Supercritical CO2 extraction of an immunosuppressant produced by solid-state fermentation
Ilknur Alpak, Ruhan Askin Uzel, Sayit Sargin, Ozlem Yesil-Celiktas
Mycophenolic acid (MPA) is a secondary metabolite of Penicillium species with diverse biological properties and has clinical applications mainly as an immunosuppressive agent. Production of MPA was carried out using Penicillium brevicompactum (DSM 2215) by solid-state fermentation (SSF). Six different carbon sources (wheat bran, rice husk, rice bran, potato peel and rice husk - rice bran, rice bran-potato peel mixture) were examined by SSF in order to obtain the highest yield of mycophenolic acid...
Mimicking human pathophysiology in organ-on-chip devices.
Ozlem Yesil-Celiktas, Shabir Hassan, Amir K. Miri, Sushila Maharjan, Rawan Al-kharboosh, Alfredo Quiñones-Hinojosa, Yu Shrike Zhang
Convergence of life sciences, engineering, and basic sciences has opened new horizons for biologically inspired innovations, and a considerable number of organ‐on‐a‐chip platforms have been developed for mimicking physiological systems of biological organs such as the brain, heart, lung, kidney, liver, and gut. Various biophysicochemical factors can also be introduced into such organ‐on‐a‐chip platforms to study metabolic and systemic effects spanning from drug toxicity to different pathologic manifestations. There is also a pressing need to develop better disease models for common pathologies using variations of these platforms...
Silica‐based organic‐inorganic hybrid nanoparticles and nanoconjugates for improved anticancer drug delivery
Esra Ilhan-Ayisigi, Ozlem Yesil-Celiktas
After the introduction of first generation MSNs for drug delivery with some challenges such as large particle sizes, irregular morphologies and aggregations, second generation provided uniform spherical morphologies, tunable pore/particle sizes and compositions. Henceforth, organic‐inorganic hybrid mesoporous silica nanosystems have grown rapidly and utilized for active and passive targeting of tumorigenic cells especially conjugated with organic polymers followed by third generation counterparts with improved functionalities for cancer therapy...
Cytotoxicity of silica nanoparticles with transcaucasian nose-horned viper, Vipera ammodytes transcaucasiana, venom on U87MG and SHSY5Y neuronal cancer cells.
Çigdem Celen, Ceren Kececiler, Mert Karis, Bayram Gocmen, Ozlem Yesil-Celiktas, Ayşe Nalbantsoy
Highly bioactive compounds of the snake venom make them particular sources for anticancer agent development. They contain very rich peptide-protein structures. Therefore, they are very susceptible to environmental conditions such as temperature, pH, and light. In this study, Vipera ammodytes transcaucasiana venom was encapsulated in PAMAM-G4 dendrimer by sol-gel method in order to prevent degradation of venom contents from the environmental conditions...
Advances in glioblastoma multiforme treatment: new models for nanoparticle therapy.
Elif Ozdemir-Kaynak, Amina Ann Qutub, Ozlem Yesil-Celiktas
The most lethal form of brain cancer, glioblastoma multiforme, is characterized by rapid growth and invasion facilitated by cell migration and degradation of the extracellular matrix. Despite technological advances in surgery and radio-chemotherapy, glioblastoma remains largely resistant to treatment. New approaches to study glioblastoma and to design optimized therapies are greatly needed. One such approach harnesses computational modeling to support the design and delivery of glioblastoma treatment. In this paper, we critically summarize current glioblastoma therapy, with a focus on emerging nanomedicine and therapies that capitalize on cell-specific signaling in glioblastoma. We follow this summary by discussing computational modeling approaches focused on optimizing these emerging nanotherapeutics for brain cancer...
Effects of hydrostatic pressure and supercritical carbon dioxide on the viability of Botryococcus braunii algae cells.
Ece Yildiz-Ozturk, Esra Ilhan-Ayisigi, Arnoud Togtema, Joao Gouveia, Ozlem Yesil- Celiktas
In bio-based industries, Botryococcus braunii is identified as a potential resource for production of hydrocarbons having a wide range of applications in chemical and biopolymer industries. For a sustainable production platform, the algae cultivation should be integrated with downstream processes. Ideally the algae are not harvested, but the product is isolated while cultivation and growth is continued especially if the doubling time is slow. Consequently, hydrocarbons can be extracted while keeping the algae viable. In this study, the effects of pressure on the viability of B. braunii cells were tested hydrostatically and under supercritical CO2 conditions...
A generic model for diffusive dynamics of the substrate and fluorescein tagged enzyme in microfluidic platform
Ece Yildiz-Ozturk, Mesut Yucel, Ozlem Yesil-Celiktas
The aim of this study was to develop a model that describes enzymatic conversion in a microfluidic system along with convective and diffusive transport of substrate/product within the microchannels...
Optimization of microwave assisted extraction of Morus nigra L. fruits maximizing tyrosinase inhibitory activity with isolation of bioactive constituents
Halil Koyu, Aslihan Kazan, Serdar Demir, Mehmet Zeki Haznedaroglu, Ozlem Yesil-Celiktas
Morus nigra L. is a beneficial food due to rich phenolic components. While aiming higher yields for bioactive constituents, reduction in terms of raw material, solvent, time and energy gained more importance to provide a sustainable life for human and nature. Microwave assisted extraction (MAE) of Morus nigra fruits was optimized in order to elicit process parameters maximizing bioactive metabolites and tyrosinase inhibitory activity...
Advances in glioblastoma multiforme treatment: new models for nanoparticle therapy. Frontiers Physiology
Elif Ozdemir-Kaynak, Amina Ann Qutub, Ozlem Yesil-Celiktas (2018)
The most lethal form of brain cancer, glioblastoma multiforme, is characterized by rapid growth and invasion facilitated by cell migration and degradation of the extracellular matrix. Despite technological advances in surgery and radio-chemotherapy, glioblastoma remains largely resistant to treatment. New approaches to study glioblastoma and to design optimized therapies are greatly needed. One such approach harnesses computational modeling to support the design and delivery of glioblastoma treatment...
Novel application of β-glucuronidase immobilized silica gel formulation to microfluidic platform for biotransformation of β-glucuronides. Biotechnology Letters
Cahit Muderrisoglu, Sayit Sargin, Ozlem Yesil-Celiktas (2018)
Objective: To improve the efficiency of reactions of β-glucuronidase (GUS)-assisted glucuronic acid (GluA) removal within a microfluidic system...
Effects of hydrostatic pressure and supercritical carbon dioxide on the viability of Botryococcus braunii algae cells. Bioresource Technlogy
Ece Yildiz-Ozturk, Esra Ilhan-Ayisigi, Arnoud Togtema, Joao Gouveia, Ozlem Yesil- Celiktas (2018)
In bio-based industries, Botryococcus braunii is identified as a potential resource for production of hydrocarbons having a wide range of applications in chemical and biopolymerindustries. For a sustainable production platform, the algae cultivation should be integrated with downstream processes. Ideally the algae are not harvested, but the product is isolated while cultivation and growth is continued especially if the doubling time is slow...
A generic model for diffusive dynamics of the substrate and fluorescein tagged enzyme in microfluidic platform. Microsystem Technologies
Ece Yildiz-Ozturk, Mesut Yucel, Ozlem Yesil-Celiktas (2018)
The aim of this study was to develop a model that describes enzymatic conversion in a microfluidic system along with convective and diffusive transport of substrate/product within the microchannels. Hence, a 1-D partial differential equation model based on Fick’s Law was employed in order to describe the substrate/product concentration distributions within the system. Enzyme immobilized in PEO-inclusive/non-inclusive TEOS-based hydrogels were tagged with fluorescein and examined under confocal laser scanning microscopy to evaluate the distribution of the enzyme...
Optimization of microwave assisted extraction of Morus nigra L. fruits maximizing tyrosinase inhibitory activity with isolation of bioactive constituents, Food Chemistry, 248, 183-191.
Halil Koyu, Aslihan Kazan, Serdar Demir, Mehmet Zeki Haznedaroglu, Ozlem Yesil-Celiktas (2018)
Morus nigra L. is a beneficial food due to rich phenolic components. While aiming higher yields for bioactive constituents, reduction in terms of raw material, solvent, time and energy gained more importance to provide a sustainable life for human and nature. Microwave assisted extraction (MAE) of Morus nigra fruits was optimized in order to elicit process parameters maximizing bioactive metabolites and tyrosinase inhibitory activity...