22 research outputs found

    Pegylated doxorubicin gold complex: From nanovector to potential intercalant agent for biosensor applications

    Get PDF
    We report an original approach to synthesize hybrid gold nanostructures in which doxorubicin (DOX), mixed to Poliethylenglycole diacid (PEG-COOH) led to original hybrid gold nanovector (DOX IN PEG AuNPs). In this work, we investigate the ability of DOX IN PEG-AuNPs to detect the amplification of the hybridization process by a sensitive Quartz crystal Microbalance with dissipation (QCM-D) by intercalation process. The sensing layer was carried out by self-assembled monolayer of β mercaptoethylamine (cysteamine) on gold-coated quartz crystal sensor composed by a rigid homobifunctional cross-linker 1,4 phenilenediisothiocyanate (PDITC) linked covalently with amino-probe oligonucleotides. By QCM characterization in the range from 8 µM to 20 nM, we demonstrate high specificity of DOX IN PEG-AuNPs-DNA with a limit of detection (LOD) of 9 nM. This result is very promising for development of sensitive and effective nanoparticle-based biosensor for quantifying small biomolecules concentration in physiological liquids. These results open a possibility to realize a new class of nanovector which will be tailored for different biomedical application, such as imaging, targeting and drugs delivery. Keywords: Quartz Crystal Microbalance (QCM), Chemical surface, DNA hybridization, Gold nanoparticles, Doxorubici

    Gold nanoparticles as nanostructuring and transduction agents for biosensors. Application in the immunodetection of diclofenac and enterotoxin A from S.aureus

    No full text
    Ce travail s’est focalisé sur l’apport des nanoparticules d’or (GNPs) dans la construction d’immunocapteurs piézoélectriques et plasmoniques. Deux stratégies ont été mises en œuvre, mettant à profit les propriétés physico-chimiques uniques des GNPs La première approche a consisté à nanostructurer la surface de capteurs piézoélectriques par des GNPs en exploitant leur haut rapport volume / surface. La deuxième stratégie a consisté à employer les GNPs comme transducteur de biocapteurs colorimétriques en exploitant leurs propriétés optiques. Dans une première partie, la nanostructuration de matériaux plans recouverts d'or ou de silicium par des GNPs (14 nm) a été réalisée. Chaque étape d'élaboration des films fins de nanoparticules a été vérifiée par différentes techniques de caractérisation de surface comme la mesure d’angle de contact, la spectroscopie IR, XPS et MEB. Ces surfaces ont été ensuite employées au développement d’immunocapteurs piézoélectriques pour la détection de diclofénac, un polluant pharmaceutique et d’entérotoxine A (SEA), une toxine bactérienne produite par la bactérie S. aureus.L’apport des GNPs a été mis en évidence par comparaison des performances des immunocapteurs plans et nanostructurés. Dans une deuxième partie, la construction d’un immunocapteur colorimétrique opérant en phase homogène a été réalisée en mettant à profit le changement de la position de la bande de résonance localisée de plasmon de surface (LSPR) résultant du changement d'indice de réfraction local induit par la réaction immunologique entre la SEA et un bioconjugué GNP-anti-SEA. Ces études constituent une alternative séduisante pour la détection rapide dans la gamme du ng/mL.This project focussed on the asset of gold nanoparticles (GNPs) in the build up of piezoelectric and plasmonic immunosensors. Two strategies were implemented, taking advantage of the unique physico-chemical features of GNPs. The first approach consisted in nanostructuring the surface of piezoelectric sensors by GNPs, to exploit their high surface / volume ratio. The second approach consisted in employing the GNPs as transducer in colorimetric biosensors, by making use of their optical properties. In a first part, nanostructuration of planar materials covered with gold or silicon by GNPs (14 nm) was achieved. Each step of the construction of thin films of GNPs was checked by various surface characterization techniques, including contact angle measurements, IR spectroscopy, XPS and SEM. These surfaces were then employed in the development of piezoelectric immunosensors for the detection of the pharmaceutical pollutant diclofenac and staphylococcal enterotoxin A (SEA), a bacterial toxin produced by S. aureus. The input of GNPs was evidenced by comparison with the performances of planar immunosensors. In a second part, the build up of a colorimetric immunosensor operating in the homogeneous phase was achieved by making use of the shift of the localized surface plasmon resonance (LSPR) band resulting from the change of local refraction index induced by the immunological reaction between SEA and GNP-anti-SEA bioconjugate. These studies establish a model for the development of immunosensor for a rapid detection in the ng/mL range

    Les nanoparticules d'or comme agents de nanostructuration et de transduction pour les biocapteurs. Application à l'immunodétection du diclofénac et de l'entérotoxine A de S. aureus

    No full text
    This project focussed on the asset of gold nanoparticles (GNPs) in the build up of piezoelectric and plasmonic immunosensors. Two strategies were implemented, taking advantage of the unique physico-chemical features of GNPs. The first approach consisted in nanostructuring the surface of piezoelectric sensors by GNPs, to exploit their high surface / volume ratio. The second approach consisted in employing the GNPs as transducer in colorimetric biosensors, by making use of their optical properties. In a first part, nanostructuration of planar materials covered with gold or silicon by GNPs (14 nm) was achieved. Each step of the construction of thin films of GNPs was checked by various surface characterization techniques, including contact angle measurements, IR spectroscopy, XPS and SEM. These surfaces were then employed in the development of piezoelectric immunosensors for the detection of the pharmaceutical pollutant diclofenac and staphylococcal enterotoxin A (SEA), a bacterial toxin produced by S. aureus. The input of GNPs was evidenced by comparison with the performances of planar immunosensors. In a second part, the build up of a colorimetric immunosensor operating in the homogeneous phase was achieved by making use of the shift of the localized surface plasmon resonance (LSPR) band resulting from the change of local refraction index induced by the immunological reaction between SEA and GNP-anti-SEA bioconjugate. These studies establish a model for the development of immunosensor for a rapid detection in the ng/mL range.Ce travail s’est focalisé sur l’apport des nanoparticules d’or (GNPs) dans la construction d’immunocapteurs piézoélectriques et plasmoniques. Deux stratégies ont été mises en œuvre, mettant à profit les propriétés physico-chimiques uniques des GNPs La première approche a consisté à nanostructurer la surface de capteurs piézoélectriques par des GNPs en exploitant leur haut rapport volume / surface. La deuxième stratégie a consisté à employer les GNPs comme transducteur de biocapteurs colorimétriques en exploitant leurs propriétés optiques. Dans une première partie, la nanostructuration de matériaux plans recouverts d'or ou de silicium par des GNPs (14 nm) a été réalisée. Chaque étape d'élaboration des films fins de nanoparticules a été vérifiée par différentes techniques de caractérisation de surface comme la mesure d’angle de contact, la spectroscopie IR, XPS et MEB. Ces surfaces ont été ensuite employées au développement d’immunocapteurs piézoélectriques pour la détection de diclofénac, un polluant pharmaceutique et d’entérotoxine A (SEA), une toxine bactérienne produite par la bactérie S. aureus.L’apport des GNPs a été mis en évidence par comparaison des performances des immunocapteurs plans et nanostructurés. Dans une deuxième partie, la construction d’un immunocapteur colorimétrique opérant en phase homogène a été réalisée en mettant à profit le changement de la position de la bande de résonance localisée de plasmon de surface (LSPR) résultant du changement d'indice de réfraction local induit par la réaction immunologique entre la SEA et un bioconjugué GNP-anti-SEA. Ces études constituent une alternative séduisante pour la détection rapide dans la gamme du ng/mL

    Gold Colloid-Nanostructured Surfaces for Enhanced Piezoelectric Immunosensing of Staphylococcal Enterotoxin A

    No full text
    International audienceWe describe the use of gold nanoparticles (AuNP) as a nanostructuring agent on quartz crystal sensor chips to engineer staphylococcal enterotoxin A (SEA) piezoelectric biosensors with amplified response. AuNPs were assembled on gold- or silicon-coated quartz crystal sensor chips by a wet chemistry process involving their chemisorption to preformed thiol and amine terminated Self-Assembled Monolayers (SAMs). The purpose of this nanostructuration was to modify the topography of the surface and improve the accessibility of the binding sites on the surface of the sensor chips. Biointerfaces, comprising a polyclonal antibody against staphylococcal enterotoxin A (SEA), were further built up on these gold nanoparticle-coated sensors and their ability to capture SEA was monitored in real time with a quartz crystal microbalance with dissipation monitoring. It was found out that, although the surface density in capture antibody was similar on both nanostructured and planar sensors, the sensor response, expressed as frequency shift recorded during the binding of SEA to the antibody, was significantly higher for the nanostructured sensors as compared to the planar ones. All the same, the limit of detection was lower for the nanostructured sensors: 8 ng/mL vs 20 ng/mL for the planar sensors. This was rationalized by a possibly better accessibility of the antigen binding sites rather than a consequence of specific surface increase. Using a sandwich type assay, gold nanoparticles coated silicon quartz sensor chips provided the lowest limit of detection of ca. 1 ng/mL in a total assay time of 25 min

    Layer-by-layer generation of PEG-based regenerable immunosensing surfaces for small-sized analytes

    No full text
    International audienceSmall molecules (haptens) like pharmaceuticals or peptides can serve as targets for antibody binding in competitive immunoassay-based flow-through assays. In this work, a strategy for preparing polyethylene glycol (PEG) coatings for subsequent hapten immobilization on glass-type silica surfaces is presented and characterized in detail. Two substrates bearing terminal silanol groups were utilized, a glass slide and a silicon wafer. First, surfaces were thoroughly cleaned and pretreated to generate additional silanol groups. Then, a silane layer with terminal epoxy groups was created using 3-glycidyloxypropyltrimethoxysilane (GOPTS). Epoxy groups were used to bind a layer of diamino-poly(ethylene glycol) (DAPEG) with terminal amino groups. Finally, the low molecular weight compound diclofenac was bound to the surface to be used as model ligand for competitive biosensing of haptens. The elementary steps were characterized using atomic force microscopy (AFM), water contact angle measurement, grazing-angle attenuated total reflection (GA-ATR) FT-IR spectroscopy, and X-ray photoelectron spectroscopy (XPS). The data collected using these techniques have confirmed the successive grafting of the molecular species, evidencing, that homogeneous monolayers were created on the silica surfaces and validated the proposed mechanism of functionalization. The resulting surfaces were used to investigate polyclonal anti-diclofenac antibodies recognition and reversibility using quartz crystal microbalance with dissipation (QCM-D) measurements or an automated flow-through immunoassay with chemiluminescence (CL) read-out. For both techniques, recognition and reversibility of the antibody binding were observed. The stability of sensors over time was also assessed and no decrease in CL response was observed upon 14 days in aqueous solution. The herein presented strategy for surface functionalization can be used in the future as reproducible and reusable universal platform for hapten biosensors
    corecore