Ultralow Ru Single Atoms Confined in Cerium Oxide Nanoglues for Highly-Sensitive and Robust H 2 O 2 -Related Biocatalytic Diagnosis.

Exploring highly efficient, portable, and robust biocatalysts is a great challenge in colorimetric biosensors. To overcome the challenging states in creating single-atom biocatalysts, such as insufficient activity and stability, here, this work has engineered a unique CeO 2 support as nanoglue to tightly anchor the Ru single-atom sites (CeO 2 -Ru) with strong electronic coupling for achieving highly sensitive and robust H 2 O 2 -related biocatalytic diagnosis. The morphology and chemical/electronic structure analysis demonstrates that the Ru atoms are well-dispersed on CeO 2 surface to form high-density active sites. Benefiting from the unique structure, the prepared CeO 2 -Ru exhibits outstanding peroxidase (POD) like catalytic activity and selectivity to H 2 O 2 . Steady-state kinetic study results show that the CeO 2 -Ru presents the highest V max and turnover number than the state-of-the-art POD-like biocatalysts. Consequently, the CeO 2 -Ru discloses a high efficiency, good selectivity, and robust stability in the colorimetric detection of L-cysteine, glucose, and uric acid. Notably, the limit of detection (LOD) can reach 0.176 × 10 -3 m for the L-cysteine, 0.095 × 10 -3 m for the glucose, and 0.088 × 10 -3 m for the uric acid via cascade reaction. This work suggests that the proposed unique CeO 2 nanoglue will offer a new path to create single-atom noble metal biocatalysts and take a step closer to future biotherapeutic and biocatalytic applications.