Encapsulation of TOPO stabilized NaYF4:Er3+,Yb3+ nanoparticles in biocompatible nanocarriers: Synthesis, optical properties and colloidal stability

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2017-11, Vol.532, p.556-563
• Main Authors: Bazylińska, Urszula, Wawrzyńczyk, Dominika
• Format: Article
• Language: English
• Subjects: Double emulsion process; Lanthanide luminescence; Non-ionic surfactants; Up-converting nanocrystals
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2017.03.040

[Display omitted] •NaYF4:Er,Yb NPs ∼5nm in size were synthesized with TOPO used as a stabilizing ligands.•The modified double emulsion evaporation method was successful in the up-converting NPs encapsulation.•PLGA, Span 80 and Cremophor A25 act as the obtained nanosystems stabilizers.•The encapsulation process retain the optical properties of NaYF4:Er3+,Yb3+ NPs.•The obtained nanocarriers have potential applications as theranostic agents. The emulsification process leading to up-converting NaYF4:Er3+,Yb3+ NPs encapsulation, was performed using a modified water/oil/water double emulsion evaporation method, where poly(lactic-co-glycolic acid) was used as biocompatible polymer. Span 80 and Cremophor A25 were applied as non-ionic surfactants and dichloromethane as oily phase. The use of trioctylphosphine oxide ligands for the synthesis of up-converting NaYF4:Er3+,Yb3+ NPs allowed to obtain spherical particles with sizes below 10nm, what further facilitated the efficient encapsulation process. Those newly designed nanosystems were subjected to analysis of their morphology, colloidal stability and optical properties by: dynamic light scattering, ζ-potential, atomic force microscopy, transmission electron microscopy and measuring the up-conversion emission spectra of free and loaded NaYF4:Er3+,Yb3+ NPs. The encapsulated NaYF4:Er3+,Yb3+ NPs showed increased colloidal stability for a long period of 60 days of storage in different conditions. Simultaneously, the encapsulation process did not significantly influenced their optical properties and strong visible emission could be observed upon nearinfrared excitation.