Quantum Dot Nanobead-Based Fluorescence-Linked Immunosorbent Assay for Detection of Glycinin in Soybeans and Soy Products

Soybean glycinin, as a major soybean allergen, is difficult to accurately quantify due to its large molecular weight and complex structure. CdSe/ZnS quantum dot nanobead (QB) is a core/shell fluorescent nanomaterial with strong fluorescent signals and high sensitivity at 630 nm. An immunosorbent assay based on CdSe/ZnS quantum dot nanobeads (QBs-FLISA) was developed for the glycinin quantification in soybean and soybean products. Here, the purified glycinin was coated on the microporous plate to serve as the coating antigen, and CdSe/ZnS nanobead conjugated with anti-glycinin polyclonal antibodies was used as fluorescent detection probe. The target glycinin in the sample and the coated antigen on the plate competitively adsorbed the antibody labeled the CdSe/ZnS QBs probes. The limits of detection and quantitation for glycinin were 0.035 and 0.078 μg mL-1, respectively. The recoveries of the spiked samples ranged from 89.8% to 105.6%, with relative standard deviation less than 8.6%. However, compared with ELISA, the sensitivities of QBs-FLISA for the detection of glycinin were increased by 7 times, and the detection time was shortened by two-thirds. This QBs-FLISA method has been effectively applied to the detection of soybean seeds with different varieties and soy products with different processing techniques, which will provide a rapid screening method for soybean and soybean products with low allergens.

Preparation of Monoclonal Antibody and Development of Indirect Competitive Enzyme-Linked Immunosorbent Assay and Fluorescence-Linked Immunosorbent Assay for Detecting 3-Amino-5-methylmorpholino-2-oxazolidinone (AMOZ) in Edible Animal Tissue

To monitor the illegal used of furaltadone, a highly sensitive indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and fluorescence-linked immunosorbent assay (FLISA) based on a monoclonal antibody (mAb) were developed for the detection of 3-amino-5-methylmorpholino-2-oxazolidinone (AMOZ), the major metabolite of furaltadone in animal tissues. The highly specific mAb, which was very sensitive to a nitrophenyl derivative of AMOZ (2-NP-AMOZ) with IC50 values of 0.11 and 0.09 ng/mL for ic-ELISA and FLISA, respectively, was selected for the development of immunoassays. For both the ic-ELISA and FLISA for AMOZ-spiked experiments, acceptable recovery rates of 81.1-105.3% and coefficients of variation of 4.7-9.8% were obtained. In addition, results from both ic-ELISA and FLISA methods for spiked samples' data showed excellent correlation coefficients ranging from 0.9652 to 0.9927. Meanwhile, the proposed ic-ELISA and FLISA for thirty spiked samples were confirmed by standard LC-MS/MS with high correlation coefficients of 0.9911 and 0.9921, respectively. These results suggest that the developed ic-ELISA and FLISA are valid and cost-effective tools for high-throughput monitoring methods for AMOZ residues in animal tissues.

An In Situ Generated Prussian Blue Nanoparticle-Mediated Multimode Nanozyme-Linked Immunosorbent Assay for the Detection of Aflatoxin B1

This work aims to develop a novel multimode (photothermal/colorimetric/fluorescent) nanozyme-linked immunosorbent assay (NLISA) based on the in situ generation of Prussian blue nanoparticles (PBNPs) on the surface of magnetic nanoparticles (MNPs). Being considered the most toxic among the mycotoxins, aflatoxin B1 (AFB1) was chosen as the proof-of-concept target. In this strategy, MNPs, on which an AFB1 aptamer was previously assembled via streptavidin-biotin linkage, are anchored to 96-well plates by AFB1 and antibody. In the presence of HCl and K₄Fe(CN)₆, PBNPs formed in situ on the MNP surface, thereby achieving photothermal and colorimetric signal readout due to their photothermal effect and intrinsic peroxidase-like activity. Based on fluorescence quenching by MNPs, Cy5 fluorescence was recovered by the in situ generation of PBNPs to facilitate ultrasensitive fluorescence detection. Photothermal and colorimetric signals allow portable/visual point-of-care testing, and fluorescent signals enable accurate determination with a detection limit of 0.54 fg/mL, which is 6333 and 28 times lower than those of photothermal and colorimetric analyses, respectively. We expect that this proposed multimode NLISA can not only reduce the false-positive/negative rates through the multisignal crossdetection in AFB1 monitoring but also provide a universal way of sophisticated instrumentation-free, easy-to-use, cost-effective, and highly sensitive detection of other food hazards.

Peptide Linker Affecting the Activity Retention Rate of VHH in Immunosorbents

VHH-based immunosorbents are an emerging and promising tool for the removal of toxic substances from plasma. However, the small size of VHHs is a double-edged sword, bringing both benefits and drawbacks to the immunosorbent. The small size of the VHH allows a higher coupling density, while the closer distance to the resin might create steric hindrance for paratope access. The latter could be avoided by inserting a linker between the VHH and the gel attachment site. Here, we report an approach to improve the activity retention of the immobilized VHH by selecting suitable linkers between the VHH and the site-specific immobilization site on the resin. Seven peptide linkers differing in length and flexibility were fused to the VHH and contained the formylglycine generating enzyme (FGE) recognition sequence. These constructs were expressed in the cytoplasm of bacteria and purified, the VHH production yield and affinity for its cognate antigen was measured. Furthermore, the fGly conversion, the immobilization of the aldehyde-containing nanobodies, the immobilization on resin and the antigen binding activity of the VHH-based immunoadsorbents was monitored. The VHH with longer and rigid, proline-rich linkers exhibited good expression yield of approximately 160 mg/L of culture, a fGly conversion of up to 100%, and the highest activity retention rate of more than 68%. This study unveiled two suitable linkers for the preparation of VHH-based immunosorbents that will assist the development of their clinical application.

A Lipid-Nanopillar-Array-Based Immunosorbent Assay

Since infectious diseases, particularly viral infections, have threatened human health and caused huge economical losses globally, a rapid, sensitive, and selective virus detection platform is highly demanded. Enzyme-linked immunosorbent assay (ELISA) with flat solid substrates has been dominantly used in detecting whole viruses for its straightforwardness and simplicity in assay protocols, but it often suffers from limited sensitivity, poor quantification range, and a time-consuming assay procedure. Here, a lipid-nanopillar-array-based immunosorbent assay (LNAIA) is developed with a nanopillar-supported lipid bilayer substrate with fluorophore-modified antibodies for rapid, sensitive, and quantitative detection of viruses. 3D nanopillar array structures and fluid antibodies with fluorophores facilitate faster and efficient target binding and rapid fluorophore localization for quick, reliable analysis on binding events with a conventional fluorescence microscopy setup. LNAIA enables quantification of H1N1 virus that targets down to 150 virus particles with 5-orders-of-magnitude dynamic range within 25 min, which cannot be achieved with conventional ELISA platforms.

A Lipid-Nanopillar-Array-Based Immunosorbent Assay

Since infectious diseases, particularly viral infections, have threatened human health and caused huge economical losses globally, a rapid, sensitive, and selective virus detection platform is highly demanded. Enzyme-linked immunosorbent assay (ELISA) with flat solid substrates has been dominantly used in detecting whole viruses for its straightforwardness and simplicity in assay protocols, but it often suffers from limited sensitivity, poor quantification range, and a time-consuming assay procedure. Here, a lipid-nanopillar-array-based immunosorbent assay (LNAIA) is developed with a nanopillar-supported lipid bilayer substrate with fluorophore-modified antibodies for rapid, sensitive, and quantitative detection of viruses. 3D nanopillar array structures and fluid antibodies with fluorophores facilitate faster and efficient target binding and rapid fluorophore localization for quick, reliable analysis on binding events with a conventional fluorescence microscopy setup. LNAIA enables quantification of H1N1 virus that targets down to 150 virus particles with 5-orders-of-magnitude dynamic range within 25 min, which cannot be achieved with conventional ELISA platforms.

Sensitive and Simple Competitive Biomimetic Nanozyme-Linked Immunosorbent Assay for Colorimetric and Surface-Enhanced Raman Scattering Sensing of Triazophos

The biomimetic enzyme-linked immunosorbent assay (BELISA) is widely used for detection of small-molecule compounds as a result of low cost and reagent stability of molecularly imprinted polymers (MIPs). However, enzyme labels used in BELISA still suffer some drawbacks, such as high production cost and limited stability. To overcome the drawbacks, a biomimetic nanozyme-linked immunosorbent assay (BNLISA) based on MIPs and nanozyme labels was first proposed. For nanozyme labels, platinum nanoparticles (PtNPs) acted as peroxidase by catalyzing the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) into an ideal surface-enhanced Raman scattering (SERS) marker. Blue TMB²⁺ and bovine serum albumin (BSA)-hapten showed superior selectivity when competing with targets for binding sites on MIPs, named the Pt@BSA-hapten probe. The BNLISA method was employed to detect triazophos with a limit of detection of 1 ng mL^-1 via colorimetric and SERS methods. Replacing traditional enzymes with nanozymes for combination with MIPs may bring about a new prospect for other compound analyses.

Magnetic Nanozyme-Linked Immunosorbent Assay for Ultrasensitive Influenza A Virus Detection

Rapid and sensitive detection of influenza virus is of soaring importance to prevent further spread of infections and adequate clinical treatment. Herein, an ultrasensitive colorimetric assay called magnetic nano(e)zyme-linked immunosorbent assay (MagLISA) is suggested, in which silica-shelled magnetic nanobeads (MagNBs) and gold nanoparticles are combined to monitor influenza A virus up to femtogram per milliliter concentration. Two essential strategies for ultrasensitive sensing are designed, i.e., facile target separation by MagNBs and signal amplification by the enzymelike activity of gold nanozymes (AuNZs). The enzymelike activity was experimentally and computationally evaluated, where the catalyticity of AuNZ was tremendously stronger than that of normal biological enzymes. In the spiked test, a straightforward linearity was presented in the range of 5.0 × 10^-15-5.0 × 10^-6g·mL^-1 in detecting the influenza virus A (New Caledonia/20/1999) (H1N1). The detection limit is up to 5.0 × 10^-12 g·mL^-1 only by human eyes, as well as up to 44.2 × 10^-15 g·mL^-1 by a microplate reader, which is the lowest record to monitor influenza virus using enzyme-linked immunosorbent assay-based technology as far as we know. Clinically isolated human serum samples were successfully observed at the detection limit of 2.6 PFU·mL^-1. This novel MagLISA demonstrates, therefore, a robust sensing platform possessing the advances of fathomable sample separation, enrichment, ultrasensitive readout, and anti-interference ability may reduce the spread of influenza virus and provide immediate clinical treatment.

A Highly Sensitive Immunosorbent Assay Based on Biotinylated Graphene Oxide and the Quartz Crystal Microbalance

A high-sensitivity flow-based immunoassay is reported based on a gold-coated quartz crystal microbalance (QCM) chip functionalized directly in the QCM without requiring covalent conjugation steps. Specifically, the irreversible adsorption of a biotinylated graphene oxide-avidin complex followed by loading of a biotinylated capture antibody is applied to avoid more complex conventional surface modification chemistries and enable chip functionalization and sensing all within the QCM instrument. The resulting immunosensors exhibit significantly lower nonspecific protein adsorption and stronger signal for antigen sensing relative to simple avidin-coated sensors. Reproducible quantification of rabbit IgG concentrations ranging from 0.1 ng/mL to 10 μg/mL (6 orders of magnitude) can be achieved depending on the approach used to quantify the binding with simple mass changes used to detect higher concentrations and a horseradish peroxidase-linked detection antibody that converts its substrate to a measurable precipitate used to detect very low analyte concentrations. Sensor fabrication and assay performance take ∼5 h in total, which is on par with or faster than other techniques. Quantitative sensing is possible in the presence of complex protein mixtures, such as human plasma. Given the broad availability of biotinylated capture antibodies, this method offers both an easy and flexible platform for the quantitative sensing of a variety of biomolecule targets.

Metal-amplified Density Assays, (MADAs), including a Density-Linked Immunosorbent Assay (DeLISA)

This paper reports the development of Metal-amplified Density Assays, or MADAs - a method of conducting quantitative or multiplexed assays, including immunoassays, by using Magnetic Levitation (MagLev) to measure metal-amplified changes in the density of beads labeled with biomolecules. The binding of target analytes (i.e. proteins, antibodies, antigens) to complementary ligands immobilized on the surface of the beads, followed by a chemical amplification of the binding in a form that results in a change in the density of the beads (achieved by using gold nanoparticle-labeled biomolecules, and electroless deposition of gold or silver), translates analyte binding events into changes in density measureable using MagLev. A minimal model based on diffusion-limited growth of hemispherical nuclei on a surface reproduces the dynamics of the assay. A MADA - when performed with antigens and antibodies - is called a Density-Linked Immunosorbent Assay, or DeLISA. Two immunoassays provided a proof of principle: a competitive quantification of the concentration of neomycin in whole milk, and a multiplexed detection of antibodies against Hepatitis C virus NS3 protein and syphilis T. pallidum p47 protein in serum. MADAs, including DeLISAs, require, besides the requisite biomolecules and amplification reagents, minimal specialized equipment (two permanent magnets, a ruler or a capillary with calibrated length markings) and no electrical power to obtain a quantitative readout of analyte concentration. With further development, the method may be useful in resource-limited or point-of-care settings.

Two-dimensional periodic relief grating as a versatile platform for selective immunosorbent assay and visualizing of antigens

In this study, we fabricated a nanopillar array of silicon oxide, involving very-large-scale integration (VLSI) and reactive ion etching (RIE), as two-dimensional periodic relief gratings (2DPRGs) on Si surfaces. Antihuman ALB was successively oriented on the pillar surface of 2DPRG modified protein G as an optical detector that is specific for targeted antigen. The antibody modified 2DPRG alone produces insignificant structure change, but upon immunocapture of antigens, the antigen filling in the 2DPRG leads to a dramatic change of the pillar scale. Binding of the antibodies to the 2DPRG occurs in a way that still allows them to function and selectively bind antigen. The performance of the sensor was evaluated by capturing HRP-human ALB on the antibody-modified 2DPRG and measuring the effective refractive index (neff) resulting from the attachment of antigens. The neff values of the 2DPRG are found to relate with the pillar scale of the 2DPRG, generated by antigen coupling, resulting in color change from pure green to orange, observed by the naked eye along an incident angle of 10-20°. Moreover, we calculated the filling factors inside the 2DPRG with effective-medium theory to verify the pillar structure changes. This technique eliminates much of the surface modifications and the secondary immunochemical or enzyme-linked steps that are common in immunoassays. Such films have potential applications as optical biosensors.

[New bioaffine sorbents for selective elimination of autoantibodies against human thyroperoxidase in autoimmune thyroid diseases]

New bioaffine sorbents containing bioselective ligand, synthetic analog of the human thyroperoxidase antigenic determinant--tetrapeptide H-Glu-Gln-betaAla-Lys-OMe, immobilized on two polymeric matrixes--a polyacrylamide gel and CNBr-activated sepharose 4B were synthesized. The offered immunosorbents were shown have high selectivity in relation to autoantibodies against thyroperoxidase and can find an application for medicine and experimental biochemistry for selective elimination of autoantibodies from serum or plasma of the patients suffering from autoimmune thyroid diseases.

Expression characteristics of major histocompatibility complex class I-related chain A antibodies and immunoadsorption effect in sensitized recipients of kidney transplantation

BACKGROUND

Sensitized recipients have a high risk of immunological graft loss due to hyperacute rejection and/or accelerated acute rejection. The presence of major histocompatibility complex class I-related chain A (MICA) antibodies has also been described associated with an increased rate of kidney-allograft rejection. The aim of this study was to describe the expression of MICA antibodies in sensitized recipients of renal transplantation and evaluate its influence on the kidney transplantation recipients.

METHODS

A total of 29 sensitized recipients were included in this study. All patients received the MICA antibodies detection before and after protein A immunoadsorption. Panel reactive antibody (PRA), HLA-matches, acute rejection and postoperative one to four-week serum creatinine level were also collected and analyzed, respectively. No prisoners were used in this study.

RESULTS

Eight patients (27.6%) in all 29 sensitized recipients expressed the MICA antibodies but did not show higher acute rejection rate than the non-expressed patients (3/8, 37.5% vs. 8/21, 38.1%; P = 1.000). Recipients with PRA > 40% showed higher expression levels of MICA antibodies than the recipients with PRA < 40% (7/16, 43.8% vs. 1/13, 8.3%; P = 0.044). HLA mismatch did not have any effect on the expression of MICA antibodies (P = 1.000). MICA antibodies positive group had higher serum creatinine level than the control in postoperative one week ((135.4 ± 21.4) µmol/L vs. (108.6 ± 31.6) µmol/L, P = 0.036), but no significant difference in postoperative four weeks ((89.0 ± 17.1) µmol/L vs. (77.1 ± 15.9) µmol/L, P = 0.089). MICA antibodies decreased significantly after protein A immunoadsorption.

CONCLUSIONS

MICA antibodies increase in the sensitized recipients, which have significant effects on the function of allograft in early postoperative period. Protein A immunoadsorption can decrease MICA antibodies effectively in sensitized recipients.

Application of a permethrin immunosorbent assay method to residential soil and dust samples

A low-cost, high throughput bioanalytical screening method was developed for monitoring cis/trans-permethrin in dust and soil samples. The method consisted of a simple sample preparation procedure [sonication with dichloromethane followed by a solvent exchange into methanol:water (1:1)] with bioanalytical detection using a magnetic particle enzyme-linked immunosorbent assay (ELISA). Quantitative recoveries (83-126%) of cis/trans-permethrin were obtained for spiked soil and dust samples. The percent difference of duplicate ELISA analyses was within +/- 20% for standards and +/- 35% for samples. Similar sample preparation procedures were used for the conventional gas chromatography/mass spectrometry (GC/MS) analysis except that additional cleanup steps were required. Recoveries of cis/trans-permethrin ranged from 81 to 108% for spiked soil and dust samples by GC/MS. The ELISA-derived permethrin concentrations were highly correlated with the GC/MS-derived sum of cis/trans-permethrin concentrations with a correlation coefficient (r) of 0.986. The ELISA method provided a rapid qualitative screen for cis/trans-permethrin in soil and dust while providing a higher sample throughput with a lower cost as compared to the GC/MS method. The ELISA can be applied as a complementary, low-cost screening tool to prioritize and rank samples prior to instrumental analysis for exposure studies.

[Preparation of magnetic latexes and their use for the immunodetection of microbial antigens]

The possibility of detecting antigens of plague, tularemia, and brucellosis microbes with magnetic latex (ML)-based test systems has been demonstrated. MLs were prepared from latexes (polyacroleine microspheres, 1.2-1.8 +/- 0.1 microm) by exposing the particles to a 25-35%-solution of ferrous sulfate for 0.5 h and then to a 15-25%-aqueous solution of ammonia for 0.5 h in a 100 degrees C water bath and dehydrating after each operation. The possibility of preparing magnetic latex immunosorbents (MLIS) by ligand immobilization on ML and using them in magnetic latex ELISA (ML-ELISA) for the detection of microbial antigens was demonstrated. The detection limit in ML-ELISA equaled 10(2)-10(3) microbial cells in 1 ml (cells/ml). Relative experimental error was not higher than 8%.

Extracorporeal Whole Blood Immunoadsorption of Autoimmune Myasthenia Gravis by Cellulose Tryptophan Adsorbent

Whole blood immunoadsorption (WBIA) system, using an adsorbent to remove pathogenic antibodies of myasthenia gravis (MG), was studied. Cellulose-tryptophan adsorbent was synthesized and its adsorption capacity of binding with acetylcholine receptor in the plasma of MG patient was evaluated. Experimental autoimmune myasthenia gravis (EAMG) rabbits were induced by Ta183-200 peptide. The rabbits underwent extracorporeal whole blood adsorption for 2 h. Results showed no significant damages on blood cells and no changes in the concentration of electrolytes. Total protein decreased by 12.0% (P < 0.05), and globulin protein decreased 23.9 +/- 5.6% (P < 0.05). The mean overall removal of antibodies against Ta183-200 was 41.12%. The percentage of decrement of compound muscle action potential in 3, 5, 10Hz of EAMG rabbits all dropped down after the treatment. In conclusion, the adsorbent is biocompatible, was safe for whole blood immunoadsorption, and can remove antibodies in an MG patient effectively. Whole blood immunoadsorption improved clinical manifestation and neuromuscular function of the EAMG rabbits.

High-Porosity Activated Carbon as a Possible Matrix For Native DNA and Dextran-Sulfate Immobilization

In this study, specific and nonspecific activity of calf thymus DNA and Dextran-Sulfate (DS)-containing synthetic carbonic adsorbents (0.7-7mg of each ligands per 1 cm3 of activated carbonic beads, 0.3-0.6mm diameter, bulk density gamma=0.1-0.2g/cm3) have been compared in stir-bath and micro-column in vitro tests. DS coating as well as DNA coating does not demonstrate deep influence on the unspecific adsorptive activity of carbonic matrix toward creatinine, vitamin B12, and unconjugated bilirubin. No essential difference has been found in the specific activity of DNA and DS containing adsorbents toward anti-ds- and anti-ss-DNA-antibodies, as well as antibodies against DNA-protein complexes (anti-DNP-antibodies): in both cases the percentage of decrease of appropriate antibody concentration varied between 35 and 51% for single-pass microcolumn experiments with moderate enhancement of extraction efficacy (up to 60-75%) due to additional recirculation (2 h) or preliminary plasma dilution in 2-5 times. In the micro-column experiments with the proinflammatory cytokines DNA or DS-coating did not diminish TNF-alpha, IL-1beta, and IL-6 adsorption from 3% BSA solution, but even improves to some extent its removal compared with uncoated matrix.

[Efficacy of immunoadsorbent treatment in experimental allergic encephalomyelitis]

Hemoperfusion through the granulated hemoadsorbent SCN, fibrous carbonic adsorbent AUVM and immunoadsorbent (SCN with immobilized MBP) was applied for the treatment of experimental allergic encephalomyelitis (EAE) in guinea pigs. EAE was induced by single subcutaneous injection of 100 microg of MBP in complete Freund's adjuvant. Hemoperfusion was performed on the stage of EAE manifestation or in latent period. It was found that immunoadsorbent has the highest therapeutic efficacy and allows to eliminate up to 32% anti-MBP antibodies from the serum of guinea pigs with EAE, has up to 84% and 90% of adsorptive capacity of small and middle weight endogenous substances, respectively, and reduces the level of metabolites with molecular weight less than 30 kDa in blood plasma up to 36%.

Luminescent biocompatible quantum dots: a tool for immunosorbent assay design

We have developed several conjugation strategies based on noncovalent self-assembly for the attachment of proteins and other biomolecules to water-soluble luminescent colloidal semiconductor nanocrystals (quantum dots [QDs]). The resulting QD-protein conjugates were employed in designing a variety of bioinspired applications, including single and multiplexed immunosorbent assays to detect toxins and small molecule explosives. In these studies we showed that QD fluorophores offer several important advantages. In particular, their tunable broad excitation spectra combined with narrow fluorescence emission peaks permit single-line excitation of multiple color nanocrystals, with facile signal deconvolution to extract individual contributions from each population (e.g., size) of QDs in multiplexed assays. Furthermore, the QDs strong resistance to photobleaching under continuous illumination relative to many organic dyes makes them ideal fluorophores for long-term cellular imaging studies. This chapter details the materials and methods for the synthesis of surface-functionalized CdSe-ZnS core-shell QDs, the construction and preparation of recombinant proteins, the conjugation of antibodies (and antibody fragments) to QDs, and the use of antibody-conjugated QDs in fluoroimmunoassays.

Miniaturized monolithic disks for immunoadsorption of cardiac biomarkers from serum

Immunoadsorbers based on 2.0 x 6.0 mm i.d., epoxy-bearing, methacrylate-based monolithic disks were developed in order to target myoglobin and N-terminal pro-natriuretic peptide (NT-proBNP), two biomarkers involved in cardiovascular disease. In both cases, antibodies were successfully coupled to the polymeric disk material. The developed immunoadsorbers permitted the selective isolation of myoglobin and NT-proBNP from human serum. Myoglobin was successfully isolated and detected from serum samples at concentrations down to 250 fmol microL(-1). However, the affinity of the antibodies was not sufficient for the analysis of low-concentration clinical samples. Frontal analysis of anti-NT-proBNP disks revealed the ability of the immunoadsorber to bind up to 250 pmol NT-proBNP, which is more than sufficient for the analysis of clinical samples. Anti-NT-proBNP disks showed good stability over more than 18 months and excellent batch-to-batch reproducibility. Moreover, anti-NT-proBNP disks permitted the isolation of NT-proBNP at concentrations down to 750 amol microL(-1) in serum, corresponding to concentrations of strongly diseased patients. Using reversed-phase trapping columns, the detection of NT-proBNP eluted from immunoadsorbers by mass spectrometry was achieved for concentrations down to 7.8 fmol microL(-1).

Advantages and limitations of on-line solid phase extraction coupled to liquid chromatography–mass spectrometry technologies versus biosensors for monitoring of emerging contaminants in water

On-line solid phase extraction (SPE) coupled to liquid chromatography-mass spectrometry (LC-MS) and biosensors are advanced technologies that have found increasing application in the analysis of environmental contaminants although their application to the determination of emerging contaminants (previously unknown or unrecognized pollutants) has been still limited. This review covers the most recent advances occurred in the areas of on-line SPE-LC-MS and biosensors, discusses and compares the main strengths and limitations of the two approaches, and examines their most relevant applications to the analysis of emerging contaminants in environmental waters. So far, the on-line configuration most frequently used has been SPE coupled to liquid chromatography-(tandem) mass spectrometry. Sorbents used for on-line SPE have included both traditional (alkyl-bonded silicas and polymers) and novel (restricted access materials (RAMs), molecularly imprinted synthetic polymers (MIPs), and immobilized receptors or antibodies (immunosorbents) materials. The biosensor technologies most frequently applied have been based on the use of antibodies and, to a lesser extent, enzymes, bacteria, receptors and DNA as recognition elements, and the use of optical and electrochemical transducing elements. Emerging contaminants investigated by means of these two techniques have included pharmaceuticals, endocrine disrupting compounds such as estrogens, alkylphenols and bisphenol A, pesticides transformation products, disinfection by-products, and bacterial toxins and mycotoxins, among others. Both techniques offer advantageous, and frequently comparable, features such as high sensitivity and selectivity, minimum sample manipulation, and automation. Biosensors are, in addition, relatively cheap and fast, which make them ideally suited for routine testing and screening of samples; however, in most cases, they can not compete yet with on-line SPE procedures in terms of accuracy, reproducibility, reliability (confirmation) of results, and capacity for multi-analyte determination.

New Ligand Coupling Procedure for Formation of an Immunoadsorption Wall

To prevent the occurrence of dialysis-related amyloidosis, an immunoadsorption wall based on polyacrylamide has been manufactured by a recently developed, partially incomplete, two-stage polymerization method. During the preparation process, efficient utilization of coupling antibodies is the key to large-scale production of such a toxin removal modality. In this study, we attempted to carry out the ligand coupling procedure after formation of a cyanogen bromide (CNBr)-activated stationary phase, using anti-beta2-microglobulin (beta-2M) antibodies. In vitro immunoadsorption tests show that the levels of beta-2M decrease rapidly within the first 2 hours for all the immunoadsorption tests. After that, nearly blank values were reached for tests of initial levels of c. 30 microg/mL and c. 82 microg/mL, whereas a relatively constant level of c. 10 microg/mL was maintained for the test of initial levels of c. 185 microg/mL. The maximum surface binding capacity of the prepared immunoadsorption walls is estimated by fitting experimental data, using a mathematical model of saturation kinetics. The present comparative investigation also suggests the manufacturing process for an immunoadsorption wall could be improved and facilitated by this new ligand coupling procedure without compromising the resulting binding capacity. Furthermore, the experimental protocols as well as the present methodology could be helpful for development of a clinically applicable immunoadsorption wall.

Frontal analysis for characterizing the adsorption–desorption behavior of β-lactoglobulin on immunoadsorbents

High-performance frontal affinity chromatography was employed to study the adsorption-desorption kinetics characterizing the retention of beta-lactoglobulin (beta-LG) onto polyclonal anti-beta-lactoglobulin (anti-beta-LG) chromatographic supports. The adsorption and desorption processes were studied by analyzing two different elution fronts separated by a relatively long rinsing step. The method consists in performing two successive frontal injections of the protein. In between, the column was rinsed with a given volume of mobile phase (buffer alone). During this rinsing stage, a partial desorption may occur and a novel amount of protein could be adsorbed in the second frontal injection step. The whole process (first adsorption, possible desorption, and second adsorption) was simulated by a numerical procedure, in which the column was divided into a large number of slices. A model based on bi-Langmuir type kinetics was used to describe the adsorption of the protein on the support. The model assumes a non-uniform adsorbent with two types of binding sites. At equilibrium the adsorption isotherm is of the bi-Langmuir type. A global adsorption effect was considered which includes the effective binding process and the mass transfer resistances due to the transport to the binding site. Therefore, the column capacity and the kinetic parameters of the model (apparent adsorption and desorption rate constants) were determined from the best fit of the first and second adsorption fronts to the experimental ones. The other parameters of the model are the saturation capacities for the adsorption on each type of sites. The equilibrium affinity constants were estimated in a single experiment from the ratio of the apparent adsorption and desorption rate constants. The high values found (around 10(8) M(-1)) reveal a strong interaction of beta-LG with the immunoadsorbent. Kinetic measurements were carried out at different flow rates. Both the apparent adsorption and desorption kinetics were faster at larger flow rates, indicating an important contribution of the mass transfer resistance in the stagnant fluid at the particle boundary. However, as expected, close values were found for the resulting equilibrium constants calculated from the ratio of the apparent adsorption and desorption rate constant determined at various flow rates.

Development and Characterization of a New Stationary Phase for an Immunoadsorption Wall

This study introduces a newly developed method for the formation of a stationary phase superficially embedded with immunoadsorbent, that is partially incomplete two-stage polymerization of acrylamide. Preliminary experimental studies show that binding activity of the immunoadsorbent was satisfactorily maintained after immobilization. With an appropriate configuration of selected immunoadsorption matrices and immunoisolation barriers, it is hoped that this stationary phase could be used to resolve some difficult problems arising from the accumulation of certain middle molecular weight toxins not removed by other blood purification procedures.

In vitro assessment of a new ABO immunosorbent with synthetic carbohydrates attached to sepharose

Transplantation across the ABO barrier is sometimes done in cases of emergency, such as acute liver failure, but is also carried out in elective cases, e.g. kidneys from living donors. Reducing the recipient anti-A/B antibody titres is often necessary in ABO-incompatible kidney transplantation. This is usually done by the use of techniques such as plasmapheresis and protein A- or sepharose-linked anti-human Ig immunoadsorption. A new ABO immunosorbent with synthetic A- or B-trisaccharide carbohydrate epitopes linked to a sepharose matrix has been tested. Columns made of this material have been tested in vitro with plasma from A- and B-individuals, assessed for antibody reduction capacity, flow characteristics, biocompatibility, and unspecific protein adsorption. The columns have a high capacity for ABO antibody removal, reducing titres by three to seven steps in one passage. We noted a high biocompatibility, with no unspecific protein adsorption, no activation of coagulation factors, and a low activation of complement, no immune complex formation and no cytotoxicity towards cultured mammalian L929 cells.

[New approach to an increase of specificity in determination of antibodies to lipopolysaccharides of Gram-negative bacteria by solid-phase enzyme-linked immunosorbent assay]

A simple and effective method is proposed to increase the sorption of lipopolysaccharides (LPS) of Gram-negative bacteria on the polystyrene surfaces, in which there is no need of preliminary modification of the surface of the solid phase with poly-L-lysine. The method consists in using 0.05 M carbonate buffer (pH 9.6) with 70% of ammonium sulfate at the stage of LPS immobilization. As a result, LPS absorption increases essentially, and the level of non-specific reactions remains low. This makes the usage of additional blocking reagents unnecessary and allows increasing sensitivity and specificity in determination of anti-LPS-antibodies by the solid-phase enzyme-linked immunosorbent assay.

Affinity binding of cells to cryogel adsorbents with immobilized specific ligands: effect of ligand coupling and matrix architecture

The capture of human acute myeloid leukemia KG-1 cells expressing the CD34 surface antigen and the fractionation of human blood lymphocytes were evaluated on polyvinyl alcohol (PVA)-cryogel beads and dimethyl acrylamide (DMAAm) monolithic cryogel with immobilized protein A. The affinity ligand (protein A) was chemically coupled to the reactive PVA-cryogel beads and epoxy-derivatized monolithic cryogels through different immobilization techniques and the binding efficiency of the cell surface receptors specific antibody-labeled cells to the gels/beads was determined. The binding of cells to monolithic cryogel was higher (90-95%) compared with cryogel beads (76%). B-lymphocytes, which bound to the protein A-cryogel beads, were separated from T-lymphocytes with yields for the two cell types 74 and 85%, respectively. About 91% of the bound B-cells could be recovered without significantly impairing their viability. Our results show differences in the percentage of cell-binding to the immunosorbents caused by ligand density, flow shear forces and bond strength between the cells and the affinity surface once distinct chemical coupling of protein A, size of beads, sequence of antibody binding to protein A adsorbents, morphology and geometry of surface matrices were compared.

An Effective and Rapid Method for Functional Characterization of Immunoadsorbents Using POROS Beads and Flow Cytometry

To facilitate the construction, functional characterization, and use of immunoadsorbents, we have developed a flow cytometry method that allows rapid assessment of large numbers of particle-bound antibodies. Protein G derivitized POROS beads were used to bind affinity-purified antibodies specific for synthetic peptides designed from human plasma proteins. The antibodies were covalently coupled to the beads and used to capture and release synthetic peptides that had been labeled at the C-terminus with the fluorochrome Alexa Fluor 488. Antibody coupling and specificity of antigen binding and release were measured by analysis of the POROS affinity beads by flow cytometry. The affinity-capture matrixes were also used through several antigen-binding and release cycles without loss of peptide binding efficiency. The ability to produce and characterize extremely small amounts of POROS affinity matrices will facilitate their use in protein microchemical procedures such as protein chip technology, monoclonal antibody screening and mass spectrometry, applications where analytes are limiting or present in low abundance in complex mixtures.

An immunoassay for atrazine using tunable immunosorbent

A novel, simple, economical, and environmentally friendly tunable immunosorbent-based immunoassay for sensitive and selective determination of atrazine is reported. Tunable immunosorbents consisting of a fusion between an elastin-like polypeptide made up of 77 repeating units of the pentapeptide VPGVG and a single-chain Fv of an anti-atrazine antibody were synthesized biologically and purified by temperature-triggered phase transition. A competitive immunoassay based on the competition of atrazine-horseradish peroxidase and atrazine was established with IC(50) and lower detection limit of 0.16 and 0.01 ppb, respectively. Excellent recoveries (mean values ranging between 92 and 104%) were demonstrated in simulated atrazine-contaminated water samples.

Emerging technologies in extracorporeal treatment: focus on adsorption

As an extracorporeal technique for blood purification, haemoadsorption was introduced in the early 1960s along with other physico-chemical methods. The problem of poor biocompatibility of uncoated adsorbents was resolved by coating adsorbent granules with haemocompatible membranes. Use of coated adsorbents instead of uncoated ones reduces the efficiency of haemoperfusion. As a result, for many years the use of adsorption was limited to only acute poisoning. Since the 1990s interest in the use of adsorbents in extracorporeal medical devices has been rising again. In this paper some recent developments in synthesis and application of novel uncoated medical adsorbents are discussed.

Peptide based adsorbers for therapeutic immunoadsorption

Peptides as ligands for immunoadsorption exhibit several potential advantages over native proteins. Two newly developed adsorbers are based on peptides covalently coupled to sepharose CL-4B. Globaffin is capable of binding immunoglobulins independent from their antigen specificity and thus, applicable in transplant recipients and several antibody mediated autoimmune diseases. Among others, the most important disorders suitable for the treatment with Globaffin are rheumatoid arthritis, systemic lupus erythematosus, and acute renal transplant rejection. Coraffin is a specific adsorber using two linear peptide ligands mimicking epitopes of the beta1-adrenergic receptor, that bind corresponding autoantibodies from patients suffering from idiopathic dilated cardiomyopathy. Specific immunoadsorption has been shown to be beneficial for patients with dilated cardiomyopathy. Coraffin can be used as a new therapeutic option for these patients, who get only limited benefit from medical therapy. Both adsorbers may be combined with all approved apheresis control devices available.

Immusorba TR and PH

Immusorba TR (IM-TR) and PH (IM-PH) were developed as adsorbents with non-biological materials as affinity ligands to remove pathogenic autoantibodies. The adsorbents of IM-TR and IM-PH are polyvinyl alcohol gel immobilized with tryptophan and phenylalanine as ligand, respectively. IM-TR is clinically applied for treatment of autoimmune neurological diseases such as myasthenia gravis and Guillain-Barre syndrome. IM-PH is used for not only neurological diseases such as GBS and multiple sclerosis but also collagen diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). As many autoantibodies with different specificities have been found to have similar affinities to the ligand of Immusorba, it is expected that Immusorba will be applied to more diseases and contribute to the clarification of the mechanisms of the development of diseases by the identification of adsorbed unknown pathogenic substances with Immusorba.

Use of adsorbent and supercritical carbon dioxide to concentrate flavor compounds from orange oil

Orange oil is composed largely of terpene hydrocarbons but is a source of flavor and fragrance compounds (oxygenated) that are present in low concentrations. To increase the ratio of oxygenated compounds to terpene hydrocarbons, orange oil was partially fractionated by adsorption of the oxygenated compounds onto porous silica gel, with full utilization of its adsorbent capacity, and then further purified by desorption into supercritical carbon dioxide. The desorption of 24 compounds was monitored by GC and GC-MS. Adsorption alone removed three-fourths of the terpene hydrocarbons, and fractional extraction by supercritical carbon dioxide (SC-CO(2)) improved the separation further. Response surface methodology was used in the experimental design, and regression analysis was used to determine the effects of process variables. Extraction at low temperatures and flow rates improved separation by SC-CO(2). Decanal was concentrated to 20 times that of the feed oil by using SC-CO(2) at 13.1 MPa, 35 degrees C, and 2 kg/h. The systems were operating at close to equilibrium conditions because of the fine dispersal of the oils and the excellent mass transfer properties of supercritical carbon dioxide.

Sorption of lead ions on diatomite and manganese oxides modified diatomite

Naturally occurring diatomaceous earth (diatomite) has been tested as a potential sorbent for Pb(II) ions. The intrinsic exchange properties were further improved by modification with manganese oxides. Modified adsorbent (referred to as Mn-diatomite) showed a higher tendency for adsorbing lead ions from solution at pH 4. The high performance exhibited by Mn-diatomite was attributed to increased surface area and higher negative surface charge after modification. Scanning electron microscope pictures revealed a birnessite structure of manganese oxides, which was featured by a plate-like-crystal structure. Diatomite filtration quality was improved after modification by manganese oxides. Good filtration qualities combined with high exchange capacity emphasised the potential use of Mn-diatomite in filtration systems.

Differences between synthetic oligosaccharide immunoabsorbents in depletion capacity for xenoreactive anti-Galalpha1-3Gal antibodies from human serum

Extracorporeal immunoabsorption for removal of anti-Galalpha1-3Gal (anti-Gal) antibodies in putative pig-to-human xenotransplantation is considered a major prophylactic measure to avoid hyperacute and acute vascular rejections. However, the efficacy of the procedure does depend on choosing the appropriate oligosaccharide epitopes for the binding of human anti-Gal. The synthetic oligosaccharides Galalpha1-3Gal (B-disaccharide, Bdi) and Galalpha1-3Galbeta1-4Glc ('type 6' trisaccharide, Tri6), covalently coupled to Sepharose via polyacrylamide (Sorbents Bdi and -Tri6, respectively), as well as a mixture thereof (Sorbent Mix), were examined for their efficacy to absorb anti-Gal from 20 human serum samples. Sorbent Bdi removed 81% of anti-Gal IgM and 85% of -IgG when assessed on Bdi by ELISA, but only 49% of IgG and 75% of IgM when assessed on Tri6. Sorbent Tri6 and -Mix showed significantly better absorption capacities in so far as Sorbent Tri6 removed 65% of anti-Gal IgM and 80% of -IgG as assessed on Bdi and 85% of IgM/87% of IgG when tested on Tri6, and Sorbent Mix absorbed > 90% anti-Gal of both isotypes of either specificity. Direct hemagglutination of rabbit erythrocytes (ER) was reduced by 75% (median value, range 0-94%) and the median cytotoxicity to PK15 target cells by > 94% after absorption on Sorbent Mix. Neither the decrease in ER agglutination titers nor the reduction of PK15 cytotoxicity revealed significant differences between the three immunoabsorbents tested. The large variation ranges of absorption efficacies within the 20 tested sera suggest that "tailor-made" immunoabsorption treatments may be needed for putative xenotransplant recipients.

Development of a DNA immunoadsorbent: coupling DNA on sepharose 4FF by an efficient activation method

To remove anti-DNA antibodies from a patient's plasma with systemic lupus erythematosus (SLE), a DNA immunoadsorbent was developed by covalently coupling calf thymus DNA on activated Sepharose 4FF. Sepharose 4FF was activated with 5-norbornene-2,3-dicarboximido carbonochloridate (Cl-CO-ONB), which was proven to be a very effective method for preparation of affinity chromatographic adsorbents. The activation was carried out in dry acetone using 4-(dimethylamine)pyridine (DMAP) and triethylamine (TEA) as catalysts at 4 degrees C or at room temperature. The coupling of DNA to the activated support was investigated as a function of pH, temperature, time, concentration of DNA, and activation level. It was found that the pH for optimal coupling is 3.0, and the amount of coupled DNA increases with an increase either in the concentration of DNA or the activation level. The maximum amount of coupled DNA could reach 1.0 mg DNA/ml support. The incubation of 5 to 20 ml of SLE plasma with 1.0 ml of adsorbent resulted in an 80 to 90% decline in the anti-DNA antibody level. Nonspecific adsorption for normal IgG and total protein is less than 15%.

[The properties of new affinity adsorbent for adsorbing the cycle immune complex in blood]

This study was designed to select an affinity adsorbent from 5 kinds of adsorbents available. The adsorbent AA3 was found being specific to the adsorption of pathologic cycle immune complex (CIC). The physical properties such as specific surface area, proe volume and average pore diameter of adsorbents were determined. A discussion on the factors that affect the adsorption of CIC is also presented in this paper.

Preparation of DNA-immobilized immunoadsorbent for treatment of systemic lupus erythematosus

A new DNA-immobilized immunoadsorbent was prepared to remove the pathogenic anti-DNA antibody from the serum of systemic lupus erythematosus (SLE) patients. A non-woven poly(ethylene terephthalate) (PET) fabric made of 3.5-microm diameter fibers was used as the support of the immunoadsorbent. A cationic monomer, N,N-dimethylaminoethyl methacrylate (DAM), was graft polymerized onto the PET fiber surface by UV irradiation or with a chemical initiator. Polyion complexation between the cationic groups of the graft chains and DNA molecules was employed to immobilize DNA onto the fiber surface. No DNA leaching was observed when the DNA-immobilized fabrics were placed in 0.9 and 2.0 wt% NaCl solution at 37 degrees C overnight. In vitro evaluation of this DNA-immobilized immunoadsorbent demonstrated that this adsorbent could selectively adsorb anti-DNA antibody from the serum of SLE patients.

An improved affinity support and immunoadsorbent with a synthetic blood group oligosaccharide and polymer coating for hemoperfusion

An improved affinity support and an immunoadsorbent suitable for extracorporeal perfusion of whole blood (or plasma) are reported. The affinity support consists of calcined diatomite-type silica particles to which a synthetic oligosaccharide hapten, viz. A-trisaccharide representing human blood group A, with a linking spacer-arm is chemically attached. The immunoadsorbent thus obtained is surface-modified with a polymer coating. The modified immunoadsorbent is not hemolytic and shows no loss of biological activity in reducing antibody titers in vitro. An important feature of the improved immunoadsorbent is that the polymer coating provides a better surface resistance and therefore stability to the affinity support to prevent the release of potentially harmful fines. The usefulness of a physically stable support as an affinity adsorbent for the selective removal of specific antibodies or unwanted substances directly from the blood circulation by extracorporeal immunoadsorption has profound medical significance because this would provide an efficient but safe and practical alternative to therapeutic intervention using plasma exchange or plasma perfusion, both of which require plasmapheresis.

Immusorba TR and Immusorba PH: basics of design and features of functions

Immusorba was reported by Yamazaki et al. to be the world's first practical immunoadsorbent in 1982. Since then, this immunoadsorbent has accumulated an abundance of clinical achievements. Immusorba has such unique functions that it is used in treating various diseases and holds possibilities for application to more diseases. Immusorba was designed as an artificial receptor for rheumatoid factor (RF) based on structural analysis of heat-denaturated globulin. Subsequently, new substances that it can adsorb have been found as seen in reports on the adsorption performance of Immusorba to anti-acetylcholine receptor antibodies (anti-AChR Abs) and antiganglioside antibodies. Along with this, Immusorba has been used in treating a wide range of diseases. The greatest characteristic of Immusorba is that its adsorption capability is selective rather than specific, making it effective against a great number of diseases.

Use of an immunoaffinity column for tetrachlorodibenzo-p-dioxin serum sample cleanup

Covalently linking 1-amino-3,7,8-trichlorodibenzo-p-dioxin with either keyhole limpet hemocyanin (KLH) or bovine serum albumin (BSA) provided antigens that generated antibodies in chickens. Competitive ELISA analysis demonstrated that the antibodies isolated from egg yolk (IgY) bound with 1,3,7,8-tetrachlorodibenzo-p-dioxin (1,3,7,8-TCDD). The antibodies were linked to CNBr-Sepharose to generate an immunoaffinity column. Radiolabeled 1,3,7,8-TCDD in a 0.05% Tween 20 solution was retained by the column and could be eluted by increasing the Tween 20 concentration. The binding efficiency for 10.7 ng per ml gel matrix ranged from 85 to 97%. Immunoaffinity columns generated by this method did not effectively bind 14C-1,3,7,8-TCDD from serum samples. Diluting the serum 1:20 with 0.05% Tween 20 increased the binding efficiency. Alternately, ethanol-hexane extraction followed by solid phase extraction on a carbon column using a fat removal protocol also provided an appropriate preaffinity column cleanup for serum samples. After this preaffinity column cleanup, spiked serum samples applied to the immunoaffinity column showed binding efficiencies of over 90%.

Study of an anti-human transthyretin immunoadsorbent. Influence of coupling chemistry on binding capacity and ligand leakage

A variant of transthyretin (TTR Val30Met) has been identified as the main protein precursor of the amyloid fibrils deposited in familial amyloidotic polyneuropathy (FAP). Specific removal of TTR in an extracorporeal immunoadsorption procedure is currently under investigation as a possible treatment of FAP. Immunoadsorbents were constructed by immobilizing murine anti-TTR monoclonal antibody 88.6.BA9 onto agarose gel supports via several different coupling chemistries. The influence of coupling conditions such as pH and antibody density, and of perfusion variables, such as antigen concentration and applied flow-rate, on the TTR capture efficiency, was determined. Cyanogen bromide-, carbonyldiimidazole- and aldehyde-activated (ALD) supports conjugated with antibody at optimal pH, provided immunoadsorbents with comparable TTR binding capacities. Regarding stability, leakage was lowest for the ALD based immunoadsorbents, particularly at high pH.

Lipoprotein(a) apheresis in severe coronary heart disease: an immunoadsorption method

Lipoprotein(a) (Lp[a]) is associated with an increased cardiovascular risk. It is similar to low-density lipoprotein with an additional molecule of apo A covalently linked to apo B-100 by one disulfide bridge. Apo A is highly homologous to plasminogen. The kringle 4 motive of plasminogen is repeated between 10 and 40 times in apo (a). Currently, there is no drug therapy available to lower Lp(a). Since October 1993, we have carried out over 160 immunoadsorption treatments on 3 patients with elevated Lp(a) as their only risk factor and a history of myocardial infarction. Lp(a) was removed from plasma by sepharose coupled anti-Lp(a) columns. Lp(a) levels were lowered from above 170 mg/dl to below 30 mg/dl immediately after Lp(a) apheresis. To achieve this, the patient's plasma volume had to be treated 2 to 3 times. Nonspecific protein loss during column changes remained negligible. There were no serious unwanted effects during or after treatment. Minor circulatory problems (tachycardia, flush) occurred in 11% of the treatments but only with plasma flow rates above 55 ml/min. In 1 patient, coronary angiography after 2 years and in another patient after 1 year showed no progression. The third patient has not yet had repeat coronary angiography. Like the others, he reported subjective improvement after 1 year of apheresis. It is concluded that Lp(a) apheresis may retard progression of atherosclerosis in patients with selective Lp(a) elevation. Further studies to support this hypothesis are needed.

Modified polyacrylamide microspheres as immunosorbent

Extracorporeal immunoadsorption system has been used for the specific removal of immunologically active substances from the blood. In this study, an attempt is made to utilise polyacrylamide microspheres as a matrix for immunoadsorption. Phenyl alanine is coupled onto the polymer beads using glutaraldehyde. These modified beads exhibit a high binding affinity for gamma-globulin compared to bare beads. The surface modified ones showed selective adsorption of immunoglobulins of IgG class. The C3 adsorption pattern is not altered significantly upon modification. Modified beads are found to be less hemolytic after modification. However, more studies are to be conducted for the development of a hemoperfusion column based on this modified matrix.

Immunoaffinity column cleanup procedure for analysis of ivermectin in swine liver

A simple and sensitive method for the analysis of ivermectin (22,23-dihydroavermectin B1) in swine liver based on immunoaffinity column cleanup is described. The immunosorbent was prepared by coupling polyclonal anti-ivermectin antibodies to carbonyl diimidazole-activated Sepharose CL-4B. After extraction with methanol, ivermectin was cleaned up on an immunoaffinity column, and determined by reversed-phase liquid chromatography with UV absorbance detection at 245 nm. Recoveries of ivermectin from fortified samples of 5-10 micrograms kg-1 levels ranged 85-102%, with coefficients of variation of 6-12%. The limit of detection was 2 micrograms kg-1 in a 5-g samples.

Immunoaffinity column cleanup and liquid chromatographic method for determining ivermectin in sheep serum

A simple and sensitive method was developed for determining ivermectin in sheep serum. The sample is cleaned up on an immunoaffinity column and determined by liquid chromatography with detection at 245 nm. Recoveries ranged from 90.3 to 98.8% (93.9 +/- 4.3%) for samples fortified with 2.0-50 ng ivermectin/mL. Coefficients of variation were 3.2-11.0%. The limit of detection was 1 ng/mL in 5.0 mL serum.