Hydrogen cyanide is a potential PA biomarker If

Hydrogen cyanide is a potential PA biomarker. If a point-of-care device could detect HCN in the breath of young CF patients with a pulmonary PA colonization, the need for invasive techniques and repeated anesthesia for obtaining broncho-alveolar lavage to diagnose PA would be minimized. To make a simple model system for the presence of HCN in breath, a gas setup with an open flow cell connected to a tank of 5ppm HCN(g) in N2 was used. The SERS substrate was placed inside the flow cell and exposed to the gas for 30s. To vary the amount of HCN molecules exposing the substrate, the pressure through the open system was changed among samples. In the present paper SERS measurements on 5ppm HCN gas and on serial dilutions of potassium cyanide (KCN) in the region from 10nM to 1mM are presented. A KCN concentration range of 100nM to 1μM is the region of relevance, corresponding to ppb gas levels. The aim of the project is to detect PA colonization in the patients’ breath at an earlier stage than allowed by today’s conventional methods.
Experimental
Results and discussion
Conclusion By use of the applied SERS technique we have shown that it is possible to quantify the amount of cyanide down to ppb level, which is needed for detection of P. aeruginosa lung colonization in the breath of children with cystic fibrosis. It was possible to distinguish samples with different KCN concentration down to 1μM (corresponding to 18ppb) using the CN stretching region located close to 2133cm−1, thus the detection limit was between 18ppb (detected) and 1.8ppb (not detected). Future work includes measurements on bacterial cultures and patient samples.
Conflict of interest
Acknowledgments
Introduction In recent years, the technology of capturing and storing renewable energy has been extensively discussed and investigated. The reduction of carbon dioxide to generate reduced carbon compounds for use as fuels and chemical feedstocks is an essential requirement for carbon-based sustainable energy economy [1]. Interconversion system of formate/carbon dioxide (HCOO−/CO2) is one of the answers for the purpose. Furthermore, this system has another merit of CO2 fixation, since CO2 is known to a major cause of the present global warming [2]. CO2 fixation helps not only to produce renewable energy and to develop new carbon JAK STAT Compound Library but also to decrease the atmospheric CO2 level [3]. Formate is the first stable intermediate during the reduction of CO2 to methanol or methane and is increasingly recognized as a new energy source [4,5]. In addition, it can easily be handled, stored, and transported. However, when CO2 is reduced and formate is oxidized directly on electrodes, a variety of products are generated and quite high overpotential is required [6,7]. The non-catalyzed thermal decomposition of formate is dominated by the reaction channels, the decarboxylation/dehydrogenation yielding carbon dioxide and hydrogen. For the desired pathway higher activation energy is necessary [8]. Catalysts developed so far to overcome this problem are inefficient and expensive [9–17]. One of the most promising strategies for solving these issues is the utilization of enzymes as catalysts. Enzymes have novel properties of substrate specificities and high catalytic efficiencies, allowing them to function in a specific biological reaction under mild conditions, such as room temperature, atmospheric pressure and neutral pH. Formate dehydrogenase (FoDH) is a key enzyme in the energy conversion reactions of methylotrophic aerobic bacteria, fungi, and plants. The enzyme, in general, catalyzes the oxidation of formate to CO2. However, certain FoDHs have been reported to act as CO2 reductases [18–22]. It is now established that some redox enzymes are able to catalyze reactions reversibly [23]. For example, DMSO-reductase [24]; [25], CO dehydrogenase [26], fumarate:menaquinone oxidoreductase, succinate:quinone reductase [27] and some hydrogenases [28]. A great variability is found in bacterial FoDHs and they can be divided into two major classes based on their metal content/structure and consequent catalytic strategies [29]. The metal-independent FoDH class comprises NAD-dependent FoDHs in the category of the d-specific dehydrogenases of the 2-oxyacid family [30–32]. These enzymes are found in aerobic bacteria, yeast, fungi and plants. Because these enzymes have no redox cofactors or metal ions, the formate oxidation to CO2 has been suggested to involve the direct hydride transfer from formate to NAD+. The metal-containing FoDH class comprises only prokaryotic FoDHs in the category of the molybdenum and tungsten-containing enzyme families. This class of FoDHs is composed of complex subunits with different redox cofactors, and the active site harbors one molybdenum or tungsten atom that catalyzes the proton/electrons transfer in their active site, at which the formate oxidation takes place. Accordingly, the metal-containing FoDH class can be sub-divided as molybdenum-containing FoDH and tungsten-containing FoDH.