Hydrophobic Pocket Modification and Humanized Catalytic Antibodies with Glutathione Peroxidase Activity(Ⅰ)——Preparation and Characterization of Haptenes and Conjugates

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Design and efficient synthesis of novel haptens and complete antigens for the AOZ,a toxic metabolite of furazolidone

A good strategy was brought forward for designing efficient haptens and complete antigens for 3-amino-2-oxazolidinone （AOZ）. Haptens designed newly were achieved facilely in good yield by using LiCI-N（Et）3 as new catalysis system, the structure of which was elucidated by spectroscopy analysis, such as NMR and MS. Novel antigens for AOZ were prepared successfully by convenient active ester method. The ratios of haptens 3 and 4 to carrier proteins were proven respectively as 41 ： 1 （5a）, 39：1 （6a）, 11：1 （5b） and 9：1 （6b） by trinitrobenzene sulfonic acid （TNBS） method. The results of indirect competitive ELISA （ic-ELISA） of antiserums indicated that the haptens with a short unsaturated side chain can evoke specific immune response effectively.

A New Hapten for Immunoassay of Aldicarb

A new hapten, aldicarb oxime succinic ester （AOSE）, was synthesized for immunoassay of aldicarb. It was conjugated to proteins by active ester method. Polyclonal antibody was raised against AOSE-BSA （bovine serum albumin） conjugate. Enzyme-linked immunosorbent assays （ELISAs） showed that this antiserum had high affinity to aldicarb and can be used for sensitive and selective immunoassay of aldicarb.

Characterization of Hapten-Protein Conjugates for Immunoassay of Polycyclic Aromatic Hydrocarbons(PAHs)

Preparation and characterization of the hapten-protein conjugates are fundamental to developing environmental immunoassays. As a hapten, 1-pyrenebutyric acid（PBA） was conjugated to the carrier protein of bovine serum albumin（BSA） or ovalbumin（OVA） by active ester method. Infrared spectra（IR） showed that PBA-BSA and PBA-OVA conjugates were successfully prepared. The number of the haptens conjugated to the carrier protein was determined by ultraviolet spectra（UV） and matrix-assisted laser desorption ionization time-of-flight mass spectrometry（MALDI-TOF-MS）. The calculated average binding ratios of PBA/BSA and PBA/OVA were 18：1 and 10：1 by UV, and 31：1 and 22：1 by MALDI-TOF-MS, respectively. Although there was a discrepancy between the results determined by the two methods, both of them were useful for the characterization of the hapten-protein conjugates. The antibody was produced against the antigen of PBA-BSA, and the affinity was tested by the double agar diffusion method The conjugates and the antibody could be used for developing a sensitive and selective immunoassay of polycyclic aromatic hydrocarbons（PAHs）.

Design and Synthesis of 6α-Corticosteroid Haptens and Their Bovine Serum Albumin (BSA) Conjugates

The site of attachment of protein carrier to corticosteroids has great influence on the specificity of produced antibody. In order to obtain highly specific and accurate antibodies for bioimmunoassay determination of cortisol, different tether lengths of 6-corticosteroid haptens and their BSA conjugates were designed and synthesized.

Development of Anti-Isoproturon Polyclonal Antibody

A competitive enzyme-linked immunosorbent assay （ELISA） suitable for the determination of the urea herbicide isoproturon, 3-（4-isopropylphenyl）-l,l-dimethylurea, in food and environmental samples was developed. Two haptens named 1-（3- carboxypropyl）-3-（4-isopropylphenyl）-1-methylurea （hapten 4C） and 1-（5-carboxypentyl）-3-（4-isopropylphenyl）-1- methylurea （hapten 6C） were synthesized. The haptens were coupled to bovine serum albumin （BSA） and ovalbumin （OVA）, respectively, using the N-hydroxysuccinimide reaction. The hapten 6C-BSA conjugate was used as the immunogen, with which a high-titer anti-isoproturon polyclonal antibody （pAb） was successfully obtained by immunization of New Zealand white rabbits. The hapten 4C-OVA conjugate was used as coating antigen and a method of the indirect competitive ELISA for isoproturon was established. The haptens were confirmed with TLC, IR, and 1H NMR. The conjugation molar ratios of hapten 4C to OVA and hapten 6C to BSA were 36：1 and 46：1, respectively, as calculated by a UV spectrophotometry. The highest titer of the anti-isoproturon sera determined by a non-competitive indirect ELISA procedure was 1.6 × 10^5. The optimal concentrations of the coating antigen and the dilution of the anti-isoproturon sera used in the ELISA were 0.1 mg·L^-1 and 1.0 × 10^5, respectively. The concentration of isoproturon that inhibits 50% of antibody-antigen binding （IC50） was 0.07 mg·mL^-1. The cross-reactivities of six urea herbicides including chlorbromuron, fluometuron, monolinuron were lower than 0.1%. Isoproturon is a small molecule without immune activity and active functional group for attaching to carrier protein. To produce an antibody against isoproturon with high titer and high specificity is the most important step in the development of an immunochemical method for the determination of isoproturon in food and environmental samples. The two haptens synthesized in this study have carboxyl groups and accommodate different lengths of spacer arms, and the phenyl and isopropyl groups are fully exposed. An anti-isoproturon polyclonal antibody with high titer and high specificity was successfully obtained by immunization of rabbits with the conjugate of the hapten attached to the protein carrier.

Development and characterization of new polyclonal antibodies specific for three polychlorinated biphenyls

Three polychlorinated biphenyls （PCBs） congeners and their corresponding haptens bearing four carbon length carboxylic groups that can be linked to a protein for raising antibodies were synthesized. The three resultant immunogens were fabricated and used to stimulate immune responses in rabbits to survey the characteristics of the haptens. Three of the resultant polyclonal antibodies （Pabs） were obtained. The antiserum exhibited relatively high antibody titres （1：32-64） in double agar diffusion.

The Synthesis of a Novel Phosphorus Containing Antigen

Antigen 12, containing a phosphonyl peptide hapten with free C-terminal carboxylic group, was synthesized by 11 reaction steps. The design of the hapten was based on the transition state of peptide hydrolysis catalyzed by carboxypeptidase A.

Studies on Increasing the Activity of Selenium-Containing Abzyme (Ⅰ)——Synthesis, Characterization and Properties of Hapten and Antigen

The thiol group of glutathione (GSH) reacts specifically with 2.4-di-m-trochlorobenzene to give S-substituted dinitrophenyl glutathione (GSH-S-DNP);two carboxyl groups of GSH-S-DNP were further esterified by n-butanol to produce the hapten,multisubstrate analog GSH-S-DNP Butyl Ester (GSH-S-DNP BE).The primary structure of the hapten was characterized by the free ammo group analysis,1H NMR,IR determinations and the elemental analysis.The hapten was then conjugated to bovine serum albumin (BSA) in the presence of glutaraldehyde.The reaction mixture was purified by Ultrogel AcA54 coluni chromatography to give the antigen.On an average,25 haptens were bound to each BSA molecule.Electrophoresis analysis showed that the average molecular weight of the antigen was 87 KD.CD spectrum showed that the α-helix content of the antigen increased.

Development of the Artificial Antigens for the Organophosphorus Insecticide Chlorpyrifos

This study reported that the hapten of the organophosphorus insecticide chlorpyrifos, O,O-diethyl-O-[3,5-dichloro-6-(2-carboxyethyl)thio-2-pyridyl]phosphorothioate(named AR) wassynthesized by using technical grade chlorpyrifos reacted with 3-marcapropanoic acid in hotalkaline solution. The hapten was conjugated to bovine serum albumin (BSA) with the modifiedactive ester method to form artificial immune antigen. The ratio of AR:BSA was 39:1. Theartificial coating antigen for chlorpyrifos was synthesized by conjugating AR to ovalbumin(OVA) with the mixed-anhydride method, and the ratio was 13:1. The anti-chlorpyrifos polyclonalantibodies were obtained by using the artificial immune antigen (AR-BSA) to immune in therabbits.

Synthesis and Density Functional Theory(DFT) Calculation of Haptens for PAHs

Five PAHs haptens 3 a～3 e were synthesized from naphthalene, anthracene, chrysene, pyrene and acenaphthene via two steps including Friedel-Crafts acylation and WolffKishner-Huang reduction. The sixth hapten 4-(acenaphthylen-3-yl)butanoic acid(3 f) was prepared from hapten 3 e via three steps including esterification, bromination and elimination. Their structures were confirmed by melting point, ~1H NMR and ^(13)C NMR. Their optical properties and crystal structures were also investigated. The results of density functional theory(DFT) calculation provided the supports that the size, shape(geometry) and electronic properties at the corresponding parts of 3 a～3 f did not change significantly, compared to those of PAHs. The haptens 3 a～3 f were coupled with bovine serum albumin(BSA) to make antigens. The coupling ratios were 1:20～1:38. These results show that the haptens could be used to induce specific antibodies for PAHs.

Synthesis and Characterization of Specific Haptens Used to Generate Abzyme with Glutathione Peroxidase Activity

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Rational hapten design and establishment of broad-spectrum indirect competitive enzyme-linked immunosorbent assay for benzimidazoles monitoring in milk

Objectives Benzimidazoles(BZs)are commonly used for the treatment of soil-transmitted helminth infections in veterinary clinics;however,misuse and overdosing of BZs will cause residual problems and have the potential to damage human health through the food chain.Thus,the existence of BZs in foods needs more attention.This study aims to establish a broad-spectrum immunoassay for rapid detection and to simultaneously monitor BZs in milk.Materials and Methods Based on structure analysis,a‘zero epitope loss’strategy,which introduced a spacer arm into the imino group of the imidazole ring of albendazole,was first adopted for hapten modification to obtain an ultra-sensitive and broad-spectrum antibody.An indirect competitive enzyme-linked immunosorbent assay(icELISA)was established for the detection of 18 BZs in milk sample with a single-step pretreatment.A quantitative structure–activity relationship model was constructed to interpret and predict the recognition.Results The antibody could recognize 20 BZs and the half-inhibitory concentrations ranged from 0.054 to 417.58 ng/mL,the limits of detection of icELISA ranged from 0.4 to 89.4 ng/mL,and the mean recovery rates ranged from 76.49%to 120.40%,with a coefficient of variation<20%.Substituent R1 of BZs was considered to be the main influencing factor for recognition,and the comparative molecular field analysis model(q2=0.724,r2=0.998)was finally chosen for further prediction.Conclusions The results indicated that the established icELISA could simultaneously identify 18 BZs,with good accuracy and precision,which was suitable for rapid detection of BZs in milk.

Development of an Indirect Competitive ELISA Based on Polyclonal Antibody for the Detection of Diethylstilbestrol in Water Samples

An indirect competitive enzyme-linked immunosorbent assay （icELISA） based on polyclonal antibody for the estrogen diethylstilbestrol （DES） was developed. With this aim, two different haptens mono-O-3-carboxypropyldiethylstilbestrol （DES-CP） and mono-O-carboxymethyldiethylstilbestrol （DES-CM） with carboxylic group that preserve the molecular structure character of diethylstilbestrol were synthesized. The haptens were conjugated with the carder proteins bovine serum albumin （BSA） by mixed-anhydride method for immunogen and conjugated with ovalbumin （OVA） by active ester method for coating antigen. Polyclonal antibodies for diethylstilbestrol were raised by immunizing mice with immune antigen DES-CP-BSA. Under optimized system, the lowest limit of detection （LLD） of diethylstilbestrol was 0.01 ng/mL, and IC50= 1.02 ng/mL. Its analogs were tested and no obvious cross-reactivity was found to anti-diethylstilbestrol antibody. DES-fortified water samples were determined by simple dilution to diminish the matrix effect. The comparison between the amount of DES estimated by ELISA and the amount added indicates good agreement for all water samples tested, with mean recovery values ranging from 86% to 120.2%.

Development of Monoclonal Antibody-based Enzyme-linked Immunosorbent Assay to the Estrogen Diethylstilbestrol

Diethylstilbestrol （DES） is a synthetic estrogen that has ever been used worldwide. Polyclonal antibodies （PAbs） were used in immunoassay for detection of DES residues in environmental and agricultural samples in previous paper. In this paper, an indirect competitive enzyme-linked immunosorbent assay （icELISA） was developed based on monoclonal antibody （MAb） for the determination of diethylstilbestrol. Mono-o-carboxypropyldiethylstilbestrol （DES-CP） and mono-o-carboxymethyldiethylstilbestrol （DES-CME） were synthesized to be haptens. DES-CP was coupled to bovine serum albumin （BSA） to be an immunogen in BALB/c female mouse for MAb production. The MAb was characterized for specificity and affinity to DES in icELISA. Under the optimum condition, the icELISA showed an ICs0 of 9.8 ng/mL, the limit of detection （IC20） of 2.3 ng/mL and a working range of 2-42 ng/mL. Hexestrol and dienestrol exhibited cross-reactivity values were 44% and 27%, respectively. Cross-reactivity of natural estrogen 17β-estradiol was less than 0.1%. The influences of some factors such as salt concentration, pH and organic solvent concentration on the assay were evaluated. The concentrations of DES in the fortified water samples determined by the assay were correlated well with the fortification levels. The results were conf＇m＇ned with analysis by HPLC.

Syntheses of haptens and hapten-protein conjugates for insecticide propoxur and cyhalothrin

A facile procedure was described for the hapten design of the N-methylcarbamate insecticide propoxur.Two new haptens of propoxur(hapten 1a and hapten 1b) were synthesized by introducing appropriate spacers in the pesticide aromatic moiety of the analyte molecular structure.First,the propoxur reacted with nitric acid to yield the intermediate product.Then hapten 1a was prepared via the reduction of the intermediate product,and hapten 1b was formed by the acylation of hapten 1a with succinic anhydride.In addition,we have also developed a simple method to prepare hapten 2 for the pyrethroid insecticide cyhalothrin,which only requires two steps including the reactions of nitration and reduction.Three haptens were coupled to carrier proteins to prepare the corresponding artificial antigens.The molecular structures of these three haptens were identified by 1H NMR and MS,and those of the artificial antigens were confirmed by UV-vis.

Preparation of hapten-specific monoclonal antibody for cadmium and its ELISA application to aqueous samples

High-affinity and specific monoclonal antibodies against cadmium-ethylene diamine tetraacetic acid(EDTA)complex have been produced using the hybridoma technique.A hapten was synthesized and characterized by Fourier Transform Infrared Spectroscopy(FT-IR)and UVVis.Competitive enzyme-linked immunosorbent assay(ELISA)for quantitative detection of cadmium in aqueous sample was developed.The monoclonal antibody with high level of binding affinity for Cd-IEDTA-BSA and high specificity for soluble Cd-EDTA complex showed less than 0.99%cross-reactivity with other 11 metals.The limit of detection was 0.10μg·L^(-1),and the effective linear range was 10^(-1)-10^(3)μg·L^(-1).The intra-and inter-assay coefficient variations were 1.5%-6.3%and 3.2%-7.4%,respectively.The spike recovery in different water samples were between 98.5%and 110.3%.The detection limit of this assay was well below the allowable concentration of cadmium(3μg·L^(-1)),and the working range was wider than that of other methods which showed the range of 2.19-86.38 and 0-10^(3)μg·L^(-1).The competitive ELISA established in this paper was sensitive and accurate in the screening of cadmium in aqueous samples.The results will lay a solid foundation for construction of an immunoassay kit for cadmium.

Immunological Detection of Arbutin

The relative molecular mass of Arbutin is small. Both fluorolabeling and radiolabeling may affect its properties and functions. Therefore, the immunoassay of Arbutin was studied. Arbutin was coupled to bovine serum albumin to get the Arbutin\|BSA conjugate with high molar ratio of Arbutin to BSA. Two rabbits were injected with the conjugate to develop the anti\|Arbutin serum. Ammonium sulfate precipitation and affinity chromatography were used to purify the antibody. Double agar diffusion test and enzyme\|linked immunosorbent assay (ELISA) were adopted to identify the antibody titer. The results demonstrated that the purity and activity of the antibody are high. The method proposed is satisfactory for the immunological detection of Arbutin.

Staphylococcal enterotoxin B-derived haptens promote sensitization

T helper 2 （Th2） polarization is a major pathological feature in allergic diseases; its etiology is not fully understood. This study aims to elucidate the adjuvant effect of the microbial product-derived small peptides in the initiation of antigen-specific Th2 polarization. In this study, a clinical survey of patients with chronic rhinosinusitis （CRS） and food allergy （FA） was carried out. The Staphylococcal enterotoxin B （SEB）-derived small peptides （Ssps） were examined in the human stool extracts. The formation of Ssp/antigen adducts was tested in a protein-protein combination assay. The bone marrow-derived dendritic cells （BMDCs） were employed to test the role of Ssp/ovalbumin （OVA） adducts in the dendritic cell （DC） maturation. A mouse model was developed to test the role of Ssp/OVA adducts in the initiation of ＂l＇h2 polarization in the intestine. The results showed that 54 （18.2%} patients with FA were diagnosed among 296 patients with SEB＋ CRS; only eight （2.9%） FA patients were identified among 272 patients with SEB- CRS. Ssps were detected in the stool protein extracts from FA patients with SEB＋ CRS, but not in those with SEB- CRS. Ssp/OVA adducts induced DC maturation, speeded up DC migration, activated CD4＋ T cells in the regional lymph nodes and induced skewed Th2 polarization in the local tissue. We conclude that patients with SEB ＋ CRS are prone to suffering from FA. SEB can be degraded to Ssps in the gastrointestinal tract. The Ssps can bind macromolecular antigens to form adducts to promote the antigenicity of the antigens and induction of the antigen-specific Th2 polarization and inflammation in the local tissue.

Polyclonal antibody-catalyzed hydrolysis of naproxen ethyl ester

In 1986 two monumental reports appearing on antibody catalysis which combined the tremendous diversity of antibody with catalytic power of enzyme opened new horizons of chemical and immunogical fields. Since then, a large number of catalytic antibodies have been prepared successively by using designed organic molecules as haptens conjugated to carrier proteins to immunize the animals and screening out the desired monoclonal antibodies through hybridoma technology. So far more than fifty examples