Erkut Yılmaz

Quartz crystal microbalance based nanosensor for lysozyme detection with lysozyme imprinted nanoparticles

The aim of this study is to prepare quartz crystal microbalance (QCM) nanosensor for the real-time detection of lysozyme. In the first part, the lysozyme imprinted (MIP) nanoparticles were prepared by mini-emulsion polymerization. The MIP nanoparticles were characterized by TEM, zeta-sizer and FTIR-ATR measurements. Particle size was found around 50 nm. The MIP nanoparticles were attached by dropping of nanoparticle solution to gold surface and then, dried at 37°C for 6h. QCM nanosensor was characterized with AFM and ellipsometer. The observations indicated that the nanoparticle film was almost monolayer. The detection limit was found as 1.2 ng/mL. The specificity of the QCM nanosensor was shown by using albumin as a competitor molecule. The results show that the QCM nanosensor has high selectivity and sensitivity with a wide range of lysozyme concentrations in both aqueous solutions (0.2-1500 μg/mL) and natural sources (egg white) (460-1500 ng/mL).

Selective separation of human serum albumin with copper(II) chelated poly(hydroxyethyl methacrylate) based nanoparticles.

Poly(hydroxyethyl methacrylate) (PHEMA) nanoparticles with an average size of 300 nm in diameter and with a polydispersity index of 1.156 were produced by surfactant free emulsion polymerization. Specific surface area of the PHEMA nanoparticles was found to be 996 m(2)/g. Metal-chelating ligand 3-(2-imidazoline-1-yl)propyl(triethoxysilane) (IMEO) was covalently attached to the PHEMA nanoparticles. IMEO content was 0.97 mmol IEMO/g. The morphology and properties of these nanoparticles were characterized with scanning electron microscopy, Fourier transform infrared spectroscopy and atomic force microscopy. The Cu2+-chelated PHEMA-IMEO nanoparticles were used in the adsorption-elution studies of human serum albumin (HSA) in a batch system. Maximum HSA adsorption amount of the Cu2+ chelated nanoparticles was 680 mg HSA/g. The PHEMA-IMEO-Cu2+ nanoparticles exhibited a quite high adsorption capacity and fast adsorption rate due to their high specific surface area and the absence of internal diffusion resistance.

Specific adsorption of the autoantibodies from rheumatoid arthritis patient plasma using histidine-containing affinity beads

Rheumatoid arthritis is characterized by chronic polyarthritis and destruction of multiple joints. In this study, poly(hydroxyethyl methacrylate-N-methacryloyl-(L-histidine)-methylester) (PHEMAH) beads were used in the removal of pathogenic antibodies from rheumatoid arthritis patient plasma in a packed bed column. PHEMAH beads, in the size range of 80–120 μm, were produced by suspension polymerization. The beads were contacted with blood in an in vitro system. Loss of blood cells and clotting times were followed. PHEMAH beads were characterized by scanning electron microscopy. We found that PHEMAH beads had a spherical shape and porous structure. Loss of cells in the blood contacting with PHEMAH beads was negligible. IgM-antibody adsorption capacity decreased significantly with the increase of the plasma flow-rate. With increasing IgM-antibody concentration, the amount of IgM-antibody adsorbed per unit mass increased and then reached saturation. Maximum IgM-antibody adsorption amount was 69.2 mg/g. IgM-antibody molecules could be repeatedly adsorbed and desorbed without noticeable loss in the IgM-antibody adsorption amount.

Cibacron Blue F3GA modified disposable pencil graphite electrode for the investigation of affinity binding to bovine serum albumin

In this work, Cibacron Blue F3GA (CB) modified pencil graphite electrodes (PGEs) were prepared and their affinities to bovine serum albumin were investigated. Preparation of the PGEs was performed using cyclic voltammetry (CV) and passive adsorption techniques. Improved electrochemical results were obtained with the PGEs prepared by CV technique compared to the PGEs prepared by passive adsorption technique. In order to obtain more sensitive results number of scans used in CV technique and the effect of concentration of CB were studied. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS) were used for the characterization of modified electrodes. The modified PGEs were then used for the electrochemical monitoring of affinity interaction between CB and bovine serum albumin. The effect of BSA concentration and interfering species (tryptophan, glucose and immunoglobulin G) on the response of the electrode were examined. The aim of this study was to prepare an easy, fast, stable and cheap modified electrode for the investigation of the well-known affinity of CB to serum albumin. The electrochemistry can provide alternative routes for dye-protein interaction instead of using classical time-consuming methods.

Molecular Imprinting Applications in Forensic Science

Producing molecular imprinting-based materials has received increasing attention due to recognition selectivity, stability, cast effectiveness, and ease of production in various forms for a wide range of applications. The molecular imprinting technique has a variety of applications in the areas of the food industry, environmental monitoring, and medicine for diverse purposes like sample pretreatment, sensing, and separation/purification. A versatile usage, stability and recognition capabilities also make them perfect candidates for use in forensic sciences. Forensic science is a demanding area and there is a growing interest in molecularly imprinted polymers (MIPs) in this field. In this review, recent molecular imprinting applications in the related areas of forensic sciences are discussed while considering the literature of last two decades. Not only direct forensic applications but also studies of possible forensic value were taken into account like illicit drugs, banned sport drugs, effective toxins and chemical warfare agents in a review of over 100 articles. The literature was classified according to targets, material shapes, production strategies, detection method, and instrumentation. We aimed to summarize the current applications of MIPs in forensic science and put forth a projection of their potential uses as promising alternatives for benchmark competitors.

Multiclonal plastic antibodies for selective aflatoxin extraction from food samples

Herein, we focused on developing a new generation of monolithic columns for extracting aflatoxin from real food samples by combining the superior features of molecularly imprinted polymers and cryogels. To accomplish this, we designed multiclonal plastic antibodies through simultaneous imprinting of aflatoxin subtypes B1, B2, G1, and G2. We applied Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and spectrofluorimetry to characterize the materials, and conducted selectivity studies using ochratoxin A and aflatoxin M1 (a metabolite of aflatoxin B1), as well as other aflatoxins, under competitive conditions. We determined optimal aflatoxin extraction conditions in terms of concentration, flow rate, temperature, and embedded particle amount as up to 25ng/mL for each species, 0.43mL/min, 7.0, 30°C, and 200mg, respectively. These multiclonal plastic antibodies showed imprinting efficiencies against ochratoxin A and aflatoxin M1 of 1.84 and 26.39, respectively, even under competitive conditions. Finally, we tested reusability, repeatability, reproducibility, and robustness of columns throughout inter- and intra-column variation studies.