Yazar "Yilmaz, Fatma" seçeneğine göre listele

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    Öğe
    Novel QCM and SPR sensors based on molecular imprinting for highly sensitive and selective detection of 2,4-dichlorophenoxyacetic acid in apple samples
    (Elsevier, 2019) Cakir, Oguz; Bakhshpour, Monireh; Yilmaz, Fatma; Baysal, Zubeyde
    This study aims to develop molecularly imprinted based quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) sensors for highly sensitive and selective detection of 2,4-dichlorophenoxyacetic acid (2,4-D) and to determine their accuracy and precision by liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a reference technique. Here, we synthesized non-imprinted (NIP) and 2,4-D-imprinted (MIP) [ethylene glycol dimetacrylate-N-metacryloyl-(L)-tryptophan methyl ester-p(EGDMA-MATrp)] polymeric nanofilms by using molecular imprinting technique. MIP and NIP nanofilms were characterized by fourier transform infrared spectroscopy attenuated total reflectance (FTIR-ATR), atomic force microscope (AFM), contact angle and ellipsometer measurements. The molecular imprinting procedures were successfully carried out and it was found that the prepared polymeric surfaces were highly desirable for sensitive recognition by QCM and SPR sensors. Competitive experiments for the sensors revealed that MW nanofilms were found to show more sensitivity and selectivity than NIP ones. The sensor responses have a good linear relationship with 2,4-D concentrations in the range of 0.23-8.0 nM with a limit of detection at 20.17 ng/L for QCM and 24.57 ng/L for SPR sensors. In conclusion, both QCM and SPR sensor systems showed good accuracy and precision, with recovery percentages between 90 and 92% and 87-93%, respectively. Furthermore, they have a fast response time, reusability, high selectivity and sensitivity and low limit of detection.
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    Öğe
    Preparation of a new quartz crystal microbalance sensor based on molecularly imprinted nanofilms for amitrole detection
    (Biointerface Research Applied Chemistry, 2018) Cakir, Oguz; Yilmaz, Fatma; Baysal, Zubeyde; Denizli, Adil
    Quartz crystal microbalance (QCM) sensors have been used to detect a variety of biomolecules due to their simplicity, specificity and sensitivity, real-time measurement, low cost and no labeling requirements. A new QCM sensor was prepared by using molecular imprinting method for selective recognition of amitrole. N-metacryloyl-(L)-tryptophan methyl ester (MATrp) was selected as a proper functional monomer and polymerized with ethylene glycol dimethacrylate (EGDMA). Pesticide imprinted poly(ethylene glycol dimetacrylate-N-metacryloyl-(L)-tryptophan methyl ester) [poly(EGDMA-MATrp)] nanofilms were attached to gold surfaces of QCM sensor chips and were characterized by several techniques such as atomic force microscope (AFM), an ellipsometer, FTIR-ATR and contact angle measurements. Kinetic and affinity binding of amitrole was investigated by binding the pesticide imprinted and nonimprinted sensor chips to QCM sensor chips. The imprinted nanofilms were found to show more sensitivity towards the target molecule than the nonimprinted ones. Furthermore, adsorption kinetics were determined by passing pesticide solutions at different concentrations through QCM sensor systems. The most proper model was found to be Langmuir adsorption model for these affinity systems. In addition, competitive adsorption experiments were performed to display selectivity of the pesticide imprinted nanofilms. The prepared sensor was also efficiently applied for the selective detection of amitrole in green pepper.