Synthesis of ultraluminescent gold core-shell nanoparticles as nanoimaging platforms for biosensing applications based on metal-enhanced fluorescence

D. GONTERO; ALICIA V. VEGLIA; A. G. BRACAMONTE; D. BOUDREAU

RSC Advances

Royal Society of Chemistry

Lugar: Londres; Año: 2017 vol. 7 p. 10252 - 10258

Core shell nanoparticles are versatile nanostructures that can be used as luminescent biosensing platformsin many nanotechnological developments. Ultraluminescent fluorescent gold core?shell nanoparticlesbased on Metal-Enhanced Fluorescence (MEF) were synthesized. The nanoparticles obtained wereformed by 40.0 nm cores and variable silica spacer lengths. Silica spacer lengths from 6.0 to 25.0 nmwere obtained. The plasmon maximal wavelength of the core?shell nanoparticles was shifted to a longerwavelength from a gold nanoparticle plasmon centered at 537.0 nm to 545.0 nm and 548 nm from6.0 nm to 20.0 nm spacer length, respectively. The effect of the gold core on emission was evaluated bydetermination of Metal Enhanced Fluorescence enhancement factors (MEFef), applying the sodiumcyanide method for core leaching. We observed maximal MEF ef= 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 confocalfluorescence microscopy it was possible to detect ultraluminescent gold core?shell nanoparticleaggregates and obtain an MEFEF that can rise to 40. These parameters and properties were discussedfrom the point of view of fluorescent platform applications. Moreover in order to show the potentialapplication of these nanoparticles in biodetection and nanomedicine, Escherichia coli bacteria werelabelled with ultraluminescent nanoparticles. Bright and clear bacteria images were obtained by laserfluorescence microscopy. Based on these results, future applications for individual bacterial detectionwill be developed