Local Overheating of Biotissue Labeled With Upconversion Nanoparticles Under Yb3+ Resonance Excitation.

Ivan V Krylov,Natalya V Sholina,Vasilina V Rocheva,Alla N Generalova,Roman A Akasov,Alexey A Dmitriev,Nataliya V Melnikova,Dmitry A Khochenkov,Andrey V Nechaev,Evgeny V Khaydukov,Andrey V Ivanov

doi:10.3389/fchem.2020.00295

Abstract

Local overheating of biotissue is a critical step for biomedical applications, such as photothermal therapy, enhancement of vascular permeability, remote control of drug release, and so on. Overheating of biological tissue when exposed to light is usually realized by utilizing the materials with a high-absorption cross section (gold, silica, carbon nanoparticles, etc.). Here, we demonstrate core/shell NaYF4:Yb3+, Tm3+/NaYF4 upconversion nanoparticles (UCNPs) commonly used for bioimaging as promising near-infrared (NIR) absorbers for local overheating of biotissue. We assume that achievable temperature of tissue labeled with nanoparticles is high enough because of Yb3+ resonance absorption of NIR radiation, whereas the use of auxiliary light-absorbing materials or shells is optional for photothermal therapy. For this purpose, a computational model of tissue heating based on the energy balance equations was developed and verified with the experimentally obtained thermal-graphic maps of a mouse in response to the 975-nm laser irradiation. Labeling of biotissue with UCNPs was found to increase the local temperature up to 2°C compared to that of the non-labeled area under the laser intensity lower than 1 W/cm2. The cellular response to the UCNP-initiated hyperthermia at subcritical ablation temperatures (lower than 42°C) was demonstrated by measuring the heat shock protein overexpression. This indicates that the absorption cross section of Yb3+ in UCNPs is relatively large, and microscopic temperature of nanoparticles exceeds the integral tissue temperature. In summary, a new approach based on the use of UCNP without any additional NIR absorbers was used to demonstrate a simple approach in the development of photoluminescent probes for simultaneous bioimaging and local hyperthermia.

Highlights

Upconversion nanoparticles (UCNPs) and UCNPbased nanoconstructions showed a great potential in biomedical applications for near-infrared (NIR)–to–NIR bioimaging (Chen et al, 2014; Wu et al, 2014; Li et al, 2015; Generalova et al, 2016), photodynamic (Khaydukov et al, 2016; Xu et al, 2017; Qiu et al, 2018; Liu et al, 2019), and photothermal therapy (PTT) (Zhu et al, 2016; Chan et al, 2018)
We demonstrated core/shell NaYF4: Yb3+, Tm3+/NaYF4 upconversion nanoparticles (UCNPs) as promising NIR absorbers for local biotissue overheating
Our modeling results indicate that the absorption cross section of Yb3+ in UCNPs is larger than the literature value, while microscopic temperature of NPs exceeds the integral tissue temperature

Summary

Introduction

Upconversion nanoparticles (UCNPs) and UCNPbased nanoconstructions showed a great potential in biomedical applications for near-infrared (NIR)–to–NIR bioimaging (Chen et al, 2014; Wu et al, 2014; Li et al, 2015; Generalova et al, 2016), photodynamic (Khaydukov et al, 2016; Xu et al, 2017; Qiu et al, 2018; Liu et al, 2019), and photothermal therapy (PTT) (Zhu et al, 2016; Chan et al, 2018). Temperature feedback of UCNPs coated with carbon layer as a light absorber was used for the precise tumor PTT with minimal damage to normal tissue (Zhu et al, 2016). The UCNP structure with additional layers or NPs as light-absorbing materials for PTT is often cumbersome and complicates the preparation of nanoprobes

Methods

Results

Conclusion