Bulk and Surface Acoustic Wave Sensor Arrays for Multi-Analyte Detection: A Review

Bulk acoustic wave (BAW) and surface acoustic wave (SAW) sensor devices have successfully been used in a wide variety of gas sensing, liquid sensing, and biosensing applications. Devices include BAW sensors using thickness shear modes and SAW sensors using Rayleigh waves or horizontally polarized shear waves (HPSWs). Analyte specificity and selectivity of the sensors are determined by the sensor coatings. If a group of analytes is to be detected or if only selective coatings (i.e., coatings responding to more than one analyte) are available, the use of multi-sensor arrays is advantageous, as the evaluation of the resulting signal patterns allows qualitative and quantitative characterization of the sample. Virtual sensor arrays utilize only one sensor but combine itwith enhanced signal evaluation methods or preceding sample separation, which results in similar results as obtained with multi-sensor arrays. Both array types have shown to be promising with regard to system integration and low costs. This review discusses principles and design considerations for acoustic multi-sensor and virtual sensor arrays and outlines the use of these arrays in multi-analyte detection applications, focusing mainly on developments of the past decade

Investigation of Human Pathogen Using Electronic Nose for Early Diagnosis

Electronic nose (E-nose) known as gas sensor array is a device that analyze the odor measurement give the fast response and less time consuming for clinical diagnosis. Many bacterial pathogens could lead to life threatening infections. Accurate and rapid diagnosis is crucial for the successful management of these infections disease. The conventional method need more time to detect the growth of bacterial. Alternatively, the bacteria are Pseudomonas aeruginosa and Shigella cultured on different media agar can be detected and classifies according to the volatile compound in shorter time using electronic nose (E-nose). Then, the data from electronic nose (E-nose) is processed using statistical method which is principal component analysis (PCA). The study shows the capability of electronic nose (E-nose) for early screening for bacterial infection in human stomach

Fluorescent-based nanosensors for selective detection of a wide range of biological macromolecules: A comprehensive review

Thanks to their unique attributes, such as good sensitivity, selectivity, high surface-to-volume ratio, and versatile optical and electronic properties, fluorescent-based bioprobes have been used to create highly sensitive nano -biosensors to detect various biological and chemical agents. These sensors are superior to other analytical instrumentation techniques like gas chromatography, high-performance liquid chromatography, and capillary electrophoresis for being biodegradable, eco-friendly, and more economical, operational, and cost-effective. Moreover, several reports have also highlighted their application in the early detection of biomarkers associ-ated with drug-induced organ damage such as liver, kidney, or lungs. In the present work, we comprehensively overviewed the electrochemical sensors that employ nanomaterials (nanoparticles/colloids or quantum dots, carbon dots, or nanoscaled metal-organic frameworks, etc.) to detect a variety of biological macromolecules based on fluorescent emission spectra. In addition, the most important mechanisms and methods to sense amino acids, protein, peptides, enzymes, carbohydrates, neurotransmitters, nucleic acids, vitamins, ions, metals, and electrolytes, blood gases, drugs (i.e., anti-inflammatory agents and antibiotics), toxins, alkaloids, antioxidants, cancer biomarkers, urinary metabolites (i.e., urea, uric acid, and creatinine), and pathogenic microorganisms were outlined and compared in terms of their selectivity and sensitivity. Altogether, the small dimensions and capability of these nanosensors for sensitive, label-free, real-time sensing of chemical, biological, and pharma-ceutical agents could be used in array-based screening and in-vitro or in-vivo diagnostics. Although fluorescent nanoprobes are widely applied in determining biological macromolecules, unfortunately, they present many challenges and limitations. Efforts must be made to minimize such limitations in utilizing such nanobiosensors with an emphasis on their commercial developments. We believe that the current review can foster the wider incorporation of nanomedicine and will be of particular interest to researchers working on fluorescence tech-nology, material chemistry, coordination polymers, and related research areas

Genetic, Biochemical, and Functional Characterization of Heme Metabolism in Group A Streptococcus

Heme is vital to a variety of cellular functions in bacteria ranging from energy generation to iron reserve. Group A streptococcus (GAS) is a prevalent bacterial pathogen that is responsible for an array of human diseases ranging from simple, self-limiting, mucosal and skin infections to invasive and systemic manifestations. GAS needs iron for growth and can satisfy this nutritional requirement by scavenging the metal from heme. The pathogen produces powerful hemolysins that facilitate heme release during infection. Heme is captured and relayed through the GAS cell wall and cytoplasmic membrane by dedicated receptors and transporters. To-date, the fate of the acquired heme is unknown in Streptococci. Although heme is nutritionally beneficial for GAS growth, its pro-oxidant and lipophilic nature makes it a liability with damaging effects on cellular components. The conundrum associated with heme use is particularly pertinent to GAS pathophysiology since invasive GAS infections involve massive hemolysis and the generation of unescorted heme in excess. In this dissertation, I aimed to describe the mechanisms that GAS uses for heme catabolism while managing its toxicity. I conducted a biochemical characterization of a new enzyme, HupZ in GAS that degrades heme in vitro. Similar to the heme oxygenase-1 (HO-1), HupZ activity leads to the formation of iron, CO, and a biliverdin-like product. I also investigated the impact of heme on GAS physiology and identified key mediators in the repair and detoxification process. This study demonstrated that heme exposure leads to a general stress response that involves the activation of antioxidant defense pathways to restore redox balance. Further, I studied a 3-gene cluster, pefRCD (porphyrin-regulated efflux RCD), which was activated by environmental heme, and provided support to my hypothesis that the pefRCD gene encodes a heme-sensing regulator (PefR) and heme efflux system (PefCD). I showed that the pef system protects GAS cells from heme-induced damage to the membrane and DNA by preventing cellular accumulation of heme. In conclusion, this dissertation addresses key knowledge gaps in GAS physiology and provides new insights into heme metabolism of GAS

STUDY OF IRON SPECIATION IN ANTARCTIC MARINE MATRICES IN RELATION TO CLIMATE CHANGE

Iron (Fe) is the most important trace element in the ocean, as it is required by phytoplankton for photosynthesis and nitrate assimilation, and it is the primary limiting micronutrient in the High Nutrient Low Chlorophyll (HNLC) region across large parts of the Southern Ocean. To understand the availability of this element for organisms, speciation studies have been carried out, which allow to define the chemical species in which the element is distributed. Both temperature and pH influence chemical and biological processes, and could have effects on Fe biogeochemistry and on its speciation. The aim of this work was to determine the concentrations of Fe in polar marine matrices and to study its speciation, focusing in particular on the study of organic ligands able to complex this element. The work focused both on the aspects related to the development of the analytical methods used for these studies, and on the environmental and biological aspects, in order to frame the results obtained in the Antarctic environmental context, by using multivariate analysis methods, such as principal component analysis (PCA), for a better comprehension of the analytical data obtained. Considering the influence of other chemical parameters on iron and its speciation, aspects related to nutrient parameters and the carbonate system were evaluated, and the use of these chemical parameters as possible tracers for Ross Sea water masses was also considered. Particular attention was given to the evaluation of pH considering the effects of ocean acidification and indirectly also on iron speciation, with the development of accurate methods for the assessment of this parameter. Studies were also carried out in Antarctica in the Ross Sea, both for sampling and for on-site measurements in the frame of the ESTRO (Effect of the eaSTern inflow of water on the ROss Sea salinity field variability) project

Program and Abstracts of the Annual Meeting of the Georgia Academy of Science, 2010

The annual meeting of the Georgia Academy of Science took place March 27–28, 2010, at Columbus State University, Columbus, Georgia. Presentations were provided by members of the Academy who represented the following sections: I. Biological Sciences, II. Chemistry, III. Earth & Atmospheric Sciences, IV. Physics, Mathematics, Computer Science, Engineering & Technology, V. Biomedical Sciences, VI. Philosophy & History of Science, VII. Science Education, and VIII. Anthropology

Characterization and Metabolic Engineering of Transcription Factors and Redox Dynamics in Candidate Consolidated Bioprocessing Biocatalysts

This thesis studies the metabolic engineering of candidate consolidated bioprocessing biocatalyst microorganisms through targeting regulatory genes, with an emphasis on redox metabolism. Consolidated bioprocessing is the single-step hydrolysis and conversion of lignocellulosic material to biofuels. The biocatalysts considered are Clostridium thermocellum and Caldicellulosiruptor bescii, and the primary product of interest is ethanol. Both organisms are thermophilic anaerobic bacteria which encode and express genes that facilitate the deconstruction and solubilization of lignocellulose into fermentable carbohydrates. Furthermore, these organisms ferment these carbohydrates into ethanol, organic acids, as well as other fermentation products. We seek to improve redox metabolism and osmotolerance in these organsisms toward a biorefining objective goal of engineering a biocatalyst capable of facilitating economically viable consolidated bioprocessing.Expression profiling, transcription factor regulon mapping, genetic engineering, and analytical fermentation were approaches employed to assay and understand which specific traits can be beneficially altered. The traits sought to be altered are characteristically complex, co-opting many cellular sub-processes to enable a molecular mechanism resulting in an observable trait. Such traits are notoriously difficult not only to understand, but to alter through classical metabolic engineering. Instead, the possibility of making system-wide changes through a minimal number of genetic alterations to methodically selected and/or screened regulatory genes was investigated.Active redox-dependent systems were characterized in both bacteria, many of which are controlled by the global redox-state sensing transcription factor Rex. Eliminating Rex control over gene expression in C. bescii resulted in a more reduced intracellular redox state, and ultimately drives increased ethanol synthesis. A method for quantifying important redox metabolites intracellularly is also adopted and validated for use with C. thermocellum. This approach was extended to less characterized gene targets and, arguably, even more complex traits. Screening of single-gene deletion mutants identified two strains of C. bescii showing phenotypic growth differences in elevated osmolarity conditions. One strain housed a deletion of the fapR gene, while the other a deletion of the fruR/cra gene. Characterizing these transcription factors and their regulons elucidates mechanisms which this organism uses to facilitate survival at elevated osmolarities. We are also able to construct genetic variants in C. bescii which are substantially more osmotolerant than native strains, highlighting the usefulness of these genes as targets and the applicability, and important considerations, of our metabolic engineering approach

Applications of planar oxygen optodes in biological aquatic systems

The work presented in this thesis investigates two-dimensional (2D) oxygen distribution and dynamics in biological aquatic systems with the help of recently developed porphyrin-based planar oxygen optodes and the modular luminescence lifetime imaging (MOLLI) system. The general characteristics of the used optodes were determined in experiments described in chapter 5. It is shown that planar optodes cannot easily be used to determine highly accurate oxygen distributions and dynamics, when very high spatial (< 15 µm) and temporal (< 3 s) resolutions are required (chapter 5 and 6). Major problems are the light guidance effect, relatively noisy oxygen data and the slow response time of the optodes. The oxygen data measured with porphyrin-based planar optodes are robust enough to visualise 2D oxygen heterogeneities and dynamics qualitatively in various biological systems. Porphyrin-based oxygen optodes proved to be powerful tools in aquatic systems where qualitative determination and visualisation of the heterogeneity and dynamics of 2D oxygen distributions are the focus of interest. One of the most appreciatory applications for planar optodes are permeable sediments (chapters 2, 3, 4 and 6 )

Advances in Bioengineering

The technological approach and the high level of innovation make bioengineering extremely dynamic and this forces researchers to continuous updating. It involves the publication of the results of the latest scientific research. This book covers a wide range of aspects and issues related to advances in bioengineering research with a particular focus on innovative technologies and applications. The book consists of 13 scientific contributions divided in four sections: Materials Science; Biosensors. Electronics and Telemetry; Light Therapy; Computing and Analysis Techniques