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    The Detection of Chemical and Biological Threat Agents Using Nanomaterial-Based Plasmonic Nanosensors
    (CRC Press, 2024) Aşir, Süleyman; Türkmen, Deniz; Ovezova, Mamajan; Göktürk, Ilgim; Yilmaz, Gaye Ezgi; Yilmaz, Fatma
    It is important to detect chemical and biological threat agents for homeland security and defense, and new detection methods with intelligent capabilities need to be developed. The hazards caused by biological and chemical threat agents and the limited availability of modern methods for detecting these agents form the basis of the need to develop new sensors. In recent years, nanomaterial-based plasmonic sensors have been widely used in applications for detecting chemical and biological threat agents due to their advantages. The large surface area to volume ratio of nanomaterials has enabled many possibilities for the creation of new nanosensors to be used for sensing. Herein, we provide an overview of biological and chemical threat agents. After giving a brief overview of the working principles of plasmonic sensors, the applications used to detect a broad spectrum of biological and chemical threat agents is extensively discussed. The final section summarizes concluding remarks about the identification of biological and chemical threat agents using nanomaterial-based plasmonic nanosensors and future perspectives. © 2024 selection and editorial matter, Adil Denizli; individual chapters, the contributors.
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    Dye affinity cryogels for plasmid DNA purification
    (Elsevier, 2015) Çimen, Duygu; Yılmaz, Fatma; Perçin, Işık; Türkmen, Deniz; Denizli, Adil
    The aim of this study is to prepare megaporous dye-affinity cryogel discs for the purification of plasmid DNA (pDNA) from bacterial lysate. Poly(hydroxyethyl methacrylate) [PHEMA] cryogel discs were produced by free radical polymerization initiated by N,N,N',N'-tetramethylene diamine (TEMED) and ammonium persulfate (APS) redox pair in an ice bath. Cibacron Blue F3GA was used as an affinity ligand (loading amount: 68.9 mu mol/g polymer). The amount of pDNA adsorbed onto the PHEMA-Cibacron Blue F3GA cryogel discs first increased and then reached a plateau value (i.e., 32.5 mg/g cryogel) at 3.0 mg/mL pDNA concentration. Compared with the PHEMA cryogel (0.11 mg/g cryogel), the pDNA adsorption capacity of the PHEMA-Cibacron Blue F3GA cryogel (32.4 mg/g polymer) was improved significantly due to the Cibacron Blue 3GA immobilization onto the polymeric matrix. pDNA adsorption amount decreased from 11.7 mg/g to 1.1 mg/g with the increasing of NaCl concentration. The maximum pDNA adsorption was achieved at 4 degrees C The overall recovery of pDNA was calculated as 90%. The PHEMA-Cibacron Blue F3GA cryogel discs could be used five times without decreasing the pDNA adsorption capacity significantly. The results show that the PHEMA-Cibacron Blue F3GA cryogel discs promise high selectivity for pDNA. (C) 2015 Elsevier B.V. All rights reserved.
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    Electrochemical detection of cortisol by silver nanoparticle-modified molecularly ımprinted polymer-coated pencil graphite electrodes
    (Amer Chemical Soc, 2023) Shama, Nemah Abu; Asır, Süleyman; Göktürk, Ilgım; Yılmaz, Fatma; Türkmen, Deniz; Denizli, Adil
    The sensitive cortisoldetection by an electrochemicalsensor basedon silver nanoparticle-doped molecularly imprinted polymer was successfullyimproved. This study describes the method development for cortisoldetection in both aqueous solution and biological samples using molecularlyimprinted poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-histidine methyl ester)-coated pencil graphite electrodesmodified with silver nanoparticles (AgNPs) by differential pulse voltammetry(DPV). The cortisol-imprinted pencil graphite electrode (PGE) hasa large surface area because of doped AgNPs with enhanced electroactivity.The prepared molecularly imprinted polymer was characterized by scanningelectron microscopy. The DPV response of the synthesized electrodewith outstanding electrical conductivity was clarified. Cortisol-imprintedpolymer-coated PGEs (MIP), cortisol-imprinted polymer-coated PGEswith AgNPs (MIP@AgNPs), and nonimprinted polymer-coated PGEs withAgNPs (NIP@AgNPs) were evaluated for sensitive and selective detectionof cortisol in aqueous solution. Five different cortisol concentrations(0.395, 0.791, 1.32, 2.64, and 3.96 nM) were applied to the MIP@AgNPs,and signal responses were detected by the DPV with a regression coefficient(R (2)) value of 0.9951. The modified electrodeshowed good electrocatalytic activity toward cortisol for the linearconcentration range from 0.395 to 3.96 nM, and a low limit of detectionwas recorded as 0.214 nM. The results indicate that the MIP@AgNPssensor has great potential for sensitive and selective cortisol determinationin biological samples.
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    Gold-modified molecularly imprinted N-methacryloyl-(l)-phenylalanine-containing electrodes for electrochemical detection of dopamine
    (MDPI, 2022) Shama, Nemah Abu; Aşır, Süleyman; Özsöz, Mehmet; Göktürk, Ilgım; Türkmen, Deniz; Yılmaz, Fatma; Denizli, Adil
    A molecularly imprinted polymer-based pencil graphite electrode (MIP PGE) sensor, modified with gold nanoparticles, was utilized for the detection of dopamine in the presence of other biochemical compounds using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), depending on its strong electroactivity function. The pulse voltammetry methods recorded the highest response. In addition to the high oxidation rate of DA and the other biomolecule interferences available in the sample matrix used, which cause overlapping voltammograms, we aimed to differentiate them in a highly sensitive limit of detection range. The calibration curves for DA were obtained using the CV and DPV over the concentration range of 0.395-3.96 nM in 0.1 M phosphate buffer solution (PBS) at pH 7.4 with a correlation coefficient of 0.996 and a detection limit of 0.193 nM. The electrochemical technique was employed to detect DA molecules quantitatively in human blood plasma selected as real samples without applying any pre-treatment processes. MIP electrodes proved their ability to detect DA with high selectivity, even with epinephrine and norepinephrine competitor molecules and interferences, such as ascorbic acid (AA). The high level of recognition achieved by molecularly imprinted polymers (MIPs) is essential for many biological and pharmaceutical studies.
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    Megaporous poly(hydroxy ethylmethacrylate) based poly(glycidylmethacrylate-N-methacryloly-(L)-tryptophan) embedded composite cryogel
    (Elsevier Science Bv, 2015) Türkmen, Deniz; Bereli, Nilay; Derazshamshir, Ali; Perçin, Işık; Shaikh, Huma; Yılmaz, Fatma
    One-step activation, purification, and stabilization of lipase enzyme were performed by using composite hydrophobic support at low ionic strength with increased surface area during embedding process. A novel hydrophobic poly(hydroxyethylmethacrylate) [PHEMA] based, poly(glycidyl methacrylate-N-methacryloly-(L)-tryptophan) [PGMATrp] bead embedded composite cryogel membrane having specific surface area of 195 m(2)/g was used as hydrophobic matrix for adsorption of commercial Candida Rugosa lipase in a continuous system. PGMATrp embedded PHEMA cryogel membrane with 60-100 mu m pore size was obtained by dispersion polymerization of GMA and MATrp to form PGMATrp beads followed by embedding of PGMATrp to HEMA via APS and TEMED redox pair. The introduction of hydrophobic MATrp monomer into bead structure aiming to increase interaction between lipase and composite membrane was estimated using nitrogen stoichiometry of elemental analysis and found to be 239 mu mol/g of polymer. Hydophobicity increment due to embedding process was confirmed by measuring contact angle, it was found 42 degrees and 48.4 degrees for the PHEMA and PHEMA/PGMATrp composite cryogel respectively. Some parameters i.e. pH, flow-rate, protein concentration, temperature, salt type and ionic intensity were evaluated on the adsorption capacity in a continuous system. Fast protein liquid chromatography (FPLC) studies were performed for specific adsorption of lipase onto the PHEMA/PGMATrp embedded composite cryogel membrane. (C) 2015 Elsevier B.V. All rights reserved.
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    Selective dopamine detection by SPR sensor signal amplification using gold nanoparticles
    (ROYAL SOC CHEMISTRY, 2021) Türkmen, Deniz; Bakhshpour, Monireh; Göktürk, Ilgım; Aşır, Süleyman; Yılmaz, Fatma
    In this study, selective and sensitive detection of the neurotransmitter dopamine (DA) in both aqueous solution and biological samples was performed using a surface plasmon resonance (SPR) sensor based on a molecular imprinting technique. For this, dopamine-imprinted poly(2-hydroxyethyl methacrylate-N-methacroyl-(l)-cysteine methyl ester-gold nanoparticles-N-methacryloyl-l-phenylalanine methyl ester) [PHEMAC-AuNPs/MAPADA] nanoparticles were prepared. Furthermore, to evaluate the imprinting efficiency, non-imprinted [PHEMAC-AuNPs/MAPA] nanoparticles were designed using the same polymerization procedure except for the addition of dopamine molecules. To examine the effect of incorporating AuNPs to increase the SPR signal response, control experiments were carried out via the SPR biosensor produced using [PHEMAC/MAPADA] nanoparticles prepared without the addition of AuNPs. Characterization studies of dopamine- + imprinted [PHEMAC-AuNPs/MAPADA] and non-imprinted [PHEMAC-AuNPs/MAPA] nanoparticles was performed with a zetasizer and an FTIR-ATR spectrophotometer. In addition, dopamine-imprinted [PHEMAC-AuNPs/MAPADA] and non-imprinted [PHEMAC-AuNPs/MAPADA] SPR sensors were characterized by ellipsometer and contact angle measurements. The high imprinting efficiency (I.F: 9.67) of the dopamine-imprinted [PHEMAC-AuNPs/MAPADA] SPR sensor was determined by comparing it with the non-imprinted [PHEMAC-AuNPs/MAPA] SPR sensor. A good linear relationship was obtained in the 0.01-0.5 ppb concentration range with correlation coefficients of 0.9818 and 0.9819, respectively. The dopamine-imprinted [PHEMAC-AuNPs/MAPADA] SPR sensor was 5.53 and 4.59 times more selective for the target molecule dopamine than for epinephrine (EP) and norepinephrine (NE), respectively. The repeatability of the [PHEMAC-AuNPs/MAPADA] SPR sensor was assessed with a 0.5 ppb dopamine solution, with the percent relative standard deviation of the intra-assays (RSD) being less than 1.7%, indicating negligible loss of dopamine sensing capability after four adsorption-desorption cycles with the same sensor.
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    Simple and fast pesticide nanosensors: Example of surface plasmon resonance coumaphos nanosensor
    (MDPI, 2023) Oymen, Beste; Jalilzadeh, Mitra; Yılmaz, Fatma; Aşır, Süleyman; Türkmen, Deniz; Denizli, Adil
    Here, a molecular imprinting technique was employed to create an SPR-based nanosensor for the selective and sensitive detection of organophosphate-based coumaphos, a toxic insecticide/veterinary drug often used. To achieve this, UV polymerization was used to create polymeric nanofilms using N-methacryloyl-l-cysteine methyl ester, ethylene glycol dimethacrylate, and 2-hydroxyethyl methacrylate, which are functional monomers, cross-linkers, and hydrophilicity enabling agents, respectively. Several methods, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle (CA) analyses, were used to characterize the nanofilms. Using coumaphos-imprinted SPR (CIP-SPR) and non-imprinted SPR (NIP-SPR) nanosensor chips, the kinetic evaluations of coumaphos sensing were investigated. The created CIP-SPR nanosensor demonstrated high selectivity to the coumaphos molecule compared to similar competitor molecules, including diazinon, pirimiphos-methyl, pyridaphenthion, phosalone, N-2,4(dimethylphenyl) formamide, 2,4-dimethylaniline, dimethoate, and phosmet. Additionally, there is a magnificent linear relationship for the concentration range of 0.1-250 ppb, with a low limit of detection (LOD) and limit of quantification (LOQ) of 0.001 and 0.003 ppb, respectively, and a high imprinting factor (I.F.4.4) for coumaphos. The Langmuir adsorption model is the best appropriate thermodynamic approach for the nanosensor. Intraday trials were performed three times with five repetitions to statistically evaluate the CIP-SPR nanosensor's reusability. Reusability investigations for the two weeks of interday analyses also indicated the three-dimensional stability of the CIP-SPR nanosensor. The remarkable reusability and reproducibility of the procedure are indicated by an RSD% result of less than 1.5. Therefore, it has been determined that the generated CIP-SPR nanosensors are highly selective, rapidly responsive, simple to use, reusable, and sensitive for coumaphos detection in an aqueous solution. An amino acid, which was used to detect coumaphos, included a CIP-SPR nanosensor manufactured without complicated coupling methods and labelling processes. Liquid chromatography with tandem mass spectrometry (LC/MS-MS) studies was performed for the validation studies of the SPR.