| In the present work, montmorillonite nanocomposites (MN), CTAB-pillared montmorillonite nanocomposites (CMN) and Al2O3-pillared montmorillonite nanocomposites (AMN) were prepared by means of nano-technology, Structural Characterization were investigated with AFM, XRD and FTIR pathens. Compared with MN, the performance of CMN and AMN on mycotoxins adsorption and prevention of mycotoxicosis from Caco-2 were comprehensively studied by using a series of investigations such as isotherms, desorption rate, selectivity of adsorption and MTT assay. The effects of CMN and AMN on mycotoxins transit in the Caco-2 cell monolayer were also investigated. The main results were listed as following:1 Preparation and characterision of pillared montmorillonite nanocompositesNa-montmorillonite, CTAB and A1C13·6H2O were used as main materials to prepare MN, CMN and AMN by nano-technology. The AFM patterns showed that MN, CMN and AMN particles were below 100nm in size. The XRD pattens showed that the d001 value of MN, CMN and AMN were 1.251nm,1.879nm and 1.497nm. Compared with MN, the particle size of CMN and AMN decreased by 24.77nm and 20.56nm, respectively, the the d001 value increased by 0.628nm and 0.246nm, respectively. FTIR pattens showed that CTAB and Al2O3 had located the interlayer space of CMN and AMN, respectively.The XRD pattens of the complex of CMN-ZEA, CMN-OTA, CMN-AFB1, AMN-ZEA, AMN-OTA and AMN-AFB1 shower that the d001 value of the above complex were increased by 0.057nm,0.066nm,0.066nm,0.005nm,0.036nm and 0.02nm, compared with CMN or AMN, respectively, which might somehow explain why CMN was better than AMN in mycotoxin adsorption.The FTIR pattens of the complex of CMN-ZEA, CMN-OTA, CMN-AFB,, AMN-ZEA, AMN-OTA and AMN-AFB1 shower that the alkyl carbon chain, oxygen atom in A12O3, carbonyl oxygen atom and unsaturated carbon duplet bond might involved in mycotoxin adsorption on CMN or AMN.2 In vitro adsorption of mycotoxins on pillared montmorillonite nanocompositesIn vitro adsorption of ZEA, OTA, AFB1, AFB2, AFG1 and AFG2 on MN, CMN and AMN were investigated, together with their stability and selectivity of these mycotoxins. Both CMN and AMN exhibited outstanding performance on the adsorption of these mycotoxins. The maximum adsorption of ZEA, OTA, AFB1, AFB2, AFG1 and AFG2 by CMN and AMN was 1830.21μg/g and 1034.90μg/g (P＜0.05),3663.53μg/g and 2466.61μg/g (P＜0.05),3112.43μg/g and 2087.37μg/g (P<0.05),1479.79μg/g and 1210.60μg/g (P＜0.05),1882.35μg/g and 523.72μg/g (P＜0.05),975.89μg/g and 905.94μg/g (P>0.05) calculated with Freundlich adsorption isotherms, respectively, whereas the maximum adsorption was 1250.00μg/g and 1428.57μg/g (P＜0.05), 1111.11μg/g and 1250.00μg/g (P＜0.05), 2000.00μg/g and 1250.00μg/g (P＜0.05),1428.57μg/g and 1666.67μg/g (P＜0.05), 1250.00μg/g and 1250.00μg/g, 1000.00μg/g and 1111.11μg/g (P>0.05), calculated with Langmuir adsorption isotherms, respectively. The maximum adsorption of ZEA, OTA, AFB,, AFB2, AFG1 and AFG2 by MN was 199.34μg/g and 555.56μg/g, 156.49μg/g and 285.71μg/g,393.01μg/g and 2500.00μg/g,1100.27μg/g and 1666.67μg/g,714.29μg/g and 258.64μg/g,250.09μg/g and 1000.00μg/g calculated with Freundlich and Langmuir adsorption isotherms, respectively. Compared with MN, the maximum adsorption of CMN and AMN on all of these mycotoxins were significantly increased (P＜0.05).Better stability and selectivity of these mycotoxins adsorption on CMN and AMN were also observed, with a very low desorption rate from 6:0% to 20.0% and no significant decline in mycotoxin adsorption amount by the co-existing primary feed nutrient, such as Lys, Met, Vit B1, VitB2, Ca2+ and Fe2+。Fast adsorption on CMN and AMN were acquired with these mycotoxins and the adsorption-desorption process reached equilibrium within 60 min. The results showed that both higher temperature and lower pH values could lead to the increased adsorption amount of all mycotoxins involved on CMN and AMN (P>0.05).3 Effect of pillared montmorillonite nanocomposites and mycotoxins on Caco-2 cellThe Caco-2 cell was inhired to evaluate the cytotoxicity of CMN, AMN, OTA, AFB1, AFB2, AFG1 and AFG2 at different levels and duration of expersure. At the same time, the ability of CMN and/or AMN to protect Caco-2 against cytotoxicity induced by the mycotoxins was also investigated.The results showed that all mycotoxins involved decreased the relative survival index of Caco-2 at every levels and duration of exposure examined. Good dose-effect relationships were observed at the lower mycotoxins levels and shorter duration of exposure. With the presence of CMN and AMN at all levels and duration of exposure, the relative survival index of Caco-2 maintained above 88.76%. The cytotoxicity level of CMN and AMN on Caco-2 was Calss I, according to the People's Republic of China national standards on human implantation materials, and could be used for mycotoxin Transit research in Caco-2 cells model.Data also revealed that the relative survival indexes of Caco-2 were greatly increased in the presence of CMN and AMN at all levels when simultaneously exposed at 900 ng/ml level of mycotoxins. Compared with the positive control of ZEA, addition of CMN and AMN at all levels significantly increased the relative survival index of Caco-2 by 95.2%,101.9%,103.4%,104.8% and 55.1%,62.1%, 65.6%,72.5%, respectively (P<0.05). Compared with the positive control of OTA, addition of CMN and AMN at all levels significantly increased the relative survival index of Caco-2 by 123.9%,137.3%,142.5%,145.4% and 80.2%,88.9%,95.0%, 104.3%. Compared with the positive control of AFB1, addition of CMN and AMN at all levels significantly increased the relative survival index of Caco-2 by 865.7%, 902.5%,917.4%,942.8% and 646.5%,680.6%,700.8%,770.0%. Compared with the positive control of AFB2, addition of CMN and AMN at all levels significantly increased the relative survival index of Caco-2 by 716.5%,746.4%,761.7%,771.2% and 602.5%,617.9%,640.5%,670.4%. Compared with the positive control of AFG1, addition of CMN and AMN at all levels significantly increased the relative survival index of Caco-2 by 796.4%,833.5%,843.2%,860.9% and 640.6%,600.0%,708.5%, 739.1%. Compared with the positive control of AFG2, addition of CMN and AMN at all levels significantly increased the relative survival index of Caco-2 by 605.4%, 617.3%,634.7%,646.6% and 508.5%,521.6%,537.4%,564.1%. As a result, CMN and AMN can effectively protect Caco-2 against cytotoxicity induced by mycotoxins in high levels.4 Effect of pillared montmorillonite nanocomposites on mycotoxins transit in Caco-2 cell monolayerThe Caco-2 cell model of intestinal epithelial transport was used to evaluate the transit index of 900ng/ml OTA, AFB1, AFB2, AFG1, AFG2 across cell monolayers from the apical-to-basolateral in the presence of 0.25% CMN and AMN.200μl solution in the basolateral side was removed for HPLC analysis of mycotoxins after three hours' interaction at 37℃and transit index of each mycotoxin across the cell monolayers was calculated according to the data.The results showed that:the transit index of ZEA, OTA, AFB1, AFB2, AFG,, AFG2 significantly decreased by 90.78%,93.68%,91.37%,87.95%,90.72% and 87.48%(P<0.05) in the presence of 0.25% CMN, respectively, when compared with the control group, whereas the transit index significantly decreased by 85.34%, 88.87%,84.09%,83.74%,87.55% and 82.43%(P<0.05) in the presence of 0.25% AMN, respectively. Compared with AMN, the transit index of the above mycotoxins also significantly dropped by 37.14%,43.21%,45.78%,25.90%,25.50% and 28.69% (P<0.05) in the presence of 0.25% CMN, respectively.
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