RESUMO
It is well known that an excess of hydroxyl radicals (ËOH) in the human body is responsible for oxidative stress-related diseases. An understanding of the relationship between the concentration of ËOH and those diseases could contribute to better diagnosis and prevention. Here we present a supersensitive nanosensor integrated with an electrochemical method to measure the concentration of ËOH in vitro. The electrochemical sensor consists of a composite comprised of ultrasmall cerium oxide nanoclusters (<2 nm) grafted to a highly conductive carbon deposited on a screen-printed carbon electrode (SPCE). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to analyze the interaction between cerium oxide nanoclusters and ËOH. The CV results demonstrated that this electrochemical sensor had the capacity of detecting ËOH with a high degree of accuracy and selectivity, achieving a consistent performance. Additionally, EIS results confirmed that our electrochemical sensor was able to differentiate ËOH from hydrogen peroxide (H2O2), which is another common reactive oxygen species (ROS) found in the human body. The limit of detection (LOD) observed with this electrochemical sensor was of 0.6 µM. Furthermore, this nanosized cerium oxide-based electrochemical sensor successfully detected in vitro the presence of ËOH in preosteoblast cells from newborn mouse bone tissue. The supersensitive electrochemical sensor is expected to be beneficially used in multiple applications, including medical diagnosis, fuel-cell technology, and food and cosmetic industries.
Assuntos
Peróxido de Hidrogênio , Nanocompostos , Animais , Técnicas Eletroquímicas , Eletrodos , Limite de Detecção , CamundongosRESUMO
The objective of this study is to evaluate the influence of water distribution system conditions (pH, total organic carbon, residual chlorine, and phosphate) on haloacetic acids (HAAs) biodegradation. A series of batch microcosm tests were conducted to determine biodegradation kinetics and collected biomass was used for real time quantitative reverse transcription polymerase chain reaction analyses to monitor how these drinking water distribution system conditions affect the relative expression of bacterial dehalogenase genes. It was observed that tested water distribution system conditions affected HAA biodegradation with different removal efficiencies (0-100%). HAA biodegradation was improved in tested samples with TOC (3â¯mg/L) and pH 8.5 compared to those of TOC (0â¯mg/L) and pH 7, respectively. However, slight improvement was observed with the increased PO4 concentration (3.5â¯mg/L), and the presence of residual chlorine even at low concentration prohibited biodegradation of HAAs. The observed trend in the relative expression of dehII genes was compatible with the HAA biodegradation trend. Overall relative expression ratio of dehII genes was lower at pH 7, phosphate (0.5â¯mg/L), and TOC (0â¯mg/L) in comparison with pH 8.5, phosphate (3.5â¯mg/L), and TOC (3â¯mg/L) in the same experimental conditions.