Multimodal near-infrared-emitting PluS Silica nanoparticles with fluorescent, photoacoustic, and photothermal capabilities

Abstract

Purpose

The aim of the present study was to develop nanoprobes with theranostic features, including – at the same time – photoacoustic, near-infrared (NIR) optical imaging, and photothermal properties, in a versatile and stable core–shell silica-polyethylene glycol (PEG) nanoparticle architecture.

Materials and methods

We synthesized core–shell silica-PEG nanoparticles by a one-pot direct micelles approach. Fluorescence emission and photoacoustic and photothermal properties were obtained at the same time by appropriate doping with triethoxysilane-derivatized cyanine 5.5 (Cy5.5) and cyanine 7 (Cy7) dyes. The performances of these nanoprobes were measured in vitro, using nanoparticle suspensions in phosphate-buffered saline and blood, dedicated phantoms, and after incubation with MDA-MB-231 cells.

Results

We obtained core–shell silica-PEG nanoparticles endowed with very high colloidal stability in water and in biological environment, with absorption and fluorescence emission in the NIR field. The presence of Cy5.5 and Cy7 dyes made it possible to reach a more reproducible and higher doping regime, producing fluorescence emission at a single excitation wavelength in two different channels, owing to the energy transfer processes within the nanoparticle. The nanoarchitecture and the presence of both Cy5.5 and Cy7 dyes provided a favorable agreement between fluorescence emission and quenching, to achieve optical imaging and photoacoustic and photothermal properties.

Conclusion

We obtained rationally designed nanoparticles with outstanding stability in biological environment. At appropriate doping regimes, the presence of Cy5.5 and Cy7 dyes allowed us to tune fluorescence emission in the NIR for optical imaging and to exploit quenching processes for photoacoustic and photothermal capabilities. These nanostructures are promising in vivo theranostic tools for the near future.

Keywords:

• dye-doped nanoparticles
• optical imaging
• NIR imaging
• photoacoustic imaging
• photothermal therapy
• PEGylated nanoparticles

Acknowledgments

This work was supported by: MIUR (PON 01_01078 granted to Luca Prodi) and University of Bologna (FARB project A.10.N2.RICER.FARB2RODAA granted to Luca Prodi).

Author contributions

Stefania Biffi: designed methods and experiments, analyzed the data, interpreted the biological results, and wrote the paper; Luca Petrizza: performed the synthesis and characterization of nanoparticles and dyes, wrote the supplementary information, interpreted photophysical data, and revised the paper; Enrico Rampazzo: designed the synthesis and characterization of nanoparticles and dyes, interpreted photophysical data, and wrote the paper and supplementary information; Chiara Garrovo: performed in vitro cell experiments, interpreted the biological results, and revised the paper; Laura Andolfi: performed the microcopy analyses, interpreted the biological results, and revised the paper; Pierangela Giustetto: performed PAI experiments, interpreted imaging results, and revised the paper; Ivaylo Nikolov, Gabor Kurdi, and Miltcho Boyanov Danailov: designed the laser irradiation setup, performed the laser irradiation and thermal camera analysis, analyzed photothermal results, and revised the paper; Giorgio Zauli and Paola Secchiero: interpreted the results and reviewed the paper; Luca Prodi: defined the research theme, designed methods and experiments, interpreted the results, and wrote the paper. All authors contributed toward data analysis, drafting and critically revising the paper and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.