Invasiv Meme Kanseri Hücresi Tayini İçin Kuvars Kristal Mikroterazi Sensörlerin Hazırlanması
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The aim of this study is to prepare a quartz crystal microbalance (QCM) biosensor for the detection of high-invasive breast cancer cells. For the selectivity of the sensor, the interaction between transferrin receptors overexpressed on the surface of breast cancer cells and transferrin was used. The QCM biosensor was prepared by modifiying poly(HEMA) particles which, along with transferrin, attached on the gold surface of the QCM sensor. In the first step, nanoparticles were prepared by a miniemulsion polymerization reaction of 2-hydroxyethyl methacrylate HEMA and ethylene glycol dimethacrylate (EGMA). The nanoparticles were characterized by zeta-sizer measurements. After that, the nanoparticles were immobilized by dropping a small amount of nanoparticle solution onto the gold surface and then drying at 37 Co for 6 hours. P(HEMA) particles which attached on the surface of the QCM sensor were modified with transferrin. Carbodiimide was used as an activation agent for modification. For the modification of p(HEMA) particles that attached on the surface of the sensor with transferrin, a QCM chip with p(HEMA) particles, transferrin and carbodiimide were put into pH 7.4 phophate buffer solution and kept in an agitated incubator, at room temperature for 24 hours. When preparing the QCM sensor without transferrin, p(HEMA) particles were unmodified. The prepared QCM sensor was characterized with atomic force microscopy (AFM), elipsometer, fourier transform infrared spectro- photometry (FTRI) and contact angle measurement. The thickness measurement and AFM observation indicated that the nanoparticle thin films were almost monolayer. After the characterization studies, the sensors with and without transferrin were connected to a QCM system to carry out kinetic and affinity studies on the high-invasive breast cancer cells. A cell solution of human breast cancer cell line MDA-MB-231 with diffirent concentrations were applied to the QCM system to determine the adsorption kinetics. The Langmuir- Freundlich adsorpsiton model was found as the most suitable model for this affinity system. In order to show the selectivity of the modified sensor with transferrin, competitive adsorption of MDA-MB-231 (high invasive), MCF-7 (low invasive) and serum and medium starved MDA-MB-231 was investigated. The results showed that the nanosensor with transferrin had high selectivity and sensitivity for cells which belong to high invasive human breast cancer cell line MDA-MB-231.