Enzymatic enhancing of triplet\u2013triplet annihilation upconversion by breaking oxygen quenching for background-free biological sensing

Ling Huang,Kai Huang,Timmy Le,Gang Han

doi:10.1038/s41467-021-22282-1

Abstract

Triplet-triplet annihilation upconversion nanoparticles have attracted considerable interest due to their promises in organic chemistry, solar energy harvesting and several biological applications. However, triplet-triplet annihilation upconversion in aqueous solutions is challenging due to sensitivity to oxygen, hindering its biological applications under ambient atmosphere. Herein, we report a simple enzymatic strategy to overcome oxygen-induced triplet-triplet annihilation upconversion quenching. This strategy stems from a glucose oxidase catalyzed glucose oxidation reaction, which enables rapid oxygen depletion to turn on upconversion in the aqueous solution. Furthermore, self-standing upconversion biological sensors of such nanoparticles are developed to detect glucose and measure the activity of enzymes related to glucose metabolism in a highly specific, sensitive and background-free manner. This study not only overcomes the key roadblock for applications of triplet-triplet annihilation upconversion nanoparticles in aqueous solutions, it also establishes the proof-of-concept to develop triplet-triplet annihilation upconversion nanoparticles as background free self-standing biological sensors.

Highlights

Triplet-triplet annihilation upconversion nanoparticles have attracted considerable interest due to their promises in organic chemistry, solar energy harvesting and several biological applications
As a proof-of-principle, palladium(II) meso-tetraphenyltetrabenzoporphyrin (PdTPBP) and perylene were used as the sensitizer and annihilator, as they are one of the most investigated and effective long-wavelength activating triplet annihilation upconversion (TTA-UC) dye pairs used in organic solvent[42]
In summary, we developed a straightforward strategy to overcome the oxygen quenching problem to turn on the upconversion emissions of TTA-UCNP in the aqueous solution

Summary

Introduction

Triplet-triplet annihilation upconversion nanoparticles have attracted considerable interest due to their promises in organic chemistry, solar energy harvesting and several biological applications. We envisioned that such a reaction can be used to remove oxygen in an aqueous solution to turn on and amplify the upconversion emissions of TTA-UCNP (Fig. 1a). In the presence of both GOX and glucose, intense blue upconversion emission was observed at 480 nm (Fig. 2a).

Results

Conclusion