11 research outputs found
Cell Separation In Microfluidic Channels
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013Bu çalışmada yaklaşık 15 mikron çapında olan MDA-MB-231 ve yaklaşık 20 micron çapında olan MCF7 insan meme kanseri hücreleri içeren karışımdan MCF7 konsantrasyonu için Dean akışından faydalanan dönel kanal tasarımı yapılmıştır. Buna göre dört farklı yükseklik x genişlik değerlerine sahip olan kanallar üretilmiştir. Bu kanallar, bir giriş ve üç çıkışa sahiplerdir. Hedef hücre olan MCF7 hücre iki farklı floresan boya ile boyanmış ve öncelikle bu boyaların hücrelerin yüzde kaçında etkili olduğunu belirlemek için akış sitometrisi ile analiz edilmiştir. Bu analizden sonra ilk önce dizilim için uygun debileri bulmak üzere deney kurulmuş ve boyalı MCF7 hücreleri ve boyanmamış MDA-MB-231 hücreleri her birinden 100 ml’de bir milyon olacak şekilde toplam iki milyon hücre içeren karışım hazırlanmıştır. Bu karışımdan her bir kanal için 20’şer ml alınarak deneyler gerçekleştirilmiştir. Bu deneyler sırasında yüksek debilerde çalışılması gerektiği anlaşılmıştır. deneylere göre gerekli debiye ulaşıldığında kanalların 2. çıkışlarında MCF7 hücreleri dizilimi olduğu görülmüş ve bu akış sitometrisi analizi ile de doğrulanmıştır. İkinci yapılan deneylerde MCF7 hücreleri ilkinden farklı bir boyayla boyanmıştır ve daha fazla sayıda debi incelenmiştir. Üretilen dönel kanallar, ucuz ve küçük boyutlu, hızlı ve daha doğru sonuç alınabilecek bir teşhis cihazı geliştirmede ön çalışma olarak kullanılabilecek bir tasarım olmuştur.In this work, Dean force coupled curved microchannels were designed for concentration of MCF7 human breast cancer cells from a suspension that contains MDA-MB-231 (~ 15 μm in diameter) and MCF7 (~ 20 μm in diameter) human breast cancer cell lines. Channels which have four different height x width dimensions were fabricated. Channels had one inlet and three outlets. Target cell –MCF7- has stained with two different fluorescent dye and effectiveness of these dyes were investigated with flow cytometry. Experiments were performed to determined apoppriate flow rates for focusing. Then, a million labeled MCF7 and a million unlabeled MDA-MB-231 cells were mixed in 100 ml solution. 20 ml cell suspension was used for each experiment. It was understood that high flow rates are required for focusing of MCF7 cells and according to first experiment there was MCF cell focusing at second outlets . Experiments showed that MCF7 enrichment at the second outlets of each channel and it was confirmed with flow cytometry analysis. Then another group of MCF7 cells were stained with another fluorescent dye for second experimental group and more flow rate values were investigated. These curved channels can be regarded as a prototype of a microfluidic diagnostic device with their fast reaction time, relatively accurate results, cost effective and miniaturized features.Yüksek LisansM.Sc
Thermal and mechanical manipulation of iron oxide nanoparticles for targeted drug/gene delivery and therapeutics
Superparamagnetic iron oxide nanoparticles provide a platform to deliver therapeutic agents to any desired group of cells in a safe fashion. These particles can be manipulated by externally applied magnetic fields, targeted to specific tissues and heated in focused fields for cancer treatment. Hyperthermia performance of SPIONs depends on the magnetic field strength as well as the field frequency. A part of this dissertation displays the therapeutic effect of Poly(acrylic acid)-coated, anti-HER2- tagged SPIONs on breast cancer cells using a low magnetic field strength of 0.8 kAm-1, which is significantly lower compared to the literature, with a frequency of 400 kHz. HER2-positive SKBR3 and MDA-MB-453 cell lines successfully internalized the nanoparticles. The particles, which were not toxic to these cell lines, led to a prominent decrease in cell proliferation and survival in MDA-MB-453 cells when subjected to hyperthermia. Gene therapy is another developing method for the treatment of various diseases. A strong alternative is magnetofection, which involves the use of SPIONs and external magnetic field to enhance the localization of SPIONs at the target site. A new magnetic actuation system consisting of four rare earth magnets on a rotary table was designed and manufactured to have improved magnetofection. The actuation effect was revealed with green fluorescent protein DNA bearing-nanoparticle transfection to MCF7 cells. The applied magnetic field in this system increased the transfection efficiency and viability relative to traditional transfection methods. At the same time, it also reduced the transfection time (down to 1 hour) of the standard polyethylenimine transfection protoco
Therapeutic nanoparticles and their targeted delivery applications
Nanotechnology offers many advantages in various fields of science. In this regard, nanoparticles are the essential building blocks of nanotechnology. Recent advances in nanotechnology have proven that nanoparticles acquire a great potential in medical applications. Formation of stable interactions with ligands, variability in size and shape, high carrier capacity, and convenience of binding of both hydrophilic and hydrophobic substances make nanoparticles favorable platforms for the target-specific and controlled delivery of micro- and macromolecules in disease therapy. Nanoparticles combined with the therapeutic agents overcome problems associated with conventional therapy; however, some issues like side effects and toxicity are still debated and should be well concerned before their utilization in biological systems. It is therefore important to understand the specific properties of therapeutic nanoparticles and their delivery strategies. Here, we provide an overview on the unique features of nanoparticles in the biological systems. We emphasize on the type of clinically used nanoparticles and their specificity for therapeutic applications, as well as on their current delivery strategies for specific diseases such as cancer, infectious, autoimmune, cardiovascular, neurodegenerative, ocular, and pulmonary diseases. Understanding of the characteristics of nanoparticles and their interactions with the biological environment will enable us to establish novel strategies for the treatment, prevention, and diagnosis in many diseases, particularly untreatable ones
Nanoparticle based induction heating at low magnitudes of magnetic field strengths for breast cancer therapy
Magnetic hyperthermia has received much attention during the last decade due to its implementation in cancer treatment. Recently, functionalized superparamagnetic iron oxide nanoparticles (SPION) emerged as a strong alternative adjuvant treatment approach, which complements conventional methods such as chemotherapy. In this study, we demonstrate the anticancer effect of Poly(acrylic acid)-coated, anti-HER2-tagged SPIONs on breast cancer cells using a low magnetic field strength of 0.8 kAm−1, which is significantly lower compared to the literature, with a frequency of 400 kHz. Specificity was achieved via anti-HER2 antibody attachment to nanoparticles. HER2-positive SKBR3 and MDA-MB-453 cell lines internalized the nanoparticles successfully. These nanoparticles, which were not toxic to these cell lines, led to a prominent decrease in cell proliferation and survival in MDA-MB-453 cells when subjected to hyperthermia. Therefore, the hyperthermia-targeted SPION approach could be developed as a potential cancer treatment approach against breast cancer and possible other cancer types
Effect of varying magnetic fields on targeted gene delivery of nucleic acid-based molecules
Several physical methods have been developed to introduce nucleic acid expression vectors into mammalian cells. Magnetic transfection (magnetofection) is one such transfection method, and it involves binding of nucleic acids such as DNA, RNA or siRNA to magnetic nanoparticles followed by subsequent exposure to external magnetic fields. However, the challenge between high efficiency of nucleic acid uptake by cells and toxicity was not totally resolved. Delivery of nucleic acids and their transport to the target cells require carefully designed and controlled systems. In this study, we introduced a novel magnetic system design providing varying magnet turn speeds and magnetic field directions. The system was tested in the magnetofection of human breast (MCF-7), prostate (DU-145, PC-3) and bladder (RT-4) cancer cell lines using green fluorescent protein DNA as a reporter. Polyethylenimine coated superparamagnetic iron oxide nanoparticles (SPIONs) were used as nucleic acid carriers. Adsorption of PEI on SPION improved the cytocompatibility dramatically. Application of external magnetic field increased intracellular uptake of nanoparticles and transfection efficiency without any additional cytotoxicity. We introduce our novel magnetism-based method as a promising tool for enhanced nucleic acid delivery into mammalian cells
Magnetofection of green fluorescent protein encoding DNA-bearing polyethyleneimine-coated superparamagnetic iron oxide nanoparticles to human breast cancer cells
Gene therapy is a developing method for the treatment of various diseases. For this purpose, the search for nonviral methods has recently accelerated to avoid toxic effects. A strong alternative method is magnetofection, which involves the use of superparamagnetic iron oxide nanoparticles (SPIONs) with a proper organic coating and external magnetic field to enhance the localization of SPIONs at the target site. In this study, a new magnetic actuation system consisting of four rare-earth magnets on a rotary table was designed and manufactured to obtain improved magnetofection. As a model, green fluorescent protein DNA-bearing polyethyleneimine-coated SPIONs were used. Magnetofection was tested on MCF7 cells. The system reduced the transfection time (down to 1 h) of the standard polyethyleneimine transfection protocol. As a result, we showed that the system could be effectively used for gene transfer
On cavitation inception and cavitating flow patterns in a multi-orifice microfluidic device with a functional surface
During the last decade, hydrodynamic cavitation has been implemented in various applications such as energy harvesting and biomedical applications. Facile hydrodynamic cavitation methods are required for fulfilling the requirements in these applications. In this study, a new generation microfluidic device containing eight parallel micro-orifices with a new design was fabricated and tested with the purpose of intensifying the cavitating flows and early cavitation inception. The roughness elements in the micro-orifices facilitated cavitation inception. This study presents a general perspective of occurrence of different cavitating flow patterns in microscale and addresses the ambiguities about the conditions for the formation of a specific flow pattern. Cavitation inception occurred with the appearance of small bubbles emerging from roughness elements at a rather low upstream pressure in the open loop experimental setup. A reduction in the cavitation number resulted in the formation of different flow patterns such as cavitation clouds, twin cavities, sheet cavities, and bubbly flows. Having several flow patterns with different intensities all together within a single microfluidic device is the main advantage of the proposed device over the state of the art microfluidic devices. Generation of flow patterns with various released energy levels makes this proposed device a unique multi-functional platform, which can be implemented to a lab on a chip platform for applications such as nanoparticle synthesis and wound healing
Design and fabrication of a vigorous "cavitation-on-a-chip" device with a multiple microchannel configuration
Hydrodynamic cavitation is one of the major phase change phenomena and occurs with a sudden decrease in the local static pressure within a fluid. With the emergence of microelectromechanical systems (MEMS), high-speed microfluidic devices have attracted considerable attention and been implemented in many fields, including cavitation applications. In this study, a new generation of 'cavitation-on-a-chip' devices with eight parallel structured microchannels is proposed. This new device is designed with the motivation of decreasing the upstream pressure (input energy) required for facile hydrodynamic cavitation inception. Water and a poly(vinyl alcohol) (PVA) microbubble (MB) suspension are used as the working fluids. The results show that the cavitation inception upstream pressure can be reduced with the proposed device in comparison with previous studies with a single flow restrictive element. Furthermore, using PVA MBs further results in a reduction in the upstream pressure required for cavitation inception. In this new device, different cavitating flow patterns with various intensities can be observed at a constant cavitation number and fixed upstream pressure within the same device. Moreover, cavitating flows intensify faster in the proposed device for both water and the water-PVA MB suspension in comparison to previous studies. Due to these features, this next-generation 'cavitation-on-a-chip' device has a high potential for implementation in applications involving microfluidic/organ-on-a-chip devices, such as integrated drug release and tissue engineering.QC 20210611</p