Development of the quartz crystal microbalance based biosensor functionalized with HER2 antibody that detects breast cancer cells

Here in this thesis project, we aimed to develop a reliable, effective, rapid, sensitive and specific QCM-based system to identify a small number of HER2 overexpressed breast cancer cells via receptor-specific ligands and/or antibodies. For this purpose, the QCM chip was coated with polymeric nanoparticles. The monomer phase was prepared using hydroxyethylmethacrylate (HEMA) and ethylene glycol dimethacrylate (EDMA). Nanoparticles were analyzed by Zeta Sizer and FTIR measurements. The nanoparticles were formed homogeneously and their size was 73.22 nm. The obtained poly hydroxyethylmethacrylate (PHEMA) nanoparticles was dropped the chip surface and for nanoparticle attachment, the chip surface was incubated for 20 minutes under UV light in a dust free environment. The properties of the nanoparticles that bound to the chip surface were determined by ellipsometer, contact angle, AFM and SEM measurements. The nanoparticle coated gold chip surface was functionalized with HER2 antibody via carbodiimide. Simultaneous cell analysis was performed for SKBR3, MDA-MB 231 and fibroblast cells with solutions containing 10-500 cells/ml, the cells passed over the chip surface at a rate of 0.5 ml/min. The mass increases (m) per cell/cm2 unit area were compared for the QCM sensor surface. The detection limit (LOD) of the HER2 bound QCM chip was found to be 10 cells/ml. In the study to determine cell selectivity, the HER2 bound chip was found to have 6.32 fold more selective to the SKBR3 cells than the MDA-MBB 231 cells and 8.40 fold higher than fibroblast cells. The reusability of the HER2 bound chip was found to be 250 cells/ml. There was no change in the binding capacity of chip for 5 cycles. Based on the results obtained of this thesis study, it was concluded that, although the QCM system developed to detect increased HER2 expression in SKBR3 breast cancer cells, it may contribute to the development of a new QCM sensor systems that can be used for diagnosis of other types of cancers with increased HER2 expression.