Recep Üzek

Nanospines incorporation into the structure of the hydrophobic cryogels via novel cryogelation method: An alternative sorbent for plasmid DNA purification

In this study, it was aimed to prepare hydrophobic cryogels for plasmid DNA (pDNA) purification from Escherichia coli lysate. The hydrophobicity was achieved by incorporating a hydrophobic ligand, N-methacryloyl-(L)-phenylalanine (MAPA), into the cryogel backbone. In addition to the conventional cryogelation process, freeze-drying step was included to create nanospines. Three different cryogels {poly(2-hydoxyethyl methacrylate-N-methacryloyl-L-phenylalanine)-freeze dried, [P(HEMA-MAPA)-FD]; poly(2-hydoxyethyl methacrylate-N-methacryloyl-L-phenylalanine, [P(HEMA-MAPA)] and poly(2-hydoxyethyl methacrylate)-freeze dried, [P(HEMA)-FD]} were prepared, characterized, and used for DNA (salmon sperm DNA) adsorption studies from aqueous solution. The specific surface areas of cryogels were determined to be 21.4 m(2)/g for P(HEMA)-FD, 17.65 m(2)/g for P(HEMA-MAPA) and 36.0 m(2)/g for P(HEMA-MAPA)-FD. The parameters affecting adsorption such as temperature, initial DNA concentration, salt type and concentration were examined in continuous mode. The maximum adsorption capacities were observed as 45.31 mg DNA/g, 27.08 mg DNA/g and 1.81 mg DNA/g for P(HEMA-MAPA)-FD, P(HEMA-MAPA) and P(HEMA)-FD, respectively. Desorption process was performed using acetate buffer (pH 5.50) without salt. First, pDNA was isolated from E. coli lysate and the purity of pDNA was then determined by agarose gel electrophoresis. Finally, the chromatographic performance of P(HEMA-MAPA)-FD cryogel for pDNA purification was tested in FPLC. The resolution (R(s)) was 2.84, and the specific selectivity for pDNA was 237.5-folds greater than all impurities.

Fabrication of surface plasmon resonance nanosensor for the selective determination of erythromycin via molecular imprinted nanoparticles

The main objective of this study was to develop a novel surface plasmon resonance (SPR) nanosensor method based on a more rapid and selective determination of erythromycin (ERY) in the aqueous solution. This study is a combination of three techniques, which are miniemulsion polymerization, molecular imprinting and surface plasmon resonance techniques. In the first part, nanoparticles prepared with methacryl groups of functional monomer at surface acted as reactive sites for erythromycin as a template molecule. The molecularly imprinted nanoparticles were characterized by FTIR, SEM and zetasizer. After immobilization of nanoparticles on gold surface of SPR chip, nanosensor was characterized with contact angle measurements. This nanosensor was then used for selective determination of erythromycin. The linearity range and detection limit were obtained as 0.99 (r(2)) and 0.29 ppm, respectively. Association kinetic analysis, Scatchard, Langmuir, Freundlich and Freundlich-Langmuir isotherms were applied data. The selectivity of the SPR nanosensor was determined by using competitor agents (kanamycin sulfate, neomycin sulfate, spiramycin). The non-imprinted nanosensor was also used to evaluate the selectivity of ERY imprinted nanosensor. Finally, the nanosensor was tested for repeatability and it gave satisfactory response. These results demonstrate a method which is of low cost, rapid and provide reliable results in order to be used in detection of erythromycin from aqueous solution.

Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles

In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes.

Surface imprinting approach for preparing specific adsorbent for IgG separation

In this study, we focused our attention on preparing of a new adsorbent for specific separation of immunoglobulin G (IgG). In this respect, we applied core–shell surface imprinting approach. Silica microspheres were selected as core-material to prepare specific surface imprinted polymer against IgG. Silica surface was activated via acidic treatment and modified with 3-methacryloyloxypropyl trimethoxysilane (MPTMS). Then, IgG molecules were imprinted on the surface of microspheres by using N-methacryloyl-L-aspartic acid as complexing/functional monomer. The core–shell silica microspheres were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, thermo gravimetric analysis and zeta size analysis. Then, the microspheres were used for the separation of IgG from aqueous solution to evaluate/optimize conditions. The effect of parameters such as concentration, pH, ionic strength, and temperature on the separation of IgG were evaluated in their relevant ranges. The maximum IgG adsorption capacities of IgG-imprinted and non-imprinted core–shell silica microspheres were found to be 15.43 and 9.43u2009mg/g, respectively, at pH 6.0 phosphate buffer. 1.0u2009M NaCl was used as a desorption agent. Selectivity of the imprinted microspheres was also investigated by using human serum albumin and haemoglobin as competitor molecules.

Molecularly imprinted surface plasmon resonance (SPR) based sensing of bisphenol A for its selective detection in aqueous systems

Bisphenol A (BPA) imprinted poly(ethylene glycol dimethacrylate-N-methacryloyl-L-phenylalanine-vinyl imidazole) [poly(EGDMA-MAPA-VI)] film deposition on a SPR sensor with improved efficiency is described in this paper. The molecularly imprinted SPR sensor was characterized by FTIR-ATR, atomic force microscopy and ellipsometry. A water-compatible molecularly imprinted film has been developed for rapid, sensitive, and label-free detection of BPA in aqueous solutions prepared in Milli Q water, tap water and synthetic wastewater. The real-time response allows the detection of BPA with concentrations ranging from 0.08 to 10 μg L−1 with LOD and LOQ values of 0.02 and 0.08 μg L−1 in Milli Q water, 0.06 and 0.2 μg L−1 in tap water and 0.08 and 0.3 μg L−1 in synthetic wastewater, respectively. A significant increase in sensitivity was therefore expected due to the use of the imprinted poly(EGDMA-MAPA-VI) thin film. The method showed good recoveries and precision for the samples spiked with BPA. The results suggest that the imprinted SPR sensing method can be used as a promising alternative for the detection of BPA. The sensor data fitted well with the Langmuir adsorption model. The selectivity studies showed that the imprinted cavities formed in the polymeric nanofilm recognize BPA preferentially rather than 4-nitrophenol, hydroquinone, phenol and 8-hydroxy quinoline with a relative selectivity coefficient of 2.5, 2.6, 2.7 and 2.5, respectively. The prepared BPA imprinted SPR sensor enables high sensitivity, label-free detection, real-time monitoring, low volume sample consumption, quantitative evaluation, and determination of kinetic rate constants very well. In addition, the SPR based BPA sensor is easy to use and can be a cost effective solution due to the reusability of the prepared sensor. Furthermore, the storage stability will be higher than antibody-based detection methods.

Synthesis of a specific monolithic column with artificial recognition sites for L-glutamic acid via cryo-crosslinking of imprinted nanoparticles

In this study, a new molecular imprinting (MIP)-based monolithic cryogel column was prepared using chemically crosslinked molecularly imprinted nanoparticles, to achieve a simplified chromatographic separation (SPE) for a model compound, L-glutamic acid (L-Glu). Cryogelation through crosslinking of imprinted nanoparticles forms stable monolithic cryogel columns. This technique reduces the leakage of nanoparticles and increases the surface area, while protecting the structural features of the cryogel for stable and efficient recognition of the template molecule. A non-imprinted monolithic cryogel column (NIP) was also prepared, using non-imprinted nanoparticles produced without the addition of L-Glu during polymerization. The molecularly imprinted monolithic cryogel column (MIP) indicates apparent recognition selectivity and a good adsorption capacity compared to the NIP. Also, we have achieved a significant increase in the adsorption capacity, using the advantage of high surface area of the nanoparticles.

Detection of ciprofloxacin through surface plasmon resonance nanosensor with specific recognition sites

Abstract The novel nanosensor based on Surface Plasmon Resonance (SPR) was developed for sensitive and selective detection of ciprofloxacin via molecularly imprinted nanoparticles (MIP/NPs). NPs were synthesized through miniemulsion polymerization technique with methacrylic acid as a functional monomer. FTIR, SEM, zetasizer and contact angle measurements were used for the characterization of MIP/NPs. After modification the SPR chip surface, the nanosensor was used for detection of ciprofloxacin in aqueous solution. According to selected concentration range, the correlation coefficient and limit of detections were obtained as 0.993 (R2) and 3.21 and 7.1 ppb in ultrapure water and SWW, respectively. Association kinetic analysis, Scatchard, Freundlich, Langmuir and Freundlich-Langmuir isotherms were also performed on the data to investigate adsorption behaviour of ciprofloxacin on the surface of nanosensor. Tetracycline and enrofloxacin were used as competitor agents to examine the selectivity of nanosensor. Performance of the SPR nanosensor was also investigated by using synthetic wastewater (SWW) for detection of CPX. The reusability of nanosensor was investigated and good repeatability was obtained with 5.81% RSD. As a result, selective, simple and low-cost method to detect ciprofloxacin in aqueous solution was developed by combining MIP/NPs and SPR.