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Öğe The Preparation of p acrylonitrile-co- acrylamide hydrogels for uranyl ion recovery from aqueous environments(Hacettepe Üniversitesi, 2014) Alpaslan, Duygu; Aktaş, Nahit; Yılmaz, Selehattin; Şahiner, Nurettin; Güven, OlgunThe synthesis of poly acrylonitrile-co-acrylamide p AN-co-AAm hydrogels with different amounts of acrylonitrile AN and acrylamide AAm monomers were carried out by concurrent use of redox and microemulsion polymerization techniques. The prepared hydrogels were amidoximated for sorption of uranyl ion from aqueous medium. Batch type UO2 2+ ion sorption by p AN-co-AAm 0.25:1 mole ratio was carried out and an sorption capacity of 220 mg UO2 2+ mg/g dried hydrogel was found. The highest amount of UO22+ ion sorption, 277 mg/g dry gel was accomplished at pH 4Öğe Moxifloxacin-Impregnated Contact Lenses for Treatment of Keratitis in Rabbit Eyes(Wiley, 2025) Erdoğan, Hakika; Güngör, Buket; Sağbaş Suner, Selin; Sılan, Coşkun; Saraydın, Serpil U.; Saraydın, Dursun; Ayyala, Ramesh S.; Şahiner, NurettinMoxifloxacin (MOX) was loaded into commercial contact lenses (CLs) via supercritical carbon dioxide (ScCO2) to attain MOX-impregnated CL for keratitis treatment. This study aimed to investigate Pseudomonas keratitis treatment with MOX-impregnated CL compared to the traditional eyedrop administration. MOX impregnation was accomplished employing optimum parameters of 2.5 h drug exposure time, 25 MPa pressure, and 313 K for ScCO2 conditions using ethanol co-solvent rendering sustainable delivery, up to 7 days at effective dosage formulation. The MOX-impregnated CL was found to be safe with no significant toxicity on fibroblast cells after 5 days of contact time. Bacterial viability in vivo keratitis treatment in rabbit eyes was significantly decreased to 10(2) from 10(9) CFU/cornea for MOX-impregnated CL treatment, almost similar to exhaustive conventional 0.5% MOX eye drop treatments. The MOX-impregnated CL treatment revealed no conjunctival hyperemia, edema, or secretion for all eyes in the relevant group, and transparent cornea with no keratitis focus was obtained for two of the eyes (n = 6). The normal histological structure was seen with MOX-impregnated CL treatment on healthy eyes. Moreover, polymorphonuclear cell infiltration observed in keratitis eyes without any treatment was significantly decreased to a few polymorphonuclear cells in the groups treated with MOX eyedrops and MOX-impregnated CL.Öğe An application of a disposable electrode for the sensitive, selective, and cost-effective voltammetric determination of antiparkinsonism drug entacapone based on both its oxidation and reduction(Springer, 2025) Vural, Kader; Giray Dilgin, Didem; Dilgin, YusufEntacapone (ETC) is an important drug active ingredient frequently used together with levodopa (LD) and carbidopa (CD) in the treatment of Parkinson's disease. This study describes a simple, selective, sensitive, and cost-effective voltammetric determination of ETC based on both its oxidation and reduction at a disposable graphite pencil electrode (GPE). The electrochemical oxidation and reduction of ETC were investigated by recording cyclic voltammograms (CVs) of ETC based on the pH of the supporting electrolyte at a fixed scan rate and the scan rate at the supporting electrolyte of 0.10 M H2SO4. The analytical performance studies were carried out by recording differential pulse voltammograms (DPVs) under optimized conditions and by considering both the anodic and the irreversible cathodic peak at - 130 mV. DPV results show that the disposable and unmodified GPEs have linear ranges of 2.5-1500 and 2.5-1000 nM with detection limits of 0.79 and 0.69 nM for reduction and oxidation, respectively. The effects of some potential interferants were investigated, and no significant interference among the studied compounds, such as CD, LD, and dopamine (DA), was observed. The DP voltammetric procedure using disposable GPE was applied to determine ETC in pharmaceutical tablets using antiparkinsonism treatment including triple compounds (ETC, CD, and LD) and an artificial urine sample. Acceptable results for both samples show that ETC can be cost-effectively determined with high accuracy, sensitivity, and precision in real samples.Öğe A comprehensive investigation of PtNPs/PEI N-GQDs nanocomposite: DFT modeling, anticancer activity, and biosensing applications(Springer, 2025) Altınok Güneş, Buket; Kırlangıç, Ömer Faruk; Kılıç, Murat; Ketenoğlu, Didem; Aslan, Ayşenur; Kabaş, Sultan Yağmur; Kabaş, Afşar; Kaya, İsmet; Yıldız, MustafaThis research focuses on the synthesis and characterization of a novel nanocomposite, PtNPs/PEI N-GQDs, utilizing FTIR, UV-Vis, SEM, TEM, XPS, and XRD techniques. The study investigates the cytotoxic, apoptotic, and antiangiogenic effects of the nanocomposite on OVCAR-3 cells, aiming to understand the interplay between nanomaterials and cancer. Additionally, the electrochemical properties of PtNPs/PEI N-GQDs-modified glassy carbon electrodes (GCE) are explored, emphasizing analyses of HOMO-LUMO energy levels and band gap energy. Density Functional Theory (DFT) analysis results further support these findings by providing insights into the electronic structure and energetics of the nanocomposite. The nanocomposite exhibits promising electrochemical behavior, demonstrating high capacitance and sensitivity in glucose detection through cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Selectivity towards glucose among interfering bioanalytes is highlighted, showcasing potential applications in tumor monitoring and diagnosis. Furthermore, the nanocomposite displays significant toxicity against cancer cells, inducing apoptosis and cell cycle arrest. Antiangiogenic effects are also observed, suggesting potential therapeutic benefits. Overall, these findings underscore the multifunctional properties of the synthesized nanocomposite, offering insights into its potential for cancer therapy and biosensor applications for glucose detection in bodily fluids.Öğe Tannic acid-based bio-MOFs with antibacterial and antioxidant properties acquiring non-hemolytic and non-cytotoxic characteristics(Elsevier, 2025) Şahiner, Nurettin; Güven, Olgun; Demirci, Şahin; Sağbaş Suner, Selin; Şahiner, Mehtap; Arı, Betül; Can, MehmetTannic acid (TA) based bio-metal phenolic networks (bio-MPNs) were prepared by using Cu(II), Zn(II), Bi(III), Ce(III), La(III), and Ti(IV) metal ions. TA-based bio-MPNs exhibited wedge-shaped pores between 16.4 and 25.8 nm pore size ranges. The higher gravimetric yield% was achieved for TA-Bi(III), and TA-Ti(IV) bio-MPNs with more than 90 %, and higher surface area was observed for TA-La(IIII) bio-MPNs as 56.2 m(2)/g with 17.3 nm average pore sizes. All TA-based MPNs are non-hemolytic with less than 5 % hemolysis ratio, whereas TA-based Bio-MPNs do not affect blood clotting with > 90 % blood clotting indexes except for TA-Cu(II) Bio-MPNs at 0.1 mg/mL concentration. Moreover, TA-Bi(III) and TA-Ce(III) Bio-MPNs were found to be safer materials showing no significant toxicity on L929 fibroblast cells at 100 mu g/mL concentration, along with TA-based Bio-MPNs prepared with Cu(II), Zn(II), La(III), and Ti(IV) metal ions that could be safely used in in vivo applications at 1 mu g/mL concentration. It has been proven by 2 different antioxidant tests that the prepared TA-based Bio-MPNs show antioxidant properties even if their TA-derived antioxidant properties decrease. Furthermore, all types of TA-based Bio-MPNs show great antimicrobial activity depending on the metal ion or microorganism types and the highest antibacterial/antifungal effect was determined for TA-Cu(II), and TA-Zn(II) Bio-MPNs with the lowest MBC/MFC values against Pseudomonas aeruginosa ATCC 10145, Bacillus subtilis ATCC 6633, and Candida albicans ATCC 10231.Öğe Application of a novel anthracene derivative polymer for sensitive voltammetric determination of chloramphenicol in pharmaceutical and food samples(Pergamon-Elsevier Science Ltd, 2025) Karakaya, Serkan; Kaya, İsmet; Kolcu, Feyza; Dilgin, YusufThe application of new polymers for the preparation of modified electrodes is an interesting research area, which is highly significant in the electrochemical antibiotic drug sensors for food safety and environmental sides. Herein, we successfully report the synthesis of a new anthracene-based monomer (N1, N4-bis(anthracene-9-ylmethylene)-2,5-dichlorobenzene-1,4-diamine (ADCA) and Poly(ADCA) modified carbon-based electrode has been used in sensitive and selective differential pulse voltammetric determination of chloramphenicol (CPNL) for the first time. In this platform, the proposed monomer was successfully electro-polymerized onto a cheap, lowcost, and disposable pencil graphite electrode (PGE). The cyclic and differential pulse voltammetric experiments proved that the polymer-modified electrode Poly(ADCA)/PGE) has great electrocatalytic efficiency on the reduction of CPNL. The proposed platform shows a comparable performance in terms of wide linear ranges (2.0-100 and 100-1000 mu M), a low detection limit (0.55 mu M) and high sensitivity (11405 mu A mM- 1 cm- 2) by differential pulse voltammetry (DPV). Additionally, the Poly(ADCA)/PGE exhibited high selectivity and antiinterference facilities for the CPNL. The fabricated sensor showed a promising potential for the determination of CPNL in food (honey, and milk), bottled water, and pharmaceutical (eye ointment) samples with acceptable accuracies and precisions.Öğe Conductive poly(bromophenol red) film coated graphene oxide-ZnO nanocomposite modified electrode for enzymeless voltammetric determination of ethyl-paraoxon(Academic Press Inc Elsevier Science, 2025) Karakaya, Serkan; Demir, Cansu; Zaman, Buse Tuğba; Bakirdere, Sezgin; Dilgin, YusufThis work proposes a sensitive and nonenzymatic electrochemical platform for the cyclic voltammetric determination of ethyl-paraoxon (E-POX) at a poly-bromophenol red (poly(BPR) film coated graphene oxide (GO) and ZnO nanocomposite modified glassy carbon electrode (poly(BPR)@GO-ZnO/GCE). The incorporation of poly (BPR) matrix with GO-ZnO nanocomposite provides a considerable synergistic effect for the voltammetric determination of E-POX by providing a large surface area, more active sites, and high conductivity. The results showed that the poly(BPR)@GO-ZnO/GCE exhibits two linear response ranges from 0.10-3.0 mu M and 5.0-200 mu M with a limit of detection (LOD) of 31 nM and a high sensitivity of 5259 mu A mM-1 cm- 2. Real-world applicability of designed platform was successfully tested in agricultural (tomato and cucumber) and tap water samples, and acceptable recovery values (98.1-114.2 %) were obtained. It is concluded that the proposed platform (poly(BPR), GO, and ZnO) may bring remarkable approaches to the future fabrication of electrochemical sensors.Öğe Synthesis, molecular, and photophysicochemical characterizations of phthalocyanine dyes containing sodiumsulfonatenaphthalen-2-olate groups(Elsevier, 2025) Saruhan, Serkan; Pişkin, Mehmet; Özturk, Ömer Faruk; Odabaş, ZaferIn this study, novel highly water-soluble 6-sodiumsulfonatenaphthalen-2-olate substituted phthalocyanines from the organic near-infrared dye class and contained zinc(II) or indium(III) metal ions in their cavity, were designed, and synthesized to explore their potential use as photosensitizers in photodynamic therapy. The molecular structures of the starting materials and dyes were characterized using elemental analysis, FT-IR, UV-vis, 1H-NMR, 13C-NMR, and MALDI-TOF mass spectrometry. The solubility and aggregation behaviors of these phthalocyanine dyes have been investigated in polar solvent types such as dimethylsulfoxide and N,Ndimethylformamide, ethanol, methanol, and water, as well as in phosphate-buffered saline. They have high solubility in the studied solvents and do not show any tendency to aggregate, except for water. Their photophysical and photochemical properties were investigated in N,N-dimethylformamide. The influence of the presence and position of substituents on their macrocyclic and the nature of the metal species in their cavities on their photophysical and photochemical parameters were reported. The fluorescence properties of the zinc(II) dyes studied were enhanced, while those of indium(III) dyes were low but sufficient as photosensitizers. The suitable and sufficient photophysicochemical properties of the water-soluble near-infrared new phthalocyanine dyes denote they can be potential candidates as Type II photosensitizers for photocatalytic applications.Öğe Hydroxylated-graphitic carbon nitride@graphene oxide composites for sensitive electrochemical determination of COVID-19 drug molnupiravir: Effect of modifier composition(Elsevier, 2025) Emre, Deniz; Yılmaz, Selehattin; Bilici, AliIn this research, pencil graphite electrode (PGE) surfaces were modified with a two-dimensional and multifunctional composite material consisting of hydroxylated graphitic carbon nitride (hCN) and graphene oxide (GO) components for sensitive voltammetric determination of coronavirus disease (COVID-19) drug molnupiravir (MLP). The synthesis of carbon nitride, hCN, GO, and the composite material (hCN@GO) included thermal polymerization, hydroxylation, intermediate Hummer's method, and sonochemical processes, respectively. Then, the resulting composite material was electrochemically loaded on the PGE surface. The effects of various experimental parameters, such as the supporting electrolyte, pH, buffer concentration, and scan speed, on the analytical signal were investigated. The most vital one was the composite composition loaded on the PGE. The highest signal was obtained when the PGE surface was coated with the hCN:GO ratio of 30:70 (as weight%). The findings assigned electrode modification with proper composition led to an approximately 17-fold increase in the electrochemically active surface area and a 100-fold decrease in the charge transfer resistance of bare PGE. Thus, it could achieve approximately a 3-fold lower detection limit. The sensor exhibited a linear response in the 7-300 nM MLP concentration range with a detection limit of 2.2 nM without significant interference.Öğe Schiff bases and oligomers derived from trifluoromethylaniline-based monomers: Thermal, optical, electrochemical properties and applications as fluorescent probes for Sn2+(Elsevier, 2025) Karacan Yeldir, Elif; Kaya, İsmet; Tutluel, OğuzhanWithin the scope of the study, three different Schiff bases were synthesized from 3,5-bis(trifluoromethyl)aniline, a halogen-containing aniline derivative, with three different aldehydes, 3-hydroxy-4-methoxy-benzaldehyde, salicylaldehyde and 2-hydroxy-1-naphthaldehyde. These three synthesized Schiff bases were evaluated as monomers and oxidatively polymerized in the presence of sodium hypochlorite, a strong oxidant. The structural properties of these three monomers and three polymers were elucidated with the help of UV-Vis, FT-IR, 1 H NMR, 13C NMR spectra. Their molecular weights were determined by gel permeation chromatography (GPC) and it was determined that the macromolecules obtained as a result of the oxidation reaction were in the oligomer order. In order to investigate their electrochemical properties, cyclic voltammetry (CV) was used to find their oxidationreduction potentials. The HOMO-LUMO potentials and electrochemical band gap values of the synthesized Schiff bases and oligomers were calculated. Thermal stabilities of the monomers and oligomers were determined by thermogravimetric-differantial thermal analysis (TG-DTA). It was determined that the thermal stabilities of the obtained oligomers were higher than those of the Schiff bases. The glass transition temperature (Tg) and surface morphologies of oligomers were determined from DSC and SEM measurements, respectively. Their optical properties were examined by UV-Vis and fluorescence spectra. It was found that 1-(((3,5-bis(trifluoromethyl) phenyl)imino)methyl) naphthalene-2-ol (TFMHN), one of the Schiff bases, has a turn-on fluorescence sensor property with increasing fluorescence emission intensity in the presence of Sn2+ among a series of metal ions and can be used as a selective and sensitive fluorescence probe for Sn2+ with a limit of dedection (LOD) value of 7.14 x 10- 8 M.Öğe Synthesis and characterization of fluorescent and thermally stable poly (azomethine-ether)s: Optical and morphological properties(Elsevier Sci Ltd, 2025) Tezel, Ruhiye Nilay; Kaya, İsmetIn this work, we described the synthesis and characterization of dialdehyde monomers and poly(azomethineether)s based on them. In the first stage, aromatic bridged dialdehyde monomers were synthesized using 2,4Bis(chloromethyl)-1,3,5-trimethylbenzenedihalide with three different aldehydes (4-hydroxybenzaldehyde, 3methoxy-4-hydroxybenzaldehyde, and 3-ethoxy-4-hydroxybenzaldehyde). Subsequently, corresponding poly (azomethine-ether) derivatives were synthesized through the polycondensation reaction of synthesized dialdehyde monomers with o-toluidine and o-dianisidine diamine compounds. The structures of the obtained dialdehyde and poly(azomethine-ether)s were confirmed by FT-IR, UV-Vis and NMR measurements. The physicochemical properties of the as-prepared poly(azomethine-ether)s have been confirmed through X-ray diffraction (X-RD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX) spectroscopic techniques. In FT-IR, -CH--N- peak around at 1625 cm-1 attributed to the successful conversion of dialdehydes and diamines into poly(azomethine-ether). The semicrystalline nature of the poly (azomethine-ether)s was shown through the X-RD diffractometer. The optical band gaps were found to be in the range of 2.80-2.92 eV, as measured by UV/Vis analysis. These poly(azomethine-ether)s exhibit direct band gap values in the blue/violet region of visible light, which creates opportunities for future studies related to daylight optoelectronic devices. Additionally, thermal behavior was analyzed using TGA and DSC, revealing that the materials are highly stable and rigid.Öğe Tailored α-hydroxyphosphonate derivatives: Green synthesis, spectroscopic characterization, DFT analysis, and high-efficiency corrosion protection for copper in acidic media(Elsevier, 2025) Ferkous, Hana; Guezane-Lakoud, Samia; Sedik, Amel; Boublia, Abir; Delimi, Amel; Kahlouche, Abdesalem; Boulechfar, Cherifa; Dilgin, YusufThis study presents a comprehensive investigation into the synthesis, characterization, and corrosion inhibition performance of four novel alpha-hydroxyphosphonate compounds-diethyl alpha-hydroxy phenyl phosphonate (DHPP), diethyl alpha-hydroxy 4-chlorophenyl phosphonate (DHCP), diethyl alpha-hydroxy 4-methoxyphenyl phosphonate (DHMP), and E-diethyl alpha-hydroxy phenylallylic phosphonate (DHPAP). Synthesized using an environmentally friendly solvent-free method, the structures of these compounds were confirmed via Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy. Their efficacy as corrosion inhibitors for copper in a 1 M HCl environment was systematically evaluated using Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP). Among the inhibitors, DHMP exhibited the highest performance, achieving inhibition efficiencies of 93.46 % (EIS) and 83.25 % (PDP), followed by DHPP, DHCP, and DHPAP (efficiency order: DHMP > DHPP > DHCP > DHPAP). Surface characterization through Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) revealed the formation of protective barrier layers, effectively reducing surface roughness and minimizing copper dissolution. To elucidate the molecular basis of inhibition, Density Functional Theory (DFT) calculations provided insights into electronic properties, including HOMOLUMO energy gaps, Mulliken charges, and Molecular Electrostatic Potential (MEP) distributions. Further analyses using Non-Covalent Interaction (NCI) and Quantum Theory of Atoms in Molecules (QTAIM) emphasized the critical role of van der Waals forces and hydrogen bonding in stabilizing inhibitor-copper interactions. COSMORS studies confirmed favorable solvation behavior and charge distribution, reinforcing the experimentally observed adsorption mechanisms. This work underscores the multifunctionality of alpha-hydroxyphosphonates as effective corrosion inhibitors for industrial applications, while also paving the way for their optimization and broader utilization in corrosion science. The findings highlight the potential of these compounds to significantly advance the development of eco-friendly and efficient corrosion protection strategies.Öğe Nanocellulose hydrogels from agricultural wastes: methods, properties, and application prospects(Royal Soc Chemistry, 2025) Altynov, Yerkebulan; Bexeitova, Kalampyr; Nazhipkyzy, Meruyert; Azat, Seitkhan; Konarov, Aishuak; Rakhman, Damira; Şahiner, NurettinEscalating environmental concerns and the depletion of non-renewable resources have intensified interest in sustainable and eco-friendly materials. Cellulose-based hydrogels, renowned for their biocompatibility, biodegradability, and excellent mechanical properties, have emerged as promising candidates for diverse applications, including biomedicine, agriculture, and water purification. This review focuses on methods for extracting nanocellulose from agricultural wastes and their use in creating cellulose hydrogels. Special emphasis is placed on the mechanical, chemical, thermal, and environmental properties of nanocellulose, as well as its applications in packaging materials, medical devices, biocomposites, and filtration systems. The literature review examines cellulose extraction methods, hydrogel properties, and their industrial applications. The key advantages and disadvantages of these methods are identified, and directions for future research are proposed. This work provides a comprehensive overview of the current state of research on cellulose-based hydrogels and contributes to the development of more efficient and sustainable production methods for these materials.Öğe Nanoparticles for Biomedical Use Derived from Natural Biomolecules: Tannic Acid and Arginine(MDPI, 2025) Şahiner, Mehtap; Sağbas Suner, Selin; Şahiner, NurettinBackground/Objectives: Tannic acid (TA) is a well-known natural phenolic acid composed of ten gallic acids linked to each other with ester bonding possessing excellent antioxidant properties in addition to antimicrobial and anticancer characteristics. Arginine (ARG) is a positively charged amino acid at physiological pH because of nitrogen-rich side chain. Method: Here, poly(tannic acid-co-arginine) (p(TA-co-ARG)) particles at three mole ratios, TA:ARG = 1:1, 1:2, and 1:3, were prepared via a Mannich condensation reaction between TA and ARG by utilizing formaldehyde as a linking agent. Results: The p(TA-co-ARG) particles in 300-1000 nm size range with smooth surfaces visualized via SEM analysis were attained. Abundant numbers of functional groups, -OH, -NH2, and -COOH stemming from TA and ARG constituent confirmed by FT-IR analysis. The isoelectric point (IEP) of the particles increased from pH 4.98 to pH 7.30 by increasing the ARG ratios in p(TA-co-ARG) particles. The antioxidant capacity of p(TA-co-ARG) particles via gallic acid (GA) and rosmarinic acid (RA) equivalents tests revealed that particles possess concentration-dependent antioxidant potency and increased by TA content. The alpha-glucosidase inhibition of p(TA-co-ARG) particles (2 mg/mL) 1:1 and 1:2 mole ratios revealed significant enzyme inhibition ability, e.g., 91.3 +/- 3.1% and 77.6 +/- 12.0%. Interestingly, p(TA-co-ARG) (1:3 ratio) possessed significant antibacterial effectiveness against Escherichia coli (ATCC 8739) and Staphylococcus aureus (ATCC 6538) bacteria. Furthermore, all p(TA-co-ARG) particles at 1000 mg/mL concentration showed >80% toxicity on L929 fibroblast cells and increased as ARG content of p(TA-co-ARG) particles is increased. Conclusions: p(TA-co-ARG) showed significant potential as natural biomaterials for biomedical use.Öğe Natural Molecule-Derived Nanogels from Hematoxylin and l-lysine for Biomedical Use with Antimicrobial Properties(MDPI, 2025) Şahiner, Mehtap; Tian, Zhi; Allen-Gipson, Diane; Sunol, Aydın K.; Şahiner, NurettinHematoxylin (HT) is a natural staining dye used in histopathology, often combined with Eosin for H&E staining. A poly(hematoxylin-co-l-lysine) (p(HT-co-l)) nanonetwork was synthesized through a one-step Mannich condensation reaction using formaldehyde as a linking agent. The resulting p(HT-co-l) nanogels had an average size of about 200 nm and exhibited a smooth surface and desirable functional groups such as -OH, -NH2, and -COOH, as recognized by FT-IR analysis. The isoelectric point (IEP) of the p(HT-co-l) nanogel was determined as pH 7.9, close to physiological environments, despite HT being acidic IEP at pH 1.7 and l-lysine being basic IPE at pH 8.7. The time-dependent swelling studies of p(HT-co-l) nanogels were carried out using dynamic light scattering (DLS) in different salt solutions, e.g., MgCl2, KNO3, KCl, PBS, and DI water environments revealed that nanogels have high swelling ability depending on the medium, e.g., >10-fold in a saline solution compared to distilled water within 1.5 h. Hydrolytic degradation studies in PBS demonstrated a linear release profile up to 125 h at 37.5 degrees C. The p(HT-co-l) nanogels also demonstrated significant antimicrobial and antifungal activities against E. coli (ATCC 8739), S. aureus (ATCC 6538), and C. albicans (ATCC 10231). Furthermore, biocompatibility tests indicated that p(HT-co-l) nanogels are more biocompatible than HT alone, as tested with human Nuli-1 bronchial epithelial cells.Öğe Hydrogen Production from Chemical Hydrides via Porous Carbon Particle Composite Catalyst Embedding of Metal Nanoparticles(MDPI, 2025) Demirci, Şahin; Polat, Osman; Şahiner, NurettinPorous carbon particles (PCPs) prepared from sucrose via the hydrothermal method and its modified forms with polyethyleneimine (PEI) as PCP-PEI were used as templates as in situ metal nanoparticles as M@PCP and M@PCP-PEI (M:Co, Ni, or Cu), respectively. The prepared M@PCP and M@PCP-PEI composites were used as catalysts in the hydrolysis of NaBH4 and NH3BH3 to produce hydrogen (H2). The amount of Co nanoparticles within the Co@PCP-PEI structure was steadily increased via multiple loading/reducing cycles, e.g., from 29.8 +/- 1.1 mg/g at the first loading/reducing cycles to 44.3 +/- 4.9 mg/g after the third loading/reducing cycles. The Co@PCP-PEI catalyzed the hydrolysis of NaBH4 within 120 min with 251 +/- 1 mL H2 production and a 100% conversion ratio with a 3.8 +/- 0.3 mol H2/(mmol catmin) turn-over frequency (TOF) and a lower activation energy (Ea), 29.3 kJ/mol. In addition, the Co@PCP-PEI-catalyzed hydrolysis of NH3BH3 was completed in 28 min with 181 +/- 1 mL H2 production at 100% conversion with a 4.8 +/- 0.3 mol H2/(mmol catmin) TOF value and an Ea value of 32.5 kJ/mol. Moreover, Co@PCP-PEI composite catalysts were afforded 100% activity up to 7 and 5 consecutive uses in NaBH4 and NH3B3 hydrolysis reactions, respectively, with all displaying 100% conversions for both hydrolysis reactions in the 10 successive uses of the catalyst.Öğe AChE Inhibition Capability of Nanogels Derived from Natural Molecules: Tannic Acid and Lysine for Alzheimer's Disease(MDPI, 2025) Şahiner, Mehtap; Sağbaş Suner, Selin; Şahiner, NurettinBackground/Objectives: Tannic acid (TA), a known natural polyphenolic acid with many bioactivities including antioxidants, antibacterial, and antiviral, can be combined with a natural essential amino acid L-lysine (LYS) in nanogel formulations to produce p(TA-co-LYS) (p(TA-co-LYS)) nanogels. Methods: A 1:1 mole ratio of TA:LYS was used to prepare corresponding spherical nanogels employing formaldehyde as a linker via the Mannich reaction. Results: The attained p(TA-co-LYS) particles were in 283 +/- 57 nm size ranges (via SEM analysis) and possessed smooth surfaces. The zeta potential measurements of p(TA-co-LYS) nanogels suspension at different solution pHs revealed the isoelectric point (IEP) of pH 4.9, suggesting that the particles are negatively charged at the physiological pH range (e.g., at 7.4). In addition to the antioxidant efficacy of nanogels confirmed by three different tests, p(TA-co-LYS) particles showed significant Fe(II) ion chelating capacity at 350 mu g/mL concentrations compared to bare TA, which is 21%, whereas the LYS molecule had a chelating capacity of 100% at the same concentrations. Moreover, it was found that p(TA-co-LYS) nanogels inhibited the Acetylcholinesterase enzyme (AChE) at a concentration-dependent profile, e.g., at 333 mu g/mL concentration of p(TA-co-LYS), 57.2% of the enzyme AChE activity was inhibited. Furthermore, the minimum inhibition concentrations of p(TA-co-LYS) nanogels of Gram-negative Escherichia coli (ATCC 8739) and Gram-positive Staphylococcus aureus (ATCC 6538) were determined as 12.5 mg/mL. Conclusions: As cytotoxicity studies of p(TA-co-LYS) nanogels on L929 fibroblast cells also ascertained that these particles can be safely used in many biomedical applications, including antioxidant materials, drug delivery devices, and enzyme inhibitors.Öğe Toxicity Evaluation of Sulfobetainized Branched Polyethyleneimine via Antibacterial and Biocompatibility Assays(MDPI, 2025) Şahiner, Mehtap; Sağbaş Suner, Selin; Demirci, Şahin; Ayyala, Ramesh S.; Şahiner, NurettinBranched polyethyleneimine (PEI), possessing different types of amines-e.g., primary, secondary, and tertiary-in the polymer chains are well known for their antibacterial properties and DNA condensing ability, affording substantial advantages in many biomedical uses, including gene therapy. However, because of PEI's toxicity, depending on the molecular weight, its widespread biomedical use is hindered. Therefore, in this study, PEIs with different molecular weights-i.e., 600, 1200, and 1800 g/mol-were modified with 1,3-propane sultone, undergoing a sulfobetainization reaction in a single step to attain a zwitterionic structure: sulfobetainized PEI (b-PEI). The sulfobetainization reaction was carried out twice to increase the zwitterionic repeating unit on PEI chains. The increasing number of SO3- groups on the PEI chains was confirmed by the increased peak intensities around 1160 and 1035 cm-1 on the FT-IR spectrum, which are assigned to symmetric and asymmetric S=O peaks. The elemental analysis results for first- and second- betainization PEIs, abbreviated as b1-PEI and b2-PEI, respectively, were revealedthe increased wt% of S confirming the successful multiple-sulfobetainization of the PEI chains. Thermal stability analyses of PEIs and their corresponding multiple-sulfobetainized forms showed that multiple-sulfobetainization reactions increased the thermal stability of bare PEI chains. PEIs with lower molecular weights exhibited more antimicrobial properties. As PEI is sulfobetainated, its antimicrobial properties can be further adjusted via sulfobetainization (once or twice), or by adjusting the corresponding solution pH, or by protonating them with different acids with different counter anions. The cell toxicity of PEI on L929 fibroblast cells was slightly increased by increasing the molecular weight of the PEI, but all forms of sulfobetainized PEIs were found to be safe (no toxicity), even at 1000 mu g/mL concentrations.Öğe Arginine-functionalized graphene quantum dots@palladium composite modified pencil graphite electrode for electrochemical detection of DNA-mitomycin C interaction(Elsevier Ltd, 2025) Denizhan, Nuray; Yılmaz, Selehattin; Özkan-Arıksoysal, Dilsat; Emre, Deniz; Bilici, AliIn the present study, modified pencil graphite electrodes were prepared by synthesizing a novel nanocomposite with palladium and arginine-functionalized graphene quantum dots (Arg@GQDs) for the electrochemical monitoring of anticancer compound mitomycin C (MC) and double-stranded DNA (dsDNA) interaction for the first time. The oxidation responses of both guanine in DNA and the MC drug were measured in the same potential scanning range, and the drug-DNA interaction was determined by the differential pulse voltammetry (DPV) method. To improve the performance of the developed system, experimental parameters such as dsDNA and MC concentration and their interaction times were optimized. The surfaces obtained after the modification were characterized using scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Ultraviolet-Visible Spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FTIR), X-ray photon spectroscopy (XPS), Thermogravimetric analysis (TGA) cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The developed nanocomposite-modified electrodes (Arg@GQD@Pd@PGEs) provided higher guanine oxidation signals than PGEs. The limit of detection (LOD) values for dsDNA immobilized on PGE and Arg@GQD@Pd@PGEs were 0.713 pg 50 μL−1 and 0.019 pg 50 μL−1, respectively. © 2025 Elsevier B.V.Öğe Mechanically stable superhydrophilic antifog surface by microwave assisted sol-gel method(Elsevier B.V., 2021) Okkay, Hikmet; Satı, Sadık; Cengiz, UğurIn this study, optically transparent and mechanically stable of superhydrophilic composite thin films were fabricated via a low-cost one-step one pot microwave-assisted sol-gel technique. The microwave reaction time was optimized according to surface characterization of homo TMOS surfaces. The reaction time was arranged as 17.5 min having low cost compared to the conventional sol-gel technic. The wettability performance and antifogging behavior of PVA-TMOS composite films were investigated according to variation of the PVA content. The static contact angle values of the composite surfaces were found to vary between 30o and 5o. Superhydrophilic surface having tilt angle is 9o showed a good antifogging performance. Mechanical durability of the composite surface was also characterized by scratching and adhesive tape test. In addition, the time depending water contact angle was also measured for 100 days. It is found that TMPV96 composite film having 0.096 (wt,%) content of PVA showed higher mechanical performance with transparent superhydrophilic surface.
