Ultraluminescent gold Core-shell nanoparticles beyond the 80 nm as NanoImaging platforms for Biosensing and genotyping applications

MAXIME RIOUX; DANIELA GONTERO; ALICIA V. VEGLIA; A. GUILLERMO BRACAMONTE

Simposio; Precision Medicine 2017. LabRoots-ACS; 2017

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Core-shell nanoparticles are versatile nanostructures that can be used as luminescent biosensing platforms in many nanotechnological developments, as for example for microdevices applied to biodetection and phenotyping integrated. In order to develop this Nanotechnology, multifunctional Nanostructures with particular properties for biolabelling, biodetection, bioimaging accompanied with an enhanced image resolution, and phenotyping, should be synthesized. Metallic Core-shell nanoparticles are versatile platforms that can be used for ultraluminescent nanoparticle design based on Metal Enhanced Fluorescence (MEF) due to their stability in aqueous media, relatively easily chemical surface functionalization; decrease in photobleaching of fluorophores attached and enhanced luminescent properties. Boudreau et al. developed ultraluminescent silver Core-shell nanoparticles for DNA detection based on MEF coupled to Forster Reaction Energy Transfer (FRET) with a flow method and NanoImaging system. By this manner it was possible to direct molecular detection of SRY gene from unamplified genomic DNA in blood samples. For these reasons, the goal of this Research work it was to develop a biocompatible Ultraluminiscent Nanoplatform for bacteria labelling, detection, and energy transfer receptor via FRET for genotyping applications. Ultraluminescent fluorescent gold Core-shell nanoparticles based on Metal-Enhanced Fluorescence (MEF) were synthesized. The nanoparticles obtained were formed by 40.0 nm cores and variable silica spacer lengths (See scheme 1). Silica spacer lengths from 6.0 to 25.0 nm were obtained. The plasmon maximal wavelength of the Core-shell nanoparticles was shifted to a longer wavelength from a gold nanoparticle plasmon centered at 537.0 nm to 545.0 nm and 548 nm from 6.0 nm to 20.0 nm spacer length, respectively. The effect of the gold core on emission was evaluated by determination of Metal Enhanced Fluorescence enhancement factors (MEFEF), applying the sodium cyanide Method for core leaching. We observed maximal MEFEF= 8.1 and 7.2 for 6.0 and 14.0 nm, respectively, and a significant decrease at longer silica spacer lengths. From NanoImaging by confocal fluorescence microscopy it was possible to detect Ultraluminescent gold Core-shell nanoparticles aggregates and obtain MEFEF that can rise to 40. These parameters and properties were discussed from the point of view of fluorescent platform applications as energy transfer receptor for FRET processes involved in DNA detection. Moreover in order to show the potential application of these nanoparticles in Biodetection and Nanomedicine, Escherichia coli bacteria were labelled with Ultraluminiscent nanoparticles. It was obtained bright and clear bacteria images by Laser fluorescence Microscopy. Based on these results currents experiments applied to individual bacteria detection and genotyping by PCR and free PCR are in progress.