Polydopamine-Coated Co3O4 Nanoparticles as an Efficient Catalase Mimic for Fluorescent Detection of Sulfide Ion

Abstract

Surface engineering of nanozymes has been recognized as a potent strategy to improve their catalytic activity and specificity. We synthesized polydopamine-coated Co3O4 nanoparticles (PDA@Co3O4 NPs) through simple dopamine-induced self-assembly and demonstrated that these NPs exhibit catalase-like activity by decomposing H2O2 into oxygen and water. The activity of PDA@Co3O4 NPs was approximately fourfold higher than that of Co3O4 NPs without PDA, possibly due to the additional radical scavenging activity of the PDA shell. In addition, PDA@Co3O4 NPs were more stable than natural catalase under a wide range of pH, temperature, and storage time conditions. Upon the addition of a sample containing sulfide ion, the activity of PDA@Co3O4 NPs was significantly inhibited, possibly because of increased mass transfer limitations via the absorption of the sulfide ion on the PDA@Co3O4 NP surface, along with NP aggregation which reduced their surface area. The reduced catalase-like activity was used to determine the levels of sulfide ion by measuring the increased fluorescence of the oxidized terephthalic acid, generated from the added H2O2. Using this strategy, the target sulfide ion was sensitively determined to a lower limit of 4.3 µM and dynamic linear range of up to 200 µM. The fluorescence-based sulfide ion assay based on PDA@Co3O4 NPs was highly precise when applied to real tap water samples, validating its potential for conveniently monitoring toxic elements in the environment.

Core–Shell Structured Nanozyme with PDA-Mediated Enhanced Antioxidant Efficiency to Treat Early Intervertebral Disc Degeneration

“…From the FTIR spectra (Figure I), the absorption peaks for CNO appear at 3406 and 1612 cm –1 , ascribed to the stretching and bending vibrations of O–H, while for PDA@CNO, two additional absorption peaks are present at 1510 and 1295 cm –1 , respectively, caused by the stretching vibrations of N–H and C–O within the PDA shell. Notably, a blue shift occurs to the O–H absorption in PDA@CNO compared to that in CNO, which implies that the core of CNO has interacted with the shell of PDA, enabling the electron transfer between the core and the shell . Additionally, the zeta potential (Figure J) declined from 13.0 of CNO to 8.8 of PDA@CNO, further proving the successful construction of the core–shell structure after PDA encapsulation.…”

“…Notably, a blue shift occurs to the O−H absorption in PDA@CNO compared to that in CNO, which implies that the core of CNO has interacted with the shell of PDA, enabling the electron transfer between the core and the shell. 42 Additionally, the zeta potential (Figure 1J) declined from 13.0 of CNO to 8.8 of PDA@CNO, further proving the successful construction of the core−shell structure after PDA encapsulation. The compositions and elemental states of CNO and PDA@ CNO nanoparticles were further analyzed by XPS.…”

Co‐based Nanozymatic Profiling: Advances Spanning Chemistry, Biomedical, and Environmental Sciences

“…Kim et al synthesized PDA@Co 3 O 4 NPs to detect sulfide ions in water. [83] Their nanomaterials have additional radical scavenging activity due to the PDA shell, which enhances their POD activity and inhibits the fluorescence formation of terephthalic acid (TA) in the presence of H 2 O 2 . The interaction of S 2− with PDA inhibits the decomposition of H 2 O 2 and improves the fluorescence signal of TA.…”

“…[ 82 ] Furthermore, coating these nanozymes with polydopamine (PDA) enhances their stability and acts as a free radical scavenger, increasing their enzymatic activity up to four times the original level. [ 83 ] However, such modifications may also pose challenges for their catalytic activity. For instance, in the case of Co‐N‐CNTs, the anionic surfactant SDS is used as a surface modifier.…”

Synthesis of Fe-Doped Peroxidase Mimetic Nanozymes from Natural Hemoglobin for Colorimetric Biosensing and In Vitro Anticancer Effects

“…There is a wide collection of nanomaterials that reproduce the functions of natural enzymes [ 14 , 15 , 16 , 17 , 18 , 19 ]. The most studied aspect is the peroxidase-like activity of nanozymes, which is the catalytic conversion of hydrogen peroxide to water [ 20 , 21 , 22 , 23 , 24 ].…”