Yeşeren Saylan

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 9.43 mg/g, respectively, at pH 6.0 phosphate buffer. 1.0 M 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.

Molecular Imprinting of Macromolecules for Sensor Applications

Molecular recognition has an important role in numerous living systems. One of the most important molecular recognition methods is molecular imprinting, which allows host compounds to recognize and detect several molecules rapidly, sensitively and selectively. Compared to natural systems, molecular imprinting methods have some important features such as low cost, robustness, high recognition ability and long term durability which allows molecularly imprinted polymers to be used in various biotechnological applications, such as chromatography, drug delivery, nanotechnology, and sensor technology. Sensors are important tools because of their ability to figure out a potentially large number of analytical difficulties in various areas with different macromolecular targets. Proteins, enzymes, nucleic acids, antibodies, viruses and cells are defined as macromolecules that have wide range of functions are very important. Thus, macromolecules detection has gained great attention in concerning the improvement in most of the studies. The applications of macromolecule imprinted sensors will have a spacious exploration according to the low cost, high specificity and stability. In this review, macromolecules for molecularly imprinted sensor applications are structured according to the definition of molecular imprinting methods, developments in macromolecular imprinting methods, macromolecular imprinted sensors, and conclusions and future perspectives. This chapter follows the latter strategies and focuses on the applications of macromolecular imprinted sensors. This allows discussion on how sensor strategy is brought to solve the macromolecules imprinting.

Surface plasmon resonance sensors for real-time detection of cyclic citrullinated peptide antibodies

ABSTRACT Surface plasmon resonance (SPR) sensors have been used for detection of various biomolecules because of their simplicity, high specificity and sensitivity, real-time detection, low cost, and no requirement of labeling. Recently, molecularly imprinted polymers that are easy to prepare, less expensive, stable, have talent for molecular recognition and also are used for creation selective binding sites for target molecule on the SPR sensors. Here, we show that preparation of cyclic citrullinated peptide antibody (anti-CCP) imprinted SPR sensor to detect CCP antibodies. For this purpose, anti-CCP/AAm pre-complex was synthesized by interacting acrylamide (AAm) monomer with anti-CCP. Then, anti-CCP imprinted (anti-CCP/PAAm) SPR sensor was obtained by reacting with anti-CCP/AAm pre-complex in the presence of the crosslinker, and initiator/activator pair. Besides this, non-imprinted (PAAm) SPR sensor was also prepared without using anti-CCP template. The SPR sensors were characterized and then adsorption-desorption studies were performed with pH 7.0 phosphate buffer (10 mM) and acetic acid (10%) with Tween 20 (1%) in pH 7.0 phosphate buffer. Selectivitiy of sensors was investigated by using immunoglobulin M (IgM) and bovine serum albumin (BSA). To determine the adsorption model of interactions between anti-CCP solutions and anti-CCP/PAAm SPR sensor, different adsorption models were performed. The calculated maximum reflection, detection limit, association and dissociation constants were 1.079 RU/mL, 0.177 RU/mL, 0.589 RU/mL and 1.697 mL/RU, respectively. Repeatability experiments of anti-CCP/PAAm SPR sensor was performed four times with adsorption-desorption-regeneration cycles without any performance losing. Results showed that anti-CCP/PAAm SPR sensor had high selectivity and sensitivity for detection of CCP antibodies.

Monolithic Boronate Affinity Columns for IgG Separation

In this study, monolithic high performance liquid chromatography (HPLC) composite columns were synthesized for immunoglobulin G (IgG) separation by boronate affinity chromatography. 4-Vinyl phenyl boronic acid (VPBA) was polymerized with 2-hydroxyethyl methacrylate (HEMA). The poly(HEMA-VPBA) monoliths were crushed into fine particles by using ball-milling. Then, the crushed particles were embedded into poly(2-hydroxyethyl methacrylate) (PHEMA) cryogels to prepare monolithic HPLC composite columns. The PHEMA cryogel was also synthesized to evaluate the efficiency of the embedding process. The monolithic HPLC composite columns were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), surface area measurements, boron content analysis, swelling studies, and flow rate-back pressure relation. The performance of IgG separation of monolithic composite columns was determined with HPLC and the parameters such as pH, IgG concentration, temperature, flow rate, and ionic strength were investigated. The maximum adsorption was observed at pH 8.0 phosphate buffer. The IgG separation from human plasma was also performed and selectivity experiments were carried out with human serum albumin (HSA) and hemoglobin (Hb) as 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.

Recognition of Lysozyme Using Surface Imprinted Bacterial Cellulose Nanofibers

Abstract Here, we developed the lysozyme imprinted bacterial cellulose (Lyz-MIP/BC) nanofibers via the surface imprinting strategy that was designed to recognize lysozyme. This study includes the molecular imprinting method onto the surface of bacterial cellulose nanofibers in the presence of lysozyme by metal ion coordination, as well as further characterizations methods FTIR, SEM and contact angle measurements. The maximum lysozyme adsorption capacity of Lyz-MIP/BC nanofibers was found to be 71 mg/g. The Lyz-MIP/BC nanofibers showed high selectivity for lysozyme towards bovine serum albumin and cytochrome c. Overall, the Lyz-MIP/BC nanofibers hold great potential for lysozyme recognition due to the high binding capacity, significant selectivity and excellent reusability.

Molecular Fingerprints of Hemoglobin on a Nanofilm Chip

Hemoglobin is an iron carrying protein in erythrocytes and also an essential element to transfer oxygen from the lungs to the tissues. Abnormalities in hemoglobin concentration are closely correlated with health status and many diseases, including thalassemia, anemia, leukemia, heart disease, and excessive loss of blood. Particularly in resource-constrained settings existing blood analyzers are not readily applicable due to the need for high-level instrumentation and skilled personnel, thereby inexpensive, easy-to-use, and reliable detection methods are needed. Herein, a molecular fingerprints of hemoglobin on a nanofilm chip was obtained for real-time, sensitive, and selective hemoglobin detection using a surface plasmon resonance system. Briefly, through the photopolymerization technique, a template (hemoglobin) was imprinted on a monomeric (acrylamide) nanofilm on-chip using a cross-linker (methylenebisacrylamide) and an initiator-activator pair (ammonium persulfate-tetramethylethylenediamine). The molecularly imprinted nanofilm on-chip was characterized by atomic force microscopy and ellipsometry, followed by benchmarking detection performance of hemoglobin concentrations from 0.0005 mg mL−1 to 1.0 mg mL−1. Theoretical calculations and real-time detection implied that the molecularly imprinted nanofilm on-chip was able to detect as little as 0.00035 mg mL−1 of hemoglobin. In addition, the experimental results of hemoglobin detection on the chip well-fitted with the Langmuir adsorption isotherm model with high correlation coefficient (0.99) and association and dissociation coefficients (39.1 mL mg−1 and 0.03 mg mL−1) suggesting a monolayer binding characteristic. Assessments on selectivity, reusability and storage stability indicated that the presented chip is an alternative approach to current hemoglobin-targeted assays in low-resource regions, as well as antibody-based detection procedures in the field. In the future, this molecularly imprinted nanofilm on-chip can easily be integrated with portable plasmonic detectors, improving its access to these regions, as well as it can be tailored to detect other proteins and biomarkers.

Surface Plasmon Resonance Sensors for Medical Diagnosis

Surface plasmon resonance (SPR) sensors have fascinated impressive attention to detect clinically related analytes in recent years. SPR sensors have also multiple advantages over existing conventional diagnostic tools such as easy preparation, no requirement of labeling, and high specificity and sensitivity with low cost, and they provide real-time detection capability. There are some articles and reviews in literature focusing on the applications of SPR-based sensors for the diagnosis of medically important entities such as proteins, cells, viruses, disease biomarkers, etc. These articles generally give information on the determination of such structures merely, whereas this presented manuscript combines recent literature for most of the medically important structures together including proteins, hormones, nucleic acids, whole cells, and drugs that especially the latest applications of SPR sensors for medical diagnosis to follow up new strategies and discuss how SPR strategy is brought to solve the medical problems.

Surface plasmon resonance based nanosensors for detection of triazinic pesticides in agricultural foods

Abstract Herein, we have focused on the preparation of triazinic pesticide imprinted SPR nanosensors for detection of herbicides. Triazinic pesticides are weedkillers that are related with possible carcinogenic effects, birth defects, and menstrual problems when uptake by humans. Although there are restrictions and bans on their use in some countries they are still one of the most widely used pesticides in the world. The development of rapid, sensitive, and inexpensive diagnosis tools for environmental and biological monitoring is currently a research area of great interest. Surface plasmon resonance (SPR) nanosensors have been used widely for the detection of triazinic pesticides because of their simplicity, lack of requirement for labeling and ease of miniaturization, low cost, high specificity and sensitivity, and real-time measurement. Molecularly imprinted polymers that have molecular recognition talent, are easy to prepare, less expensive, stable, and can be manufactured with good reproducibility, are used for the creation of biorecognitive surfaces on the SPR nanosensors. Herein, we have focused on the production of triazinic pesticide-imprinted SPR nanosensors.

Molecularly imprinted plasmonic biosensors for hemoglobin detection

In this study, we focus our attention on the molecularly imprinted surface plasmon resonance biosensor to detect hemoglobin that chosen as a model protein. The molecularly imprinted surface plasmon resonance biosensor was tested for real-time detection of hemoglobin from aqueous solutions. The kinetic studies were performed by using a different concentration of hemoglobin solutions. The responses that related to the change of reflectivity were used to evaluate adsorption properties. To show the selectivity of the molecularly imprinted surface plasmon resonance biosensor, competitive adsorption of transferrin, bovine serum albumin and myoglobin was also investigated. According to the results, the molecularly imprinted surface plasmon resonance biosensor can be a cost effective solution due to the sensitivity, reusability, fast response, and easy to use and also used as an alternative method for the detection of other proteins.