Key Takeaways & Executive Findings
- •• • Anti-swelling hydrogels achieve equilibrium swelling ratios below 150%, a critical threshold for maintaining dimensional stability and preventing mechanical property degradation in physiological environments, essential for long-term implants and wound dressings. • • Preparation strategies include hydrophobic interactions, increased cross-linking density, and nanocomposite structures, which collectively reduce water uptake and enhance structural integrity, as evidenced by studies on alginate-based and polyelectrolyte complex hydrogels. • • Specific formulations, such as UV cross-linked injectable dihydrocaffeic acid grafted chitosan hydrogels, demonstrate non-swelling behavior and promote wound healing, indicating the clinical relevance of anti-swelling properties. • • Anti-swelling hydrogels with tissue-matchable mechanical properties and ultralow swelling are developed for wet wound closure and tissue adhesion, with burst pressure tolerance exceeding 200 mmHg, meeting surgical requirements for hemostasis and sealing.
Abstract
Hydrogels are extensively utilized in biomedical fields such as drug delivery, tissue engineering, and wound dressings due to their excellent biocompatibility, high water content, and tunable physicochemical properties. However, conventional hydrogels often undergo uncontrolled swelling in physiological environments, leading to mechanical degradation, structural destabilization, and functional failure, which severely restricts their long-term applicability. Recent advances have focused on developing anti-swelling hydrogels with equilibrium swelling ratios typically below 150%, achieved through strategies including the introduction of hydrophobic interactions, enhancement of cross-linking density, and incorporation of nanocomposite structures. These approaches significantly improve dimensional stability and mechanical integrity under physiological conditions. This review systematically summarizes the common preparation strategies for anti-swelling hydrogels and highlights their latest progress in biomedical applications, including wound dressings, tissue adhesives, and implantable devices. The advantages and future directions, such as smart responsiveness and multifunctional integration, are critically discussed. The review aims to provide theoretical guidance and technical references for the development of next-generation high-performance medical hydrogel materials.
1. Introduction
Traditional hydrogels, despite their promising biocompatibility and high water content, suffer from uncontrolled swelling in physiological environments. This swelling leads to volume expansion, reduced mechanical strength, and compromised adhesion, which are detrimental for long-term biomedical applications such as implantable sensors, tissue grafts, and bioadhesives. For instance, when used as artificial blood vessels, swelling can decrease the internal diameter, impairing blood flow and increasing thrombosis risk. These limitations have driven the development of anti-swelling hydrogels that maintain dimensional and mechanical stability under physiological conditions.
This review addresses the bottleneck by systematically categorizing preparation strategies—hydrophobic modification, increased cross-linking density, and nanocomposite reinforcement—that effectively suppress swelling. By achieving equilibrium swelling ratios below 150%, these hydrogels overcome the instability issues of conventional counterparts. The review further evaluates their performance in wound healing, tissue adhesion, and other biomedical applications, providing a roadmap for designing next-generation hydrogels with tailored anti-swelling properties and multifunctional capabilities.
Loading authentic research manuscript (Pages 1–5)...
ZHANG Ya, JIA Lianghao, FANG Yuxi, XIANG Tao, ZHOU Shaobing (2026). Anti-swelling hydrogels: from preparation strategies to biomedical applications. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3929-4
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What are the primary mechanisms by which anti-swelling hydrogels resist swelling in physiological environments?
Anti-swelling hydrogels employ several mechanisms: (1) introduction of hydrophobic groups to reduce water affinity, (2) increasing cross-linking density to tighten the network and limit water uptake, and (3) incorporating nanocomposite fillers that physically obstruct swelling. These strategies collectively lower the equilibrium swelling ratio below 150%, as reported in the review.
How do anti-swelling properties translate into improved mechanical performance for load-bearing applications?
By preventing excessive water absorption, anti-swelling hydrogels maintain their polymer network integrity, preserving mechanical strength and elasticity. For example, hydrogels with tissue-matchable mechanical properties and ultralow swelling exhibit burst pressure tolerance exceeding 200 mmHg, making them suitable for wet wound closure and tissue adhesion where mechanical robustness is critical.
What are the scalability challenges in manufacturing anti-swelling hydrogels for clinical translation?
Scalability challenges include achieving uniform cross-linking and hydrophobic modification at industrial scales, ensuring batch-to-batch consistency, and maintaining cost-effectiveness. The review highlights strategies such as one-step soaking and UV cross-linking, which are amenable to scale-up, but further optimization is needed to meet regulatory standards.
Can anti-swelling hydrogels be engineered to respond to physiological stimuli for smart drug delivery?
Yes, future directions include incorporating stimuli-responsive moieties that trigger drug release or degradation in response to pH, temperature, or enzymatic activity. The review discusses smart responsiveness as a key development area, aiming to combine anti-swelling stability with controlled release for advanced therapeutic applications.
What evidence supports the clinical efficacy of anti-swelling hydrogels in wound healing?
Studies cited in the review demonstrate that anti-swelling hydrogels, such as UV cross-linked dihydrocaffeic acid grafted chitosan, promote wound healing by maintaining a moist environment without excessive swelling, which could otherwise cause tissue compression. These hydrogels also exhibit antibacterial and hemostatic properties, as shown in alginate-based formulations, supporting their clinical potential.
Related Chinese Research & Cross-Citations
Ammonium Vanadate Cathodes in Aqueous Zinc-Ion Batteries: Design Strategies and Research Progress
Aqueous zinc-ion batteries (AZIBs) offer a compelling combination of high safety, environmental compatibility, and abundant zinc resources, positioning them as viable candidates for grid-scale energy storage. Their practical deployment, however, is constrained by cathode materials that suffer from structural degradation, sluggish Zn2+ diffusion, and inadequate electronic conductivity. Ammonium vanadates (AVOs) have emerged as high-performance cathodes owing to their layered or tunneled frameworks, which accommodate reversible Zn2+ (de)intercalation with diffusion coefficients superior to conventional vanadium oxides. This review systematically examines recent advances in AVO cathodes for AZIBs, correlating morphological variations—including nanowires, nanobelts, and microflowers—with electrochemical characteristics. The analysis establishes structure–performance relationships that govern capacity retention, rate capability, and cycling stability. Key optimization strategies are critically assessed: defect engineering to enhance electronic conductivity and active site density, interlayer spacing modulation via pre-intercalated cations or structural water to facilitate Zn2+ transport, and composite construction with conductive carbonaceous or polymeric matrices to mitigate dissolution and improve mechanical integrity. Despite these advances, challenges persist in achieving long-term cycling stability (>10,000 cycles) and high areal mass loading (>10 mg cm-2) required for commercial viability. The review concludes by outlining future research directions, including operando characterization of degradation mechanisms and scalable synthesis routes for AVO cathodes in practical AZIB configurations.
Microenvironment-responsive therapeutic platforms: Innovations for spinal cord injury repair
Spinal cord injury (SCI) remains a formidable clinical challenge due to the complex, dynamic lesion microenvironment that impedes axonal regeneration and functional recovery. This highlight examines a microenvironment-responsive therapeutic platform integrating microneedle delivery, ferroptosis modulation, and hydrogen therapy. The platform leverages the pathological hallmarks of SCI—oxidative stress, iron dyshomeostasis, and lipid peroxidation—to achieve spatiotemporally controlled cargo release. By combining microneedle arrays for minimally invasive intraparenchymal administration with hydrogen-releasing biomaterials, the system addresses the dual bottlenecks of poor drug penetration across the blood-spinal cord barrier and insufficient neutralization of reactive oxygen species. Ferroptosis inhibition is achieved through iron chelation and glutathione peroxidase 4 (GPX4) stabilization, while hydrogen gas scavenges hydroxyl radicals and peroxynitrite. This multimodal strategy attenuates secondary injury cascades, reduces glial scar formation, and promotes neural stem cell differentiation. The work is supported by the National Natural Science Foundation of China (82574518) and the Talent Cultivation Project of Paring Academicians with Young Talents in higher education institutions in Zhejiang. The authors declare no conflict of interest. This highlight underscores the translational potential of microenvironment-responsive platforms for SCI repair, emphasizing the need for rigorous preclinical validation and scalable manufacturing.
Dual-Site Adsorption over Phosphorus-Doped Copper Oxide for Efficient CO2 Electroreduction to Ethylene
Electroreduction of CO2 to ethylene offers a promising route for renewable electricity storage, yet achieving high ethylene selectivity at industrial current densities remains challenging due to the large energy barrier for C–C coupling. Here, we report a “MOF-assisted in situ doping” strategy to introduce the oxophilic nonmetal phosphorus (P) into the copper oxide (CuO) lattice, constructing a localized Cu–P dual-site adsorption configuration for the key *OCCHO intermediate. The optimized catalyst delivers an impressive Faradaic efficiency of 64.6% for ethylene with a partial current density of 646 mA cm-2. Comprehensive structural characterizations demonstrate that P mainly occupies Cu sites, generating abundant lattice defects and oxygen vacancies. In situ synchrotron infrared spectroscopy and theoretical calculations reveal that P doping modulates the electronic structure of Cu, optimizes the binding energies of *CO and *CHO, and stabilizes *OCCHO via P–O/Cu–C dual-site adsorption, thereby significantly lowering the asymmetric C-C coupling energy barrier to 0.74 eV. This work highlights a dual-site microenvironment regulation strategy for CO2-to-ethylene electroreduction.
Hydrophilic Single-Atom Interface Unlocks Low-Potential CO Removal on Pt in PEMFCs
Proton exchange membrane fuel cells (PEMFCs) fed with reformate hydrogen suffer severe anode poisoning by trace CO, necessitating high CO electrooxidation potentials that degrade performance and durability. This work introduces a Pt@CrSA-N-C anode catalyst featuring a hydrophilic Cr single-atom interface that simultaneously weakens CO adsorption on Pt via electronic regulation and promotes water activation, thereby lowering the CO oxidation onset potential to approximately 0.13 V vs. RHE. The onset potential was determined by two independent methods: the first potential at which the background-corrected current exceeds 0 mA cm-2 during CO oxidation reaction tests in a three-electrode system, and the potential at which the forward scan current exceeds the N2 background current in CO-stripping voltammetry. The catalyst achieves a maximum power density under 100 ppm CO that surpasses reported advanced catalysts, as compiled in Table S5. Structural, spectroscopic, and electrochemical characterizations collectively establish a coherent rationale for the hydrophilic single-atom interface strategy. This approach addresses the longstanding trade-off between CO tolerance and Pt utilization, offering a viable route for low-potential CO removal in practical PEMFC anodes.
An Ionoelastomer-Based Bioinspired Wearable Electronics with Tele-Perception and Tactile Sensation for Machine Learning-Assisted Rehabilitation Management
Comprehensive assessment of rehabilitation efficiency is essential for designing appropriate training programs for better musculoskeletal functional recovery. Existing contact-receptor-dependent rehabilitation assessment systems mostly focus on assessing the restoration of muscle function by evaluating grip strength or joint flexion angle; however, parameters reflecting neuromuscular synergistic function are always overlooked. Herein, we develop an ionoelastomer-based soft artificial electroreceptor (SAER) that integrates tele-perception and tactile sensation to track the rehabilitation process, collecting signals related to approaching speed and grip strength sequentially. The SAER uses polyurethane ionoelastomer incorporated with quasi-solid conductive salt as the electric field receptor, and is integrated on a rehabilitation-training ball after assembly to establish an untethered detection device; this enables the remote capture of hand approaching parameter within a 9 cm range, followed by the quantification of grip strength when contacting and grasping. Furthermore, a data-driven assessment system is established by integrating machine learning, which accurately classifies rehabilitation efficiency into six levels; it supports for rehabilitation evaluation and training programs adjustment. Overall, the SAER-based rehabilitation management system establishes a paradigm that synergistically evaluating parameters corresponding to neuromuscular functional restoration and holds strong potential for home-based active rehabilitation for minimizing dependence on frequent clinical supervision.
Microwave-Absorbing Materials with Strong Environmental Adaptability for Corrosion Protection, Anti-Icing, and Thermal Management
Microwave-absorbing materials (MAMs) deployed on naval vessels, aerospace vehicles, and critical electronic systems face coupled electromagnetic, marine salt-spray corrosion, and extreme-temperature loads that legacy single-function absorbers cannot withstand. This review consolidates progress on three environmentally adaptive MAM classes: corrosion-protective, anti-icing, and thermal-management absorbers. The electromagnetic loss and impedance-matching fundamentals are first established, then the synergistic mechanisms, design strategies, and characterization protocols for each class are examined against representative material systems and their measured performance. The analysis identifies a shared design logic—multiscale hierarchical architecture, interfacial polarization engineering, and multifunctional phase integration—while distinguishing the divergent protection mechanisms: barrier and passivation effects for corrosion, surface-energy and latent-heat regulation for anti-icing, and phonon–electron transport decoupling for thermal management. Persistent bottlenecks include the trade-off between impedance matching and protective-layer density, the absence of standardized coupled-field test protocols, and the scarcity of long-term salt-spray and thermal-cycling durability data. Future directions are delineated: intelligent self-adaptive absorbers, multiphysics-coupled simulation frameworks, and environmentally benign multifunctional integration. The review provides a theoretical and technical basis for the design, construction, and engineering scale-up of next-generation high-performance absorbers for aerospace, electronic, and marine equipment.