Surface modifications for the development of piezoimmunosensors (original) (raw)
Related papers
Journal of Materials Science: Materials in Medicine, 2011
Self-assembled monolayers (SAMs) on coinage metallic material can provide versatile modeling systems for studies of interfacial electron transfer, biological interactions, molecular recognition and other interfacial phenomena. Recently, a bio-sensing system has been produced by analysis of the attachment of antibody using alkanethiols, to form SAMs on the face of Au-quartz crystal microbalance (QCM) surfaces. In this study, the attachment of anti-afetoprotein monoclonal antibody to a SAMs surface of 11-mercaptoundecanoic acid was achieved using watersoluble N-ethyl-N 0 -(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide as coupling agents. Surface analyses were utilized by X-ray photoelectron spectroscopy and atomic force microscopy. The quantization of immobilized antibody was characterized by the frequency shift of QCM and the radioactivity change of 125 I labeled antibody. The limit of detection and linear range of the calibration curve of the QCM method were 15 ng/ml and 15-850 ng/ml. The correlation coefficients of a-fetoprotein concentration between QCM and radioimmunoassay were 0.9903 and 0.9750 for the standards and serum samples, respectively. This report illustrates an investigation of SAMs for the preparation of covalently immobilized antibody biosensors.
Analytical Biochemistry, 1999
A simple, highly sensitive immunosensor for the direct determination of immunoglobulin (Ig) in canine serum based on a piezoelectric crystal accommodated in a flow-cell was developed and optimized. The new biosensor is also useful for discriminating between Ig subclasses present in canine serum by using specific monoclonal antibodies binding to the coated crystal. Various canine monoclonal anti-IgG were deposited onto the surface of the gold-coated crystal resonator using the self-assembly technique to form a receptor layer. The highly ordered self-assembled monolayers thus obtained provide a well-controlled surface structure and many advantages as regards sensing performance. The results obtained with the proposed immunosensor were compared with those provided by a protein A-based orientation-controlled immobilization method for the same monoclonal antibodies and also with direct physical adsorption of the antibodies. The crystal was accommodated in a flow-cell that was inserted into a buffer flowing stream in order to make resonant frequency measurements.
A Reusable and Specific Protein A-Coated Piezoelectric Biosensor for Flow Injection Immunoassay
Biotechnology Progress, 2000
A hydrophilic matrix of periodate-oxidized dextran was used as a double-sided linker to covalently immobilize Staphylococcus aureus protein A (SpA) molecules onto a poly-L-lysine-modified piezoelectric crystal surface to improve their stability, activity, and binding specificity with human immunoglobulin G (IgG) in flow injection assays. The prepared sensing crystals displayed best sensitivity and reusability at a flow rate of 140 µL/min. A human IgG concentration as low as 0.3 nM can be detected by this system. Up to 19 successive assay repetitions were achieved without significant loss of sensitivity using the same crystal. The analysis of adsorption kinetics indicates that such a preparation can greatly increase the amount of available active human IgG binding sites on immobilized SpA. Hardly any response arising from unspecific binding was detected. In addition, the sensing crystal prepared by this method was found to retain activity better than one prepared via direct deposition when stored in either wet or dry states. Finally, the prepared SpA-coated crystals were applied to the affinity immobilization of polyclonal goat anti-Schistosoma japonicum glutathione-S-transferase (GST) and were able to subsequently detect GST and its genetically engineered mutant either in a purified form or in the crude cell lysate.
Biosensors and Bioelectronics, 1994
In the present study, the specific binding between protamine and immunoglobulin M (IgM) has been exploited to construct a piezoelectric crystal based immunobiosensor for the determination of concentration of IgM. The system consisted of highly stable IC based oscillator, 8-digit frequency counter and modified piezoelectric crystal device. The crystal surface was physically modified and chemically treated (refluxed) with strong acid to produce stable hydroxylic groups of silicon oxide. This modified surface reacted strongly with coupling reagents for binding of protein molecules. The protamine was immobilized by using either y-aminopropyltriethoxy silane (y-APTES) or 2 .2 .2-trifluoroethanesulfonyl chloride (tresyl chloride). Scanning electron microscope images of piezo crystal revealed that tresyl activated surface presented more surface area for binding than y-APTES modified surface and showed better sensitivity. This immobilization technique also improved the reproducibility and long term stability of the detection system. Using the system described, the IgM concentration up to the level of 10 ng/ ml could be detected without interference of IgG .
Analytica Chimica Acta, 2005
A novel piezoelectric immunosensor based on mixed self-assembled monolayers (mixed SAMs) formed by short-chain amine-and carboxylterminated thiols has been developed to immobilize antigens onto gold electrodes for detecting antisperm antibody (AsAb) in human serum samples. The properties and the enhanced performance of the affinity biosensor interface based on mixed SAMs are investigated. Most importantly, analytical results of several human serum samples using the developed technique are in satisfactory agreement with those given by the enzyme-linked immunosorbent assay (ELISA) method in the concentration ranging from 32.3 to 300.0 mU/ml. It means the procedure proposed in this paper is likely to have a great potential in research and may play an important clinical role in a few years later.
Glow-discharge treated piezoelectric quartz crystals as immunosensors for HSA detection
Biosensors and Bioelectronics, 2002
The aim of this study is to develop an immunoaffinity sensor based on piezoelectric crystals for human serum albumin (HSA) detection in aqueous media. Quartz crystals were treated with ethylene diamine (EDA) plasma in a glow-discharge apparatus in order to substitute amino groups on their surfaces. Then anti-HSA antibodies were immobilized via these amino groups by using glutaraldehyde (GA) as cross-linker. Immobilization of the antibody on the quartz crystal was examined for different pH, antibody concentration and treatment time. The optimum conditions for anti-HSA immobilization were evaluated by the measurements of the activity of the surface against HSA. The optimum values of pH, antibody concentration and treatment time were found 6.2, 0.15 mg/ml and 2 h, respectively. For detection of HSA into the solution, two methods were used. In the first (dip and dry) method, the frequency shifts were measured in air after the 1 h interaction of the anti-HSA immobilized crystals with HSA solution. In the other (direct) method, the frequency shifts were followed continuously for 60 min. while the probe was immersed in the HSA solution. An increase for the frequency shifts was observed with increasing of HSA concentration of 16 Á/128 mg/ml. Both the immobilization and antibody-interaction conditions were found important on the extend of these specific interaction. The relations between the HSA concentrations and frequency shifts were exponential in both methods.
Analytical Methods, 2014
Immunosensors are bioaffinity sensors incorporating immune system molecules that are utilized for analyte recognition and signal transduction yielding a measurable signal upon analyte detection. A lot of effort has been made to optimize the immobilization matrix on the sensor surface since the outcome of the ligand immobilization procedure determines sensitivity, specificity and longevity of the developed immunosensor. In this work, antibodies against bovine leukemia virus antigen gp51 were chemically reduced to "half" antibody fragments that were later employed as recognition ligands. Antibody fragments at different concentrations were immobilized via thiolate bonds on planar gold and gold nanoparticle modified surfaces of a quartz crystal microbalance with dissipation sensor. Antibody fragment immobilization and interaction with antigen were investigated. Antibody fragment surface mass densities after the immobilization on planar gold and gold nanoparticle modified sensor surfaces were directly dependent on the initial antibody concentration. The highest analytical response was exhibited by antibody fragments immobilized at the smallest surface mass density on planar gold and gold nanoparticle modified surfaces. Bovine leukemia virus antigen gp51 interaction with antibody fragments was compared with non-specific gp51 interaction with bovine serum albumin on planar gold and gold nanoparticle modified surfaces by employing DD/Df plots.
Single-Chain Fragment Variable Antibody Piezoimmunosensors
Analytical Chemistry, 2005
In this paper, we describe a novel nonlabeled biosensor with high diagnostic potential for rapid and sensitive detection of antigens in complex biological samples. The biosensor comprises a piezoimmunosensor (PZ) displaying a specially constructed recombinant antibody on its surface. The recombinant single-chain fragment variable (scFv) antibody contained a cysteine within the linker amino acid sequence used to join the scFv variable heavy and light chains. The presence of cysteine induced the scFv construct to self-assemble as a densely packed rigid monolayer on the gold surface of a quartz crystal microbalance. scFv molecules in this self-assembled mono-layer (SAM) exhibited a defined orientation and high areal densities, with scFv-modified microbalance surfaces displaying 35 times as many variable antigen-binding sites per square centimeter as surfaces modified with whole antibody. Experimental data show that the scFv SAM PZ is superior to Fab fragment, Fab fragment containing a free sulfhydryl group (i.e., Fab-SH), and whole antibody PZs regarding sensitivity and specificity. Because of their small uniform size (MW ≈ 27000) and the ease with which they can be modified using genetic engineering, scFv's have significant advantages over whole antibodies in microbalance biosensor systems. We demonstrate here that the use of scFv containing a cysteine within the scFv linker sequence (i.e., scFv-cys) for preparation of biosensor surfaces markedly increases the density of available antigen-binding sites, yielding a system that is highly selective, rapid, and capable of detecting low concentrations of antigens in complex samples.
Lectin coated piezoelectric crystal biosensors
Sensors and Actuators B: Chemical, 1992
The lectins Helix pomatia and Ptilota plumosa have been covalently immobilised on the surfaces of silver electroded AT-cut quartz crystals to form sugar and erythrocyte specific sensors. Using fully immersed crystals the dissociation constant for the Helix pomatia-n-acetyl D-galactosamine complex has been found to be typically 1.2 mM. A microdelivery mode has also been investigated and using this mode the dissociation constant for Ptilota plumosa with D-galactose was found to be order of lo3 cells.-7 mM. The lower detection limit for erythrocytes was of the
Analytical Biochemistry, 2001
In this study, a quartz crystal microbalance (QCM) system operated repetitively in flow injection analysis (FIA) mode, is reported. Four immobilization approaches of seven different methods include: (i) physical adsorption; (ii) two thioamine thiolation methods, using cysteamine and cystamine for gold chemisorption and further coupling; (iii) two oxidized dextran spacer methods, coupling of cysteamine and cystamine thiolated QCM surface with periodate-oxidized dextran for further Schiff acid-base reaction; and (iv) two thiol-gold chemisorption-based self-assembled monolayer (SAM), applying short-chain, C 3 , and longchain, C 11 , mercapto fatty acids to insolubilize human serum albumin (HSA) on QCM surface. Effects of these protein immobilization methods on FIA immunoassay of anti-HSA were compared. At the 0.01 mg/ml anti-HSA level, the lowest analyte concentration tested, the SAM using 11-mercaptoundecanoic acid as QCM surface activating agent generated a larger frequency shift than the other immobilization methods. This implied that the use of thiolated long-chain fatty acid constructed as self-assembled monolayer may thereby potentially be a useful protein immobilization method in QCM-FIA application.