 , 2008 2008 Citations: 69
E-Beam lithography designed substrates for surface enhanced Raman spectroscopy NA Cinel, S Cakmakyapan, S Butun, G Ertas, E Ozbay Photonics and Nanostructures-Fundamentals and Applications 15, 109-115 , 2015 2015 Citations: 55
‘Fairy Chimney’‐shaped tandem metamaterials as double resonance SERS substrates NA Cinel, S Bütün, G Ertaş, E Özbay small 9 (4), 531-537 , 2013 2013 Citations: 53
Time-Resolved XPS Analysis of the SiO 2 /Si System in the Millisecond Range UK Demirok, G Ertas, S Suzer The Journal of Physical Chemistry B 108 (17), 5179-5181 , 2004 2004 Citations: 46
Enhanced peak separation in XPS with external biasing G Ertas, UK Demirok, S Suzer Applied surface science 249 (1-4), 12-15 , 2005 2005 Citations: 44
XPS measurements for probing dynamics of charging S Suzer, H Sezen, G Ertas, A Dâna Journal of Electron Spectroscopy and Related Phenomena 176 (1-3), 52-57 , 2010 2010 Citations: 40
X-ray photoelectron spectroscopy for resistance-capacitance measurements of surface structures G Ertas, UK Demirok, A Atalar, S Suzer Applied Physics Letters 86 (18) , 2005 2005 Citations: 38
XPS analysis with external bias: a simple method for probing differential charging G Ertas, S Suzer Surface and Interface Analysis: An International Journal devoted to the … , 2004 2004 Citations: 38
A benzimidazole-based turn-off fluorescent sensor for selective detection of mercury (II) EGC Ergun, G Ertas, D Eroglu Journal of Photochemistry and Photobiology A: Chemistry 394, 112469 , 2020 2020 Citations: 30
Electrothermal atomic absorption spectrometric determination of gold by vapor formation and in situ trapping in graphite tubes G Ertaş, OY Ataman Applied spectroscopy 58 (10), 1243-1250 , 2004 2004 Citations: 29
Charging/discharging of thin PS/PMMA films as probed by dynamic X-ray photoelectron spectroscopy H Sezen, G Ertaş, A Daˆna, S Suzer American Chemical Society (ACS) , 2007 2007 Citations: 28
Determination of absolute transport efficiencies of Be, Cd, In, Pb and Bi for electrothermal vaporization sample introduction into an inductively coupled plasma using an in … G Ertas, JA Holcombe Spectrochimica Acta Part B: Atomic Spectroscopy 58 (9), 1597-1612 , 2003 2003 Citations: 24
Photopatterning of PMMA Films with Gold Nanoparticles: Diffusion of AuCl 4 − Ions E Yilmaz, G Ertas, E Bengu, S Suzer The Journal of Physical Chemistry C 114 (43), 18401-18406 , 2010 2010 Citations: 23
Optimization of ETV-ICP (TOF) MS and transient signal profiles for reducing isobaric interferences G Ertas, JA Holcombe Journal of Analytical Atomic Spectrometry 20 (8), 687-695 , 2005 2005 Citations: 22
Heating of magnetic fluid systems driven by circularly polarized magnetic field OO Ahsen, U Yilmaz, MD Aksoy, G Ertas, E Atalar Journal of magnetism and magnetic materials 322 (20), 3053-3059 , 2010 2010 Citations: 20
Methods for probing charging properties of polymeric materials using XPS H Sezen, G Ertas, S Suzer Journal of Electron Spectroscopy and Related Phenomena 178, 373-379 , 2010 2010 Citations: 20
Interference effect of iron on the determination of gold in geological samples using the vapor generation technique and preconcentration in a graphite furnace G Ertaş, OY Ataman Applied spectroscopy 60 (4), 423-429 , 2006 2006 Citations: 20
