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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, ZubeydeThis 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.Öğe Pestisit tayini için manopartiküllerle duyarlılığı arttırılmış moleküler baskılama temelli yüzey plazmon rezonans sensörlerin hazırlanması(Iğdır Üniversitesi Fen Bilimleri Enstitüsü, 2018) Çakır, Oğuz; Bakhshpour, Monireh; Yılmaz, Fatma; Baysal, ZübeydePestisitler yıllardır tarım alanlarında kullanılmaktadır. Ancak bu yaygın kullanım, bilimsel ve endüstriyel topluluklarda pestisitlerin uzun vadeli insan sağlığı riskleri üzerine bilinen toksisitelerinden dolayı endişeyi arttırmıştır. Böylelikle pestisitlerin tayin edilmesi, hem insanlar üzerinde artan toksik etkilerinden hem de kullanımının kontrol altına alınmasından dolayı büyük bir öneme sahiptir. Bu çalışmada, seçici, hassas, hızlı ve gerçek zamanlı klorpirifos tayini için ilk olarak, poli[etilenglikol dimetakrilat-N-metakriloil-(l)-triptofan metil ester poly(EGDMA-MATrp) nanopartikülleri hazırlandı ve zeta sizer ile karakterize edildi. Ardından, klorpirifos baskılı SPR nanosensör hazırlanarak atomik kuvvet mikroskobu (AFM) ve temas açısı ölçümleri ile karakterize edildi. Kalınlık ölçümleri ve AFM görüntüleri, nanopartiküllerden oluşan ince filmlerin hemen hemen tek tabakalı olduğunu gösterdi. Baskılanmış ve baskılanmamış nanosensörlerin klorpirifos tayin duyarlılığı 0.015-2.9 nM aralığında klorpirifos çözeltileri ile araştırıldı. Baskılanmış nanopartiküllerin, baskılanmamışlara göre daha fazla duyarlılık gösterdiği belirlendi. Langmuir adsorpsiyon modeli, bu afinite sistemi için en uygun model olarak belirlendi. Klorpirifos baskılanmış nanopartiküllerin seçiciliğini göstermek için 2.9 nM derişimindeki klorpirifos, diazinon ve parationun yarışmalı adsorpsiyonu araştırıldı. Sonuç olarak, SPR nanosensörlerin hızlı yanıt, kullanım kolaylığı, hassasiyet, seçicilik ve gerçek zamanlı ölçüm alınabilme özelliğinden dolayı pestisit analizleri için alternatif bir yöntem olarak kullanılma potansiyeline sahip olduğu görüldü.Öğe Poly(Hydroxyethyl methacrylate) immunoaffinity cryogel column for the purification of human immunoglobulin M(MDPI Multidisciplinary Digital Publishing Institute, 2020) Bakhshpour, Monireh; Topçu, Aykut Arif; Bereli, Nilay; Alkan, Huseyin; Denizli, AdilHuman immunoglobulin M (hIgM) antibodies are considered as hopeful tools for diseases therapy. Therefore, chromatography approaches are used to purify hIgM with a single step. In this study, we prepared a poly(hydroxyethyl methacrylate) based immunoaffinity p(HEMA-I) cryogel column by using cyanamide to immobilize antihuman immunoglobulin on the p(HEMA) cryogel for purification of hIgM in aqueous solution and artificial human plasma. The characterization of the p(HEMA) cryogel column was performed by using a scanning electron microscope (SEM), micro-computerized tomography (µ-CT), Fourier transform infrared spectroscopy (FTIR), swelling degree and macro-porosity. Further, the optimizations of various parameters were performed such as, pH, ionic strength, temperature and concentration of hIgM in aqueous solutions. In addition, the Langmuir adsorption model was supported by experimental results. Maximum adsorbed amount of hIgM corresponded to 11.1 mg/g at pH 5.75 [morpholino ethanesulfonic acid (MES buffer)]. Our results indicated that the p(HEMA-I) cryogel column can be reused at least 10 times without significant loss in adsorption capacity. As a natural source, artificial human plasma was selected for hIgM adsorption and the purity of hIgM was evaluated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).Öğe Sensitive and selective detection of amitrole based on molecularly imprinted nanosensor(Wiley, 2021) Çakır, Oğuz; Bakhshpour, Monireh; Göktürk, İlgim; Yılmaz, Fatma; Baysal, ZübeydeHerein, a surface plasmon resonance (SPR)-based nanosensor was fabricated using molecular imprinting technique for the selective and sensitive detection of amitrole, a commonly used highly toxic pesticide. For this purpose, polymeric nanofilms involving N-methacryloyl-L-tryptophan methyl ester and ethylene glycol dimethacrylate which are functional monomer and cross-linker, respectively, were prepared on the SPR chips surface via the ultravoilet polymerization method. The nanofilms were characterized by several techniques such as ellipsometry, Fourier transform infrared-attenuated total reflection, atomic force microscope and contact angle measurements. The kinetic analyses for amitrole detection were examined through amitrole-imprinted and nonimprinted SPR sensor chips. The developed imprinted sensor showed high selectivity to the amitrole molecule than similar molecules and a good linear relationship for the 0.06-11.90 nM concentration range with a low limit of detection value of 0.037 nM. The high imprinting efficiency (I.F: 62.38) of the amitrole-imprinted SPR sensor was determined by comparing it with the non-imprinted SPR sensor. The most suitable model of this sensor is the Langmuir adsorption model. To statistically assess the reusability of the sensor, intraday experiments were tested three times with five replicates. The relative standard deviation% value less than <1.5 indicates high reproducibility for both sensor production and reproducibility of the method. The prepared sensor was also applied efficiently for the selective detection of the amitrole in spiked samples prepared from vegetables to evaluate the matrix effect. As a result, amitrole-imprinted SPR sensors have been estimated to be highly selective, fast responsive, easy to use, reusable and sensitive in detecting amitrole in both natural source and aqueous solutions. Label-free amitrole detection was performed by an aminoacid-based SPR sensor fabricated without the need for complex coupling processes.
