Synthesis of Citrinin Artificial Antigen and Its Coupling Ratio Determination

[Objective] This study was to establish a method for the rapid and accurate detection of the coupling ratio of artificial antigen. [Method] Artificial synthetic antigen of citrinin （CIT） was first conjugated with vector protein bovine serum albumin （BSA） and then identified by SDS-PAGE electrophoresis,and its coupling ratio was measured by UV absorption and mass spectrometry. [Result] The identification result showed that artificial antigen of CIT was successfully coupled,and the coupling ratio was 8.4 by UV absorption while 6.0 by mass spectrometry. [Conclusion] The comparison experiment showed that mass spectrometry could rapidly identify the artificial antigen and accurately detect its coupling ratio. This study provided basis for the preparation of CIT antigen as well as the establishment of an for enzyme-linked immunosorbent assay （ELISA） for citrinin determination.

Preparation of Artificial Antigen and Egg Yolk-derived Immunoglobulin(IgY) of Citrinin for Enzyme-Linked Immunosorbent Assay

Objective To prepare artificial antigens and anti-citrinin egg yolk-derived immunoglobulin （IgY） to build an enzyme-linked immunosorbent assay （ELISA） for citrinin （CTN）. Methods CTN was conjugated with bovine serum albumin （BSA）, ovalbumin （OVA） with formaldehyde condensation method to prepare artificial antigens and identified by ultraviolet （UV） spectrometry and Infrared （IR） spectrometry. Artificial antigens for CTN and anti-CTN IgY were purified with polyethylene glycol two-step precipitation method and identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE）. ELISA with IgY was established. Cross-reactivity of IgY with various structural similarities to CTN and possible co-occurrence with CTN in agricultural commodities were studied. Results UV and IR absorption spectra suggested that CTN was correlated with the carrier protein of BSA or OVA. SDS-PAGE patterns showed that the anti-CTN IgY was almost pure with a molecular weight of approximate 100 KD. The indirect competitive ELISA showed that the detection limit of CTN was 10 ng·mL^-1, with a good linearity ranging 20-640 ng·mL^-1. Conclusion Artificial antigens of CTN can be successfully synthesized. The established ELISA can be used to determine CTN- contaminated samples.

Synthesis and Identification of Artificial Antigen for Imidacloprid

This study reported that a hapten of imidacloprid, 1-[（6-Carboxylethylthio-3- pyridinyl）methyl]-N -nitro-imidazolidinimine was synthesized using technical material of imidacloprid to react with 3-mercaptopropionic acid in hot alkaline solution. The hapten was conjugated to bovine serum albumin （BSA） and ovalbumin （OVA） to form the immuno-antigens and the coating antigen, respectively. The antibody with high titer （2.56 × 10^4） was obtained after immuning rabbits. The results showed that the antibody had a high affinity to imidacloprid tested by enzyme-linked immunosorbent assay （ELISA）, which IC50 and IC20 were 20.7 and 1.1 μg L^-1; and the cross reactibilities to those compounds related with imidacloprid were less than 1.4%.

Particle elasticity influences polymeric artificial antigen presenting cell effectiveness in vivo via CD8+T cell activation,macrophage uptake,and the protein corona

Adoptive cell therapy(ACT)is an immunotherapy strategy for cancer that has seen widespread clinical success.During ACT,patient-derived lymphocytes are stimulated with the antigen of interest ex vivo,proliferated,then returned to the patient to initiate an antigen-specific antitumor response.While effective,this process is resource-intensive and logistically impossible for many patients.Particulate artificial antigen presenting cells(aAPCs)offer a potential“off-the-shelf”alternative to ex vivo ACT.While particulate aAPCs perform well in vitro,they have had limited success in vivo due to poor bioavailability after injection.Barriers to bioavailability include rapid clearance,unfavorable biodistribution,and inadequate interactions with CD8+T cells at sites of interest.Biomaterial properties such as elasticity have been shown to vastly impact the bioavailability and particle-cell interactions,but this has yet to be investigated in the context of aAPCs for in vivo T-cell stimulation.Previous literature likewise indicates that biomaterial properties,especially elasticity,can modulate T-cell activation in vitro.With the goal of creating a more biomimetic,next-generation particulate aAPC,we developed a poly(ethylene)glycol hydrogel particle platform with tunable elasticity to investigate the impact of elasticity on antigen-specific T cell activation for in vivo adoptive transfer.Using this knowledge,we were able to gain more precise control over in vivo T cell activation and investigate possible mechanisms including the effects of aAPC elasticity on T cell binding,macrophage uptake,and the protein corona.

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.