Axial Ligand-Engineered Single-Atom Catalysts with Boosted Enzyme-Like Activity for Sensitive Immunoassay

Abstract

Inspired by the key role of the coordination environment in the catalytic activity of enzymes, a rational design of the coordination structure of active sites at the atom scale is expected to develop high-performance enzyme-like catalysts. Here, we design a simple model system involving pentacoordinated and tetracoordinated Fe–N–C single-atom catalysts (named NG-Heme and G-Heme, respectively) to investigate structure–activity relationships. NG-Heme with axial ligand-engineered Fe sites exhibits superior enzyme-like activity to G-Heme, achieving the goal of vivid mimicking of the active sites of peroxidase. Experiments and theoretical studies reveal that the enhanced intrinsic catalytic activity originates from the “push effect” of the additional axial ligand, which can strengthen the interaction between the active site and the intermediate. Based on the outstanding catalytic activity, an NG-Heme-linked immunosorbent assay was constructed for colorimetric detection of carcinoembryonic antigen, exhibiting satisfactory sensitivity and feasibility in the analysis of clinical samples.

Homogeneity of Supported Single‐Atom Active Sites Boosting the Selective Catalytic Transformations

“…FeN 5 SAzymes with an axial coordination ligand is prepared by assembling hemin on ultrathin nitrogen-doped graphene (Figure 19d,e). [361] The interaction between Fe-N-C sites and reaction intermediates is enhanced via the push effect, boosting the ability to activate H 2 O 2 and achieving a vivid mimic of the active sites of peroxidase. With isolated active sites anchored on graphene layers, Fe-N-C SAzymes exhibit oxidase-like properties by activating O 2 into O 2 − • radicals and can be applied in biosensors.…”

Single‐Atom Nanozymes for Biomedical Applications: Recent Advances and Challenges

“…As an emerging nanomaterial, the application of SAzymes for tumor cell detection is an efficient solution. Xu Weiqing et al [18] . then designed five‐ligand and four‐ligand Fe−N−C SAzymes and experimentally demonstrated that the five‐ligand Fe−N−C SAzymes can achieve higher catalytic activity due to their additional axial ligands a colorimetric sensing system of immunosorbent carcinoembryonic antigen was constructed for the sensitive detection of cancer cells.…”

“…As an emerging nanomaterial, the application of SAzymes for tumor cell detection is an efficient solution. Xu Weiqing et al [18] then designed five-ligand and four-ligand FeÀ NÀ C SAzymes and experimentally demonstrated that the five-ligand FeÀ NÀ C SAzymes can achieve higher catalytic activity due to their additional axial ligands a colorimetric sensing system of immunosorbent carcinoembryonic antigen was constructed for the sensitive detection of cancer cells. However, there are two problems with SAzymes: first, they have low dispersion in solution [83] and tend to aggregate without achieving higher catalytic activity; second, they do not have the structure to specifically recognize biomolecules.…”

“…Finally, in terms of application, a sensitive detection method for H 2 O 2 , glucose, and AA was developed with the optimized Cu-NC-700 SAzymes. Hongye FeÀ SSN [14] Fe [15] RuÀ AlaÀ C 3 N 4 [16] AÀ CoÀ NG [17] FeÀ NÀ C [18] Apt/FeÀ NÀ C [19] FeÀ NÀ C [20] Pt/NiCo-LDH [21] FeÀ NÀ C [22] CoÀ MoS 2 [23] FeÀ N/C [24] CoÀ NÀ C [25] Biomedical therapy Cancer…”

“…Fe−SSN [14] Fe [15] Ru−Ala−C 3 N 4 [16] A−Co−NG [17] Fe−N−C [18] Apt/Fe−N−C [19] Fe−N−C [20] Pt/NiCo‐LDH [21] Fe−N−C [22] Co−MoS 2 [23] Fe−N/C [24] Co−N−C [25] …”