Self color-changing ordered mesoporous ceria for reagent-free colorimetric biosensing

Abstract

A reagent-free colorimetric detection method using mesoporous cerium oxide with a large pore size trapping an oxidative enzyme has been developed and glucose is sensitively detected with a limit of detection of 10 μM by supporting glucose oxidase on mesoporous cerium oxide.

The effect of pH and transition metal ions on cysteine-assisted gold aggregation for a distinct colorimetric response

“…Colorimetric detection using plasmonic nanoparticles (NPs) is one of the promising sensing strategies for the real-time monitoring of chemical and biological analytes by the naked eye without help from sophisticated instrumentation. 1–3 Especially, gold and silver NPs (AuNPs and AgNPs) have attracted considerable attention due to their unique optical properties to be used as chemical and biological sensors. 4,5 For example, the aggregation of AgNPs has been used to detect dopamine (DA) molecules because the catechol group of DA attaches to the surface of AgNPs via chemisorption-type interactions, resulting in the color change of AgNPs solution from yellow to pale red (or brown).…”

Rational Development of Co‐Doped Mesoporous Ceria with High Peroxidase‐Mimicking Activity at Neutral pH for Paper‐Based Colorimetric Detection of Multiple Biomarkers

“…Consequently, solidification of ceria prevents it from filling the microchannels of the template; it is thus only distributed throughout the mesochannels of KIT‐6, causing the formation of relatively small particles with large pores. [ 10 ] To synthesize Co‐m‐ceria, a small amount of Co(NO 3 ) 3 ·6H 2 O was mixed with Ce(NO 3 ) 3 ·6H 2 O before impregnation into KIT‐6, after which the mixture was subjected to a heat treatment in an adequately opened crucible (Figure S4, Supporting Information). Transmission electron microscopy (TEM) analysis clearly showed an ordered mesoporous structure for Co‐m‐ceria with a particle size of ≈100 nm and pore size of ≈17 nm, which is consistent with the result of dynamic light scattering (DLS) assay ( Figure a and Figure S5, Supporting Information).…”

“…[ 9 ] In our previous work, we reported the synthesis of mesoporous ceria with a large pore size (≈20 nm), which not only allows for increasing the ratio of Ce 3+ , but also enable the facile accommodation of oxidative enzymes for synergistic effects in molecular detection by the direct tandem reaction. [ 10 ] Further, the stability of immobilized enzymes inside the mesopores was increased by the confinement effect. However, because of the differences in optimum pH of the oxidative enzyme and of the peroxidase‐mimicking nanozyme, applications in POCT were limited.…”

Non-enzymatic colorimetric glucose detection based on Au/Ag nanoparticles using smartphone and machine learning

“…Non-biological electrodes like metal oxide nanostructures (NiO, 9 CuO, 10 ZnO, 11 MnO2, 12 CeO2, 13 Co3O4, 14 CoMoO4, 15 MnCaO2, 16 ) noble metal nanostructures (Au, 17 Ag 18 ), transition metal dichalcogenides (MoS2, 19 WSe2, 20 WS2 21 ), carbon-based nanomaterials (graphene, 22 graphene oxide, 23 carbon dots, 24 carbon nanotubes 25 ), layered double hydroxides, 26,27 and magnetic nanoparticles (MFe2O4 (M=Mg, Ni, Cu), 28 Fe3S4, 29 Fe3O4 30 ) have been used as nanozymes mimicking the enzyme activity. Among the nanostructures, silver nanoparticles (Ag NPs) and gold nanoparticles (Au NPs) offer advantages in biosensor applications due to their easy preparation, unique electrical and optical properties, and controllable size and stability which affect the sensitivity and selectivity of detection.…”