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Glucose Oxidase-Integrated Metal−Organic Framework Hybrids as Biomimetic Cascade Nanozymes for Ultrasensitive Glucose Biosensing
Summary:
The authors from Central China Normal University, Henan Provincial People’s Hospital, and Washington State University developed Fe-MOF-GOx hybrid materials (glucose oxidase-integrated Fe-MIL-88B-NH₂) with excellent cascade catalytic activity, high stability, and reusability, achieving ultrasensitive colorimetric detection of glucose (detection limit 0.487 μM) in the field of biosensing.
Background:
1. To address the problems of low catalytic efficiency, poor stability, and high diffusion resistance in traditional glucose detection systems using free glucose oxidase (GOx) and nanozymes, previous researchers developed MOF-based nanozymes and enzyme-immobilized systems. However, these systems still suffered from low cascade reaction efficiency and poor reusability.
2. The authors proposed an innovative method by covalently immobilizing GOx on Fe-MIL-88B-NH₂ (Fe-MOF) via amidation coupling, constructing a biomimetic cascade nanozyme. This integration enhances "nanoscale proximity" between enzymes and nanozymes, reducing H₂O₂ diffusion loss and improving stability and catalytic efficiency.
Research Content:
1. Synthesis:
The authors synthesized Fe-MOF via hydrothermal method using FeCl₃·6H₂O and 2-aminoterephthalic acid at 110°C for 24 hours. GOx was immobilized on Fe-MOF using EDC/NHS as cross-linking agents: GOx was activated with EDC at 37°C for 15 minutes, then mixed with NHS and Fe-MOF for 2 hours, yielding Fe-MOF-GOx with a GOx loading of 41 μg·mg⁻¹.
2. Characterizations:
1) BET and pore size distribution: Not explicitly provided, but XRD confirmed Fe-MOF’s crystalline structure was preserved after GOx immobilization (Figure S2).
2) SEM/TEM tests show the particle size of the material: Fe-MOF is spindle-shaped with a size of ~200 nm; Fe-MOF-GOx retains the same morphology, indicating no structural damage after immobilization (Figure 1a,b; Figure S1).
3) Other tests: CLSM with RhB-labeled GOx confirms successful immobilization (red fluorescence, Figure 1c,d); UV-vis spectra show Fe-MOF-GOx catalyzes TMB oxidation with a characteristic peak at 652 nm; ESR and TA fluorescence probes verify •OH generation, confirming Fe-MOF’s peroxidase-like activity.
3. Application:
The material was tested in glucose detection and practical serum analysis:
- Colorimetric detection: Fe-MOF-GOx shows a linear range of 1–500 μM for glucose, with a detection limit of 0.487 μM (S/N=3), superior to most reported biosensors (Table S2).
- Selectivity: Only glucose triggers significant absorbance change, with negligible response to lactose, fructose, and sucrose (10-fold higher concentration).
- Stability: Maintains ~90% activity after 60 days of storage and 5 reuse cycles, far exceeding free enzyme systems.
- Practical application: Detects glucose in human serum with relative standard deviations <5%, consistent with commercial glucometers (Table 1).
4. Mechanism:
The enhanced performance stems from cascade catalysis and "nanoscale proximity" effect:
- GOx catalyzes glucose oxidation to generate gluconic acid and H₂O₂.
- Fe-MOF (with peroxidase-like activity) in situ catalyzes H₂O₂ to produce •OH, which oxidizes TMB to blue ox-TMB.
- Covalent integration reduces the distance between GOx and Fe-MOF, minimizing H₂O₂ diffusion loss and improving reaction efficiency; immobilization enhances GOx stability against pH, temperature, and reuse.
Outlook:
This research realizes efficient, stable, and ultrasensitive glucose detection via Fe-MOF-GOx cascade nanozymes. The integration strategy provides a new paradigm for designing high-performance enzyme-nanozyme hybrid systems, with broad application prospects in clinical diagnosis, food safety, and environmental monitoring.
Glucose Oxidase-Integrated Metal−Organic Framework Hybrids as Biomimetic Cascade Nanozymes for Ultrasensitive Glucose Biosensing
Authors: Weiqing Xu, Lei Jiao, Hongye Yan, Yu Wu, Lijuan Chen, Wenling Gu, Dan Du, Yuehe Lin, Chengzhou Zhu
DOI: 10.1021/acsami.9b03004
Link: pubs.acs.org/doi/10.1021/acsami.9b03004
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