Antioxidant, antibacterial, and anti-adhesive activities of biosurfactants isolated from Bacillus strains.

Biosurfactants are surface-active compounds that display a range of physiological functions. The present study investigated the antioxidant, antimicrobial, and anti-adhesive or anti-biofilm potential of biosurfactants isolated from Bacillus subtilis VSG4 and Bacillus licheniformis VS16. The antioxidant activity of the biosurfactants was studied in vitro using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. At 5 mg/mL of the biosurfactant concentration, the scavenging of DPPH and hydroxyl radicals was found to be between 69.1-73.5% and 63.3-69.8%, respectively. The biosurfactants also displayed significant antibacterial activities against both Gram-positive and Gram-negative bacteria. The anti-adhesive activities of the biosurfactants were evaluated against Staphylococcus aureus ATCC 29523, Salmonella typhimurium ATCC 19430, and Bacillus cereus ATCC 11778. The biosurfactants exhibited anti-adhesive activity, even at concentrations of 3-5 mg/mL. Moreover, both biosurfactants displayed notable anti-biofilm activities with a biofilm eradication percentage ranging from 63.9 to 80.03% for VSG4 biosurfactant, and from 61.1-68.4% for VS16 biosurfactant. Furthermore, VSG4 biosurfactant exhibited emulsification and surface tension stability over a wide range of pH (4-10) and temperature up to 100 °C. These results show that VSG4 and VS16 biosurfactants can be potentially used as natural antioxidants, antimicrobials, and/or anti-adhesive agents for food and biomedical applications.

Label-Free Fluorescence Assay of S1 Nuclease and Hydroxyl Radicals Based on Water-Soluble Conjugated Polymers and WS2 Nanosheets.

We developed a new method for detecting S1 nuclease and hydroxyl radicals based on the use of water-soluble conjugated poly[9,9-bis(6,6-(N,N,N-trimethylammonium)-fluorene)-2,7-ylenevinylene-co-alt-2,5-dicyano-1,4-phenylene)] (PFVCN) and tungsten disulfide (WS2) nanosheets. Cationic PFVCN is used as a signal reporter, and single-layer WS2 is used as a quencher with a negatively charged surface. The ssDNA forms complexes with PFVCN due to much stronger electrostatic interactions between cationic PFVCN and anionic ssDNA, whereas PFVCN emits yellow fluorescence. When ssDNA is hydrolyzed by S1 nuclease or hydroxyl radicals into small fragments, the interactions between the fragmented DNA and PFVCN become weaker, resulting in PFVCN being adsorbed on the surface of WS2 and the fluorescence being quenched through fluorescence resonance energy transfer. The new method based on PFVCN and WS2 can sense S1 nuclease with a low detection limit of 5 × 10(-6) U/mL. Additionally, this method is cost-effective by using affordable WS2 as an energy acceptor without the need for dye-labeled ssDNA. Furthermore, the method provides a new platform for the nuclease assay and reactive oxygen species, and provides promising applications for drug screening.

Removal of sea salt hydrate water from seawater-derived samples by dehydration.

Aerosol particles produced from bubble bursting of natural seawater contain both sea salts and organic components. Depending on the temperature, pressure, and speed of drying, the salt components can form hydrates that bind water, slowing evaporation of the water, particularly if large particles or thick layers of salts undergo drying that is nonuniform and incomplete. The water bound in these salt hydrates interferes with measuring organic hydroxyl and amine functional groups by Fourier transform infrared (FTIR) spectroscopy because it absorbs at the same infrared wavelengths. Here, a method for separating the hydrate water in sea salt hydrates using freezing and then heating in warm, dry air (70 °C) is evaluated and compared to other methods, including spectral subtraction. Laboratory-generated sea salt analogs show an efficient removal of 89% of the hydrate water absorption peak height by 24 h of heating at atmospheric pressure. The heating method was also applied to bubbled submicrometer (Sea Sweep), generated bulk (Bubbler), and atomized seawater samples, with efficient removal of 5, 22, and 39 µg of hydrate water from samples of initial masses of 11, 30, 58 µg, respectively. The strong spectral similarity between the difference of the initial and dehydrated spectra and the laboratory-generated sea salt hydrate spectrum provided verification of the removal of hydrate water. In contrast, samples of submicrometer atmospheric particles from marine air masses did not have detectable signatures of sea salt hydrate absorbance, likely because their smaller particles and lower filter loadings provided higher surface area to volume ratios and allowed faster and more complete drying.

Efficient removal of organic pollutants with magnetic Nanoscaled BiFeO(3) as a reusable heterogeneous fenton-like catalyst.

BiFeO(3) magnetic nanoparticles (BFO MNPs) were prepared with a sol-gel method and characterized as a catalyst. It was found that BFO MNPs effectively catalyzed the decomposition of H(2)O(2) into *OH radicals, being confirmed with electron spin resonance spin-trapping technique and other radical probing techniques. The strong H(2)O(2)-activating ability of BFO MNPs showed promising applications in the oxidative degradation of organic pollutants. When BFO MNPs were used as a heterogeneous Fenton-like catalyst to degrade Rhodamine B, the apparent rate constant for the RhB degradation at 25 degrees C at pH 5.0 in the BFO MNPs-H(2)O(2) system was evaluated to be 2.89 x 10(-2) min(-1), being about 20 folds of that obtained with Fe(3)O(4) MNPs as the catalyst under similar conditions. Moreover, BFO MNPs were demonstrated to have excellent stability and reusability. The catalytic mechanism of BFO MNPs was also investigated with Monte Carlo simulations and density functional theory calculations.

Towards an integrated microfluidic device for spaceflight clinical diagnostics Microchip-based solid-phase extraction of hydroxyl radical markers.

A microchip-based solid-phase extraction method for biological fluid small molecule analysis has been developed. Using a commercially available copolymer packed into a microchip channel, extraction and preconcentration of 2,3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA from saliva was achieved. The metabolites, formed from salicylic acid by reactive oxygen species, can be used as markers of oxidative stress. The results show high recovery of both metabolites (>90+/-15% for spiked saliva) with an 80-fold concentration enhancement possible. The eluent is directly analyzed using capillary electrophoresis, with good resolution for the two metabolites. This study demonstrates the feasibility of future integrated microdevices for spaceflight small molecule biomarker analysis.

Inflammatory effects of coarse and fine particulate matter in relation to chemical and biological constituents.

There is conflicting evidence in the literature as to the predominant mechanism and also the compositional element(s) that drives the pulmonary inflammatory response of ambient particulate matter (PM). We have investigated the inflammogenic potential of coarse (2.5-10 microm) and fine (<2.5 microm) PM from both a rural and an industrial location in Germany, using bronchoalveolar lavage (BAL) of rat lungs 18 h post intratracheal instillation with PM. Irrespective of the sampling location, the coarse fraction of PM(10) but not its fine counterpart caused neutrophilic inflammation in rat lungs, in the absence of any severe pulmonary toxicity as indicated by the lack of an increase in lavage protein and lactate dehydrogenase levels. The rural sample of coarse PM also caused a significant increase in the tumor necrosis factor alpha (TNFalpha) content as well as glutathione depletion in the BAL fluid. The contrasting inflammatory responses of the different samples could not be explained by differences in the concentrations of soluble Fe, Cu, V, Ni, Cr, or Al or by the.OH generating capacities of the PM suspensions. However, the effects of the different PM samples were clearly associated with their endotoxin content, as well as their ability to induce interleukin (IL)-8 and TNFalpha from whole blood in vitro. In conclusion, on an equal mass basis, coarse but not fine PM samples from our sampling campaign induced an inflammatory reaction in the lung in the absence of gross cellular lung damage, following intratracheal instillation. Our data also indicate, in accordance with previous independent in vitro observations, that endotoxin or related contaminants may play a role in these in vivo effects.

Hydroxyl radical in living systems and its separation methods.

It has recently been shown that hydroxyl radicals are generated under physiological and pathological conditions and that they seem to be closely linked to various models of pathology putatively implying oxidative stress. It is now recognized that the hydroxyl radical is well-regulated to help maintain homeostasis on the cellular level in normal, healthy tissues. Conversely, it is also known that virtually every disease state involves free radicals, particularly the most reactive hydroxyl radical. However, when hydroxyl radicals are generated in excess or the cellular antioxidant defense is deficient, they can stimulate free radical chain reactions by interacting with proteins, lipids, and nucleic acids causing cellular damage and even diseases. Therefore, a confident analytical approach is needed to ascertain the importance of hydroxyl radicals in biological systems. In this paper, we provide information on hydroxyl radical trapping and detection methods, including liquid chromatography with electrochemical detection and mass spectrometry, gas chromatography with mass spectrometry, capillary electrophoresis, electron spin resonance and chemiluminescence. In addition, the relationships between diseases and the hydroxyl radical in living systems, as well as novel separation methods for the hydroxyl radical are discussed in this paper.