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Shabani A.,Biophage Pharma Inc. | Shabani A.,Concordia University at Montréal | Marquette C.A.,University Claude Bernard Lyon 1 | Mandeville R.,Biophage Pharma Inc. | Lawrence M.F.,Concordia University at Montréal
Talanta | Year: 2013

This study presents an investigation on the possibility of improving the detection limit of bacteria with an inexpensive electrochemical, impedimetric sensor platform, by integrating the sensor with magnetic manipulation. The approach uses T4 bacteriophage coated Dynabeads to selectively capture and concentrate E. coli K12 cells from samples, to increase the sensitivity of detection at the surface of functionalized screen-printed carbon microarrays. Fluorescence and flow cytometry measurements indicate that the surface modification of the magnetic beads, with phages, and binding with the bacteria, were successful. Integration of the screen-printed carbon-based impedimetric sensor, with a magnetic manipulation system, was found to improve the sensitivity of the device, decreasing the limit of detection of E. coli K12 from 104 to 103 cfu/mL. We have also demonstrated that this approach provides for more specific detection of bacteria, enabling the operator to account for non-specific adsorption, and detection of bacteria in more complex (real) samples (milk). © 2013 Elsevier B.V.


Yao L.,McGill University | Lamarche P.,Biophage Pharma Inc. | Tawil N.,Biophage Pharma Inc. | Khan R.,McGill University | And 4 more authors.
IEEE Transactions on Biomedical Circuits and Systems | Year: 2011

We present the design and implementation of a prototype complementary metaloxide semiconductor (CMOS) conductometric integrated circuit (IC) for colony growth monitoring and specific sensing of Escherichia coli (E. coli) bacteria. The detection of E. coli is done by employing T4 bacteriophages as receptor organisms. The conductometric system operates by measuring the resistance of the test sample between the electrodes of a two-electrode electrochemical system (reference electrode and working electrode). The CMOS IC is fabricated in a TSMC 0.35-μm process and uses a current-to-frequency (I to F) conversion circuit to convert the test sample resistance into a digital output modulated in frequency. Pulsewidth control (one-shot circuit) is implemented on-chip to control the pulsewidth of the output digital signal. The novelty in the current work lies in the ability of the CMOS sensor system to monitor very low initial concentrations of bacteria (4× 10 2 to 4× 10 4 colony forming unit (CFU)/mL). The CMOS system is also used to record the interaction between E. coli and its specific receptor T4 bacteriophage. The prototype CMOS IC consumes an average power of 1.85 mW with a 3.3-V dc power supply. © 2010 IEEE.


Shabani A.,Biophage Pharma Inc. | Shabani A.,Concordia University at Montréal | Marquette C.A.,CNRS Institute of Molecular and Supramolecular Chemistry and Biochemistry | Mandeville R.,Biophage Pharma Inc. | Lawrence M.F.,Concordia University at Montréal
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 Montréal | Tawil N.,Biophage Pharma Inc. | Sacher E.,Ecole Polytechnique de Montréal | Rioux D.,Ecole Polytechnique de Montréal | 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.


Tawil N.,Ecole Polytechnique de Montréal | Tawil N.,Biophage Pharma Inc. | Sacher E.,Ecole Polytechnique de Montréal | Mandeville R.,Biophage Pharma Inc. | Meunier M.,Ecole Polytechnique de Montréal
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 Montréal | Tawil N.,Biophage Pharma Inc. | Sacher E.,Ecole Polytechnique de Montréal | Mandeville R.,Biophage Pharma Inc. | Meunier M.,Ecole Polytechnique de Montréal
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.


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 Montréal | Tawil N.,Biophage Pharma Inc. | Sacher E.,Ecole Polytechnique de Montréal | Boulais E.,Ecole Polytechnique de Montréal | And 2 more authors.
Journal of Physical Chemistry C | Year: 2013

We report the synthesis and characterization of gold-bacteriophage hybrids for biodetection purposes. The physical and optical properties of gold nanoparticles (AuNPs) and the biological features of the phages offer a multifunctional scaffold with great potential for nanotechnologically based biomedical applications. AuNPs, stabilized (PEGylated) using heterobifunctional polyethylene glycol (PEG), were coupled to methicillin-resistant S. aureus-specific phages. The PEG ligands contain a thiol group for stable anchoring to the gold surface and a terminal carboxylic acid group for further coupling to the outside of the PEG shell by carbodiimide chemistry. Transmission electron microscopic analysis showed that the NP-phage bioconjugates are highly stable, with a median diameter of 90 nm. X-ray photoelectron spectroscopy was used to chemically characterize the surfaces of the PEG-functionalized AuNPs, the bacteriophages, and the gold-phage hybrids. The role of the interface and the covalent coupling chemistry employed to attach the phages to the AuNPs have been delineated. Successful attachment of phages to AuNPs was confirmed by the presence of amide between the primary amines of the phages and the carboxylic acid terminal groups of the NPs and by the presence of carboxyl and amine species, which form hydrogen bonds. © 2013 American Chemical Society.


Tawil N.,Ecole Polytechnique de Montréal | Tawil N.,Biophage Pharma Inc. | Mouawad F.,Biophage Pharma Inc. | Levesque S.,Institute National Of Sante Publique Du Quebec Inspq | And 3 more authors.
Biosensors and Bioelectronics | Year: 2013

Two hundred fifty Staphylococcus aureus clinical isolates were studied to determine their susceptibilities to β-lactam antibiotics. Among these isolates, 16 were methicillin-sensitive S. aureus (MSSA), 207 were methicillin-resistant S. aureus (MRSA) and 27 were borderline oxacillin-resistant S. aureus (BORSA). Currently, the reported mechanism of methicillin resistance in S. aureus is the production of a distinctive penicillin binding protein 2a (PBP2a), which exhibits low affinity toward β-lactams. A surface plasmon resonance biosensor was evaluated for its ability to identify MRSA and to distinguish these strains from MSSA and BORSA, by specifically detecting PBP2a. We found that the system permits label-free, real-time, specific detection of pathogens for concentrations as low as 10 colony forming units/milliliter (CFU/ml), in less than 20. min. This system promises to become a diagnostic tool for bacteria that cause major public concern in clinical settings. © 2013 Elsevier B.V.


Tawil N.,Ecole Polytechnique de Montréal | Tawil N.,Biophage Pharma Inc. | Sacher E.,Ecole Polytechnique de Montréal | Mandeville R.,Biophage Pharma Inc. | Meunier M.,Ecole Polytechnique de Montréal
Biosensors and Bioelectronics | Year: 2012

Early diagnosis and appropriate treatment of Escherichia coli (E. coli) O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) are key elements in preventing resultant life-threatening illnesses, such as hemorrhagic colitis, hemolytic uremic syndrome, and septicemia. In this report, we describe the use of surface plasmon resonance (SPR) for the biodetection of pathogenic bacteria, using bacteriophages as the recognition elements. T4 bacteriophages were used to detect E. coli, while a novel, highly specific phage was used to detect MRSA. We found that the system permits label-free, real-time, specific, rapid and cost-effective detection of pathogens, for concentrations of 10 3 colony forming units/milliliter, in less than 20min. This system promises to become a diagnostic tool for bacteria that cause major public concern for food safety, bioterrorism, and nosocomial infections. © 2012 Elsevier B.V.

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