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Montreal, Canada

Tawil N.,Succursale Center ville | Tawil N.,Biophage Pharma Inc. | Hatef A.,Succursale Center ville | Sacher E.,Succursale Center ville | And 4 more authors.
Journal of Physical Chemistry C | Year: 2013

Surface plasmon resonance was used for the real-time monitoring of the formation of self-assembled monolayers of l-cysteine and 11-mercaptoundecanoic acid (MUA) on gold surfaces. We provide comparative details on the kinetics of the assembly of short thiols with multiple functional groups, as opposed to longer alkanethiols with fewer functional groups. Our results indicate that the adsorption of l-cysteine is a rapid process, involving both amino-and thiol-Au interactions, followed by the exchange of amino-Au to thiol-Au species and the physisorption of a second cysteine layer. The formation of MUA is also rapid, followed by a slower structural rearrangement of the monolayer. We find that monolayer formation, for both l-cysteine and MUA, is described by the Langmuir isotherm at low concentrations only. Numerical models are introduced to describe the assembly of both higher and lower concentrations of thiolated molecules on gold. © 2013 American Chemical Society.

Tawil N.,Ecole Polytechnique de Montreal | Tawil N.,Biophage Pharma Inc. | Sacher E.,Ecole Polytechnique de Montreal | Rioux D.,Ecole Polytechnique de Montreal | And 2 more authors.
Journal of Physical Chemistry C | Year: 2015

We report the synthesis of colloidal nanoparticles, produced by the femtosecond laser ablation of a gold target, and their subsequent use in the formation of S. aureus phage-nanoparticle complexes for biodetection purposes. A detailed X-ray photoelectron spectroscopic analysis shows that the negatively charged nanoparticles that are formed interact with and subsequently internalize into the positively charged bacteriophages. These complexes render possible the specific detection of a single S. aureus bacterium in a heterogeneous sample, using dark field microscopy without complex sample treatment or amplification. © 2015 American Chemical Society.

Shabani A.,Biophage Pharma Inc. | Shabani A.,Concordia University at Montreal | Marquette C.A.,CNRS Institute of Molecular and Supramolecular Chemistry and Biochemistry | Mandeville R.,Biophage Pharma Inc. | Lawrence M.F.,Concordia University at Montreal
Analyst | Year: 2013

A direct and efficient impedimetric method is presented for the detection of Bacillus anthracis Sterne vegetative cells, using Gamma phages as probes attached to screen-printed carbon electrode microarrays. The carbon electrodes were initially functionalized through cyclic-voltammetric reduction of a nitro-aryl diazonium moiety, followed by further reduction of nitro groups to amino groups, and finally by treatment with glutaraldehyde. Functionalization (probe immobilization) using Gamma phages was verified by XPS and TOF-SIM experiments. The Gamma phage-modified microarrays were then used to detect B. anthracis Sterne bacteria in aqueous electrolyte media. Faradaic impedimetric detection of bacteria in KCl solution containing the ferri/ferro cyanide redox couple shows a gradual increase in Z′ (real impedance) values, taken from the extrapolation of the linear portion of Nyquist plots in the low frequency range, for sensors placed in contact with increasing concentrations of B. anthracis. ΔZ′ values vary from 700 to 5300 Ohms for bacteria concentrations ranging from 102 to 108 cfu mL -1. These shifts in Z′ are attributed to a decrease in diffusion controlled charge transfer to the electrode surface following capture of intact B. anthracis. No significant ΔZ′ was observed for control experiments using E. coli. K12 as a non-specific target, even at a concentration of 108 cfu mL-1. © 2013 The Royal Society of Chemistry.

Tawil N.,Ecole Polytechnique de Montreal | Tawil N.,Biophage Pharma Inc. | Sacher E.,Ecole Polytechnique de Montreal | Mandeville R.,Biophage Pharma Inc. | Meunier M.,Ecole Polytechnique de Montreal
Analyst | Year: 2014

Pathogen detection is of utmost importance in many sectors, such as in the food industry, environmental quality control, clinical diagnostics, bio-defence and counter-terrorism. Failure to appropriately, and specifically, detect pathogenic bacteria can lead to serious consequences, and may ultimately be lethal. Public safety, new legislation, recent outbreaks in food contamination, and the ever-increasing prevalence of multidrug-resistant infections have fostered a worldwide research effort targeting novel biosensing strategies. This review concerns phage-based analytical and biosensing methods targeted towards theranostic applications. We discuss and review phage-based assays, notably phage amplification, reporter phage, phage lysis, and bioluminescence assays for the detection of bacterial species, as well as phage-based biosensors, including optical (comprising SPR sensors and fiber optic assays), electrochemical (comprising amperometric, potentiometric, and impedimetric sensors), acoustic wave and magnetoelastic sensors. © 2014 The Royal Society of Chemistry.

Tawil N.,Ecole Polytechnique de Montreal | Tawil N.,Biophage Pharma Inc. | Sacher E.,Ecole Polytechnique de Montreal | Mandeville R.,Biophage Pharma Inc. | Meunier M.,Ecole Polytechnique de Montreal
Journal of Physical Chemistry C | Year: 2013

The use of bacteriophages as recognition elements for biosensing techniques has recently provoked much interest. Surface plasmon resonance, scanning electron microscopy, and atomic force microscopy were used for the real-time monitoring of the attachment of methicillin-resistant Staphylococcus aureus (MRSA) bacteriophages to gold using several immobilization methods. The MRSA bacterial capture efficiency of phage-functionalized surfaces was studied. We found that whereas the physisorption of phages to gold surfaces affects their biofunctionality, as expressed by their lysing efficiency of bacteria, phages bound via mixed self-assembled monolayers of l-cysteine and 11- mercaptoundecanoic acid permitted both the recognition and disruption of bacterial membranes. This is due to the formation of uniform islands on the gold surfaces, permitting an oriented positioning of the phages, thus better exposing their recognition proteins. © 2013 American Chemical Society.

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