A Novel Conductometric Urea Biosensor with Improved Analytical Characteristic Based on Recombinant Urease Adsorbed on Nanoparticle of Silicalite

Development of a conductometric biosensor for the urea detection has been reported. It was created using a non-typical method of the recombinant urease immobilization via adsorption on nanoporous particles of silicalite. It should be noted that this biosensor has a number of advantages, such as simple and fast performance, the absence of toxic compounds during biosensor preparation, and high reproducibility (RSD = 5.1 %). The linear range of urea determination by using the biosensor was 0.05–15 mM, and a lower limit of urea detection was 20 μM. The bioselective element was found to be stable for 19 days. The characteristics of recombinant urease-based biomembranes, such as dependence of responses on the protein and ion concentrations, were investigated. It is shown that the developed biosensor can be successfully used for the urea analysis during renal dialysis

Sampling surficial sediments of a river receiving minewater discharges

Metal contamination of sediments can be an issue for minesites discharging water. Water sampling of receiving waters is frequently undertaken. Sampling and analysis of sediment is less common. The variability of receiving environments makes the formulation of a generic sediment sampling strategy virtually impossible. Each situation needs to be carefully assessed before sampling is undertaken. This paper outlines the approach taken for one such survey. The main factors that need to be considered in a survey of surficial sediments are sample representativeness and sample variability .A simple data set from one site within a regional survey is used to illustrate the importance of these factors. The metal content of sediment is shown to vary significantly over small spatial scales. The variability associated with the spatial distribution of samples within a site is shown to be the most significant source of variability in the study. This variability could bias the results of a study if not planned for in the sampling methodology. Taking multiple samples from within each site (sub-site samples) and combining the data gives a more representative indicator of overall conditions than a single sample. The optimum number of sub-site samples to be taken from each sampling site was found to be 15. It is shown that a composite of sub-site samples can give a good indication of the average site metal content, while considerably reducing the sample preparation and analysis effort

A new sensor for detecting microrna 133B (Parkinson’s disease biomarker)

Chandra, SS ORCiD: 0000-0002-4257-5860The discovery of small non-protein coding regulatory RNAs, such as short microRNAs (miRs) has enabled the detection of diseases, e.g. Alzheimer's disease and breast cancer. The diagnoses of such diseases were previously difficult due to reasons of specificity of the technique and low concentrations of the targets. To this end, miR associated with diseases such as Parkinson's disease have started to be pursued as analytical biomarkers using electrochemical sensors. Such sensors can provide high sensitivity, low detection limits and rapid analysis times. These powerful advantages are an effective means to mitigate the problems associated with low miR concentrations and short lifespans. In this work, we report the development of a new signal-on biosensor for selective and ultrasensitive detection of miR 133b, a known biomarker for Parkinson's disease. The sensor utilizes complementary ss-DNA sequence labelled with methylene blue redox marker attached to a gold electrode surface to generate current response for miR 133b when subjected to cyclic voltammetric measurements. The continuous cycling between the oxidation and reduction of methylene blue in presence of tris(2-carboxyethyl) phosphine hydrochloride, as a strong reductant, was used to amplify the response. Under optimum conditions, the sensors achieved a linear concentration range of 10 fM to 520 pM, a detection limit of 168 aM, and a sensitivity of 0.3 nA pM−1. Furthermore, the sensors successfully distinguished between matched and mismatched sequences of miR, suggesting promising potential for eventual applications in vitro

A new sensor for detecting microrna 133B (Parkinson’s disease biomarker)

The discovery of small non-protein coding regulatory RNAs, such as short microRNAs (miRs) has enabled the detection of diseases, e.g. Alzheimer's disease and breast cancer. The diagnoses of such diseases were previously difficult due to reasons of specificity of the technique and low concentrations of the targets. To this end, miR associated with diseases such as Parkinson's disease have started to be pursued as analytical biomarkers using electrochemical sensors. Such sensors can provide high sensitivity, low detection limits and rapid analysis times. These powerful advantages are an effective means to mitigate the problems associated with low miR concentrations and short lifespans. In this work, we report the development of a new signal-on biosensor for selective and ultrasensitive detection of miR 133b, a known biomarker for Parkinson's disease. The sensor utilizes complementary ss-DNA sequence labelled with methylene blue redox marker attached to a gold electrode surface to generate current response for miR 133b when subjected to cyclic voltammetric measurements. The continuous cycling between the oxidation and reduction of methylene blue in presence of tris(2-carboxyethyl) phosphine hydrochloride, as a strong reductant, was used to amplify the response. Under optimum conditions, the sensors achieved a linear concentration range of 10 fM to 520 pM, a detection limit of 168 aM, and a sensitivity of 0.3 nA pM−1. Furthermore, the sensors successfully distinguished between matched and mismatched sequences of miR, suggesting promising potential for eventual applications in vitro

Phosphorus between soil, soil water and overland flow for established and laser graded, border-check irrigation systems

Agricultural systems contribute to excessive phosphorus (P) additions that are adversely affecting water resources worldwide. The effects of soil disturbance on P exports have not been widely reviewed. In February 2004, four established and four recently laser graded (<4 yrs) border-check irrigation bays on the Macalister Research Farm (38°00'S 146°54'E) were sampled during and after irrigation. Samples were taken at the channel inlet and every 60 m thereafter. Overland flow was sampled at the wetting front and back up the bays, and soil samples were recovered from the sampling locations two days after irrigation. Overland flow was analysed for total P (TP), the soil samples were analysed for soil Olsen P (0-20 and 0-100 mm depths) and soil water, dissolved reactive P (SWDRP) and total P (SWTP) (0-20 mm depth)

Changes in nitrogen and phosphorus concentrations in soil, soil water and surface run-off following grading of irrigation bays used for intensive grazing

Soil tests are often used to identify areas at risk of excessive phosphorus (P) exports. We investigated the changes in soil P (0-20 mm) in four recently laser-graded (<1 year) and four established (>10 years) irrigated pastures in south-eastern Australia before and after 3 years of irrigated dairy production. At the second sampling, soil water P and nitrogen (N), and P and N in surface run-off (overland flow) were also measured enabling comparison of P in surface run-off with measures of soil P. In surface soil (0-20 mm), grading reduced measures of soil P, while P sorption increased. Over 3 years, in the graded bays, Olsen P, Colwell P and P sorption decreased and water extractable P and P sorption saturation increased, while Olsen P and Colwell P decreased in the established bays. After 3 years, total dissolved P (TDP) concentrations in soil water were greater in the established bays, but dissolved reactive P (DRP) concentrations were unaffected. Organic P in soil water comprised 70 and 32% of TDP in the established and graded bays, respectively. The soil water analyses were reflected in surface run-off. After 3 years, laser grading decreased TDP, TDN, TP and TN exports in wetting front run-off by 40, 29, 41 and 36%, respectively, compared with established bays. This is an important result for the management of dairy systems as it suggests that the regular cultivation used to renovate pasture on more intensive dairy farms decreases the exports of P and N