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• The interface and hollow structure synergistic regulation strategy is proposed to solve the limited active sites of Co 3 O 4. • The charge rearrangement at heterointerface could improve the catalytic activity of nanozymes. • The hollow nanocube structure could increase specific surface area and provide rich active sites. • This work provides a novel method for the rapid and sensitive detection of AA. The development of oxidase mimic with favorable catalytic activity is of great significance for the rapid and convenient detection of ascorbic acid (AA). Herein, in this work, a synergistic regulation strategy of heterogeneous interface and hollow structure is proposed to effectively solve the problem of limited active sites obtained with Co 3 O 4. The charge rearrangement at heterointerface could improve the catalytic activity of oxidase mimic. Moreover, the hollow nanocubes structure could increase specific surface area and provide rich active sites. As a result, the target material possesses enhanced oxidase-like catalytic activity and desirable stability compared to bare Co 3 O 4 and MnO 2 , which also catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to form a blue product (ox-TMB) even without hydrogen peroxide. Ox-TMB is reduced to TMB owing to the strong reducibility of AA, which represents a decrease in absorbance at 652 nm and a colorless solution. Moreover, an efficient biosensing method for the detection of AA is developed. The relative absorbance (∆A) of the sensing platform is linearly related to the concentration of AA in the range of 0–200 μM, and the detection limit is 0.11 μM. This work provides a novel method for the rapid, cost-effective and sensitive detection of AA, and possesses a wide range of potential application value. A synergistic regulation strategy of heterogeneous interface and hollow structure is proposed to effectively solve the problem of limited active sites obtained with Co 3 O 4. This work provides a novel method for the rapid, cost-effective and sensitive detection of AA, and possesses a wide range of potential application value. [Display omitted] [ABSTRACT FROM AUTHOR]

• The CeO 2 /Co 3 O 4 hollow nanocubes with exceptional peroxidase-like activity have been successfully constructed. • The charge rearrangement at the heterointerface enhances the catalytic activity of nanozymes. • The hollow structure offers rich active sites available for enzymatic reactions. • This work establishes an effortless, cost-effective, and highly efficient "On-Off" colorimetric sensor for H 2 O 2 and ascorbic acid. The development of artificial nanostructured enzymes has garnered significant interest in the field of nanobiotechnology due to the distinct advantages. In this work, CeO 2 /Co 3 O 4 hollow nanocubes (named as CeO 2 /Co 3 O 4 HNs) with exceptional peroxidase-like activity have been prepared employing ion exchange and subsequent calcination process. In the presence of hydrogen peroxide (H 2 O 2), the CeO 2 /Co 3 O 4 HNs display high peroxidase-like activity, catalyzing the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and resulting in a color change from transparent to blue. The oxidized TMB (ox-TMB) is subsequently reduced to TMB due to the reducibility of ascorbic acid (AA), restoring the original color of solution. Consequently, a straightforward and efficient "On-Off" colorimetric sensor has been established for the accurate detection of H 2 O 2 and AA, with detection limits (LOD) of 3.56 and 0.179 μM, respectively. In summary, the prepared colorimetric sensor offers numerous advantages, including ease of operation, cost-effectiveness, rapid response, and effective visual monitoring, which holds substantial promise for applications in detection of hydrogen peroxide and ascorbic acid. [Display omitted] The CeO 2 /Co 3 O 4 hollow nanocubes with exceptional peroxidase-like activity have been successfully synthesized by employing ion exchange process and subsequent calcination method. This work establishes an effortless, cost-effective, and highly efficient "On-Off" colorimetric sensor for H 2 O 2 and ascorbic acid, with color changes serving as the basis for monitoring. [ABSTRACT FROM AUTHOR]

Bone defects are characterized by a hypoxic environment, which affects bone tissue repair. However, the role of hypoxia in the repair of alveolar bone defects remains unclear. Human periodontal ligament stem cells (hPDLSCs) are high‐quality seed cells for repairing alveolar bone defects, whose behavior changes under hypoxia. However, their mechanism of action is not known and needs to be elucidated. We hypothesized that hypoxia might be beneficial to alveolar bone defect repair and the osteogenic differentiation of hPDLSCs. To test this hypothesis, cobalt chloride (CoCl2) was used to create a hypoxic environment, both in vitro and in vivo. In vitro study, the best osteogenic effect was observed after 48 h of hypoxia in hPDLSCs, and the AKT/mammalian target of rapamycin/eukaryotic translation initiation factor 4e‐binding protein 1 (AKT/mTOR/4EBP‐1) signaling pathway was significantly upregulated. Inhibition of the AKT/mTOR/4EBP‐1 signaling pathway decreased the osteogenic ability of hPDLSCs under hypoxia and hypoxia‐inducible factor 1 alpha (HIF‐1α) expression. The inhibition of HIF‐1α also decreased the osteogenic capacity of hPDLSCs under hypoxia without significantly affecting the level of phosphorylation of AKT/mTOR/4EBP‐1. In vitro study, Micro‐CT and tissue staining results show better bone regeneration in hypoxic group than control group. These results suggested that hypoxia promoted alveolar bone defect repair and osteogenic differentiation of hPDLSCs, probably through AKT/mTOR/4EBP‐1/HIF‐1α signaling. These findings provided important insights into the regulatory mechanism of hypoxia in hPDLSCs and elucidated the effect of hypoxia on the healing of alveolar bone defects. This study highlighted the importance of physiological oxygen conditions for tissue engineering. [ABSTRACT FROM AUTHOR]