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The synthesis and electropolymerization of a pyrrolic concanavalin A derivative (pyrrole-Con A) onto a multiwalled carbon nanotube (MWCNT) deposit is reported. Glucose oxidase was then immobilized onto the MWCNT-poly(pyrrole-Con A) coating by affinity carbohydrate interactions with the polymerized Con A protein. The resulting enzyme electrode was applied to the amperometric detection of glucose exhibiting a high sensitivity of 36 mA cm(-2) mol(-1) L and a maximum current density of 350 μA cm(-2) .

Current methods of tissue fixation rely on mechanical-related technologies developed from the clothing and carpentry industries. Herein, a novel bioadhesive method that allows tuneable adhesion and is also applicable to biodegradable polyester substrates is described. Diazirine is the key functional group that allows strong soft tissue crosslinking and on-demand adhesion based on a free radical mechanism. Plasma post-irradiation grafting makes it possible to graft diazirine onto PLGA substrates. When the diazirine-PLGA films, placed on wetted ex vivo swine aortas, are activated with low intensity UV light, lap shear strength of up to 450 ± 50 mN cm(-2) is observed, which is one order of magnitude higher than hydrogel bioadhesives placed on similar soft tissues. The diazirine-modified PLGA thin films could be added on top of previously developed technologies for minimally invasive surgeries. The present work is focused on the chemistry, grafting, and lap shear strength of the alkyl diazirine-modified PLGA bioadhesive films.

The development of rapid, specific, cost-effective, and robust tools in monitoring Hg(2+) levels in both environmental and biological samples is of utmost importance due to the severe mercury toxicity to humans. A number of techniques exist, but the colorimetric assay, which is reviewed herein, is shown to be a possible tool in monitoring the level of mercury. These assays allow transforming target sensing events into color changes, which have applicable potential for in-the-field application through naked-eye detection. Specifically, plasmonic nanoparticle-based colorimetric assay exhibits a much better propensity for identifying various targets in terms of sensitivity, solubility, and stability compared to commonly used organic chromophores. In this review, recent progress in the development of gold nanoparticle-based colorimetric assays for Hg(2+) is summarized, with a particular emphasis on examples of functionalized gold nanoparticle systems with oligonucleotides, oligopeptides, and functional molecules. Besides highlighting the current design principle for plasmonic nanoparticle-based colorimetric probes, the discussions on challenges and the prospect of next-generation probes for in-the-field applications are also presented.

The human promyelocytic leukemia HL 60 and PLB 985 cell lines can differentiate into terminally mature neutrophil-like cells via dimethyl sulfoxide (DMSO) induction. In this study the luminol-dependent chemiluminescence (LCL) of both neutrophil-like cells was analayzed and compared in response to phorbol myristate acetate (PMA) and opsonized zymosan (OZ) stimulants. It was shown that, like human blood neutrophils, both neutrophil-like cells expressed high levels of CD11b, but unlike human blood neutrophils these cells almost lack LCL-detectable intracellular oxidase activity. By studying the pattern of activation to OZ and PMA and priming with GM-CSF, we concluded that there is no difference between the percentage of differentiation and function of DMSO-induced HL 60 and PLB 985. However, the LCL capacity (area under the curve) of DMSO induced PLB 985 cells was higher than that of HL 60 cells in response to both PMA and OZ, which implies a higher capacity to generate reactive oxygen species in PLB 985 cells. Copyright © 2009 John Wiley & Sons, Ltd.

Films of electrogenerated polypyrrole and hydrophilic alginate, both functionalized with biotin moieties, were used to allow for the transfer of polyphenol oxidase activity in organic media. Enzyme electrodes, based on multilayered structures, were protected at the molecular level by the affinity binding of alginate as a hydrophilic additive, and were then transferred into chlorobenzene, dichloromethane, chloroform, ethyl acetate or acetonitrile. The biosensor performance for the detection of catechol at −0.2 V was investigated, highlighting the main influence of the hydrophobicity of the solvent and, to a lesser extent, the dielectric constant. The effect of the substrate hydrophobicity on the biosensor response was examined in chlorobenzene.

At the EILATox-Oregon Workshop, nine luminescent whole-cell bacterial sensors were used for the determination of bioavailable metals in blind samples (17 synthetic and 3 environmental). A non-inducible luminescent control strain was used to determine sample matrix effects and bacterial toxicity. Whole-cell bacterial sensors capable of determining arsenic, inorganic mercury and its organic derivatives, cadmium, lead or copper were used in suspensions and a bacterial sensor for the detection of inorganic mercury was immobilized onto fibre-optic tips using calcium alginate. Bioavailable amounts of metals were estimated using calibration plots, that were constructed to determine the range of metals giving rise to a linear relationship between luminescence and the amount of metals present in the standard solutions. EILATox-Oregon sample 5, which contained 74 mg l−1 of Hg, gave a significant response with both formats of the mercury sensor. The bioavailable amounts of mercury according to the measurement of bacterial sensor in suspension and immobilized onto a fibre-optic tip were 76 and 93 mg l−1, respectively. The bacterial sensor for arsenic and copper showed a response with sample 6 (58 mg l−1 of As) and sample 8 (400 mg l−1 of metham sodium), respectively. This study showed that the bacterial sensors in suspension or immobilized onto optical fibres are capable of quantifying bioavailable metals from unknown samples. The measurement protocol of bacterial sensors is simple and possible to perform in the field. Moreover, the samples do not need any pretreatment before analysis. Construction and characterization of the strain for the detection of bioavailable copper are described. Copyright © 2004 John Wiley & Sons, Ltd.

Joseph J. Pancrazio, Philip N. McFadden, Shimshon Belkin and Robert S. Marks* 1 Center for Bio/Molecular Science and Engineering, Code 6900, US Naval Research Laboratory, Washington, DC 20375, USA 2 Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97330, USA 3 Division of Environmental Sciences, Fredy and Nadine Herrmann Graduate School of Applied Science, Hebrew University of Jerusalem, Jerusalem 91904, Israel 4 Institute for Applied Biosciences and Department of Biotechnology Engineering, Ben-Gurion University of the Negev, PO Box 653, Beer Sheva 84105, Israel

p-Nitrophenol is a common structural unit of many pesticides and was chosen as a model compound to monitor genotoxicity during photocatalytic degradation. The genotoxicity of p-nitrophenol (PNP) and its breakdown products was measured using a bioluminescent bacterial bioassay, Vitotox(TM). The genotoxic potential decreased with the concomitant photocatalytic degradation of the parent PNP concentration. The rate of genotoxicity reduction was slower than the rate of removal of the parent PNP, due to the formation of genotoxic by-products. After 6 h of photocatalytic treatment the total genotoxicity was removed. These results indicate that bioassays can be used as a simple and highly sensitive method for monitoring the general toxicity of chemical pollutants before, during and after photocatalytic treatment or other destructive processes.

We report herein a simple and effective way to photochemically immobilize biomolecules onto a fibre-optic silica surface. The system is based on a photoreactive benzophenone derivative that is bound to SiO2 surfaces of the optical fibre via a silane anchor. The benzophenone derivative was 4-allyloxybenzophenone, synthesized by standard procedures that were later used to synthesize the 4-(3′-chlorodimethylsilyl) propyloxybenzophenone and 4-(3′-dichloromethylsilyl) propyloxybenzophenone by regular hydrosilation procedures. After silanization with the benzophenone derivatives, the fibres were immersed in a cholera toxin B subunit solution and illuminated with UV light (wavelength > 345 nm). As a result of the photochemical reaction, a thin layer of the antigen was covalently bound to the benzophenone-modified surface. The photochemically modified fibre-optics were then tested as immunosensors in the detection of cholera anti-toxin antibody and revealed through chemiluminescence measurements. A secondary antibody labelled with horseradish peroxidase acted as the marker for the cholera toxin antibody. A photo-electronic set-up was designed specifically to monitor the signal. The immunosensor system was shown to be both specific and sensitive. The lowest rabbit serum titre detected was 1:1 700 000. Copyright © 2004 John Wiley & Sons, Ltd.

New chiral dicarbazole derivatives functionalized by N-hydroxysuccinimide and pentafluorophenoxy groups have been synthesized and electrochemically characterized. Upon oxidative electropolymerization of these monomers in organic electrolytes electroactive poly(dicarbazole) films were formed on platinum electrodes. The subsequent chemical grafting of glucose oxidase on the poly(dicarbazole) films was easily performed by immersion in an enzymatic aqueous solution. The amperometric response of the resulting biosensors to glucose has been studied at 0.6 V vs. aqueous saturated calomel electrode.

Biofilm matrices formed by irreversibly surface-anchored bacteria cause significant economic damage in the industrial and biomedical environments. The ubiquity of biofilms promotes increased investment in the development of technologies that will impede bacteria-surface association. Certain surface topographical fabrications may aid in preventing colonization. Herein, algal-secreted polysaccharide (Ps) biomaterial patches and metal complex films (MCF) are examined for their anti-Acinetobacter baumannii and anti-Pseudomonas aeruginosa biofilm properties. Ps moderately reduces biofilm formation; the Cu-MCF coating has significant anti-biofim activity while Zn-MCF had no effect. A mechanistic examination of these effects shows a two-fold greater coverage of the anti-adhesive surface of Cu-MCF than that of the control due to the induction of swarming motility, thus impeding bacterial transformation to the irreversibly attached state. Chemical compositions of the coatings and the interactions between coating components are examined using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectrometry. Cu-MCF surface morphology comprises protruding needle-like structures up to 100 nm in height that are lacking in both the Ps and the Zn-MCF. Their presence in an aqueous solution is yet unproven and role in preventing their bacterial attachment open to speculation. The present study highlights the need to generate novel biomaterials that integrate naturally occurring anti-adhesive polymers with specific metal ions to improve the chemical, physical and biological properties of these anti-adhesive surfaces. Cu-MCF complexes fabricated with thermal and pressure stability to prevent metal ion leakage hold promise for a broad spectrum of industrial and medical anti-biofilm applications.