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Zhao S.S.,University of Montréal | Bichelberger M.A.,University of Montréal | Colin D.Y.,University of Montréal | Pelletier J.N.,University of Montréal | And 2 more authors.
Analyst | Year: 2012

A competitive binding assay based on localized surface plasmon resonance (LSPR) of folic acid-functionalized gold nanoparticles (FA-AuNPs) and human dihydrofolate reductase enzyme (hDHFR) was developed to detect nanomolar to micromolar concentrations of the widely applied anti-cancer drug, methotrexate (MTX). By the nature of the competitive assay for MTX, the LSPR shift from specific binding between FA-AuNPs and the free enzyme was inversely proportional to the concentration of MTX. In addition, the dynamic range for MTX was tuned from 10-11 to 10-6 M by varying the concentration of hDHFR from 1 to 100 nM. Inter-day reproducibility and recovery of MTX spiked in phosphate buffer saline (PBS) were excellent. Potential interferents such as FA, trimethoprim (TMP) and 4-amino-4-deoxy-N-methylpteroic acid (DAMPA) did not occur in the concentration range of interest for MTX. Clinical samples of human serum from patients undergoing MTX chemotherapy were analyzed following a simple solid-phase extraction step to isolate MTX from the serum matrix, with a limit of detection of 155 nM. Validation of the LSPR method was carried out in comparison to Fluorescence Polarization Immunoassay (FPIA), a commonly used method in clinical settings, and LC-MS/MS, a reference technique. The results of the LSPR competitive assay compared well to FPIA and LC-MS/MS, with a slope of 2.4 and 1.1, respectively, for the correlation plots. The method established herein is intended for therapeutic drug monitoring (TDM) of MTX levels in patients undergoing chemotherapy to ensure safety and efficacy of the treatment. © 2012 The Royal Society of Chemistry.


Zhao S.S.,University of Montréal | Bukar N.,University of Montréal | Toulouse J.L.,University of Montréal | Pelechacz D.,University of Montréal | And 3 more authors.
Biosensors and Bioelectronics | Year: 2015

A multi-channel fully integrated SPR biosensor was applied for the analysis of an anti-cancer drug, methotrexate (MTX) as a potential analytical tool used in clinical chemistry laboratories for therapeutic drug monitoring (TDM). MTX concentrations in a patient's serum undergoing chemotherapy treatments can be determined by surface plasmon resonance (SPR) sensing using folic acid-functionalized gold nanoparticles (FA-AuNP) in competition with MTX for the bioreceptor, human dihydrofolate reductase (hDHFR) immobilized on the SPR sensor chip. To validate this biosensor, 13nm FA-AuNP were shown to interact with immobilized hDHFR in the absence of MTX and this interaction was inhibited in the presence of MTX. The sensor was calibrated for MTX in phosphate buffer at different dynamic range by varying nanoparticle sizes (5, 13, 23nm) and by modifying the Kd of the bioreceptor using wild-type and mutant hDHFR. Furthermore, initial binding rate data analyzes demonstrated quantitative and fast sensor response under 60s. This MTX assay was subsequently adapted to a fully integrated multi-channel SPR system built in-house and calibrated in human serum with a dynamic range of 28-500nM. The SPR system was applied to analyzes of actual clinical samples and the results are in good agreement with fluorescence polarization immunoassay (FPIA) and LC-MS/MS. Finally, the prototype system was tested by potential clinical users in a hospital setting at the biochemistry laboratory of a Montreal hospital (HÔpital Maisonneuve-Rosemont). © 2014 Elsevier B.V..


Couture M.,University of Montréal | Liang Y.,Dalian University of Technology | Poirier Richard H.-P.,University of Montréal | Faid R.,University of Montréal | And 3 more authors.
Nanoscale | Year: 2013

Modern photonics is being revolutionized through the use of nanostructured plasmonic materials, which confine light to sub-diffraction limit resolution providing universal, sensitive, and simple transducers for molecular sensors. Understanding the mechanisms by which light interacts with plasmonic crystals is essential for developing application-focussed devices. The strong influence of grating coupling on electromagnetic field distribution, frequency and degeneracy of plasmon bands has now been characterized using hexagonal nanohole arrays. An equation for nanohole arrays was derived to demonstrate the strong influence of incidence and rotation angle on optical properties of 2D plasmonic crystals such as nanohole arrays. Consequently, we report experimental data that are in strong agreement with finite difference time-domain (FDTD) simulations that clearly demonstrate the influence of the grating coupling conditions on the optical properties (such as plasmon degeneracy and bandwidth), and on the distribution of the plasmon field around nanohole arrays (including tuneable penetration depths and highly localized fields). The tuneable 3D plasmon field allowed for controlled sensing properties and by increasing the angle of incidence to 30 degrees, the resonance wavelength was tuned from 1000 to 600 nm, and the sensitivity was enhanced by nearly 300% for a protein assay using surface plasmon resonance (SPR) and by 40% with surface-enhanced Raman scattering (SERS) sensors. © 2013 The Royal Society of Chemistry.


Ngo A.T.,McGill University | Ngo A.T.,Center for Self Assembled Chemical Structures | Cosa G.,McGill University | Cosa G.,Center for Self Assembled Chemical Structures
Langmuir | Year: 2010

We report on the formation of complexes between zwitterionic phospholipid vesicles and an anionic fluorescent conjugated polyelectrolyte and the effect of mono- and divalent cations on the photophysical properties of these complexes. Our goal is to gain an understanding of the interplay of morphology and exciton transport in these complexes, information that is critical to designing efficient lipid/conjugated polymer-based sensors. Our studies further underscore the potential application of lipid/conjugated polymer complexes in light-harvesting devices. Our work focuses on the negatively charged conjugated polyelectrolyte poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene] (MPS-PPV) and its interaction with the zwitterionic lipid dioleoylphosphatidylcholine (DOPC). We utilize monovalent and divalent cations as a tool to control and explore the interaction of MPS-PPV with lipids. We show that Ca2+ ions promote the complexation of zwitterionic lipids and MPS-PPV in comparison to Na+ ions. The addition of increasing amounts of zwitterionic phospholipids in the form of vesicles gradually disrupts MPS-PPV aggregates albeit vesicle structure is preserved in Na+ buffer. Lipid complexation and the resulting MPS-PPV aggregate disruption produces an intensity enhancement and blue shifting of the MPS-PPV emission peak. In the absence of Ca2+, the intensity enhancement and blue shift reach a plateau at larger than a 10:1 lipid/MPS-PPV monomer mole ratio. In the presence of Ca2+, a plateau is reached at equimolar concentrations of MPS-PPV and lipid. Vesicle particle coalescence and agglomerate formation are observed herein. Lipid complexation and concomitant MPS-PPV shielding is shown to diminish the quenching of MPS-PPV emission by water-soluble quencher methyl viologen. FRET experiments conducted with membrane-intercalating acceptor dye DiD further underscore the large lipid/polymer interaction mediated by Ca2+. We observe efficient light harvesting and MPS-PPV-amplified emission quenching in Ca2+ buffer and to a lesser extent in Na+ buffer. Our results highlight how the interplay of a zwitterionic lipid, cations, and buffer, in combination with the conjugated polyelectrolyte MPS-PPV, provides rich diversity in architecture and photophysical properties. © 2009 American Chemical Society.


Murray-Methot M.-P.,University of Montréal | Ratel M.,University of Montréal | Masson J.-F.,University of Montréal | Masson J.-F.,Center for Self Assembled Chemical Structures | Masson J.-F.,Biosensors
Journal of Physical Chemistry C | Year: 2010

A systematic study of the optical properties and analytical response is reported for gold and silver nanohole arrays with different hole diameters with a fixed periodicity of 450 nm. Nanosphere lithography in combination with oxygen plasma etching has been used to fabricate the nanohole arrays. The plasmonic response of nanohole arrays is characterized in transmission spectroscopy (λ = 500-1000 nm spectral region), which varied with the metal composition and diameter of the nanoholes. The sensitivity to bulk refractive index (in nm/RIU) and the full width at half-maximum (FWHM) were measured for each plasmonic mode to compare the biosensing potential of the various nanohole arrays. A sensitivity of nearly 400 nm/RIU was observed and was maximal with the plasmonic band at λ = 554 nm for Ag nanohole arrays with the smallest hole diameter of 120 nm. Generally, the ratio of the full height (transmission intensity) and FWHM is constant for various hole diameters with Au nanohole arrays, whereas it improves for Ag nanohole arrays with smaller hole diameters. Various bimetallic nanohole arrays composed of a Ag underlayer covered with Au were fabricated with a hole diameter of 254 ± 20 nm and a depth of 50 ± 12 nm. Sensitivity and FH/FWHM ratio are improved for Au on Ag nanohole arrays compared with nanohole arrays of pure metal. © 2010 American Chemical Society.


Couture M.,University of Montréal | Live L.S.,University of Montréal | Dhawan A.,Indian Institute of Technology Delhi | Masson J.-F.,University of Montréal | Masson J.-F.,Center for Self assembled Chemical Structures
Analyst | Year: 2012

The debate is still ongoing on the optimal mode of interrogation for surface plasmon resonance (SPR) sensors. Comparative studies previously demonstrated that nanoparticles exhibiting a localized SPR (LSPR) have superior sensitivity to molecular adsorption processes while thin Au film-based propagating SPR is more sensitive to bulk refractive index. In this paper, it is demonstrated that nanohole arrays (1000 nm periodicity, 600 nm diameter and 125 nm depth), which support both LSPR and propagating SPR modes, exhibited superior sensitivity to bulk refractive index and improved detection limits for IgG sensing by using the Kretschmann configuration. The greater sensitivity to IgG detection in the Kretschmann configuration was obtained despite the shorter penetration depth of nanohole arrays excited in the enhanced optical transmission (EOT) configuration. The decay length of the electromagnetic field in EOT mode was estimated to be approximately 140 nm using a layer-by-layer deposition technique of polyelectrolytes (PAH and PSS) and was confirmed with 3D FDTD simulations, which was lengthen by almost a factor of two in the Kretschmann configuration. Spectroscopic data and field depth were correlated with RCWA and FDTD simulations, which were in good agreement with the experimental results. Considering these analytical parameters, it is advantageous to develop sensors based on nanohole arrays in the Kretschmann configuration of SPR. © 2012 The Royal Society of Chemistry.


Tang N.Y.-W.,University of Montréal | Tang N.Y.-W.,Center for Self Assembled Chemical Structures | Badia A.,University of Montréal | Badia A.,Center for Self Assembled Chemical Structures
Langmuir | Year: 2010

Metal-reactive organosulfur groups were patterned onto mica and silicon surfaces by dewetting instabilities during the Langmuir-Blodgett (LB) deposition of phase-separated mixed phospholipid monolayers. Monolayers were formed from binary mixtures of dipalmitoylphosphatidylcholine (DPPC), dilauroylphosphatidylcholine (DLPC), and their (ω-methyldisulfide- dialkylphosphatidylcholine analogues, DSDPPC and DSDLPC. Patterns of highly parallel stripes of condensed DPPC or DSDPPC, protruding by 0.7-0.9 nm from a fluid matrix of DLPC or DSDLPC, were observed over areas extending at least 30 × 30 μm2 in the LB films. The average stripe width varied from ca. 150 to 500 nm, depending on the lipid composition and deposition pressure. X-ray photoelectron spectroscopy confirmed that the phospholipid-monolayer-bound methydisulfides react with Au vapor to form a gold-thiolate species. The adsorption of thermally evaporated Au, Ag, and Cu onto DSDPPC/DLPC and DPPC/DSDLPC patterns was investigated by field emission gun scanning electron microscopy (FEGSEM) and atomic force microscopy (AFM). A change in phase contrast is observed in FEGSEM and AFM over the methyldisulfide-functionalized areas following metal deposition due to metal-thiolate bond formation. An increase in step height between the DSDPPC stripes and nonfunctionalized DLPC background following metal deposition, as well as the resistance of the metal-coated DSDPPC or DSDLPC regions to detergent extraction from the surface, attest to a selective metallization of the pattern. Our results indicate that the preferential adsorption of vapor-deposited metal onto the (ω-methyldisulfide-terminated phase occurs at submonolayer coverages. The chemical reactivity exhibited by the organosulfur-modified phospholipid LB films make these templates potentially interesting for the fabrication of solid-supported patterns of metal nanostructures. © 2010 American Chemical Society.


Couture M.,University of Montréal | Zhao S.S.,University of Montréal | Masson J.-F.,University of Montréal | Masson J.-F.,Center for Self assembled Chemical Structures
Physical Chemistry Chemical Physics | Year: 2013

Physical chemistry, materials science, analytical chemistry and engineering greatly contributed to the increasing popularity of bioanalytical and biophysical applications of surface plasmon resonance (SPR) by providing novel materials, surface chemistry, instrumental concepts, and theory to further understand the plasmonic phenomenon and support innovation in SPR. This perspective article portrays the contemporary state of SPR-based techniques and establishes a list of challenges to be overcome for improving bioanalytical and biophysical applications of plasmonics and surface plasmon resonance. © 2013 the Owner Societies.


Bolduc O.R.,University of Montréal | Correia-Ledo D.,University of Montréal | Correia-Ledo D.,Center for Self Assembled Chemical Structures | Masson J.-F.,University of Montréal | Masson J.-F.,Center for Self Assembled Chemical Structures
Langmuir | Year: 2012

The application of a potential to deposit a monolayer of 3-mercaptopropionic acid-histidinyl-histidinyl-histidinyl-aspartyl-aspartyl (3-MPA-HHHDD-OH) controls the density and molecular structure of the peptide monolayer, which results in different wettabilities of the surface, surface density, orientation of the molecule (extended or bent), and nonspecific adsorption of serum proteins. 3-MPA-HHHDD-OH must be deposited at 200 mV to maintain an extended configuration, which promoted low biofouling properties. © 2011 American Chemical Society.


Breault-Turcot J.,University of Montréal | Masson J.-F.,University of Montréal | Masson J.-F.,Center for Self Assembled Chemical Structures
Chemical Science | Year: 2015

Chemical measurements are rarely performed in crude blood due to the poor performance of sensors and devices exposed to biofluids. In particular, biosensors have been severely limited for detection in whole blood due to surface fouling from proteins, the interaction of cells with the sensor surface and potential optical interference when considering optical methods of analysis. To solve this problem, a dialysis chamber was introduced to a surface plasmon resonance (SPR) biosensor to create a diffusion gate for large molecules. This dialysis chamber relies on the faster migration of small molecules through a microporous membrane towards a sensor, located at a specified distance from the membrane. Size filtering and diffusion through a microporous membrane restricted the access of blood cells and larger biomolecules to a sensing chamber, while smaller, faster diffusing biomolecules migrated preferentially to the sensor with limited interference from blood and serum. The affinity of a small peptide (DBG178) with anti-atherosclerotic activity and targeting type B scavenger receptor CD36 was successfully monitored at micromolar concentrations in human serum and blood without any pre-treatment of the sample. This concept could be generally applied to a variety of targets for biomolecular interaction monitoring and quantification directly in whole blood, and could find potential applications in biochemical assays, pharmacokinetic drug studies, disease treatment monitoring, implantable plasmonic sensors, and point-of-care diagnostics. This journal is © The Royal Society of Chemistry 2015.

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