A Biosensor for Urea from Succinimide-Modified Acrylic Microspheres Based on Reflectance Transduction

New acrylic microspheres were synthesised by photopolymerisation where the succinimide functional group was incorporated during the microsphere preparation. An optical biosensor for urea based on reflectance transduction with a large linear response range to urea was successfully developed using this material. The biosensor utilized succinimide-modified acrylic microspheres immobilized with a Nile blue chromoionophore (ETH 5294) for optical detection and urease enzyme was immobilized on the surface of the microspheres via the succinimide groups. No leaching of the enzyme or chromoionophore was observed. Hydrolysis of the urea by urease changes the pH and leads to a color change of the immobilized chromoionophore. When the color change was monitored by reflectance spectrophotometry, the linear response range of the biosensor to urea was from 0.01 to 1,000 mM (R2 = 0.97) with a limit of detection of 9.97 μM. The biosensor response showed good reproducibility (relative standard deviation = 1.43%, n = 5) with no interference by major cations such as Na+, K+, NH4+ and Mg2+. The use of reflectance as a transduction method led to a large linear response range that is better than that of many urea biosensors based on other optical transduction methods

Hemoglobin determination with paired emitter detector diode

Two ordinary green light-emitting diodes used as light emitter and detector coupled with simple voltmeter form a complete, cost-effective prototype of a photometric hemoglobinometer. The device has been optimized for cuvette assays of total hemoglobin (Hb) in diluted blood using three different chemical methods recommended for the needs of clinical analysis (namely Drabkin, lauryl sulfate, and dithionite methods). The utility of developed device for real analytics has been validated by the assays of total Hb content in human blood. The results of analysis are fully compatible with those obtained using clinically recommended method and clinical analyzer

Nanoscale Potentiometry

Potentiometric sensors share unique characteristics that set them apart from other electrochemical sensors. Potentiometric nanoelectrodes have been reported and successfully used for many decades, and we review these developments. Current research chiefly focuses on nanoscale films at the outer or the inner side of the membrane, with outer layers for increasing biocompatibility, expanding the sensor response, or improving the limit of detection (LOD). Inner layers are mainly used for stabilizing the response and eliminating inner aqueous contacts or undesired nanoscale layers of water. We also discuss the ultimate detectability of ions with such sensors and the power of coupling the ultra-low LODs of ion-selective electrodes with nanoparticle labels to give attractive bioassays that can compete with state-of-the-art electrochemical detection

Prospects of Nanotechnology in Clinical Immunodiagnostics

Nanostructured materials are promising compounds that offer new opportunities as sensing platforms for the detection of biomolecules. Having micrometer-scale length and nanometer-scale diameters, nanomaterials can be manipulated with current nanofabrication methods, as well as self-assembly techniques, to fabricate nanoscale bio-sensing devices. Nanostructured materials possess extraordinary physical, mechanical, electrical, thermal and multifunctional properties. Such unique properties advocate their use as biomimetic membranes to immobilize and modify biomolecules on the surface of nanoparticles. Alignment, uniform dispersion, selective growth and diameter control are general parameters which play critical roles in the successful integration of nanostructures for the fabrication of bioelectronic sensing devices. In this review, we focus on different types and aspects of nanomaterials, including their synthesis, properties, conjugation with biomolecules and their application in the construction of immunosensing devices. Some key results from each cited article are summarized by relating the concept and mechanism behind each sensor, experimental conditions and the behavior of the sensor under different conditions, etc. The variety of nanomaterial-based bioelectronic devices exhibiting novel functions proves the unique properties of nanomaterials in such sensing devices, which will surely continue to expand in the future. Such nanomaterial based devices are expected to have a major impact in clinical immunodiagnostics, environmental monitoring, security surveillance and for ensuring food safety

Enzymes in analytical chemistry

There are three main fields of modern analytical chemistry where enzymes are presented: (1) biorecognition, biosensing and biodetection schemes, especially important in case of biosensors, (2) enzymes as analytes, and (3) enzymes as markers in immune- and genoanalysis. These analytical fields could be illustrated by the research of bioanalytics group supervised by professor Stanisław Głąb

How green is the harvest? : effects of forest biofuel management on soil resources

Efforts to develop alternative energy sources have spurred calls to increase cellulosic biofuel production from domestic biofuel sources. By 2035, the proportion of energy the United States derives from all types of biomass is expected to double from the current level of 5 percent (U.S. EIA 2009). Forests and crops have the potential to increase the amount of bioenergy and biobased products that are consumed sevenfold, which would help in achieving this percentage. While some of the greater demand for wood will derive from more efficient use of wood already harvested extracting more energy from wood will inevitably cause a change in land use and harvesting techniques to deliver a greater biomass supply. Out of this total potential of 1.3 billion dry tons more than 25 percent would have to come from more intensively managed forestlands that are currently being harvested for their timber resources (USDA and DOE 2005). For example, larger amounts of wood may be extracted from products residue, urban wood waste, or greater portion of standing trees may be removed, or harvest rotation may speed with the development of fast-growing hybrid tree varieties

The influence of different dressings on the pH of the wound environment

This study examines the effect of various wound dressings on the pH levels of a wound, using a simulated wound environment. The pH levels of a 4 different wound dressings (manuka honey dressing, sodium carboxymethylcellulose hydrofiber dressing, polyhydrated ionogen-coated polymer mesh dressing, and a protease modulating collagen cellulose dressing) were tested in a simulated horse serum wound environment. The effect of local buffering was observed and pH changes in real time were measured. All dressings were found to have low pH (below pH 4), with the lowest being the protease modulating collage cellulose dressing, with a pH of 2.3. The dressing with the strongest acid concentration was the polyhydrated, ionogen-coated, polymer mesh dressing. The low pH and strong acidic nature of the dressing investigated indicate that they may play a role in influencing the healing process in a wound