Cellular Apoptosis Induced by Deoxynivalenol.

Deoxynivalenol (DON) is synthesized by Fusarium species that frequently infect crops during storage, and it's harm risk to human is reflected in the consumption of infected food crops or indirectly through foods of animal origin. In this study, Hela and Chang liver cells were used to research the cellular apoptosis induced by deoxynivalenol. Cells were treated by DON toxin with a series of concentration and incubated for different time. MTT, fluorescence microscope, flow cytometer and Western blot methods were used to analyze the effect of DON on the cell apoptosis in vitro and in vivo systematically. The results showed that DON was toxic to the cells tested. After being treated by DON, the morphology of Chang livers and Hela cells changed significantly. The DON promoted apoptosis in a dose- and time-dependent manner. The activity of Caspase 3 was significantly increased in DON-induced apoptosis. Moreover, endogenous Glutathione (GSH) level in these cell lines was gradually decreased. In the early apoptosis progress, oxidative stress was induced by DON. When DON reached 10 µg/mL, a markedly increased content of Malondialdehyde (MDA) was detected in both Hela and Chang liver cells. Furthermore, an in vivo test indicated that DON had toxicity to mice by causing weight loss and swollen spleen, and significantly increased expression of AST and ALT. In conclusion, the DON was toxic to mice and could induce the apoptosis of tested cells undergoing a Caspase-3 related pathway.

Rapid detection of fumonisin B1 using a colloidal gold immunoassay strip test in corn samples.

Fumonisin B1 (FB1) is the most common and highest toxic of fumonisins species, exists frequently in corn and corn-based foods, leading to several animal and human diseases. Furthermore, FB1 was reported that it was associated with the human esophageal cancer. In view of the harmful of FB1, it is urgent to develop a feasible and accuracy method for rapid detection of FB1. In this study, a competitive immunoassay for FB1 detection was developed based on colloidal gold-antibody conjugate. The FB1-keyhole limpet hemoeyanin (FB1-KLH) conjugate was embedded in the test line, and goat anti-mouse IgG antibody embedded in the control line. The color density of the test line correlated with the concentration of FB1 in the range from 2.5 to 10 ng/mL, and the visual limit detection of test for FB1 was 2.5 ng/mL. The results indicated that the test strip is specific for FB1, and no cross-reactivity to other toxins. The quantitative detection for FB1 was simple, only needing one step without complicated assay performance and expensive equipment, and the total time of visual evaluation was less than 5 min. Hence, the developed colloidal gold-antibody assay can be used as a feasible method for FB1 rapid and quantitative detection in corn samples.

Development of ELISA and colloidal gold immunoassay for tetrodotoxin detetcion based on monoclonal antibody.

A monoclonal hybridoma cell named 5B9 against tetrodotoxin (TTX) was obtained after fusion of myeloma SP2/0 cells with spleen cells isolated from the immunized Balb/c mice. The 5B9 monoclonal antibody (McAb) with high affinity (about 2.55 × 10(9)) is specific to TTX, and this McAb belongs to the immunoglobulin G (IgG) isotype. Finally, an enzyme-linked immunosorbent assay (ELISA) and colloidal gold immunoassay were established based on this McAb. The linear range of ELISA to detect TTX was 5-500 ng/mL, and the limit of detection (LOD) was 4.44 ng/mL. The average CV of intra- and inter-assay was less than 8%, with the samples recovery range of 70.93-99.99%. A competitive format colloidal gold strip was developed for detection of TTX in real samples, and the LOD for TTX is 20 ng/mL, and the assay time of the qualitative test can be finished in less than 10 min without any equipment. The result from test strip revealed that the test strip has a good agreement with those obtained from ELISA.

Spectroscopic characterization of tetracationic porphyrins and their noncovalent functionalization with graphene.

In this study, the noncovalent functionalization of graphene with cationic porphyrins in an aqueous medium was investigated using UV-vis and fluorescence approaches. To characterize the interaction between graphene and cationic porphyrins, 5,10,15,20-tetra (4-pyridyl)-21H,23H-porphine, 5,10,15,20-tetrakis (1-methyl-4-pyridinio) porphyrin tetra (p-toluenesulfonate) and 5,10,15,20-tetrakis (4-trimethylammoniophenyl) porphyrin tetra (p-toluenesulfonate) porphyrin were chosen as reagents. The intermolecular interactions were found to occur immediately after mixing the cationic porphyrins with graphene. The absorption spectra of the cationic porphyrins after mixing with graphene showed distinct red shifts of the Soret and Q-bands compared to free cationic porphyrins indicating that interactions occur between the cationic porphyrins and graphene. A strong fluorescence quenching of the cationic porphyrins in the presence of graphene indicated that efficient electron or energy transfer occurred from the excited state of the cationic porphyrins to graphene. Cationic porphyrins were immobilized on the surface of graphene through electrostatic and π-π stacking interactions, and the chemical shape of graphene played an important role in the intermolecular interactions and the red shift extent of cationic porphyrins is mostly dependent on the functional groups and charges of the graphene surface. The results show that less functional groups on the graphene's surface and edge would lead to stronger π-π stacking interactions between graphene and cationic porphyrins.