Bioengineering / Biyomühendislik

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  • Article
    Citation - WoS: 18
    Citation - Scopus: 17
    Modifying Pickering Polymerized High Internal Phase Emulsion Morphology by Adjusting Particle Hydrophilicity
    (Elsevier, 2024) Durgut, Enes; Zhou, Muchu; Dikici, Betuel Aldemir; Foudazi, Reza; Claeyssens, Frederik
    This study investigates the use of submicron polymeric particles with varying crosslinking densities as the sole stabilizer for producing Polymerized High Internal Phase Emulsions (PolyHIPE). We establish a direct correlation between the crosslinking density and the hydrophilicity of the polymer particles. The hydrophilicity of these particles significantly influences the morphology and rheology of HIPEs. These differences manifest as various morphological variations in the resulting PolyHIPE templates. It was discovered that by increasing the crosslinker weight percentage in the particles from 0 % to 100 %, PolyHIPEs with semi-open, open, and closed porous structures can be obtained. Furthermore, non-crosslinked particles were observed to dissolve in the continuous phase, acting as macromolecular surfactants that generate small pores akin to surfactant-stabilized structures in PolyHIPE. These findings offer fresh insights into the relationship between particle localization at the interface, HIPE rheology, and the formation of pore throats in Pickering PolyHIPEs, leading to the creation of either closed or open porous networks. Additionally, interfacial rheological results demonstrate that particles synthesized with varying monomer-to-crosslinker ratios exhibit different interfacial elasticities, which are linked to PolyHIPE morphology.
  • Article
    Citation - Scopus: 11
    Μdacs Platform: a Hybrid Microfluidic Platform Using Magnetic Levitation Technique and Integrating Magnetic, Gravitational, and Drag Forces for Density-Based Rare Cancer Cell Sorting
    (Elsevier, 2023) Keçili, Seren; Yılmaz, Esra; Özçelik, Özge Solmaz; Anıl İnevi, Müge; Günyüz, Zehra Elif; Yalçın Özuysal, Özden; Özçivici, Engin; Tekin, Hüseyin Cumhur
    Circulating tumor cells (CTCs) are crucial indicators of cancer metastasis. However, their rarity in the bloodstream and the heterogeneity of their surface biomarkers present challenges for their isolation. Here, we developed a hybrid microfluidic platform (microfluidic-based density-associated cell sorting (µDACS) platform) that utilizes density as a biophysical marker to sort cancer cells from the population of white blood cells (WBCs). The platform utilizes the magnetic levitation technique on a microfluidic chip to sort cells based on their specific density ranges, operating under a continuous flow condition. By harnessing magnetic, gravitational, and drag forces, the platform efficiently separates cells. This approach involves a microfluidic chip equipped with a microseparator, which directs cells into top and bottom outlets depending on their levitation heights, which are inversely proportional to their densities. Hence, low-density cancer cells are collected from the top outlet, while high-density WBCs are collected from the bottom outlet. We optimized the sorting efficiency by varying the flow rates, and concentrations of the sorting medium's paramagnetic properties using standard densities of polymeric microspheres. To demonstrate the platform's applicability, we performed hybrid microfluidic sorting on MDA-MB-231 human breast cancer cells and U-937 human monocytes. The results showed efficient sorting of rare cancer cells (≥100 cells/mL) from serum samples, achieving a sorting efficiency of ∼70% at a fast-processing speed of 1 mL h−1. This label-free approach holds promise for rapid and cost-effective CTC sorting, facilitating in-vitro diagnosis and prognosis of cancer. © 2023 The Author(s)
  • Article
    Citation - WoS: 15
    Citation - Scopus: 16
    Electromechanical Rt-Lamp Device for Portable Sars-Cov Detection
    (Elsevier, 2023) Tarım, Ergün Alperay; Öksüz, Cemre; Karakuzu, Betül; Appak, Özgür; Sayıner, Ayça Arzu; Tekin, Hüseyin Cumhur
    Rapid point-of-care tests for infectious diseases are essential, especially in pandemic conditions. We have developed a point-of-care electromechanical device to detect SARS-CoV-2 viral RNA using the reverse-transcription loop-mediated isothermal amplification (RT-LAMP) principle. The developed device can detect SARS-CoV-2 viral RNA down to 103 copies/mL and from a low amount of sample volumes (2 μL) in less than an hour of standalone operation without the need for professional labor and equipment. Integrated Peltier elements in the device keep the sample at a constant temperature, and an integrated camera allows automated monitoring of LAMP reaction in a stirring sample by using colorimetric analysis of unfocused sample images in the hue/saturation/value color space. This palm-fitting, portable and low-cost device does not require a fully focused sample image for analysis, and the operation could be stopped automatically through image analysis when the positive test results are obtained. Hence, viral infections can be detected with the portable device produced without the need for long, expensive, and labor-intensive tests and equipment, which can make the viral tests disseminated at the point-of-care.
  • Conference Object
    Computational Nanotoxicology: a Case Study With Silver and Zinc Nanomaterials
    (Elsevier, 2022) Bilgi, Eyüp; Öksel Karakuş, Ceyda
    Nanomaterials (NMs) have been the focus of basic and applied research for more than two decades. According to the updated consumer materials inventory, over 1800 commercial NMs have taken their place in the market, 42% of which are in health and wellness category1. The widespread use of NMs in health-related products made not only the human exposure to the (residues of) NMs inevitable but also the long-recognized concerns over their safety a priority. Despite this pressing need, more than 70% of commercially available nano-containing products do not include sufficient information about their physicochemical and/or toxicological characteristics.
  • Conference Object
    Citation - WoS: 1
    Green Synthesis of Nanostructured Bioactive Glass for Dental Applications
    (Elsevier, 2022) Tüncer, Melisa; Yücesoy, Deniz Tanıl; Öksel Karakuş, Ceyda
    Calcium sodium phosphosilicate (known as bioactive glass) is a biomaterial commonly used in dental care products and bone tissue engineering applications due to biocompatibility, bone-forming and dentin sensitivity reduction capability. Bioactive 45S5 glass, so-called NovaMin, comprises of 45% SiO2, 24.5% Na2O, 24.5% CaO, and 6% P2O5 (wt%). It is traditionally synthesized by wet chemical methods such as melt-quenching and sol-gel which requires high temperature heating and the use of a strong acid catalyst, which brings into the question of the possibility of introducing toxic acid residues into the final product. Therefore, there is a clear need to develop environmental-friendly bioactive glass synthesis methods or to modify existing ones in a way to uplift their environmental friendliness.
  • Conference Object
    Comparative Study of the Cytotoxicity of Hydroxyapatite, Tricalcium Phosphate and Calcium Phosphate Nanomaterials on Panc-1 and Hek293 Cell Line
    (Elsevier, 2022) Çeşmeli, Selin; Öksel Karakuş, Ceyda
    Calcium phosphate-based bioceramic nanoparticles have been actively used in a range of therapeutic applications. Although they are mostly considered as biocompatible materials, the circulation of nanoparticles in the bloodstream raise further questions as to what degree of cellular damage they are capable of causing once carried out to vital organs such as kidney and pancreas. Therefore, there is a clear need to explore potential cellular damage induced by commercially used bioceramic nanoparticles such as hydroxyapatite (HAp), tricalcium phosphate (TCP) and calcium phosphate (CaP).
  • Conference Object
    Development of Novel Nanotoxicity Assessment Method Utilizing 3d Printing System
    (Elsevier, 2022) Başlar, Muhammet Semih; Öksel Karakuş, Ceyda; Aldemir Dikici, Betül
    Unique physicochemical properties of nanomaterials (NMs) make them a material of choice in various applications but also raise concerns about their potential toxicity. While the commercial use of nano-enabled materials is growing rapidly, their interaction with biological systems and environment are not yet fully understood [1, 2]. Traditionally, toxicity of nano-sized materials are assessed by 2D cell culture models due to their time and cost-related advantages but their simplicity often comes at the cost of accuracy. While these methods are considered as the first step in toxicological assessment of both nanosized and bulk-form materials, they fall short in mimicking the complexity of in vivo physiological environments.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 16
    Synergistic Effect of Type and Concentration of Surfactant and Diluting Solvent on the Morphology of Emulsion Templated Matrices Developed as Tissue Engineering Scaffolds
    (Elsevier, 2022) Claeyssens, Frederik; Aldemir Dikici, Betül; Dikici, Serkan
    Emulsion templating is an advantageous route for the fabrication of tissue engineering scaffolds. Emulsions are mostly stabilised using surfactants, and the performances of the surfactants depend on various parameters such as emulsification temperature and the presence of the electrolytes. In this study, we suggest that diluting solvent type also has a dramatic impact on the efficiency of the surfactant and morphology of the polymerised emulsions. For this, morphologies of polycaprolactone methacrylate-based polymerised emulsions, which are designed for tissue engineering applications and in vitro biocompatibilities, were shown by our group, prepared using four different surfactants, and three different solvents were investigated. Results showed that the diluting solvent used in the emulsion composition has a strong impact on the performance of the surfactant and consequently on the morphology of polymerised emulsions. Increasing surfactant concentration and diluting solvent volume have an opposite impact on the characteristics of emulsions. Scaffolds with average pore sizes changing from 10 to 78 μm could be fabricated. Establishing these relations enables us to have control over the overall morphology of polymerised emulsions and precisely engineer them for specific tissue engineering applications by tuning solvent and surfactant type and concentration.
  • Article
    Citation - WoS: 51
    Citation - Scopus: 58
    3d Printed Gelatin/Decellularized Bone Composite Scaffolds for Bone Tissue Engineering: Fabrication, Characterization and Cytocompatibility Study
    (Elsevier, 2022) Kara, Aylin; Distler, Thomas; Polley, Christian; Schneidereit, Dominik; Seitz, Hermann; Friedrich, Oliver; Tıhmınlıoğlu, Funda; Boccaccini, Aldo R
    Three-dimensional (3D) printing technology enables the design of personalized scaffolds with tunable pore size and composition. Combining decellularization and 3D printing techniques provides the opportunity to fabricate scaffolds with high potential to mimic native tissue. The aim of this study is to produce novel decellularized bone extracellular matrix (dbECM)-reinforced composite-scaffold that can be used as a biomaterial for bone tissue engineering. Decellularized bone particles (dbPTs, ∼100 ​μm diameter) were obtained from rabbit femur and used as a reinforcement agent by mixing with gelatin (GEL) in different concentrations. 3D scaffolds were fabricated by using an extrusion-based bioprinter and crosslinking with microbial transglutaminase (mTG) enzyme, followed by freeze-drying to obtain porous structures. Fabricated 3D scaffolds were characterized morphologically, mechanically, and chemically. Furthermore, MC3T3-E1 mouse pre-osteoblast cells were seeded on the dbPTs reinforced GEL scaffolds (GEL/dbPTs) and cultured for 21 days to assess cytocompatibility and cell attachment. We demonstrate the 3D-printability of dbPTs-reinforced GEL hydrogels and the achievement of homogenous distribution of the dbPTs in the whole scaffold structure, as well as bioactivity and cytocompatibility of GEL/dbPTs scaffolds. It was shown that Young's modulus and degradation rate of scaffolds were enhanced with increasing dbPTs content. Multiphoton microscopy imaging displayed the interaction of cells with dbPTs, indicating attachment and proliferation of cells around the particles as well as into the GEL-particle hydrogels. Our results demonstrate that GEL/dbPTs hydrogel formulations have potential for bone tissue engineering.
  • Article
    Citation - WoS: 13
    Citation - Scopus: 15
    The Role of Cycloastragenol at the Intersection of Nrf2/Are, Telomerase, and Proteasome Activity
    (Elsevier, 2022) Yılmaz, Sinem; Bedir, Erdal; Ballar Kırmızıbayrak, Petek
    Aging is well-characterized by the gradual decline of cellular functionality. As redox balance, proteostasis, and telomerase systems have been found to be associated with aging and age-related diseases, targeting these systems with small compounds has been considered a promising therapeutic approach. Cycloastragenol (CA), a small molecule telomerase activator obtained from Astragalus species, has been reported to positively affect several age-related pathophysiologies, but the mechanisms underlying CA activity have yet to be reported. Here, we presented that CA increased NRF2 nuclear localization and activity leading to upregulation of cytoprotective enzymes and attenuation of oxidative stress-induced ROS levels. Furthermore, CA-mediated induction of telomerase activity was found to be regulated by NRF2. CA not only increased the expression of hTERT but also its nuclear localization via upregulating the Hsp90-chaperon complex. In addition to modulating nuclear hTERT levels at unstressed conditions, CA alleviated oxidative stress-induced mitochondrial hTERT levels while increasing nuclear hTERT levels. Concomitantly, H2O2-induced mitochondrial ROS level was found to be significantly decreased by CA administration. Our data also revealed that CA strongly enhanced proteasome activity and assembly. More importantly, the proteasome activator effect of CA is dependent on the induction of telomerase activity, which is mediated by NRF2 system. In conclusion, our results not only revealed the cross-talk among NRF2, telomerase, and proteasome systems but also that CA functions at the intersection of these three major aging-related cellular pathways.