References of "Lismont, Marjorie"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailMetal Enhanced Fluorescence: effect of surface coating
Lismont, Marjorie ULg; François, Alexandre; Dreesen, Laurent ULg et al

in SPIE proceeding (2014, February)

Among the emerging treatments for cancer, Photodynamic Therapy (PDT) is thought to be one of the most promising. PDT uses light sensitive molecules, or photosensitizer, to produce, under specific ... [more ▼]

Among the emerging treatments for cancer, Photodynamic Therapy (PDT) is thought to be one of the most promising. PDT uses light sensitive molecules, or photosensitizer, to produce, under specific irradiation, toxic reactive oxygen species (ROS) to kill cancer cells. However, the amount of ROS generated is limited by both the fluorescence lifetime of the photosensitizer and its concentration around the cancer cells. Metal Enhanced Fluorescence (MEF), a phenomenon arising when a fluorophore is in closed proximity to a metallic structure such as metallic films or nanostructures, is seen as a way to solve these problems by reducing the fluorescence lifetime and increasing the fluorescence emission of the fluorophore. Protoporphyrin IX (PpIX) is a commonly used photosensitizer to treat skin cancers, which presents an intense absorption band around 400 nm while emitting around 630 nm. Because silver nanoparticles (Ag NPs) exhibit a strong Localized Surface Plasmon Resonance (LSPR) around 400 nm, MEF of the PpIX is expected when immobilized onto Ag NPs. Here, we investigate the relevant parameters influencing the coupling effects between the LSPR in Ag NPs and PpIX attached onto the Ag NPs surface when the Ag NPs are dispersed in solution or electrostatically bound to a glass slide. In particular, we study the distance-dependent of MEF by applying multiple layers of polyelectrolyte to progressively increase the distance between Ag NPs and PpIX, covalently bond to the last polyelectrolyte layer as well as exploring the use of Ag NPs of different sizes ranging from 40 to 100 nm. [less ▲]

Detailed reference viewed: 50 (12 ULg)
Full Text
See detailMicrofluidic on optical fibers: Towards a new kind of fluorescent biosensor
Lismont, Marjorie ULg; Vandewalle, Nicolas ULg; Weyer, Floriane ULg et al

Poster (2014, February)

In recent works, the behavior of droplets moving along vertical treads due to gravity was studied. It appeared that the droplet can be stopped by encountering a horizontal fiber depending on droplet ... [more ▼]

In recent works, the behavior of droplets moving along vertical treads due to gravity was studied. It appeared that the droplet can be stopped by encountering a horizontal fiber depending on droplet volumes and fiber characteristics. On the basis of this behavior and by replacing treads by two crossed optical fibers, it is possible to combine fluidics and optics to develop a new kind of fluorescent sensor. In our work, the intersection between two crossed optical fibers is used as the basic unit of an original optofluidic biosensor. These two optical fibers are used as droplets carriers: one for probe molecules and the other one for target species. The fiber's junction catches the droplets and act as a reaction center. The main advantage of using optical fibers resides in their ability to propagate and collect light to and from the droplet localized at the fiber's crossing. This optical fiber configuration can therefore allow the study of biological interactions using fluorescent labels. This new and versatile detection scheme was validated on a calcium indicator where ions detection is accomplished by using a dye, Oregon green Bapta-2, that has a Ca 2+ recognition group as well as an entity exhibiting fluorescence. A FRET recognition event, between Rh-Con A and FITC-Dextran, was also investigated to detect glucose. Finally, a prototype of a multiplexing device, composed of several juxtaposed fibers' junctions, was developed. [less ▲]

Detailed reference viewed: 59 (14 ULg)
Full Text
See detailSuccessive Droplets Encapsulation Revealed by Optofluidics
Lismont, Marjorie ULg; Robert, Damien; Vandewalle, Nicolas ULg et al

Poster (2013, November)

Digital microfluidics: an easy way to encapsulate successively water droplets by oil. Digital microfluidics is implemented to coat successively water droplets with a thin layer of silicon oil. Small water ... [more ▼]

Digital microfluidics: an easy way to encapsulate successively water droplets by oil. Digital microfluidics is implemented to coat successively water droplets with a thin layer of silicon oil. Small water droplets are settled at three fibers nodes while a larger oil drop slides down the vertical fiber. Optofluidics: an interesting way to reveal the droplet sliding motion and the encapsulation. To distinguish the different fluids, quantum dots (QDs) and rhodamine labelled polystyrene beads are diluted in oil and water, respectively.These two fluorescent probes are lighted by a 532 nm radiation.The fluorescence signal is recorded by a high speed camera, perpendicularly to the laser and to the fibers network. This set-up reveals that the oil drop passes through the water droplets without removing them from the nodes, leaving a thin oil layer around the water droplets. The coating, clearly seen on top pictures of Fig 2, prevents water evaporation. The key parameters for a good encapsulation are the fiber diameter and the oil viscosity that determine droplets size and velocity, respectively. [less ▲]

Detailed reference viewed: 15 (1 ULg)
Full Text
Peer Reviewed
See detailComparative study of Ag and Au nanoparticles biosensors based on surface plasmon resonance phenomenon
Lismont, Marjorie ULg; Dreesen, Laurent ULg

in Materials Science & Engineering : C (2012)

The specific sensitivity of surface plasmon resonance to changes in the local environment of nanoparticles allows their use as platforms to probe chemical and biochemical binding events on their surfaces ... [more ▼]

The specific sensitivity of surface plasmon resonance to changes in the local environment of nanoparticles allows their use as platforms to probe chemical and biochemical binding events on their surfaces without any labeling [1- 4]. In this paper, we perform a comparative study of gold and silver nanoparticle based biosensors, prepared within the same conditions, in order to determine which metal seems the best for biological sensing. The prototypical biocytin-avidin interaction is used to study gradual changes over time and with avidin concentration in the absorption spectra bands of biocytinylated 10 nm silver and gold nanospheres. First, the Ag nanoparticles plasmon resonance absorbance signal is about 10 times larger than the Au one. Secondly, for an equivalent concentration of avidin, the optical properties modifications are more pronounced for silver nanoparticles than for gold ones of the same geometry. These observations attest the superiority of Ag on Au nanoparticles when optical considerations are only taken into account. Finally, with both biosensors, the specificity of the interaction, checked by replacing avidin with bovine serum albumin, is relatively poor and needs to be improved. [less ▲]

Detailed reference viewed: 136 (20 ULg)
Full Text
Peer Reviewed
See detailCOMPARATIVE STUDY OF SPR BIOSENSORS BASED GOLD AND SILVER COLLOIDAL NANOPARTICLES
Lismont, Marjorie ULg; Dreesen, Laurent ULg

Poster (2011, June)

Noble metal nanoparticles (NPs) can be used as a robust tool for optical bio-sensing. These NPs are known for their strong interactions with light through their surface plasmon resonance (SPR), which ... [more ▼]

Noble metal nanoparticles (NPs) can be used as a robust tool for optical bio-sensing. These NPs are known for their strong interactions with light through their surface plasmon resonance (SPR), which corresponds to the collective oscillations of the conduction electrons on the particles [1]. Among metals, silver and gold NPs are of particular interest not only because they are air-stable but also because their SPR absorption bands are in the visible and near ultra-violet spectral regions, that appear as the most appropriate for technological applications [2]. The first advantage of such optical SPR biosensors is their ability to measure complex formation in real time. Indeed, the SPR absorption spectrum band of the NPs is sensitive to the shape, size, inter-particle distance and composition of the NP as well as the dielectric properties of the surrounding medium [2]. Because of the sensitivity of SPR to the local dielectric environment, plasmonic NPs can act as transducers that convert small changes in the local refractive index and the inter-particle distance into spectral shifts and broadening in the absorption spectra bands [3]. Biotin is a water-soluble B complex vitamin necessary for the production of fatty acids and the metabolism of fats and amino acids. The avidin is a tetrameric protein which can react with biotin to form the strongly bonded biotin-avidin complex.The prototypical biotin-avidin interaction forms the basis of a simple sol-based diagnostic technique for biological analytes. We focused on this well-known couple of bio-molecules to compare optical properties of silver and gold colloidal NPs. Gradual changes with time in the absorption spectra bands of biotinylated 10 nm silver and gold NPs were studied as a function of added avidin. After avidin addition, an increased red-shift of the SPR wavelength and a broadening of the absorption band with time are observed. These changes in the optical properties of colloidal NPs are due to the biomolecular recognition process between biotin and avidin which leads to aggregation of these NPs arising from cross-linking by the tetrameric protein. Moreover, the recognition process induces a variation of the local refractive index around these NPs and thus induces a red-shift of SPR also. The maximum SPR red-shift was reached after 45 minutes and was equal to 25 nm and 15 nm for silver NPs and gold NPs respectively. We concluded that the dielectric sensitivity of gold NPs is smaller than the silver NPs one for a same geometry and for an equivalent concentration of avidin. Therefore, the silver sol is more adapted to detection of avidin than the gold sol. The detection limit, described as the lowest concentration for clear identification of wavelength shift [4] due to biomolecular recognition is determined to be 4 nM for both silver and gold NPs. In this case, the corresponding wavelength shift is about 3 nm. The specificity of the interaction between biocytin and avidin was checked by replacing avidin by BSA. When BSA was added, we observed a SPR shift which was smaller than the detection limit of 3 nm. Future works will be devoted to transpose this kind of biomolecular recognition experiments on gold nanorods in order to improve the dynamic phototherapy efficiency of cancers. [less ▲]

Detailed reference viewed: 142 (18 ULg)
See detailComparative study of gold and silver based nanobiosensors
Lismont, Marjorie ULg; Dreesen, Laurent ULg

Poster (2011, May 25)

Due to their particular optical properties, resulting from the surface plasmon resonance (SPR) phenomenon, silver and gold nanoparticles (NPs) can be used as robust tools for optical biosensing [1 ... [more ▼]

Due to their particular optical properties, resulting from the surface plasmon resonance (SPR) phenomenon, silver and gold nanoparticles (NPs) can be used as robust tools for optical biosensing [1]. Optical SPR biosensors are able to measure complex formation in real time. Indeed, the SPR absorption spectrum band of the NPs is sensitive to the shape, size, inter-particle distance and composition of the NP as well as the dielectric properties of the surrounding medium [2]. Due to the sensitivity of SPR to the local dielectric environment, plasmonic NPs can act as transducers that convert small changes in the local refractive index and the inter-particle distance into spectral shifts and broadening in the absorption spectra bands [3]. In our study, the prototypical biocytin-avidin interaction was used to study gradual changes with time in the absorption spectra bands of biotinylated 10 nm silver and gold NPs as a function of added avidin. After avidin addition, a SPR red-shift and a broadening of the SPR bands were observed with both NPs. These optical changes evolved with time and reached their final values after around 45 min for each system. The maximum SPR red-shifts were equal to 25 nm and 15 nm for silver NPs and gold NPs, respectively. The detection limit, described as the lowest concentration for clear identification of wavelength shift due to biomolecular recognition, is determined to be 4 nM for both silver and gold NPs. The specificity of the biocytin-avidin biosensors was checked by replacing avidin by BSA. When BSA was added, we observed a SPR band shift which was smaller than the detection limit of 3 nm, attesting the biosensor selectivity. Our work demonstrates the superiority of Ag over Au NPs for the elaboration of biosensors based on SPR. [less ▲]

Detailed reference viewed: 9 (0 ULg)
Full Text
Peer Reviewed
See detailGold and silver nanomaterials based biosensors : a comparative study
Dreesen, Laurent ULg; Lismont, Marjorie ULg

Poster (2011, April)

Noble metal nanoparticles (NPs) are intensively studied due to their particular optical properties, mainly high optical absorption and diffusion yields, leading to interesting applications in biochemical ... [more ▼]

Noble metal nanoparticles (NPs) are intensively studied due to their particular optical properties, mainly high optical absorption and diffusion yields, leading to interesting applications in biochemical sensing, molecular tracking and imaging, drug delivery and photothermal therapies [1]. These unique optical properties arise from a physical process named surface plasmon resonance (SPR) which is a resonant coupling of incident light to the collective motion of electrons along the nanoparticles surface [2]. Optical SPR biosensors are able to measure complex formation in real time. Indeed, the SPR absorption spectrum band of the NPs is sensitive to the shape, size, inter-particle distance and composition of the NP as well as the dielectric properties of the surrounding medium [2]. Due to the sensitivity of SPR to the local dielectric environment, plasmonic NPs can thus act as transducers that convert small changes in the local refractive index or in the inter-particle distance into spectral shifts and broadenings of the absorption spectral bands [3]. Among metals, silver and gold NPs have received considerable interest for many reasons. For instance, they are stable in ambient atmosphere and exhibit good biocompatibility even if particular surface treatments are sometimes required. The Ag and Au NPs are also relatively easy to fabricate with different sizes and shapes allowing the tuning of the SPR optical absorption band from the near ultraviolet (400 nm) to the near infrared (1000 nm) wavelengths. In this study, our aim is to characterize two biosensors based on silver and gold spherical NPs in order to detect which one seems the best. Both NPs have a diameter close to 15 nm. We use the well-known biocytin-avidin complex as a model system because the bonding of avidin with biocytin is extremely strong with a dissociation constant three order of magnitude higher than the typical constants of antigen-antibody interactions. More precisely, we compare the intensities, the band shapes and the spectral locations of the SPR adsorption bands before and after the biomolecular recognition of avidin by biocytin molecules adsorbed on the Ag and Au NPs. The kinetic of the interaction is also discussed. Before surface treatment with biocytin, the NPs SPR bands are located around 390 and 520 nm for Ag and Au NPs, respectively. The SPR band intensity is higher for silver than for gold. Biocytin adsorption does not significantly modify the SPR spectral features. NPs do not therefore form aggregates and the local refraction index has not significantly changed. After avidin addition, a SPR red-shift and a broadening of the SPR bands are observed with both NPs as shown on Figure 1. These parameters evolved with time and reach their final values after around 45 min for each system. The aforementioned spectral changes arise from the biomolecular recognition process between biotin and avidin which leads to the NPs aggregation. The recognition process also induces a variation of the local refractive index around these NPs which contributes to the red-shift. The maximum SPR shifts are equal to 25 nm and 12 nm for silver NPs and gold NPs, respectively. Our results highlight the smaller dielectric sensitivity of gold NPs compared to the silver NPs one for a same particles’ size and for an equivalent concentration of avidin. The detection limit, described as the lowest concentration for clear identification of wavelength shift due to biomolecular recognition, is equal to 4 nM for both silver and gold NPs. With this protein concentration, 3 nm is the typical wavelength shift. The specificity of the biocytin - avidin biosensors is verified by replacing avidin by Bovine Serum Albumina (BSA). When BSA is added, we observe a SPR band shift which is smaller than the detection limit of 3 nm attesting the biosensor selectivity. Our work demonstrates the superiority of Ag over Au NPs for the elaboration of biosensors based on SPR. However, it is well-known that Ag NPs are less biocompatible than gold. This problem can be circumvented by an appropriate coating of the NPs surface prior ligand adsorption. [less ▲]

Detailed reference viewed: 72 (8 ULg)
Full Text
Peer Reviewed
See detailESR technique for non invasive way to quantify cyclodextrins effect on cell membranes
Grammenos, Angeliki ULg; Mouithys-Mickalad, Ange ULg; Guelluy, Pierre-Henri ULg et al

in Biochemical and Biophysical Research Communications (2010)

A new way to study the action of cyclodextrin was developed to quantify the damage caused on cell membrane and lipid bilayer. The Electron Spin Resonance (ESR) spectroscopy was used to study the action of ... [more ▼]

A new way to study the action of cyclodextrin was developed to quantify the damage caused on cell membrane and lipid bilayer. The Electron Spin Resonance (ESR) spectroscopy was used to study the action of Randomly methylated-beta-cyclodextrin (Rameb) on living cells (HCT-116). The relative anisotropy observed in ESR spectrum of nitroxide spin probe (5-DSA and cholestane) is directly related to the rotational mobility of the probe,which can be further correlated with themicroviscosity. The use of ESR probes clearly shows a close correlation between cholesterol contained in cells and cellular membrane microviscosity. This study also demonstrates the Rameb ability to extract cholesterol and phospholipids in time- and dose-dependent ways. In addition, ESR spectra enabled to establish that cholesterol is extracted from lipid rafts to form stable aggregates. The present work supports that ESR is an easy, reproducible and noninvasive technique to study the effect of cyclodextrins on cell membranes. [less ▲]

Detailed reference viewed: 58 (26 ULg)