Single‐Atomic Iron Doped Carbon Dots with Both Photoluminescence and Oxidase‐Like Activity

Abstract

Multifunctional nanozymes can benefit biochemical analysis via expanding sensing modes and enhancing analytical performance, but designing multifunctional nanozymes to realize the desired sensing of targets is challenging. In this work, single‐atomic iron doped carbon dots (SA Fe‐CDs) are designed and synthesized via a facile in situ pyrolysis process. The small‐sized CDs not only maintain their tunable fluorescence, but also serve as a support for loading dispersed active sites. Monoatomic Fe offers SA Fe‐CDs exceptional oxidase‐mimetic activity to catalyze 3,3′,5,5′‐tetramethylbenzidine (TMB) oxidation with fast response (Vmax = 10.4 nM s‐1) and strong affinity (Km = 168 µM). Meanwhile, their photoluminescence is quenched by the oxidation product of TMB due to inner filter effect. Phosphate ions (Pi) can suppress the oxidase‐mimicking activity and restore the photoluminescence of SA Fe‐CDs by interacting with Fe active sites. Based on this principle, a dual‐mode colorimetric and fluorescence assay of Pi with high sensitivity, selectivity, and rapid response is established. This work paves a path to develop multifunctional enzyme‐like catalysts, and offers a simple but efficient dual‐mode method for phosphate monitoring, which will inspire the exploration of multi‐mode sensing strategies based on nanozyme catalysis.

One-pot hydrothermal synthesis of metal-doped carbon dot nanozymes using protein cages as precursors

“…Fe@Fn-CDs also showed the best oxidase-like activity among the samples, which was consistent with some reported results. 35 The catalase-like activity of M@Fn-CDs was evaluated by measuring the dissolved oxygen in neutral H 2 O 2 solution. The results showed that the amount of dissolved oxygen in the H 2 O 2 solution containing Fe@Fn-CDs was significantly increased, indicating that Fe@Fn-CDs possessed catalase-like activity ( Fig.…”

Recent progress in nanozyme-based sensors for ion detection: strategies, trends, and challenges

“…To obtain highly sensitive determination or more convenient monitoring, in recent years researchers have attempted to combine nanozyme catalysis with some other detection modes for toxic ion analysis, including electrochemistry, 79 surface-enhanced Raman spectroscopy (SERS), 80,81 temperature sensing, 31 mass measurement 69 and multimodal analysis. 82 Conventional electrochemical methods have high sensitivity and fast response, allowing it to detect trace heavy metal ions effectively. However, most previous methods required complicated operating procedures, relatively expensive electrode materials, and interference from coexisting metal cations.…”

“…To obtain highly sensitive determination or more convenient monitoring, in recent years researchers have attempted to combine nanozyme catalysis with some other detection modes for toxic ion analysis, including electrochemistry, 79 surface-enhanced Raman spectroscopy (SERS), 80,81 temperature sensing, 31 mass measurement 69 and multimodal analysis. 82…”

Nanomaterial Constructs for Catalytic Applications in Biomedicine: Nanobiocatalysts and Nanozymes

“…Even though CDs with peroxidase-like activity are more reported for biocatalytic applications, there are studies where CDs mimicked the activity of other enzymes, like oxidase. For instance, single-atomic Fe doped CDs (SA Fe-CDs) were evaluated as oxidase-mimicking materials and their application in colorimetric and fluorescent assays for phosphate ions sensing [32]. SA Fe-CDs showed superior oxidase-like activity for the degradation of TMB compared to non-doped CDs; thus, the active sites are attributed to the homogeneously distributed Fe species.…”