Arellano, LiliaMartínez, RaquelPardo Montero, AlbertoDíez, IagoVelasco Rodríguez, BrendaMoreda Piñeiro, AntonioBermejo Barrera, PilarBarbosa Fernández, SilviaTaboada Antelo, Pablo2024-09-272024-09-272024Journal of Colloid and Interface Science Volume 668 , 15 August 2024, Pages 575-5860021-9797http://hdl.handle.net/10347/34907Lanthanide-doped up-converting nanoparticles (UCNPs) have emerged as promising biomedical tools in recent years. Most research efforts were devoted to the synthesis of inorganic cores with the optimal physicochemical properties. However, the careful design of UCNPs with the adequate surface coating to optimize their biological performance still remains a significant challenge. Here, we propose the functionalization of UCNPs with four distinct types of surface coatings, which were compared in terms of the provided colloidal stability and resistance to degradation in different biological-relevant media, including commonly avoided analysis in acidic lysosomal-mimicking fluids. Moreover, the influence of the type of particle surface coating on cell cytotoxicity and endocytosis/exocytosis was also evaluated. The obtained results demonstrated that the functionalization of UCNPs with poly(isobutylene-alt-maleic anhydride) grafted with dodecylamine (PMA-g-dodecyl) constitutes an outstanding strategy for their subsequent biomedical application, whereas poly(ethylene glycol) (PEG) coating, although suitable for colloidal stability purposes, hinders extensive cell internalization. Conversely, surface coating with small ligand were found not to be suitable, leading to large degradation degrees of UCNPs. The analysis of particle’ behavior in different biological media and in vitro conditions here performed pretends to help researchers to improve the design and implementation of UCNPs as theranostic nanotools.engAtribución-NoComercial 4.0 Internacional© 2024 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC licensehttp://creativecommons.org/licenses/by-nc/4.0/Up-converting nanoparticlesSurface coatingStability and degradationEndocytosis/exocytosisjournal article10.1016/j.jcis.2024.04.188open access