A multiresidue immunoassay method for determination of Fluoroquinolones (FQs) residues has been developed. For this purpose, NHS ester technology was employed to synthesize the immunogen and coating antigen of Norfloxacin (NFLX). SDS-PAGE, UV-visible spectra and Infrared spectra identification showed that the artificial antigen was conjugated successfully. Based on the square matrix titration, an icELISA method was established. The dynamic range in assay buffer was from 0.038 to 112.8 ng/mL, with LOD and IC50 value of 0.02 ng/mL and 1.2 ng/mL, respectively. This assay showed a high cross-reactivity to Ciprofloxacin (86%), Enrofloxacin (75%), Difloxacin (63%), Sarafloxacin (57%) and Pefloxacin (33.8%). The chemical effects on assay performance showed that the physiological pH (7.4) in assay buffer pursued the maximum absorbance (Amax) and the most sensitive IC50 values. The results suggest the artificial antigen was synthesized successfully, and the established immunoassay could be used for simultaneous detecting of Norfloxacin, Ciprofloxacin, Enrofloxacin, Difloxacin, Sarafloxacin and Pefloxacin residues in animal-original food samples.

A rapid indirect competitive ELISA (icELISA) format has been developed for the determination of enrofloxacin (ENR) residues in chicken. For this purpose, carbodiimide active ester method was employed to synthesize the artificial antigen of ENR-BSA, and anti- serum produced from the immunized rabbits was tested by indirect ELISA and icELISA. By the square matrix titration, the icELISA method was developed for the quantitative detection of ENR, based on the pAb. The Linear range was from 0.006 to 31.5 ng/mL, with LOD and IC50 value of 0.003 ng/mL and 0.45 ng/mL, respectively. Except for a high cross-reactivity (105.2%) to Ciprofloxacin, negligible cross-reactivity to the other compounds was observed. The recoveries of ENR were in the range of 98.3-127.5%, 85.7-112.5% and 97.4-103.8% for chicken muscle, liver and kidney, respectively. After optimization, 0.03 mol/L of HCl was used in the assay buffer and this ELISA system can tolerate acetonitrile not higher than 10%. The correlation coefficients (R2) of the ELISA and LC-MS data were 0.9472 in muscle, 0.9843 in liver, and 0.9382 in kidney. Therefore, this assay has the potential to be incorporated into a quantitative monitoring program for the rapid screening of ENR residue in food.

Ultrafine β-sialon powder is synthesized by citrate sol-gel and carbothermal reduction and nitridation (CRN) process. The presence of small amounts of β-sialon as crystal seed can obviously accelerate the formation of final β-sialon product and lower its formation temperature. The effects of nitriding temperature on the formation of the final β-sialon are investigated. The mean particle size of the prepared β-sialon powder is 100 ~ 150 nm. The β-sialon precursor gel and the ultrafine β-sialon powder are characterized by XRD, TG-DTA and SEM. The isoelectric point of ultrafine β-sialon is pH 2.46.

This paper presents the generation of monoclonal antibodies (mAbs) with high specificity against enrofloxacin (ENR) through cell fusion procedures, and the development of a mAb-based indirect competitive ELISA (icELISA) method to detect ENR residue using one of these Hybridomas (clone 4B5-D6). Under the optimal experimental conditions, this assay exhibited a working range of 0.004-38 ng/mL with IC50 and LOD values of 0.4 and 0.002 ng/mL, respectively. Except for a high cross-reactivity (105.2%) to Ciprofloxacin, negligible cross-reactivity to the other compounds was observed. After optimization, 10% of methanol was used in the assay buffer and this ELISA system can tolerate acetonitrile not higher than 10%. Recovery studies indicate that an excellent correlation between concentration spiked and concentration determined was found, and the results also suggest this assay has the potential to be incorporated into a quantitative monitoring program for the rapid screening of ENR residue in poultry tissues.

In this paper we compared growth performance, growth hormone (GH) pulsatile secretion and serum metabolites in growing Taihu and Landrace gilts at the same age. The results showed that compared with Landrace gilts, Taihu gilts decreased by 45.48% (P<0.05), 25.25% (P<0.05) in average daily gain and carcass muscle percentage, and increased by 52.44% (P<0.05), 69.50% (P<0.05) in feed/gain ratio and carcass fat percentage, respectively. While, average daily feed intake was not affected by breeds. Serum basal GH level, mean GH level and GH pulse amplitude were decreased by 26.67% (P<0.05), 20.00% (P<0.05) and 18.81% (P<0.05), respectively, but GH pulse frequency and pulse duration remained unchanged (P>0.05). Serum urea nitrogen concentration in Taihu gilts was 32.04% (P<0.05) higher, whereas, total protein level was 17.73% (P<0.05) lower than that of Landrace gilts.