Hydrogen Peroxide Displacing DNA from Nanoceria: Mechanism and Detection of Glucose in Serum

Abstract

Hydrogen peroxide (H2O2) is a key molecule in biology. As a byproduct of many enzymatic reactions, H2O2 is also a popular biosensor target. Recently, interfacing H2O2 with inorganic nanoparticles has produced a number of nanozymes showing peroxidase or catalase activities. CeO2 nanoparticle (nanoceria) is a classical nanozyme. Herein, a fluorescently labeled DNA is used as a probe, and H2O2 can readily displace adsorbed DNA from nanoceria, resulting in over 20-fold fluorescence enhancement. The displacement mechanism instead of oxidative DNA cleavage is confirmed by denaturing gel electrophoresis and surface group pKa measurement. This system can sensitively detect H2O2 down to 130 nM (4.4 parts-per-billion). When coupled with glucose oxidase, glucose is detected down to 8.9 μM in buffer. Detection in serum is also achieved with results comparable with that from a commercial glucose meter. With an understanding of the ligand role of H2O2, new applications in rational materials design, sensor development, and drug delivery can be further exploited.

Comprehensive Screen of Metal Oxide Nanoparticles for DNA Adsorption, Fluorescence Quenching, and Anion Discrimination

“…Many MONPs (e.g., TiO2, CeO2, ITO) adsorb DNA mainly via the phosphate 10 backbone. 10,[12][13][14] Here, we confirmed that phosphate backbone binding is also important for DNA adsorption onto Cr2O3, Mn2O3 and ZnO. FAM-24 mer DNA (100 nM) in Buffer A to achieve fluorescence quenching (red spectra).…”

“…[1][2][3][4][5][6] While DNA has been interfaced with metal and carbon-based nanomaterials, [6][7][8][9] limited work was carried out on metal oxide nanoparticles (MONPs). [10][11][12][13][14][15][16][17][18][19][20] MONPs represent a very important class of material due to their unique electronic, optical, magnetic and catalytic properties. DNAfunctionalized MONPs might be useful as a sensor platform for anion detection.…”

Ceria Nanoparticles as Enzyme Mimetics

“…[19] Since then, nanoceria have been also found to exhibit CAT mimetic activity in some other studies. [16,22,35,[49][50][51] As CAT mimetics, nanoceria could catalyze the H 2 O 2 decompositon, with the final harmless products as water (H 2 O) and molecular oxygen (O 2 ). Pirmohamed et al [49] …”

“…[15] Other than those, the surface of nanomaterials may offer more catalytic sites while natural enzymes offer only one active site per molecule. [16] These enzyme mimetics have great value in practical applications, and therefore become a new frontier in inorganic, materials and analytical chemistry. [17][18][19] In previous studies, ceria nanoparticles (nanoceria) and nanoceria-supported materials have been reported to have multi-enzyme mimetic activities like those of superoxide oxidase, [20,21] catalase [22,23] and oxidase.…”

Adsorption of Nanoceria by Phosphocholine Liposomes

“…Since cerium is a hard metal that has a strong affinity to phosphate, 40,44,45 we propose that the phosphate group in the lipid might be playing a critical 12 role. To test this, we added free inorganic phosphate ions to the CeO2 NPs prior to mixing them with DOPC (Figure 3a).…”