(714a) Enzyme-Mimetic Luminescent Luminescent Nanoparticles As Hydrogen Peroxide Biosensors

Authors: 
Sotiriou, G. A. - Presenter, Karolinska Institutet
Hydrogen peroxide (H2O2) is an abundant molecule associated with biological processes and reacts with natural enzymes, such as catalase. Thus, H2O2 quantification constitutes a powerful tool for detection of disease biomarkers linked to enzyme-based assays such as the plasmonic ELISA. However, the optical H2O2 biosensing without organic-dyes in biological media and at low, submicromolar, concentrations has yet to be achieved. The target of this work is to design biomimetic artificial enzymes based on antioxidant CeO2 nanoparticles that become luminescent upon their Eu3+ doping [1,2]. CeO2 nanoparticles have received a lot of attention recently due to their antioxidant enzyme-like (nanozyme) properties.

Here, europium-doped cerium oxide (CeO2:Eu3+) nanoparticles with well-controlled size (d = 4 – 16 nm) are prepared by flame aerosol technology and characterized in regards to H2O2 sensor response in physiologically-relevant solutions. Furthermore, we combine luminescent enzyme-mimetic CeO2:Eu3+ nanoparticles with optically stable Y2O3:Tb3+ nanophosphors [1,2] that serve as concentration-independent reference value in the same nanoaggregates. Finally, the luminescence excitation is enhanced by the addition of Bi3+ within the same crystal matrix that improves its excitation in the near-UV wavelength region.

The developed biosensors are coupled to enzyme-based assays that consume or generate H2O2 aiming the detection of other important bioanalytes, such as alcohol and glucose, using alcohol and glucose oxidase enzymes, respectively [3]. Upon the addition of a luminescent material with no H2O2 sensitivity, ratiometric sensors can be made for the facile and fast H2O2 detection in vitro. The sensing performance of the nanoparticles was further evaluated with hydrogen peroxide producing S. pneumoniae bacteria in biological media. Furthermore, the excitation spectrum engineering by the addition of Bi3+ ions renders these materials as suitable H2O2 biosensors with conventional fluorescent microscope filter sets utilizing the near-UV excitation. The biomimetic artificial enzyme developed here could serve as a starting point of sophisticated in vitro assays towards highly sensitive detection of disease biomarkers.

REFERENCES

[1] G.A. Sotiriou, M. Schneider & S.E. Pratsinis, “Color-Tunable Nanophosphors by Codoping Flame-Made Y2O3 with Tb and Eu”, J. Phys. Chem. C 115, 1084–1089 (2011).

[2] G.A. Sotiriou, D. Franco, D. Poulikakos, A. Ferrari, “Optically Stable Biocompatible Flame-Made SiO2-Coated Y2O3:Tb3+ Nanophosphors for Cell Imaging”, ACS Nano 6, 3888–3897 (2012).

[3] A. Pratsinis, G. A. Kelesidis, S. Zuercher, F. Krumeich, S. Bolisetty, R. Mezzenga, J-C. Leroux & G. A. Sotiriou. “Enzyme-Mimetic Antioxidant Luminescent Nanoparticles for Highly Sensitive Hydrogen Peroxide Biosensing” ACS Nano 11, 12210-12218 (2017).