In Vivo Toxicity of Upconversion Nanoparticles. Overview. Part I

Irina Y. Yanina; Vyacheslav I. Kochubey

doi:10.18287/JBPE26.12.030201

Authors

Irina Y. Yanina Saratov State University
Vyacheslav I. Kochubey Saratov State University

DOI:

https://doi.org/10.18287/JBPE26.12.030201

Keywords:

toxicity, upconversion nanoparticles, concentration, dose

Abstract

This review synthesizes current research on the in vivo dark toxicity of upconversion nanoparticles (UCNPs) for biomedical applications, including luminescent imaging, diagnostics, and photoinduced therapy. The aim is to assess key toxicity determinants – nanoparticle type, surface coating, concentration, and dose relative to body weight – and to establish safe exposure thresholds. Analysis of comprehensive histological and biochemical studies indicates that UCNPs generally exhibit low toxicity under tested conditions. The most non-toxic concentration identified across studies is 2 mg/mL. For mice, the maximum permissible dose for short-term exposure (12 h) is 10 mg/kg, and for long-term exposure (120 days) is 50 mg/kg. For rats, a dose of 5 mg/kg is safe for both short- and long-term studies. While positively charged coatings (e.g., PEI) enhance cellular uptake, they may increase cytotoxicity compared to neutral or negatively charged coatings (e.g., PAA, PEG). Dissolution of UCNPs releasing rare-earth and fluoride ions contributes to dark toxicity, but biocompatible shells (silica, PEG) reduce this effect. Overall, UCNPs demonstrate favorable biocompatibility at established doses, supporting their continued development for in vivo theranostic applications. This review is the first of three parts; subsequent parts address phototoxicity and toxicity of multimodal particles.

Author Biography

Irina Y. Yanina, Saratov State University

Field of scientific activities
Optics of biological tissues, biomedical optics, optical control parameters of biological tissues, the study of transport of drugs in biological tissues, spectroscopy and imaging in biomedicine, physics, optical and laser measurements; optical coherency and multiphotontomography;fluorescence; nanobiophotonics.
Publications
Author and co-author of 70 publications in peer-reviewed and scientific journals, conference proceedings and patent application; 60 presentations at major international conferences and workshops (oral and poster).

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