Microfabricated Reference Electrodes and their Biosensing Applications

Over the past two decades, there has been an increasing trend towards miniaturization of both biological and chemical sensors and their integration with miniaturized sample pre-processing and analysis systems. These miniaturized lab-on-chip devices have several functional advantages including low cost, their ability to analyze smaller samples, faster analysis time, suitability for automation, and increased reliability and repeatability. Electrical based sensing methods that transduce biological or chemical signals into the electrical domain are a dominant part of the lab-on-chip devices. A vital part of any electrochemical sensing system is the reference electrode, which is a probe that is capable of measuring the potential on the solution side of an electrochemical interface. Research on miniaturization of this crucial component and analysis of the parameters that affect its performance, stability and lifetime, is sparse. In this paper, we present the basic electrochemistry and thermodynamics of these reference electrodes and illustrate the uses of reference electrodes in electrochemical and biological measurements. Different electrochemical systems that are used as reference electrodes will be presented, and an overview of some contemporary advances in electrode miniaturization and their performance will be provided

Heavy metals in the riverine Lamprey lampetra fluviatilis (L. 1758)

Celem niniejszej pracy było określenie zawartości wybranych metali ciężkich (Hg, Cd, Pb, Cu i Zn) w minogu rzecznym (Lampetra fluviatilis), porównanie zawartości metali w zależności od miejsca połowu i płci oraz wykazanie, które spośród badanych narządów kumulują je w największych ilościach.Despite numerous studies of metals in ichthyofauna, research lampreys which, as Agnatha, not belong formally to the fish, although they are of interest to ichthyolgists are still very few. The purpose of this study was to determine the content of selected heavy metals (Hg, Cd, Pb, Cu and Zn) in the riverine lamprey (Lampetra fluviatilis), the comparison of metal content depending on the location of catches and sex, and to demonstrate which of the examined organs accumulate them in the largest quantities. The study included females and males from the river Odra and the Vistula, weighing from 61 to 198 grams and total length from 313 to 482 mm. For analysis muscles, gonads and gill bags were collected. Samples for the determination of mercury were wet mineralized in a mixture of concentrated nitric and perchloric acids, and for analysis of other metals in nitric acid by microwave technique. Analyse of Hg content was performed by CV AAS, Cd and Pb by GF AAS method, and Cu and Zn by ICP-AES. It has been shown that the gonads of the Odra river lampreys contained more mercury and zinc, gill bags more of cadmium and lead, than those organs of lampreys from the Vistula. Metal content in the other cases was the same. Female gonads also contained more zinc than the male gonads, and the levels of this element in both sexes slightly correlated (r = 0.453) with the mass of the gonads. High levels of zinc in the gonads is probably associated with its role in the processes of reproduction. Generally, the lowest metal concentration, except mercury, contained muscle, a lot was accumulated in the respiratory system responsible for direct down-loading of the elements from the water. There were no statistically significant relationship between the level of the analyzed metals in the organs, and body weight and total length of lampreys (correlation coefficients of r <0.365)

Multiple routes of endocytic internalization of PDGFRβ contribute to PDGF-induced STAT3 signaling.

Platelet-derived growth factor receptor β (PDGFRβ) is a receptor tyrosine kinase which upon activation by PDGF-BB stimulates cell proliferation, migration and angiogenesis. Ligand binding induces intracellular signaling cascades but also internalization of the receptor, eventually resulting in its lysosomal degradation. However, endocytic trafficking of receptors often modulates their downstream signaling. We previously reported that internalization of PDGFRβ occurs via dynamin-dependent and -independent pathways but their further molecular determinants remained unknown. Here we show that, in human fibroblasts expressing endogenous PDGFRβ and stimulated with 50 ng/ml PDGF-BB, ligand-receptor uptake proceeds via the parallel routes of clathrin-mediated endocytosis (CME) and clathrin-independent endocytosis (CIE). CME involves the canonical AP2 complex as a clathrin adaptor, while CIE requires RhoA-ROCK, Cdc42 and galectin-3, the latter indicating lectin-mediated internalization via clathrin-independent carriers (CLICs). Although different uptake routes appear to be partly interdependent, they cannot fully substitute for each other. Strikingly, inhibition of any internalization mechanism impaired activation of STAT3 but not of other downstream effectors of PDGFRβ. Our data indicate that multiple routes of internalization of PDGFRβ contribute to a transcriptional and mitogenic response of cells to PDGF

Enhancement of technical value of oil palm (Elaeis guineensis Jacq.) waste trunk through modification with 1,3-dimethylol-4,5- dihydroxyethyleneurea (DMDHEU)

Malaysia is the biggest producer of palm oil in the world. The production generates over 70 metric tons of waste trunks per hectare during replantation. Such an abundant feedstock should be considered a valuable raw material rather than an agro-waste. An approach for enhancement of low density trunks through the treatment with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) was investigated. The treatment resulted in a great improvement in the properties of the material: 45 % density gain, water absorption and thickness swelling reduced by 48 and 43 %, respectively, 2.3-fold increase in hardness as well as 3.8-fold and 3.6-fold increase in bending strength and modulus of elasticity, respectively, were observed. Thus, enhancement in the physical and mechanical performance of the material as well as the increased aesthetic value due to the color changes proved the approach to be effective for the conversion of waste biomass to new products