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  • Küçük Resim
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    Antibacterial and antibiofilm activities of sodium ibuprofen- and paracetamol-loaded nanofibers
    (Society of Chemists and Technologists of Macedonia, 2023) Alkan, Gürkan; Ulusoy, Seyhan; Akgün, Mert; Oral, Ayhan
    Nanofibers loaded with pharmaceutical agents for various medical purposes have become more important in recent years because of their advantages, such as control on release, gas permeability, high surface area, and lightweight matrices. In the present study, polylactic acid (PLA)-gelatin (Gel) nano-fibers were successfully loaded with Ibuprofen-Na/Paracetamol (henceforth Ibu-Na and Par, respectively) by electrospinning. The nanofibers were characterized by scanning electron microscopy (SEM) and Fou-rier transform infrared (FTIR) spectroscopy. The Ibu-Na/Par content of the nanofibers was determined by using high-performance liquid chromatography (HPLC). Their antibacterial activities were tested against Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa PA01, opportunistic pathogenic bacteria which are frequently asso-ciated with infections. Moreover, their antibiofilm activities against P. aeruginosa and E. faecalis were also investigated. The Ibu-Na-containing nanofibers exhibited antibacterial activity against S. aureus, E. coli, and E. faecalis. The inhibition zone diameters of PLA-Gel-Ibu-Na 300 against E. faecalis, S. aureus, and E. coli were calculated to be 23.0 ± 2.1 mm, 18.0 ± 1.5 mm, and 12.0 ± 1.2 mm, respectively. It was found that PLA-Gel-Ibu-Na 300 and PLA-Gel-Par 300 nanofibers’ capacity to show biofilm formation inhibition originated remarkable effects on P. aeruginosa, which were found to be 48 % and 50.4 %, respectively. This study indicated that Ibu-Na/Par-loaded nanofibers are promising materials for wound healing applications.
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    Catalytic Role of Nanoconfinement inside MIL-125 (Ti) on the Ring-Opening Polymerization of Simple Benzoxazines
    (American Chemical Society, 2024) Omrani, Abdollah; Deliballi, Zeynep; Kaya, Kerem; Kıskan, Barış; Akgün, Mert
    The influence of nanoscale confinement on the thermally induced ring-opening polymerization (ROP) of three different monofunctional benzoxazines (Bzs) was highlighted for the first time. The Bzs were solution-loaded or blended in/with a titanium-based metal-organic framework (MOF), i.e., MIL-125-based. The successful infiltration of the Bzs within the MOF was confirmed through comprehensive analyses using FTIR, BET, and DSC techniques. Remarkably, the nanoconfinement exhibited exceptional promotion of the Bzs ROP, resulting in a significant decrease in the onset temperature of the corresponding exotherms of as much as 127 °C for the nonsubstituted monomer. GPC traces revealed that high-molecular-weight polybenzoxazines (PBzs) were formed when fluorine-substituted Bz polymerized in the MOF-confined nanospaces. The catalytic role of nanoconfinement was further supported by analyzing the effective activation energy through the isoconversional method of Starink. ROP of the Bz-MIL-125 blend, where the effect of nanoconfinement was absent, demonstrated the catalytic role of MIL-125 with a less pronounced impact compared to the nanoconfined system.
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    Effect of mastic gum integration on improvement of polylactic acid biodegradable films
    (John Wiley and Sons Inc, 2023) Aydoğdu Emir, Ayca; Akgün, Mert; Kırtıl, Emrah
    Currently, 90% of all packaging films are composed of non-renewable, petroleum-based materials. However, these materials have a significant environmental footprint. Polylactic acid (PLA) is a well-known biodegradable thermoplastic polymer. However, the use of PLA poses some inherent challenges, like the brittleness of PLA films. For this study, with the objective of overcoming the shortcomings of PLA films, mastic gum (MG), which is an under-utilized hydrophobic polymer, was incorporated into PLA, and the resultant films were characterized for their chemical (x-ray diffraction [XRD], Fourier-transform infrared [FTIR]), thermal (thermogravimetric analysis [TGA], dynamic mechanical analysis [DMA]), optical (optical microscope, color, and opacity), and barrier properties (water vapor permeability [WVP]). MG addition yielded films with much higher opacities and decreased WVPs up to 80%. Optical microscope images revealed the presence of some defects for films with MG concentrations above 1% g/g solvent, which also decreased the film's tear resistance. Glass transition temperature (Tg) values are reduced with MG addition, resulting in less rigid films at room temperature. In the end, MG incorporation yielded more flexible films with much better water barrier properties. In addition, all other properties of the films were drastically modified with MG addition. Hence, MG/PLA is demonstrated to be a promising biopolymer combination for the preparation of biodegradable films as a food packaging material.
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    Hollow microspherical carbazole-based conjugated polymers by photoinduced step-growth polymerization
    (Royal Society of Chemistry, 2021) Çeliker, Tuğba; Suerkan, Ali; Altınışık, Sinem; Akgün, Mert; Koyuncu, Sermet; Yağcı, Yusuf
    A new photochemical approach for the synthesis of metal-free three-dimensional hollow spherical conjugated polymers is described. Irradiation of solutions containing a specially designed monomer, namely 4,4 '-bis(N-carbazolyl)-1,1 '-biphenyl (CBP) possessing both carbazole and biphenyl units, in the presence of iodonium salt (Ph2I+PF6-) at 350 nm resulted in the formation of a dark colored corresponding polymer, poly(4,4 '-bis(N-carbazolyl)-1,1 '-biphenyl) (PCBP). Polymerization proceeds through a step-growth mechanism by successive electron transfer between CBP and the iodonium ion within the photochemically formed exciplex, proton release and radical coupling reactions. The obtained polymers were characterized by UV-vis, H-1-NMR, GPC, CV and BET analyses. Dedoping of self-assembled microspheres with a significant distance resulted in more uniform spherical formations as evidenced by AFM and TEM investigations.
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    Öğe
    ITO temelli tek kullanımlık malzemelerin biyosensör teknolojilerinin geliştirilmesinde kullanımı ve kanser erken teşhisine yönelik olarak uygulanması
    (Çanakkale Onsekiz Mart Üniversitesi, 2019) Akgün, Mert; Sezgintürk, Mustafa Kemal
    Meme kanseri, günümüzde en yaygın görülen kanser türleri arasındadır. Birçok kanser çeşidinde olduğu gibi bu hastalığında erken tayini çok önemlidir. Son zamanlarda moleküler biyolojideki gelişmeler hastalığın evresini gösterebilecek yani biyobelirteçlerin kullanımını ortaya çıkartmıştır. Bu biyobelirteçler hastanın iyi ya da kötü tanısını belirlemek için kullanılan son derece önemli araçlardır. Vasküler Endoteryal Büyüme Faktörü (VEGF), anjiyogenez ve vasküler geçirgenliğin önemli bir düzenleyicisi olan ve endoteryal hücreleri için güçlü bir mitojen olarak kabul edilen bu türünün bir biyobelirtecidir. Bu çalışmada kadınların sağlığını tehdit eden meme kanserinin biyobelirteci olan VEGF'nin hassas, hızlı ve pratik bir şekilde ölçülmesini sağlayacak elektrokimyasal impedans spektroskopisine dayalı elektrokimyasal bir biyosensör tasarlanması amaçlamaktadır. Üretilen biyosensörün tüm optimizasyon işlemlerinde Elektrokimyasal İmpedans spektroskopisi (EİS) ve döngüsel voltametri (CV) tekniği kullanılmıştır. Optimizasyon çalışmalarını desteklemek, yüzey morfolojisini ve kimyasal bileşenleri aydınlatmak için taramalı elektron mikroskobu (SEM) görüntüleri, enerji yayılım x-ışını (EDX) spektrumu, haritalama, atomik kuvvet mikroskobu (AFM) ve kızıl ötesi (FTIR) spektrumları incelenmiştir. Elektrokimyasal karakterizasyon çalışmalarında tekrarlanabilirlik tekrarüretilebilirlik, depo, rejenerasyon, SFI, kare dalga voltametrisi, Kramer's Kronig çalışmaları gerçekleştirilmiştir. Bununla birlikte insan serumunda ölçümler alınmıştır.