Browsing by Author "Uysal, Bengu Ozugur"

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Citation Count: 8
2D Materials (WS2, MoS2, MoSe2) Enhanced Polyacrylamide Gels for Multifunctional Applications
(Mdpi, 2022) Uysal, Bengu Ozugur; Nayir, Seyma; Acba, Melike; Citir, Betul; Durmaz, Sumeyye; Kocoglu, Sevval; Yildiz, Ekrem
Multifunctional polymer composite gels have attracted attention because of their high thermal stability, conductivity, mechanical properties, and fast optical response. To enable the simultaneous incorporation of all these different functions into composite gels, the best doping material alternatives are two-dimensional (2D) materials, especially transition metal dichalcogenides (TMD), which have been used in so many applications recently, such as energy storage units, opto-electronic devices and catalysis. They have the capacity to regulate optical, electronic and mechanical properties of basic molecular hydrogels when incorporated into them. In this study, 2D materials (WS2, MoS2 and MoSe2)-doped polyacrylamide (PAAm) gels were prepared via the free radical crosslinking copolymerization technique at room temperature. The gelation process and amount of the gels were investigated depending on the optical properties and band gap energies. Band gap energies of composite gels containing different amounts of TMD were calculated and found to be in the range of 2.48-2.84 eV, which is the characteristic band gap energy range of promising semiconductors. Our results revealed that the microgel growth mechanism and gel point of PAAm composite incorporated with 2D materials can be significantly tailored by the amount of 2D materials. Furthermore, tunable band gap energies of these composite gels are crucial for many applications such as biosensors, cartilage repair, drug delivery, tissue regeneration, wound dressing. Therefore, our study will contribute to the understanding of the correlation between the optical and electronic properties of such composite gels and will help to increase the usage areas so as to obtain multifunctional composite gels.
Citation Count: 2
3D self-assemble formation of molybdenum disulfide (MoS2)-doped polyacrylamide (PAAm) composite hydrogels
(Tubitak Scientific & Technological Research Council Turkey, 2022) Durmaz, Sumeyye; Yildiz, Ekrem; Uysal, Bengu Ozugur; Pekcan, Onder
Polyacrylamide (PAAm), a renowned member of the hydrogel class, has many uses throughout a wide range of industrial processes, including water absorbed diapers, contact lenses, wastewater treatment, biomedical applications such as drug delivery vehicles and tissue engineering because of its physical stability, durability, flexibility easier shaping, and so on. PAAm also provides new functionalities after the incorporation of inorganic structures such as molybdenum disulfide (MoS2). During the copolymerization process, the transmittance of all samples reduced significantly after a particular time, referred to as the gel point. Microgels form a tree above the gel point as projected by Flory-Stockmayer classical theory. Because of microgels positioned at the junction points of the Cayley tree, the addition of MoS2 results in strong intramolecular crosslinking and looser composites. Moreover, fractal geometry provides a quantitative measure of randomness and thus permits characterization of random systems such as polymers. Fractal dimension of these polymer composites is calculated from power-law-dependent scattered intensity. It was also confirmed that a hydrogel rapidly formed within a few seconds, indicating a 3D network formation inside the gel. These materials may have a great potential for application in wearable and implantable electronics due to this highly desired 3D self-assemble feature.
Composite Hydrogel of Polyacrylamide/Starch as a Novel Amoxicillin Delivery System
(Mdpi, 2024) Poyraz, Yagmur; Baltaci, Nisa; Hassan, Gana; Alayoubi, Oubadah; Uysal, Bengu Ozugur; Pekcan, Onder
This study investigates the development and characterization of a novel composite hydrogel composed of polyacrylamide (PAAm), starch, and gelatin for use as an amoxicillin delivery system. The optical properties, swelling behavior, and drug release profile of the composite hydrogel's were studied to evaluate its efficacy and potential applications. UV-visible spectroscopy was employed to determine the optical properties, revealing significant transparency in the visible range, which is essential for biomedical applications. The incorporation of starch and gelatin into the polyacrylamide matrix significantly enhanced the hydrogel's swelling capacity and biocompatibility. Studies on drug delivery demonstrated a sustained release profile of amoxicillin in simulated gastrointestinal fluids, which is essential for maintaining therapeutic levels for a prolonged amount of time. The results indicate that the composite hydrogel of PAAm/starch/gelatin has good swelling behavior, appealing optical characteristics, and a promising controlled drug release mechanism. These results point to this hydrogel's considerable potential as a drug delivery method, providing a viable path toward enhancing the medicinal effectiveness of amoxicillin and maybe other medications.
Citation Count: 0
Effect of MoS₂ on Simple and Novel PEG/κ-Carrageenan Hydrogels for TNBC Cancer Drug Delivery
(Taylor & Francis inc, 2024) Hassan, Gana; Uysal, Bengu Ozugur
Molybdenum is a trace dietary element necessary for the survival of humans. Some molybdenum-bearing enzymes are involved in key metabolic activities in the human body (such as xanthine oxidase, aldehyde oxidase and sulfite oxidase). Many molybdenum-based compounds have been widely used in biomedical research. Especially, MoS2-nanomaterials have attracted more attention in cancer diagnosis and treatment recently because of their unique physical and chemical properties. MoS2 can adsorb various biomolecules and drug molecules via covalent or non-covalent interactions because it is easy to modify and possess a high specific surface area, improving its tumor targeting and colloidal stability, as well as accuracy and sensitivity for detecting specific biomarkers. At the same time, in the near-infrared (NIR) window, MoS2 has excellent optical absorption and prominent photothermal conversion efficiency, which can achieve NIR-based phototherapy and NIR-responsive controlled drug-release. Significantly, the modified MoS2-nanocomposite can specifically respond to the tumor microenvironment, leading to drug accumulation in the tumor site increased, reducing its side effects on non-cancerous tissues, and improved therapeutic effect. In this review, we introduced the latest developments of MoS2-nanocomposites in cancer diagnosis and therapy, mainly focusing on biosensors, bioimaging, chemotherapy, phototherapy, microwave hyperthermia, and combination therapy. Furthermore, we also discuss the current challenges and prospects of MoS2-nanocomposites in cancer treatment.
Citation Count: 0
The Effect of Pyranine and MoS₂ Content on the Optical Properties of Polyacrylamide-MoS₂ Composite Gels
(Taylor & Francis inc, 2024) Uysal, Bengu Ozugur; Osma, Busra; Evingur, Gulsen Akin; Pekcan, Onder
The most favorable members of the class of two-dimensional (2D) materials, molybdenum sulfide (MoS2), graphene, and tungsten disulfide (WS2) have become a thriving research frontier for many applications, ranging from catalysis to optoelectronic devices, due to their superior electronic behavior and mechanical properties. Making a new, smart, hydrogel when incorporating MoS2 into basic hydrogels can change their optical, electronic, and mechanical properties. In this work, MoS2-doped polyacrylamide (PAAm) gels were prepared via the free radical crosslinking copolymerization technique at room temperature without pyranine which is often used for crosslinking PAAm. The optical properties of PAAm-MoS2 composite gels were investigated, and they were analyzed using ultraviolet (UV) and fluorescence spectroscopy. The absorbance was measured before and after diffusion of MoS2-doped PAAm, and after the release of pyranine in and out of the composite gel, respectively. The shift of the absorption edge toward shorter wavelengths was seen when the quantity of MoS2 in the PAAm composite gels was decreased. The constituents included in the polymer composites exhibited notable photon energy absorption within the visible and ultraviolet spectra. This absorption phenomenon induced electron transitions to states of elevated energy. Parameters, such as refractive index and extinction coefficient, were analyzed with respect to the content of MoS2. When the MoS2 amount was increased in the gels, the percentage of reflectance increased. The extinction coefficient increased at longer wavelength and it decreased in the UV range, the shorter wavelength region. The results suggested that MoS2-doped PAAm composite gels show promising optoelectronic properties for developing optoelectronic devices.
Citation Count: 29
Efficient Photocatalytic Degradation of Methylene Blue Dye from Aqueous Solution with Cerium Oxide Nanoparticles and Graphene Oxide-Doped Polyacrylamide
(Amer Chemical Soc, 2023) Kalaycioglu, Zeynep; Uysal, Bengu Ozugur; Pekcan, Onder; Erim, F. Bedia
A cerium oxide nanoparticles (CeO2-NPs)/graphene oxide (GO)/polyacrylamide (PAM) ternary composite was synthesized through free-radical polymerization of acrylamide in the presence of CeO2 nanoparticles and GO in an aqueous system. The synthesized composite material was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy techniques and applied for the photocatalytic degradation of methylene blue (MB) dye from an aqueous solution. Tauc's model for direct transition was used to model for the optical band gap. The key operating parameters such as the amounts of CeO2-NPs and GO, pH, initial MB concentration, type of light irradiation, and contact time have been optimized to achieve the highest MB degradation percentage. The photocatalysis process was pH-dependent, and the optimum pH value was found to be 12.0. Under UV-A light, 90% dye degradation occurred in 90 min. The degradation of MB was also specified in terms of total organic carbon (TOC) and chemical oxygen demand (COD). Free-radical capture experiments were also performed to determine the role of radical species during the photocatalytic oxidation process. The photocatalytic process showed that the equilibrium data is in good agreement with the Langmuir-Hinshelwood kinetic model. A rate constant of 0.0259 min-1 was obtained. The hydrogel was also tested to assess its reusability, which is an important key factor in practical wastewater treatment. The photocatalytic activity only decreased to 75% after nine uses.
Citation Count: 0
Investigation of Structural and Antibacterial Properties of WS₂-Doped ZnO Nanoparticles
(Amer Chemical Soc, 2024) Eşsiz, Şebnem; Essiz, Sebnem; Uysal, Bengu Ozugur
ZnO nanoparticles, well-known for their structural, optical, and antibacterial properties, are widely applied in diverse fields. The doping of different materials to ZnO, such as metals or metal oxides, is known to ameliorate its properties. Here, nanofilms composed of ZnO doped with WS2 at 5, 15, and 25% ratios are synthesized, and their properties are investigated. Supported by molecular docking analyses, the enhancement of the bactericidal properties after the addition of WS2 at different ratios is highlighted and supported by the inhibitory interaction of residues playing a crucial role in the bacterial survival through the targeting of proteins of interest.
Citation Count: 3
Polyacrylamide mediated polyvinyl pyrrolidone composites incorporated with aligned molybdenum disulfide
(Wiley, 2022) Uysal, Bengu Ozugur; Evingur, Gulsen Akin; Pekcan, Onder
In this study, we aimed to design a mechanically durable material consisting of Molybdenum disulfide (MoS2) as 2D material and polyvinyl pyrrolidone (PVP) enhanced Polyacrylamide (PAAm) composites. Composites containing different amounts of MoS2 were synthesized via a free-radical crosslinking copolymerization method. They were characterized using UV-visible spectroscopy, fluorescence, and mechanical techniques to illuminate band gap energy, absorption, slow release kinetics, and modulus of the composites. Furthermore, the effect of swelling on the elasticity of the composites was investigated. It was observed that the elasticity exhibited similar band gap energies with respect to the MoS2 content. The results demonstrated that the MoS2 content strongly influences the optical and mechanical properties of the composites and consequently physical parameters of the composites have been correlated with the various amounts of MoS2.
Citation Count: 28
Transducer Technologies for Biosensors and Their Wearable Applications
(Mdpi, 2022) Arsan, Taner; Polat, Emre Ozan; Tabak, Ahmet Fatih; Bilget Guven, Ebru; Uysal, Bengu Ozugur; Arsan, Taner; Kabbani, Anas
The development of new biosensor technologies and their active use as wearable devices have offered mobility and flexibility to conventional western medicine and personal fitness tracking. In the development of biosensors, transducers stand out as the main elements converting the signals sourced from a biological event into a detectable output. Combined with the suitable bio-receptors and the miniaturization of readout electronics, the functionality and design of the transducers play a key role in the construction of wearable devices for personal health control. Ever-growing research and industrial interest in new transducer technologies for point-of-care (POC) and wearable bio-detection have gained tremendous acceleration by the pandemic-induced digital health transformation. In this article, we provide a comprehensive review of transducers for biosensors and their wearable applications that empower users for the active tracking of biomarkers and personal health parameters.
Citation Count: 2
Tungsten disulfide (WS2) doped polyacrylamide (PAAm) composites: Gelation and optical studies
(Elsevier Gmbh, 2021) Nayir, Sseyma; Kivrak, Sena; Kara, Iirem; Uysal, Bengu Ozugur; Pekcan, Oonder
The organic Acrylamide (AAm) copolymerization in various contents of inorganic WS2 has been reported. The aim was to investigate the effect of the WS2 amount on the obtained morphology and the gelation process of the AAm composites. It was found that during gelation process the photon intensity of transmission decreased significantly above some critical time, called the gel point, tg. The decrease in the photon intensity of transmission was related to the increase in the intensity of scattered light from the gel attributable to the production of microgel that occurs while copolymerization held in AAm with Bis-Acrylamide (BIS). Gel points were found to be increased by increasing WS2 content. Time-dependent scattering of composites manifests the growth mechanism, the greater microgel particles, as in agreement with Rayleigh's equation of scattering. It is determined that concentration of microgels is inversely proportional to the WS2 content. The composite rate constants of gelation, kr were produced and observed that it is proportional to WS2 content. It is understood that inclusion of WS2 in AAm system during gelation delays the process at early times but then contributes to increase the gelation process by increasing the rate of polymerization. Besides less compact PAAm gels are produced in the presence of WS2 atoms. It is also shown that the microgel growth mechanism and gel point of PAAm composite incorporated with WS2 can be significantly tailored by the amount of WS2. Tunable growth mechanism and critical gelation point is crucial for flexible electronic applications.