ABSTRACT
A signal-enhanced LFIA based on tyramine (TYR)-induced AuNPs aggregation has been developed for the sensitive detection of danofloxacin (DAN). In the model, the hydroxyl radical produced by HRP catalyzing H2O2 can trigger the TYR-AuNPs to aggregate on the T or C line for enhancing the detection signal. The linear range of TYR-AuNPs LFIA was 0.25-5 ng mL-1 with the limit of detection (LOD) of 0.032 ng mL-1, and the LOD was 8-fold lower than that of the traditional AuNPs LFIA (0.26 ng mL-1). The TYR-AuNPs LFIA could be used with the naked eyes to qualitatively detect DAN with a cut-off limit of 2.5 ng mL-1, which was 4-fold lower than that of the traditional AuNPs LFIA (10 ng mL-1). The recoveries of TYR-AuNPs LFIA were 86.04-105.14% and 92.41-110.19%, with the coefficient of variation of 1.71-2.05% and 4.42-5.89% in chicken and pork, respectively.
Subject(s)
Gold , Metal Nanoparticles , Fluoroquinolones , Hydrogen Peroxide , Immunoassay , Limit of Detection , TyramineABSTRACT
BACKGROUND: Sulfamethazine (SMZ), a veterinary drug widely used in animal husbandry, is harmful to human health when excess residues are present in food. In this study, a fast, reliable, and sensitive immunochromatographic assay (ICA) was developed on the basis of the competitive format by using time-resolved fluorescent nanobeads (TRFN) as label for the detection of SMZ in egg, honey, and pork samples. RESULTS: Under optimized working conditions, this method had limits of detection of 0.016, 0.049, and 0.029 ng mL-1 and corresponding linear ranges of 0.05 to 1.00, 0.05 to 5.00, and 0.05 to 1.00 ng mL-1 in egg, honey, and pork samples, respectively. The recovery experiments showed that the average recoveries ranged from 90.5% to 113.9%, 82.4% to 112.0%, and 79.8% to 93.4% with corresponding coefficients of variation of 4.1% to 11.7%, 7.5% to 11.5%, and 4.8% to 8.7% for egg, honey, and pork samples, respectively. The developed TRFN-ICA was also systematically compared with high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) by analyzing 45 actual samples from egg, honey, and pork. CONCLUSION: Overall, the developed TRFN-ICA had high reliability and excellent potential for the ultrasensitive detection of SMZ for food safety monitoring, also providing a universal platform for the on-site detection of other targets. © 2020 Society of Chemical Industry.
Subject(s)
Anti-Infective Agents/analysis , Eggs/analysis , Food Contamination/analysis , Honey/analysis , Immunoassay/methods , Meat/analysis , Sulfamethazine/analysis , Veterinary Drugs/analysis , Animals , Chickens , Immunoassay/instrumentation , Limit of Detection , Nanoparticles/analysis , SwineABSTRACT
To better understand the physiological characteristics of the silky starling (Sturnus sericeus), its body temperature (Tb), basal metabolic rate (BMR), evaporative water loss (EWL) and thermal conductance (C) elicited by different ambient temperatures (Ta) (5-30 â) were determined in the present study. Our results showed that they have a high Tb (41.6 ± 0.1 â), a wide thermal neutral zone (TNZ) (20-27.5â) and a relatively low BMR within the TNZ (3.37 ± 0.17 mL O2/g·h). The EWL was nearly stable below the TNZ (0.91 ± 0.07 mg H2O/g·h) but increased remarkably within and above the TNZ. The C was constant below the TNZ, with a minimum value of 0.14 ± 0.01 mL O2/g·h·â. These findings indicate that the BMR, Tb and EWL of the silky starling were all affected by Ta, especially when Ta was below 20 â and the EWL plays an important role in thermal regulation.
