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He et al. Soft Sci 2024;4:37 https://dx.doi.org/10.20517/ss.2024.32 Page 3 of 27

Hydrogels, due to their crosslinked 3D polymer networks, superior water contents, swelling, and
responsiveness, demonstrate characteristics of elastic solids, including deformability and softness [15-17] . The
integration of MOFs with hydrogel matrices in the form of MOFs-based hydrogel composites/systems
emerges as a strategic solution to counteract the brittleness and limited processability commonly
encountered in MOFs . This synergistic combination with the unique properties of both MOFs and
[18]
hydrogels provides new possibilities for diverse applications. The 3D network characteristic of hydrogels
plays a pivotal role in addressing the challenges posed by MOFs. Firstly, it ensures the uniform dispersion of
MOF materials within the hydrogel matrix, mitigating issues related to agglomeration and facilitating a
more homogenous distribution of MOFs throughout the composite structure. This uniform dispersion
contributes to enhanced mechanical integrity and stability, addressing one of the primary limitations of
MOFs. Furthermore, the integration of MOFs within the hydrogel matrix imparts an additional layer of
functionalities. The inherent versatility of MOFs allows for the modulation and alteration of the properties
and functions of the hydrogel matrix. The synergistic integration of MOFs and hydrogels presents a unique
opportunity to customize composite materials for specific needs, including adjustable porosity, controlled
release of substances, and improved mechanical properties. These advancements have significant
implications for various practical applications in drug delivery, sensing technologies, tissue engineering, and
environmental remediation. The combination of MOFs and hydrogels offers a sophisticated and efficient
strategy to leverage the respective strengths of these materials. The 3D structure of hydrogels not only
overcomes the limitations of MOFs but also serves as a versatile platform for the design of advanced
[19]
materials with tailored characteristics .
Overall, when compared with COF and HOF materials, MOFs present several real-time challenges and are
the most anticipated materials in diverse applications. So, it is important to focus on and tackle the
limitations involved in current MOF research. This paper offers a thorough overview of hydrogel and MOF
materials, outlining their classifications, synthesis methods, and distinctive structural and chemical
compositions. It also explores the preparation methods and applications of MOFs-based hydrogels. By
directing attention not only to traditional MOFs but also to MOFs-based hydrogels and other derivatives,
this review aims to offer valuable information and inspiration to researchers unfamiliar with MOFs,
hydrogels, MOFs-based hydrogels, and other MOFs derivative composites. The emphasis is on reviewing
the latest developments in MOFs-based hydrogels and their applications. This review seeks to help readers,
including those with limited understanding of MOFs-based hydrogels or even chemistry, grasp the concepts
of MOFs-based hydrogels and acquire the knowledge they seek. The integration of MOF and hydrogels
opens new avenues for research and development, offering innovative solutions to long-standing challenges
in materials science and paving the way for novel applications across various disciplines.

DESIGNING PRINCIPLES
What is MOFs
MOFs are compounds defined by their 3D network structures composed of transition metal ions and
organic ligands connected through coordination bonds. These porous coordination polymers are formed by
linking inorganic metal ions or clusters with organic ligands [20-23] . Figure 1 illustrates this unique structural
arrangement, which gives MOFs a hybrid nature, combining characteristics of both organic and inorganic
materials . The coordination bonding between metal ions and organic ligands generates a highly porous
[24]
framework, contributing to the distinctive properties MOFs exhibit. This structure forms a stable crystalline
material with a high density of pores and voids, making it suitable for gas adsorption, molecular storage,
catalytic reactions, and more.