Amplifying the Red-Emission of Upconverting Nanoparticles for Biocompatible Clinically Used Prodrug-Induced Photodynamic Therapy

Abstract

A class of biocompatible upconverting nanoparticles (UCNPs) with largely amplified red-emissions was developed. The optimal UCNP shows a high absolute upconversion quantum yield of 3.2% in red-emission, which is 15-fold stronger than the known optimal β-phase core/shell UCNPs. When conjugated to aminolevulinic acid, a clinically used photodynamic therapy (PDT) prodrug, significant PDT effect in tumor was demonstrated in a deep-tissue (>1.2 cm) setting in vivo at a biocompatible laser power density. Furthermore, we show that our UCNP–PDT system with NIR irradiation outperforms clinically used red light irradiation in a deep tumor setting in vivo. This study marks a major step forward in photodynamic therapy utilizing UCNPs to effectively access deep-set tumors. It also provides an opportunity for the wide application of upconverting red radiation in photonics and biophotonics.

Lanthanide‐Doped Upconversion Nanoparticles: Emerging Intelligent Light‐Activated Drug Delivery Systems

“…Recently, CaF 2 shell has emerged as a great candidate to replace the commonly used NaYF 4 shell due to its optical transparency, biocompatibility, stability, high crystallizability and negligible lattice mismatch with NaYF 4 155, 156, 157, 158, 159. For example, Wang et al demonstrated a facile way to fabricate NaYF 4 :Ln 3+ @CaF 2 nanocrystals with ≈300‐fold enhancement of upconverted emission yield compared with the parent core NaYF 4: Ln 3+ .…”

Antigen-Loaded Upconversion Nanoparticles for Dendritic Cell Stimulation, Tracking, and Vaccination in Dendritic Cell-Based Immunotherapy

“…Therefore, UCNPs have many advantages in imaging such as minimal autofluorescence background signals and high resistance to photobleaching, which make them suitable for sensitive detection and imaging in complicated biological samples. [24][25][26] In our previous studies, ultra-sensitive in vivo stem cell tracking with a detection limit down to as few as ten cells in a mouse have been realized by labeling cells with UCNPs. 27,28 Therefore, we hypothesize that engineered UCNPs loaded with antigens may be used to label and stimulate DCs, which after being administrated into animals could be tracked by in vivo UCL imaging and finally realize DC-based immunotherapy with high efficiency.…”

Upconversion nanoparticle as a theranostic agent for tumor imaging and therapy

“…[42][43][44] A class of biocompatible UCNPs with largely ampli¯ed red-emissions were also developed by Han's group. 45 The quantum yield of red emission reached 3.2, which is 15-fold stronger than the known -phase core/shell UCNPs. And the redemission of UCNPs could penetrate a deep-tissue (>1.2 cm) setting in vivo at a harmless laser power density.…”