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    Design of highly selective, and sensitive screen-printed electrochemical sensor for detection of uric acid with uricase immobilized polycaprolactone/polyethylene imine electrospun nanofiber
    (Pergamon-Elsevier Science Ltd, 2023) Muhammad, Fakhriy; Dik, Gamze; Kolak, Seda; Gedik, Kubra Karadas; Bakar, Busra; Ulu, Ahmet; Ates, Burhan
    Uric acid (UA) plays a significant role in nerve center, human metabolism, and kidney system. Therefore, it is necessary to establish a simple, rapid, and sensitive detection method for UA. In recent years, researchers have been highly attracted by nanomaterials with satisfactory functions in electrochemical applications. In this study, polycaprolactone (PCL)/polyethylene imine (PEI) nanofiber membranes were prepared and used for the immobilization of uricase (UOx). The prepared membranes were characterized in terms of structure, composi-tion, and morphology. Afterward, the quantum dot screen printed electrode (QD SPCE) was modified with PCL/ PEI nanofiber membranes with and without methylene blue (MB) as an electron mediator. The electrochemical performance of the developed sensors was investigated by cyclic voltammetry (CV), differential pulse voltam-metry (DPV), and electrochemical impedance spectroscopy (EIS). Under the optimal conditions, the modified sensors provided a broad linear range (5.0-52.0 mu M) for the electrochemical detection of UA. Limit of detection (LoD) values were determined as 3.96 mu M and 1.85 mu M for the PCL/PEI/UOx/QD SPCE and PCL/PEI/UOx/MB/ QD SPCE, respectively. The four-week stability results showed the change in current for the PCL/PEI/UOx/QD SPCE and PCL/PEI/UOx/MB/QD SPCE to be 92% and 87%, respectively. Additionally, in the mixed interference test remaining current ratios for UA were 95% and 82% for the PCL/PEI/UOx/QD SPCE and PCL/PEI/UOx/MB/ QD SPCE, respectively. Most importantly, the effectiveness of the electrodes was also verified in real sample detection with satisfactory recovery (similar to 98-112%). Overall, the results showed that the PCL/PEI/UOx/QD SPCE and PCL/PEI/UOx/MB/QD SPCE have the advantages of simplicity, high sensitivity, and good selectivity for UA determination.
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    Nature-derived otolith loaded polyethylene glycol-polycaprolactone electrospun composite nanofiber membranes: preparation, characterization, and biocompatibility evaluation
    (Springer, 2025) Pekdemir, Sibel Selcuk; Gedik, Kubra Karadas; Kurucay, Ali; Onay, Hatice; Ulu, Ahmet; Pekdemir, Mustafa Ersin; Kolak, Seda
    The electrospun nanofibers have paid much attention to biomedical applications. In this study, the electrospun composite nanofibers were prepared based on optimized polycaprolactone (PCL, 12 wt%) and polyethylene glycol (PEG, 3.6 wt%) polymers loaded with otoliths particles (OTO, 10-30 wt%) by electrospinning technique. The morphological, molecular interactions, crystallinity, and thermal properties of the composite nanofiber membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. In addition to that, swelling behaviors, biodegradability, porosity, and biocompatibility were also evaluated. Both PEG/PCL and OTO/PEG/PCL nanofibers revealed bead-less constructions with average diameters of around 500 nm. Thermogravimetric analysis revealed OTO/PEG/PCL composite membranes thermally stable up to 300 degrees C. XRD results also indicated a good crystallinity for the OTO/PEG/PCL composite membranes due to higher crystallinity of otolith. Adding otolith to PEG/PCL nanofibers did not obviously change the water uptake capacity, biodegradability, and porosity while increasing swelling ratio. Finally, membranes with the lowest otolith concentration (10% w/w) showed 96.2% cell viability, while increasing otolith concentration decreased cell viability. Based on the obtained results, the cytotoxicity of OTO/PEG/PCL membranes was evaluated with mouse fibroblast (L-929) cells by more than 85% survival during 72 h, which revealed that the OTO/PEG/PCL membranes were non-toxic. Taken together, these data suggest that OTO/PEG/PCL membranes could potentially be used as a nanofiber scaffold for applications.
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    Polymer-based anti-adhesive barriers: A comprehensive overview of current approaches for medical and biological applications
    (Elsevier Sci Ltd, 2025) Dik, Gamze; Dogan, Tugba; Gedik, Kubra Karadas; Ulu, Ahmet; Ates, Burhan
    Tissue and cell adhesions are undesirable conditions observed after surgical operations. This adhesion is seen at a high rate in many patients after the surgical operation. It is especially observed in biological parts such as the abdominal cavity, thoracic cavity, and tendons. Due to the healing of the fibrous tissues in the wound after the surgery, this part causes adhesion in the surrounding tissues and organs, and patients may develop complications such as chronic pain, intestinal obstruction and functional obstruction of organs after adhesion, may require a repeat surgical operation, and is a serious problem that may cause infertility in women. Chronic pain, intestinal obstruction, and functional obstruction of organs may develop complications after adhesion. To prevent this situation, it is very important to develop barriers with higher biocompatibility, low cost, easily applicable, and synthesizable instead of existing anti-adhesive barriers. Potential candidates with these properties are thought to be polymers. Polymers offer many options for use as anti-adhesive barriers since they can be obtained from natural sources and synthetically. These options can be designed according to the characteristics of the anti-adhesive barriers desired to be synthesized. These polymers can be produced in a short time using very simple techniques in the forms of hydrogel, membrane, fiber, film, etc. In addition to these, these polymers synthesized as anti-adhesive membranes can act as simultaneous drug release and imaging agents in various combinations. In this article, medical and biological applications of anti-adhesive barriers with various formulations developed with different polymer types are mentioned. Therefore, through this article, we report on recent work and some key points in the development of such applications.