Fabrication of photoactive heterostructures based on quantum dots decorated with Au nanoparticles

Abstract

Silica based multifunctional heterostructures, exhibiting near infrared (NIR) absorption (650–1200 nm) and luminescence in the visible region, represent innovative nanosystems useful for diagnostic or theranostic applications. Herein, colloidal synthetic procedures are applied to design a photoactive multifunctional nanosystem. Luminescent silica (SiO₂) coated quantum dots (QDs) have been used as versatile nanoplatforms to assemble on their surface gold (Au) seeds, further grown into Au spackled structures. The synthesized nanostructures combine the QD emission in the visible region, and, concomitantly, the distinctive NIR absorption of Au nanodomains. The possibility of having multiple QDs in a single heterostructure, the SiO₂ shell thickness, and the extent of Au deposition onto SiO₂ surface have been carefully controlled. The work shows that a single QD entrapped in 16 nm thick SiO₂ shell, coated with Au speckles, represents the most suitable geometry to preserve the QD emission in the visible region and to generate NIR absorption from metal NPs. The resulting architectures present a biomedical potential as an effective optical multimodal probes and as promising therapeutic agents due to the Au NP mediated photothermal effect.

Keywords:

• Quantum dots
• metal nanoparticles
• plasmonic luminescent nanostructures
• multimodal bioimaging

Classification:

• 10 Engineering and Structural materials

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

The supplemental material for this paper is available online at http://dx.doi.org/10.1080/14686996.2016.1153939

Funding

The work has been supported by PON R&C 2007–2013 MAAT-Molecular Nanotechnology for Health and Environment [project number: PON02_00563_3316357], National Sens&Micro LAB [POFESR 2007–2013], FIRB Futuro in Ricerca [RBFR122HFZ] and PRIN 2010–2011 [2010C4R8M8], and Nanomax-integrable sensors for pathological biomarkers diagnosis [N-CHEM], and PRIN 2012 Italian National Project [Prot. 2012T9XHH7] projects, Laboratorio Regionale di Sintesi e Caratterizzazione di Nuovi Materiali Organici e Nanostrutturati per Elettronica, Fotonica e Tecnologie Avanzate.