Yazar "Geyik, Gulcan" seçeneğine göre listele

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    Alginate-based bio-nanocomposite reinforced with poly(2-hydroxypropyl methacrylamide) and magnetite graphene oxide for delivery of etoposide and photothermal therapy
    (Elsevier Sci Ltd, 2024) Isiklan, Nuran; Geyik, Gulcan; Guncum, Enes
    Recently, bio-nanocomposite nanogels/hydrogels composed of natural polymers and carbon-based nano- materials are attracting increasing attention in the fields of nanomedicine and bioengineering due to their unique properties. In this study, we propose the creation of an innovative multifunctional bio-nanocomposite based on alginate graft copolymer with poly(2-hydroxypropyl methacrylamide) (SA-g-PHPM) and magnetite graphene oxide (mGO) loaded with etoposide (EPS) for drug delivery and photothermal therapy (PTT). The SA-g-PHPM/ mGO bio-nanocomposite was synthesized using an emulsion method and exhibited favorable physicochemical properties. The structural functionalities and surface morphology of the SA-g-PHPM/mGO bio-nanocomposite were comprehensively characterized using spectroscopic techniques, including FT-IR, XRD, UV, DLS, TEM/FESEM, and AFM analyses. Under near-infrared (NIR) irradiation (808 nm, 1 Wcm-(2), 10 min), the SA-g-PHPM/ mGO bio-nanocomposite demonstrated the ability to effectively induce a temperature increase exceeding 29 degrees C. Additionally, exposure to NIR light and magnetic field led to an increased release of EPS whereas an increment in percentage of mGO caused a decreased EPS release. Notably, the synergistic effects of chemotherapy, light-triggered drug release, and PTT collectively contributed to a significant enhancement in lung cancer (H1299) cell death. In conclusion, our findings suggest that the developed SA-g-PHPM/mGO/EPS bionanocomposite serves as an efficient vehicle for multimodal therapy in lung cancer.
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    Design and development of pH-responsive alginate-based nanogel carriers for etoposide delivery
    (Elsevier, 2023) Geyik, Gulcan; Guncum, Enes; Isiklan, Nuran
    Recently, pH-responsive nanogels are playing progressively important roles in cancer treatment. The present study focuses on designing and developing pH-responsive alginate-based nanogels to achieve a controlled release of etoposide (Et) while enhancing its hydrophilicity. Alginate (ALG) is grafted with 2-hydroxypropyl methacrylamide (HPMA) through a microwave-supported method, and the chemical structure of the graft copolymer (ALG-g-PHPMA) was verified by 1H/13C NMR and FTIR techniques. The ALG-g-PHPMA and anticancer drug loaded ALG-g-PHPMA@Et nanogels were obtained using an emulsion method, and their structures were characterized through FTIR, TG/DSC, AFM/TEM, BET, and DLS analyses. The ALG-g-PHPMA nanogels demonstrated a good drug encapsulation efficiency (79.60 %), displaying a pH-dependent release profile and an in vitro accelerated release of Et compared to the ALG nanogels. Thermal and BET analyses revealed enhanced stability, surface area, and porosity volume of the alginate nanogels. The grafting of PHPMA chains onto alginate altered the surface topology of the ALG nanogels, resulting in lower surface roughness. Furthermore, cytotoxicity tests showed the high biocompatibility of the ALG-g-PHPMA copolymer and its nanogels. The ALG-g-PHPMA@Et nanogels exhibited a higher anticancer effect on lung cancer (H1299) cells than free etoposide. These results suggest that the ALG-g-PHPMA nanogels can be applied as a pH-dependent nanoplatform for delivering anticancer drugs.
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    Design and fabrication of hybrid triple-responsive x-carrageenan-based nanospheres for controlled drug delivery
    (Elsevier, 2021) Geyik, Gulcan; Isiklan, Nuran
    In the last two decades, the utilization of magnetic nanospheres in intelligent polymeric structures have received increased attention of researchers in numerous biomedical applications. Here, hybrid nanostructured triple-responsive magnetic nanospheres (kappa-Car-g-P(AA/DMA)@Fe3O4) containing inorganic iron oxide core (Fe3O4) and organic graft copolymeric shell based on x-carrageenan (kappa-Car) and poly(acrylic acid/dimethylaminoethyl methacrylate) (P(AA/DMA)) were synthesized by microwave induced co-precipitation technique. The structure, size, surface morphology, magnetic property and stability of synthesized kappa-Car-g-P(AA/DMA)@Fe3O4 magnetic nanospheres were characterized using FTIR, UV, XRD, TEM, Zeta-sizer, and VSM. kappa-Car-g-P(AA/DMA)@Fe3O4 nanospheres were loaded with 5-Fluorouracil (5-FU) as an antineoplastic drug, and their 5-FU release behavior was explored in diverse graft yields, pH values, temperatures and in the existence of an alternating magnetic field. The kappa-Car-g-P(AA/DMA)@Fe3O4 nanospheres demonstrated pH-, thermo-, and magnetic field-responsive 5-FU release with good biocompatibility and excellent anticancer activity. In addition, 5-FU release under 50 mT magnetic field reached to 100% within 4 h. This work exhibits that hybrid nanospheres have a triple stimuli-responsive influence, which is of principal importance for the future design and application of multi-functional responsive platforms to develop externally stimulated release of active agents and their healthcare capability.
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    Magnetic graphene oxide functionalized alginate-g-poly (2-hydroxypropylmethacrylamide) nanoplatform for near-infrared light/ pH/magnetic field-sensitive drug release and chemo/phototherapy
    (Elsevier, 2024) Guncum, Enes; Geyik, Gulcan; Isiklan, Nuran
    Multifunctional nanoplatforms developed from natural polymers and graphene oxide (GO) with enhanced biological/physicochemical features have recently attracted attention in the biomedical field. Herein, a new multifunctional near -infrared (NIR) light-, pH- and magnetic field -sensitive hybrid nanoplatform (mGO@AL-gPHPM@ICG/EP) is developed by combining iron oxide decorated graphene oxide nanosheets (mGO) and poly(2hydroxypropylmethacrylamide) grafted alginate (AL-g-PHPM) copolymer loaded with indocyanine green (ICG) and etoposide (EP) for chemo/phototherapy. The functional groups, specific crystal structure, size, morphology, and thermal stability of the nanoplatform were fully characterized by XRD, UV, FTIR, AFM/TEM/FE-SEM, VSM, DSC/TG, and BET analyses. In this platform, the mGO and ICG, as phototherapeutic agents, demonstrate excellent thermal effects and singlet oxygen production under NIR-light (808 nm) irradiation. The XRD and DSC analysis confirmed the amorphous state of the ICG/EP in the nanoparticles. In vitro photothermal tests proved that the mGO@AL-g-PHPM@ICG/EP nanoparticles had outstanding light stability and photothermal conversion ability. The in vitro release profiles presented NIR light-, pH- and magnetic field -controlled EP/ICG release behaviors. In vitro experiments demonstrated the excellent antitumor activity of the mGO@AL-g-PHPM@ICG/EP against H1299 tumor cells under NIR laser. Benefiting from its low-cost, facile preparation, and good dualmodal therapy, the mGO@AL-g-PHPM@ICG/EP nanoplatform holds great promise in multi -stimuli -sensitive drug delivery and chemo/phototherapy.
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    Multi-stimuli-sensitive superparamagnetic ?-carrageenan based nanoparticles for controlled 5-fluorouracil delivery
    (Elsevier, 2022) Geyik, Gulcan; Isiklan, Nuran
    Herein, a novel multi-stimuli-sensitive nanoparticles with triple magnetic field, temperature, and pH-sensitive features was designed and developed as a drug nanocarrier for delivery of 5-fluorouracil (FL). For this purpose, dimethylaminoethyl methacrylate (DMA) was firstly grafted onto kappa-carrageenan (kappa-CG), and then kappa-CG-gPDMA copolymer was coated onto Fe3O4 nanoparticles via microwave-supported coprecipitation method. The prepared multi-functional magnetic nanoparticles were characterized by UV, FTIR, XRD, TEM, Zeta-sizer, and VSM analyses to confirm the formation of superparamagnetic Fe3O4@kappa-CG-g-PDMA structure. The in vitro FL release of the nanoparticles was investigated at 48 and 37 degrees C in different pH conditions and exhibited good pH- and temperature-sensitive behavior. Furthermore, the effects of graft yield and magnetic field on FL release were explored. When the magnetic field was applied at 100 kHz, the release of FL increased rapidly, demonstrating that nanoparticles had magnetic field-sensitive features. According to the results, the designed Fe3O4@kappa-CG-g-PDMA@FL nanoparticles can be considered as a smart drug delivery system for cancer therapy due to its high entrapment efficiency, slow and multi-stimuli-triggered FL release performance, and satisfactory magnetic properties.
  • Küçük Resim
    Öğe
    pH/temperature-responsive poly(dimethylaminoethyl methacrylate) grafted kappa-carrageenan copolymer: Synthesis and physicochemical properties
    (WILEY, 2020) Geyik, Gulcan; Isiklan, Nuran
    kappa-Carrageenan-graft-poly(dimethylaminoethyl methacrylate) (CRG-g-PDMA) was synthesized via free-radical copolymerization under microwave irradiation.C-13-Nuclear magnetic resonance spectroscopy (C-13-NMR), fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray diffraction (XRD) methods were used for characterization of the CRG-g-PDMA structure. The effect of reaction variables including the concentrations of the initiator and dimethylaminoethyl methacrylate (DMA) as well as the microwave irradiation time and power on graft ratio and conversion was investigated, and their highest values were obtained to be 179 and 76%, respectively. The lower critical solution temperatures (LCSTs) of the CRG-g-PDMA copolymers were determined at various pH conditions, and their value in distilled water was found as 47 degrees C. Besides, the swelling capacity of the copolymers under different pH levels was investigated and it was seen that the swelling capacity of the copolymer increased with the decrease in the pH value of the medium. The CRG-g-PDMA copolymer exhibited excellent swelling performance in acidic pH conditions and possessed responsiveness to pH and temperature stimuli.
  • Küçük Resim
    Öğe
    Synthesis, characterization and swelling performance of a temperature/pH-sensitive kappa-carrageenan graft copolymer
    (ELSEVIER, 2020) Geyik, Gulcan; Isiklan, Nuran
    A binary graft copolymerization of dimethylaminoethyl methacrylate (DMAEMA) and acrylic acid (AA) onto kappa-carrageenan (CG) was performed by using microwave irradiation in the presence of 4A'-Azobis(4-cyanovaleric acid) (ACVA). The structure of the CG-g-P(DMAEMA/AA) copolymers was confirmed using C-13 NMR, MR, DSCTFGA and XRD. The effects of the DMAEMA/AA ratio, the microwave power and irradiation duration, and the concentrations of CG and ACVA on grafting yield and grafting efficiency were all investigated, and the best values of them were found to be 150% and 85%, respectively. The lower critical solution temperatures (LCST) for CG-g-P(DMAEMA/AA) copolymers at various pH conditions were determined, and when the pH value of the medium was increased from 12 to 10, the LCST of the copolymer decreased from 53 degrees C to 39 degrees C. Moreover, swelling performance of the copolymers under various pH conditions was examined, and it was observed that the swelling ratio of the copolymer increased with a decrease in the pH value of the medium. (C) 2020 Elsevier B.V. All rights reserved.