Bioengineering / Biyomühendislik
Permanent URI for this collectionhttps://hdl.handle.net/11147/4529
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Article Citation - Scopus: 3Development of Chrono-Spectral Gold Nanoparticle Growth Based Plasmonic Biosensor Platform(Elsevier, 2024) Sözmen, Alper Baran; Elveren, Beste; Erdoğan, Duygu; Mezgil, Bahadır; Baştanlar, Yalın; Yıldız, Ümit Hakan; Arslan Yıldız, AhuPlasmonic sensor platforms are designed for rapid, label-free, and real-time detection and they excel as the next generation biosensors. However, current methods such as Surface Plasmon Resonance require expertise and well-equipped laboratory facilities. Simpler methods such as Localized Surface Plasmon Resonance (LSPR) overcome those limitations, though they lack sensitivity. Hence, sensitivity enhancement plays a crucial role in the future of plasmonic sensor platforms. Herein, a refractive index (RI) sensitivity enhancement methodology is reported utilizing growth of gold nanoparticles (GNPs) on solid support and it is backed up with artificial neural network (ANN) analysis. Sensor platform fabrication was initiated with GNP immobilization onto solid support; immobilized GNPs were then used as seeds for chrono-spectral growth, which was carried out using NH2OH at varied incubation times. The response to RI change of the platform was investigated with varied concentrations of sucrose and ethanol. The detection of bacteria E.coli BL21 was carried out for validation as a model microorganism and results showed that detection was possible at 102 CFU/ml. The data acquired by spectrophotometric measurements were analyzed by ANN and bacteria classification with percentage error rates near 0% was achieved. The proposed LSPR-based, label-free sensor application proved that the developed methodology promises utile sensitivity enhancement potential for similar sensor platforms. © 2024 The Author(s)Article Citation - Scopus: 11Μdacs 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 CumhurCirculating 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)Book Part Citation - Scopus: 2Bioprinting of Hydrogels for Tissue Engineering and Drug Screening Applications(Elsevier, 2022) Özmen, Ece; Yıldırım, Özüm; Arslan Yıldız, AhuIn tissue engineering, the 3-dimensional (3D) bioprinting method that enables the production of 3D structures by combining bioinks and cells has become one of the most promising technique. Over the last few years, 3D cell culture models gained importance in the development of disease model and drug development studies. The successful production of the 3D structures by 3D bioprinting mostly depends on the properties of the bioink to be used. Hydrogels, which are natural or synthetic polymers, are generally preferred as bioink materials with their high swelling ability, biocompatibility, biodegradability, and easy gelation ability. The convenience of hydrogels for varied bioprinting applications make them proper bioink materials for bioprinting of artificial tissues, tumor models, and tissue grafts. Bioprinting of functional tissues is successfully performed for years, and hydrogels are utilized as bioink in bone, vascular, neural, cartilage, cardiac, skin tissue engineering, and drug screening. In this chapter, bioprinting methodology, bioinks, hydrogel bioinks, and their applications are discussed in detail. © 2023 Elsevier Inc. All rights reserved.Book Part Noncoding Way of the Metastasis(Elsevier, 2022) Göker Bağca, Bakiye; Kuşoğlu, Alican; Çeşmeli, Selin; Biray Avcı, ÇığırAccording to the World Health Organization statistics, the second leading cause of death globally is cancer. Together with this, metastasis is viewed as the leading cause of cancer death in patients with the disease due to the lack of treatment modalities for malignant tumors. One of the key mechanisms related to cancer metastasis is the epithelial-mesenchymal transition which enables epithelial cancer cells to gain mesenchymal cancer cell properties with elevated migration and invasion capacity that make it easy to spread distant tissues and survive from harsh conditions. Studies indicate that metastatic cancer cells have a gene expression signature that ensures those cells have increased migratory capacity as well as increased survival rate in circulation. Recently, the relationship of metastasis with two types of noncoding RNAs (ncRNAs), microRNAs (miRNAs), and long noncoding RNAs (lncRNAs) has been getting attention. In this chapter, the role of miRNAs and lncRNAs and treatment strategies regarding the role of ncRNAs in metastasis biology will be evaluated.Article Citation - Scopus: 6Sensitive and Rapid Protein Assay Via Magnetic Levitation(Elsevier, 2022) Sözmen, Alper Baran; Arslan Yıldız, AhuMagnetic levitation (MagLev) is a newly emerging methodology for biosensing that provides a density-based analysis, which is highly sensitive and versatile. In this study, a magnetic levitation based sensor platform was used for protein detection; and sensor platform optimization was performed for both sensitivity and resolution. Bovine Serum Albumin (BSA) was used as a model protein and detection of BSA was carried out by antibody functionalized polystyrene microspheres (PSMs). Various sizes of PSMs were examined and their performances were compared by statistical analyses in terms of limit of detection (LOD), sensitivity, and resolution. Quantification of the protein was done based on the magnetic levitation height differences of antibody functionalized PSMs. For optimization of the methodology, varied PSMs were utilized, and standardization of PSM diameter, concentration of the antibody to be functionalized, and PSM dilution rates were carried out. In conclusion, 20 μm PSMs diluted to 0.005% W/V and functionalized with anti-BSA antibody at a concentration of 28 μg/ml were determined to provide the best resolution for BSA detection. A dynamic range of 100 nM to 1 mM was observed with an LOD value of 4.1 ng/ml. This sensing platform promises a novel approach with a diverse application field and it provides rapid, consistent, and reproducible results with high resolution and sensitivity.Article Citation - WoS: 8Citation - Scopus: 8Surface Microbiota and Associated Staphylococci of Houseflies (musca Domestica) Collected From Different Environmental Sources(Elsevier, 2022) Sudağıdan, Mert; Özalp, Veli Cengiz; Can, Özge; Eligül, Hakan; Yurt, Mediha Nur Zafer; Tasbasi, Behiye Busra; Acar, Elif Esma; Kavruk, Murat; Koçak, OnerHouseflies (Musca domestica) are important mechanical vectors for the transmission of pathogenic microorganisms. In this study, 129 houseflies (69 males and 60 females) were collected from 10 different environmental sources and a laboratory population was used. The surface microbiota of houseflies was identified by Next-Generation Sequencing. Staphylococci from the surfaces of houseflies were selectively isolated and their virulence genes, antibiotic susceptibilities, biofilm formation, and clonal relatedness were determined. Metagenomic analysis results demonstrated that Staphylococcus, Bacillus, and Enterococcus were mostly present on the surface of houseflies at the genus level. Additionally, the isolated 32 staphylococcal strains were identified as Staphylococcus sciuri (n = 11), S. saprophyticus (n = 9), S. arlettae (n = 6), S. xylosus (n = 4), S. epidermidis (n = 1) and S. gallinarum (n = 1). tetK, tetM, tetL, ermC, msrAB, and aad6 genes were found to carry by some of the staphylococcal strains. The strains were mostly resistant to oxacillin, penicillin, and erythromycin and three strains were multi-drug resistant. There was a statistical difference between housefly collection places and antibiotic resistance of isolated staphylococci to penicillin G, gentamicin, and erythromycin (p < 0.05). Biofilm test showed that 17 strains were strong biofilm formers, and it plays important role in the transmission of these bacteria on the surface of houseflies. Staphylococcal strains showed extracellular proteolytic and lipolytic activity in 31 and 12 strains, respectively. Closely related species were found in PFGE analysis from different environmental sources. By this study, surface microbiota and carriage of pathogenic staphylococci on the surfaces of houseflies and their virulence properties were elucidated.