Researcher:
Gülzar, Ayesha

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PhD Student

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Ayesha

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Gülzar

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Gülzar, Ayesha

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Now showing 1 - 3 of 3
  • Placeholder
    Publication
    Hydrogels for 3D frameworks
    (CRC Press, 2023) Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Karaoğlu, İsmail Can; Yalçın, Esra; Gülzar, Ayesha; Göktan, Işılay; Kızılel, Seda;  ; Graduate School of Sciences and Engineering; College of Engineering;  
    Hydrogels are 3D polymer networks that can absorb large amounts of water, making them a promising construct for tissue engineering applications. This chapter focuses on the use of hydrogels in vascularization, ophthalmology-related diseases, and pancreatic islet transplantation. Hydrogels can support blood vessel growth, known as vascularization. This is an important aspect of tissue engineering, as the formation of new blood vessels is necessary for supplying nutrients and oxygen to the engineered tissue. In the field of ophthalmological tissue engineering, hydrogels can be used as a scaffold to support the growth of limbal stem cells to repair or replace damaged corneal tissue. They can help regenerate the cornea. In addition, hydrogels can be used in islet transplantation, which is a promising approach for treating diabetes. In this context, hydrogels can create a protective environment for the transplanted islets, helping them to survive and function properly in the body. By limiting the immune response, hydrogels can help to prevent the body from rejecting the engineered tissue, improving the chances of success for transplantation. In conclusion, hydrogels are promising materials for tissue engineering, particularly in ophthalmological diseases, islet transplantation, and vascularization. By providing a supportive environment for the growth of cells and tissues, hydrogels can help improve the success of these therapies, offering new hope for patients with various conditions. © 2024 selection and editorial matter, Ram K. Gupta and Anuj Kumar;individual chapters, the contributors.
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    Publication
    Ruthenium-induced corneal collagen crosslinking under visible light
    (Assoc Research Vision Ophthalmology Inc, 2022) N/A; N/A; N/A; N/A; N/A; N/A; N/A; Department of Mechanical Engineering; N/A; Department of Chemical and Biological Engineering; Department of Mechanical Engineering; Department of Chemical and Biological Engineering; Yıldız, Erdost; Gülzar, Ayesha; Kaleli, Humeyra Nur; Nazeer, Muhammad Anwaar; Zibandeh, Noushin; Malik, Anjum Naeem; Taş, Ayşe Yıldız; Lazoğlu, İsmail; Şahin, Afsun; Kızılel, Seda; PhD Student; PhD Student; PhD Student; PhD Student; Researcher; PhD Student; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Health Sciences; Graduate School of Sciences and Engineering; Graduate School of Health Sciences; Graduate School of Sciences and Engineering; N/A; Graduate School of Sciences and Engineering; School of Medicine; College of Engineering; School of Medicine; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 200905; 179391; 171267; 28376
    Corneal collagen crosslinking (CXL) is a commonly used minimally invasive surgical technique to prevent the progression of corneal ectasias, such as keratoconus. Unfortunately, riboflavin/UV-A light-based CXL procedures have not been successfully applied to all patients, and result in frequent complications, such as corneal haze and endothelial damage. We propose a new method for corneal crosslinking by using a Ruthenium (Ru) based water-soluble photoinitiator and visible light (430 nm). Tris(bipyridine)ruthenium(II) ([Ru(bpy)3]2+) and sodium persulfate (SPS) mixture covalently crosslinks free tyrosine, histidine, and lysine groups under visible light (400-450 nm), which prevents UV-A light-induced cytotoxicity in an efficient and time saving collagen crosslinking procedure. In this study, we investigated the effects of the Ru/visible blue light procedure on the viability and toxicity of human corneal epithelium, limbal, and stromal cells. Then bovine corneas crosslinked with ruthenium mixture and visible light were characterized, and their biomechanical properties were compared with the customized riboflavin/UV-A crosslinking approach in the clinics. Crosslinked corneas with a ruthenium-based CXL approach showed significantly higher young's modulus compared to riboflavin/UV-A light-based method applied to corneas. In addition, crosslinked corneas with both methods were characterized to evaluate the hydrodynamic behavior, optical transparency, and enzymatic resistance. In all biomechanical, biochemical, and optical tests used here, corneas that were crosslinked with ruthenium-based approach demonstrated better results than that of corneas crosslinked with riboflavin/ UV-A. This study is promising to be translated into a non-surgical therapy for all ectatic corneal pathologies as a result of mild conditions introduced here with visible light exposure and a nontoxic ruthenium-based photoinitiator to the cornea. STATEMENT OF SIGNIFICANCE: Keratoconus, one of the most frequent corneal diseases, could be treated with riboflavin and ultraviolet light-based photo-crosslinking application to the cornea of the patients. Unfortunately, this method has irreversible side effects and cannot be applied to all keratoconus patients. In this study, we exploited the photoactivation behavior of an organoruthenium compound to achieve corneal crosslinking. Ruthenium-based organic complex under visible light demonstrated significantly better biocompatibility and superior biomechanical results than riboflavin and ultraviolet light application. This study promises to translate into a new fast, efficient non-surgical therapy option for all ectatic corneal pathologies.
  • Placeholder
    Publication
    Ruthenium-induced corneal collagen crosslinking under visible light
    (Elsevier, 2022) N/A; N/A; N/A; N/A; N/A; N/A; N/A; Department of Mechanical Engineering; N/A; Department of Chemical and Biological Engineering; Department of Mechanical Engineering; Department of Chemical and Biological Engineering; Gülzar, Ayesha; Yıldız, Erdost; Kaleli, Humeyra Nur; Nazeer, Muhammad Anwaar; Zibandeh, Noushin; Malik, Anjum Naeem; Taş, Ayşe Yıldız; Lazoğlu, İsmail; Şahin, Afsun; Kızılel, Seda; PhD Student; PhD Student; PhD Student; PhD Student; Researcher; PhD Student; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Health Sciences; Graduate School of Sciences and Engineering; N/A; Graduate School of Sciences and Engineering; School of Medicine; College of Engineering; School of Medicine; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 200905; 179391; 171267; 28376
    Corneal collagen crosslinking (CXL) is a commonly used minimally invasive surgical technique to prevent the progression of corneal ectasias, such as keratoconus. Unfortunately, riboflavin/UV-A light-based CXL procedures have not been successfully applied to all patients, and result in frequent complications, such as corneal haze and endothelial damage. We propose a new method for corneal crosslinking by using a Ruthenium (Ru) based water-soluble photoinitiator and visible light (430 nm). Tris(bipyridine)ruthenium(II) ([Ru(bpy)(3)](2+)) and sodium persulfate (SPS) mixture covalently crosslinks free tyrosine, histidine, and lysine groups under visible light (400-450 nm), which prevents UV-A light-induced cytotoxicity in an efficient and time saving collagen crosslinking procedure. In this study, we investigated the effects of the Ru/visible blue light procedure on the viability and toxicity of human corneal epithelium, limbal, and stromal cells. Then bovine corneas crosslinked with ruthenium mixture and visible light were characterized, and their biomechanical properties were compared with the customized riboflavin/UV-A crosslinking approach in the clinics. Crosslinked corneas with a ruthenium-based CXL approach showed significantly higher young's modulus compared to riboflavin/UV-A light-based method applied to corneas. In addition, crosslinked corneas with both methods were characterized to evaluate the hydrodynamic behavior, optical transparency, and enzymatic resistance. In all biomechanical, biochemical, and optical tests used here, corneas that were crosslinked with ruthenium-based approach demonstrated better results than that of corneas crosslinked with riboflavin/ UV-A. This study is promising to be translated into a non-surgical therapy for all ectatic corneal pathologies as a result of mild conditions introduced here with visible light exposure and a nontoxic ruthenium-based photoinitiator to the cornea. Statement of significance Keratoconus, one of the most frequent corneal diseases, could be treated with riboflavin and ultraviolet light-based photo-crosslinking application to the cornea of the patients. Unfortunately, this method has irreversible side effects and cannot be applied to all keratoconus patients. In this study, we exploited the photoactivation behavior of an organoruthenium compound to achieve corneal crosslinking. Ruthenium-based organic complex under visible light demonstrated significantly better biocompatibility and superior biomechanical results than riboflavin and ultraviolet light application. This study promises to translate into a new fast, efficient non-surgical therapy option for all ectatic corneal pathologies. (c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.