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Orthogonal Functionalisation of Upconverting NaYF 4 Nanocrystals
Author(s) -
Voliani Valerio,
GonzálezBéjar María,
HerranzPérez Vicente,
DuranMoreno Maria,
Signore Giovanni,
GarciaVerdugo Jose M.,
PérezPrieto Julia
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201301353
Subject(s) - covalent bond , ethylene glycol , amine gas treating , carboxylic acid , chemistry , dynamic light scattering , nanocrystal , reactivity (psychology) , materials science , nanoparticle , photochemistry , organic chemistry , nanotechnology , medicine , alternative medicine , pathology
A simple and straightforward method for the orthogonal functionalisation of upconverting NaYF 4 nanocrystals (UCNCs)—doped withYb 3+ and Er 3+ —based on N ‐(3‐dimethylaminopropyl)‐ N ′‐ethylcarbodiimide/ N ‐hydroxysuccinimide (EDC/NHS) selective reactions between two dyes and two different reactive groups present at the periphery of the upconverting nanocrystals is reported. Organic‐soluble UCNCs of 10 and 50 nm in size are encapsulated efficiently in a 1:1 mixture of two commercial 3000 Da poly(ethylene glycol) derivatives with two different reactive groups (amino and carboxylic groups). The water‐dispersible UCNCs are non‐cytotoxic, stable in the physiological environment, and present free amine and carboxylic reactive groups on their periphery, allowing rapid, selective, and modular covalent conjugation to payloads through EDC/NHS reactions. PEG‐encapsulated UCNCs with and without covalent conjugation to payloads are characterised in vitro through spectroscopic, dynamic light scattering, and electron microscopy measurements. Living cell analyses coupled with TEM measurements confirm the uptake and low cytotoxicity of the coated UCNCs. They are linked covalently to two different dyes, internalised by living cells, and analysed by confocal microscopy. The related colocalisation measurements prove the reactivity of both amines and carboxylic acids on the periphery of the nanocrystals. This approach demonstrates that it is possible to produce water‐dispersible and cyto‐compatible dual‐functional UCNCs.