Rapid and ultrasensitive detection of Salmonella typhimurium using a novel impedance biosensor based on SiO2@MnO2 nanocomposites and interdigitated array microelectrodes
SENSORS AND ACTUATORS B-CHEMICAL
Authors: Wang, Sihan; Peng, Tao; Meng, Qingyi; Zhu, Xiaoli; Guo, Liuchuan; Yao, Kai; Wang, Zheng; Zheng, Pimiao; Ren, Zhenhui; He, Zhiwei; Zhang, Jing; Jiang, Haiyang
Abstract
A novel impedance biosensor was developed based on the interdigitated microelectrodes using H2O2 to reduce SiO2@MnO2 nanocomposites into Mn2+, resulting in significant impedance changes in the rapid and ultrasensitive detection of Salmonella typhimurium (S. typhimurium). The captured S. typhimurium monoclonal antibodies (MAb1) were assembled on the outer layer of the magnetic beads (MBs) for specific enrichment and isolation of S. typhimurium cells in complex samples. The recognized S. typhimurium monoclonal antibodies (MAb(2)) were immobilized on the surface of the SiO2@MnO2 nanocomposites, which could react with the MBs- S. typhimurium conjugates to form the MBs- S. typhimurium -SiO2@MnO2 sandwich complexes. The MnO2 on the surface of the sandwich complexes was reduced into Mn2+ by using H2O2 achieving obvious impedance change that could be detected by the interdigitated microelectrodes. The recoveries for S. typhimurium cells at the concentrations between 2.0 x 10(1) and 2.0 x 10(5) CFU/mL were 83.1 %-97.0 % in the spiked milk samples. The limit of detection of this biosensor for S. typhimurium cells in the spiked milk samples was 21 CFU/mL. This approach possesses the merits of simple operation, high sensitivity, and low cost, potentially enabling this device to be a lab-on-a-chip for rapid screening of foodborne pathogens.
Lippia gracilisSchauer essential oil as a growth promoter for Japanese quail
ANIMAL
Authors: Rocha, G. F.; Del Vesco, A. P.; Santana, T. P.; Santos, T. S.; Cerqueira, A. S.; Zancanela, V. T.; Fernandes, R. P. M.; Oliveira Junior, G. M.
Abstract
The use of antibiotics as performance enhancers in animal feeding is declining, soLippia gracilisSchauer essential oil (LGSEO) could be used as a potential substitute for the conventionally used growth promoters. The LGSEO contains components such as carvacrol and thymol, which kill and/or control pathogenic bacteria, increase population of beneficial organisms, act against oxidative processes and onto nutrient digestibility and absorption. The aim of this study was to investigate the action and the effects of LGSEO as a growth promoter in the diet of Japanese quail by examining their productive performance, intestinal microbiology, blood biochemical parameters, hepaticthiobarbituric acid reactive substances(TBARS) content and intestinal gene expression. A total of 252 two-day-old quail (Coturnix coturnix japonica) were assigned to 3 treatments in 7 replicates, using 12 birds per experimental unit. The treatments consisted of a basal diet, basal diet + LGSEO at 400 mg/kg of diet and basal diet + chemical antimicrobial (bacitracin methylene disalicylate) at 500 mg/kg of diet. The experimental period was 34 days. The highest feed intake (P< 0.01) was found in the group receiving the conventional antimicrobial, whereas the best feed conversion (P< 0.01) was shown by the animals receiving LGSEO.Escherichia coligrowth was restricted in the quail receiving the growth promoters.Salmonellaspp. growth was controlled by the treatment containing the conventional antimicrobial. There was no difference between the treatments (P> 0.05) for the concentration of aspartate aminotransferase and alanine aminotransferase enzymes in the blood or hepatic TBARS content. Birds receiving negative-control treatment exhibited a higher expression of sodium-glucose cotransporter (SGLT1), while those receiving the treatment with essential oil showed lower catalase (CAT) and glutathione peroxidase (GPX7) expressions compared to the conventional antimicrobial and control groups, respectively.Lippia gracilisSchauer essential oil is a powerful performance enhancer for Japanese quail by virtue of its abilities to improve their intestinal environment, balance the microbial population and reduce energy expenditure for oxidative processes.