Surface plasmon resonance based biomimetic sensor for urinary tract infections.

Tailor-made Escherichia coli (E. coli) receptors were created with microcontact imprinted technique and binding events of E. coli were carried out by a surface plasmon resonance (SPR) sensor in aqueous solution and in urine mimic in real time and label-free. N-methacryloyl-(l)-histidine methyl ester (MAH) was selected as a functional monomer to design tailor-made E. coli receptors on the polymeric film and during the formation of the polymeric film on a chip surface, Ag nanoparticles (AgNPs) were entrapped into the polymer mixture in order to lower the detection limit of biomimetic SPR based sensor. The polymeric film was characterized with atomic force microscopy (AFM), scanning electron microscopy (SEM), ellipsometer and contact angle measurements. Limit of detection (LOD) was found 0.57 CFU/mL and feasibility of the biomimetic sensor was investigated in urine mimic.

Microcontact Imprinted Plasmonic Nanosensors: Powerful Tools in the Detection of Salmonella paratyphi.

Identification of pathogenic microorganisms by traditional methods is slow and cumbersome. Therefore, the focus today is on developing new and quicker analytical methods. In this study, a Surface Plasmon Resonance (SPR) sensor with a microcontact imprinted sensor chip was developed for detecting Salmonella paratyphi. For this purpose, the stamps of the target microorganism were prepared and then, microcontact S. paratyphi-imprinted SPR chips were prepared with the functional monomer N-methacryloyl-L-histidine methyl ester (MAH). Characterization studies of the SPR chips were carried out with ellipsometry and scanning electron microscopy (SEM). The real-time Salmonella paratyphi detection was performed within the range of 2.5 × 106-15 × 106 CFU/mL. Selectivity of the prepared sensors was examined by using competing bacterial strains such as Escherichia coli, Staphylococcus aureus and Bacillus subtilis. The imprinting efficiency of the prepared sensor system was determined by evaluating the responses of the SPR chips prepared with both molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs). Real sample experiments were performed with apple juice. The recognition of Salmonella paratyphi was achieved using these SPR sensor with a detection limit of 1.4 × 106 CFU/mL. In conclusion, SPR sensor has the potential to serve as an excellent candidate for monitoring Salmonella paratyphi in food supplies or contaminated water and clearly makes it possible to develop rapid and appropriate control strategies.

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.

Synthesis of hydrophobic nanoparticles for real-time lysozyme detection using surface plasmon resonance sensor.

Diagnostic biomarkers such as proteins and enzymes are generally hard to detect because of the low abundance in biological fluids. To solve this problem, the advantages of surface plasmon resonance (SPR) and nanomaterial technologies have been combined. The SPR sensors are easy to prepare, no requirement of labelling and can be detected in real time. In addition, they have high specificity and sensitivity with low cost. The nanomaterials have also crucial functions such as efficiency improvement, selectivity, and sensitivity of the detection systems. In this report, an SPR-based sensor is developed to detect lysozyme with hydrophobic poly (N-methacryloyl-(L)-phenylalanine) (PMAPA) nanoparticles. The SPR sensor was first characterized by attenuated total reflection-Fourier transform infrared, atomic force microscope, and water contact angle measurements and performed with aqueous lysozyme solutions. Various concentrations of lysozyme solution were used to calculate kinetic and affinity coefficients. The equilibrium and adsorption isotherm models of interactions between lysozyme solutions and SPR sensor were determined and the maximum reflection, association, and dissociation constants were calculated by Langmuir model as 4.87, 0.019 nM-1 , and 54 nM, respectively. The selectivity studies of SPR sensor were investigated with competitive agents, hemoglobin, and myoglobin. Also, the SPR sensor was used four times in adsorption/desorption/recovery cycles and results showed that, the combination of optical SPR sensor with hydrophobic ionizable PMAPA nanoparticles in one mode enabled the detection of lysozyme molecule with high accuracy, good sensivity, real-time, label-free, and a low-detection limit of 0.66 nM from lysozyme solutions. Lysozyme detection in a real sample was performed by using chicken egg white to evaluate interfering molecules present in the medium.

Plastic antibody based surface plasmon resonance nanosensors for selective atrazine detection.

This study reports a surface plasmon resonance (SPR) based affinity sensor system with the use of molecular imprinted nanoparticles (plastic antibodies) to enhance the pesticide detection. Molecular imprinting based affinity sensor is prepared by the attachment of atrazine (chosen as model pesticide) imprinted nanoparticles onto the gold surface of SPR chip. Recognition element of the affinity sensor is polymerizable form of aspartic acid. The imprinted nanoparticles were characterized via FTIR and zeta-sizer measurements. SPR sensors are characterized with atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FTIR) and contact angle measurements. The imprinted nanoparticles showed more sensitivity to atrazine than the non-imprinted ones. Different concentrations of atrazine solutions are applied to SPR system to determine the adsorption kinetics. Langmuir adsorption model is found as the most suitable model for this affinity nanosensor system. In order to show the selectivity of the atrazine-imprinted nanoparticles, competitive adsorption of atrazine, simazine and amitrole is investigated. The results showed that the imprinted nanosensor has high selectivity and sensitivity for atrazine.

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.

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.

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 mum, 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.