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He et al. Soft Sci 2024;4:37 https://dx.doi.org/10.20517/ss.2024.32 Page 19 of 27

MOF-based hydrogels have also been used in smart materials. Cui et al. designed self-bleaching
photochromic hydrogels by integrating zinc-based MOFs and tungsten oxide. These hydrogels respond
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rapidly to ultraviolet (UV) light, enabling “writing” and “erasing” abilities [Figure 9A] . Furthermore, Nie
et al. fabricated composite paper with ZIF-8 and cellulose pulp, which demonstrated exceptional
performance in adsorption, filtration, and sterilization, including a high PM2.5 removal efficiency of
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99.68% .
In biomedical applications, Wang et al. synthesized hydrogel-metal-organic-framework nanoparticle
composites (HMOFNCs), which immobilized enzymes and biomolecules, protecting their activity and
allowing control over biomacromolecule performance . Tang et al. advanced this field by producing a
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double-network hydrogel with strong mechanical properties and multi-color fluorescence, suitable for
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applications such as QR codes and information storage [Figure 9B] .
MOF-based hydrogels also demonstrate significant potential in proton-conducting materials. Kong et al.
developed MeSA@MOF-303-PVA hydrogels with tunable proton conductivity by doping MOF-303
nanocrystals with methanesulfonic acid (MeSA) . In agriculture, Lin et al. created dual-sensitive MOF-
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based hydrogels that enhance fertilizer release, combining temperature- and pH-sensitive units with MIL-
100(Fe) to improve water retention and slow-release performance [Figure 9C] .
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In the realm of mechanical and structural applications, Xu et al. developed nanocomposite hydrogels that
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are highly stretchable and compressible, able to recover quickly from strains of up to 500% . de Lima et al.
demonstrated that the crystal size of UiO-66 MOFs impacts water absorption and mechanical strength,
making these hydrogels valuable for biocompatible applications . Jia et al. further expanded the use of
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MOF-based hydrogels for visual detection, developing Ru@UiO-OH hydrogels that detect volatile
trimethylamine (TMA) vapor through fluorescence changes [Figure 9D] .
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MOF-based hydrogels are also being explored in energy and electronic applications. Kim et al. developed a
hydrogel coupled with a MOF film that exhibits robust thermoelectric harvesting capabilities, showing high
thermal voltage and current output . Khan et al. proposed Zn-MOF-based hydrogels with excellent tensile
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properties and electrical conductivity, making them suitable for wearable strain sensors and electronic
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skin . Finally, Xiao et al. synthesized pH-sensitive fluorescent hydrogel microneedle tips that can be
integrated with smartphones for wound pH visualization, applying machine learning algorithms for
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enhanced accuracy .
In conclusion, the diverse applications of MOF-based hydrogels, ranging from biomedical sensing to energy
harvesting and smart materials, highlight their versatility and growing importance across multiple fields. As
ongoing research continues to expand their capabilities, these hydrogels are poised to play a critical role in
future technological advancements.

CONCLUSION AND OUTLOOK
Conclusion
Recent years have witnessed an increase in literature regarding the use of MOF materials, reflecting growing
interest within the research community. Among these, MOFs-based hydrogels have gained attention. This
review summarizes the recent developments of MOFs-based hydrogels by highlighting the quantity of
reported research. Due to their impressive flexibility and physical and chemical stability, these hydrogels
have been studied and widely applied. They have been shown to offer higher performance on processability
and handling than normal MOF powders [Figure 10].