Electrochemical-Based Serological Detection of Bovine Immunoglobulin G in Calves

Bovine antibodies, such as immunoglobulin G (IgG), cannot pass the placental barrier and as such are not transferred from the mother to the foetus, in utero. Instead a calf must absorb antibodies following ingestion of colostrum postpartum. Failure of Passive Transfer (FPT) is a condition that predisposes calves to development of disease and increases the risk of mortality. Thus, continuous early monitoring of IgG absorption in a calf, within the first 24 hours of life, is imperative to allow faster treatment and prevent FPT. In this paper, we present the development of a label-free impedimetric immunosensor device for bovine IgG in serum and demonstrate its suitability to determine early FPT in new-born calves. The developed sensors were challenged to discriminate between new born calf sera, both pre- and post-colostrum feeding, and demonstrated efficent detection of IgG in under 15 minutes. Such a device could enable rapid determination of FPT, thereby improving calves’ vitality and survival rat

Label-Free Impedimetric Nanoband Sensor for Detection of Both Bovine Viral Diarrhoea Virus (BVDV) and Antibody (BVDAb) in Serum

In veterinary medicine, diagnostic tools enabling early detection of infectious disease in cattle could play a pivotal role in the control and eradication of bovine viral diarrhoea (BVD). Early identification of cattle persistently infected with bovine viral diarrhoea virus (BVDV) is critical for early diagnosis and isolation of the animal from a susceptible herd. The immediate availability of electronic test results to a veterinarian on-farm, would eliminate the need to submit samples to a commercial laboratory thereby improving animal therapeutic outcomes considerably. An impedimetric silicon chip-based biosensor platform, containing six gold nanoband electrodes as six individual sensors, was developed in this study for detection of BVD disease target molecules. Gold nanoband electrodes were first coated with an electrodeposited polymer and then modified with either monoclonal antibodies or Erns protein, for the subsequent detection of BVD virus and antibodies in whole serum, respectively. We demonstrate that the nanoband sensors have sufficient sensitivity and specificity for serological detection of both targets, with a low time-to-result (20 minutes). All serological samples were benchmarked against, and in complete agreement with, gold standard commercial ELISA methods. These initial proof-of-concept findings are of particular significance for potential on-farm point of use applications, where rapid analysis times and specificity are required to permit early diagnostics by veterinarians. </p

Highly Sensitive SERS Detection of Neonicotinoid Pesticides. Complete Raman Spectral Assignment of Clothianidin and Imidacloprid

The use of Surface Enhanced Raman Spectroscopy in the development of low cost, portable sensor devices that can be used in the field for nitroguanidine neonicotinoid insecticide detection is appealing. However, a key challenge to achieving this goal is the lack of detailed analysis and vibrational assignment for the most popular neonicotinoids. To make progress towards this goal, this paper presents an analysis of the bulk Raman and SERS spectra of two neonicotinoids, namely clothianidin and imidacloprid. Combined with first principles simulations, this allowed assignment of all Raman spectral modes for both molecules. To our knowledge, this is the first report of SERS analysis and vibrational assignment of Clothianidin and a comprehensive assignment and analysis is provided for imidacloprid. Silver nanostructured surfaces were fabricated for qualitative SERS analysis, which provides the characteristic spectra of the target molecules, and demonstrates the ability of SERS to sense these molecules at concentrations as low as 1 ng/L. These detection limits are significantly lower than reported solid state electrochemical techniques and are on a par with high-end chromatographic-mass spectroscopy laboratory methods. These SERS sensors thus allow for the selective and sensitive detection of neonicotinoids, and provides complementary qualitative and quantitative data for the molecules. Furthermore, this technique can be adapted to portable devices for remote sensing applications. Further work focuses on integrating our device with an electronics platform for truly portable residue detection

Thiamine plays a critical role in the acid tolerance of listeria monocytogenes

Understanding the molecular basis of acid tolerance in the food-borne pathogen Listeria monocytogenes is important as this property contributes to survival in the food-chain and enhances survival within infected hosts. The aim of this study was to identify genes contributing to acid tolerance in L. monocytogenes using transposon mutagenesis and subsequently to elucidate the physiological role of these genes in acid tolerance. One mutant harboring a Tn917 insertion in the thiT gene (formerly lmo1429), which encodes a thiamine (vitamin B1) uptake system, was found to be highly sensitive to acid. The acid-sensitive phenotype associated with loss of this gene was confirmed with an independently isolated mutant, from which the thiT gene was deleted (?thiT). Cells of both wild-type and ?thiT mutant that were thiamine depleted were found to be significantly more acid sensitive than control cultures. Thiamine-depleted cultures failed to produce significant concentrations of acetoin, consistent with the known thiamine dependence of acetolactate synthase, an enzyme required for acetoin synthesis from pyruvate. As acetoin synthesis is a proton-consuming process, we suggest that the acid sensitivity observed in thiamine-depleted cultures may be owing to an inability to produce acetoin

Advanced Solid State Nano-electrochemical Sensors and System for Agri 4.0 Applications

Global food production needs to increase in order to meet the demands of an ever growing population. As resources are finite, the most feasible way to meet this demand is to minimize losses and improving efficiency. Regular monitoring of factors like animal health, soil and water quality for example, can ensure that the resources are being used to their maximum efficiency. Existing monitoring techniques however have limitations, such as portability, turnaround time and requirement for additional reagents. In this work, we explore the use of micro and nano scale electrode devices, for the development of electrochemical sensing platform to digitalize a wide range of applications within the Agri-food sector. With this platform, we demonstrate the direct electrochemical detection of pesticides, specifically clothianidin and imidacloprid with detection limits of 0.22 ng/mL and 2.14 ng/mL respectively, and nitrates with a detection limit of 0.2 µM. In addition, interdigitated electrode structures also enable an in-situ pH control technique to mitigate pH as an interference and modify analyte response. This technique is applied to the analysis of monochloramine, a common water disinfectant. Concerning biosensing, the sensors are modified with biomolecular probes for the detection of both bovine viral diarrhea virus particles and antibodies, over a range of 1 ng/mL to 10 µg/mL. Finally, a portable analogue front end electronic reader is developed to allow portable sensing, with control and readout undertaken using a smart phone application. Finally, the sensor chip platform is integrated with these electronics to provide a fully functional end-to-end smart sensor system compatible with emerging AgriFood digital decision support tools