Smart Hydrogel Dressings Redefine Complex Wound Care: From Passive Barriers to Microenvironment-Modulating Platforms
核心洞察
Smart hydrogel dressings have evolved from passive wound coverage into bioactive platforms that actively modulate the wound microenvironment through stimulus-responsive drug delivery, ROS scavenging, and immunomodulation.
Chronic wounds such as diabetic ulcers and severe burns (搜索) remain arrested in persistent inflammation; advanced hydrogels target key pathological hallmarks including macrophage polarization, impaired angiogenesis, ferroptosis, and cellular senescence.
Emerging theranostic systems integrate real-time biosensing of pH, temperature, and ROS with closed-loop therapeutic release, enabling personalized, precision-guided wound management.
The clinical management of complex wounds—including severe burns (搜索), diabetic foot ulcers (搜索), and pressure injuries—is undergoing a paradigm shift as smart hydrogel dressings move from passive physical barriers to bioactive, microenvironment-modulating therapeutic platforms. Two comprehensive reviews published in Frontiers in Bioengineering and Biotechnology and Frontiers in Materials synthesize the current state of this rapidly evolving field, detailing how engineered hydrogels are being designed to actively intervene in the dysregulated healing cascade that characterizes chronic, non-healing wounds.
The wound healing process normally unfolds through four overlapping phases: hemostasis, inflammation, proliferation, and remodeling. In complex wounds, however, this cascade becomes arrested in a persistent inflammatory state driven by excessive reactive oxygen species (ROS), protease imbalance, microbial biofilms, and impaired macrophage polarization. "The pathophysiology of these complex wounds is defined by a hostile microenvironment that perpetuates tissue damage and impedes progression to the later healing stages," note the authors of the Frontiers in Materials review. Conventional dressings such as gauze and films serve primarily as passive barriers and "are ill-equipped to address the complex biochemical imbalances within chronic wounds."
Engineering Multifunctionality into Hydrogel Platforms
Modern smart hydrogels are engineered with multiple integrated functionalities. Self-healing hydrogels, constructed through dynamic covalent bonds such as Schiff base linkages, boronate esters, and disulfide exchange, can autonomously repair structural damage after mechanical disruption. These reversible chemistries also enable stimulus-responsive drug release: boronate esters dissociate under elevated ROS or glucose conditions, imine bonds hydrolyze at low pH, and metal-coordination bonds respond to changes in local redox state. As a result, "bioactive molecules are released in proportion to the inflammatory, oxidative or infectious status of the wound, rather than at a fixed rate."
A notable example is a ROS-responsive hydrogel based on polyvinyl alcohol (PVA) with a dynamic boronate ester crosslinker, incorporating gelatin methacryloyl microgels loaded with sodium fusidate and metformin hydrochloride. This system demonstrated sustained drug release, antibacterial activity exceeding 98% within 24 hours, and effective ROS scavenging. In diabetic rat models, it accelerated wound closure and enhanced vascularization and collagen remodeling.
Immunomodulation and Macrophage Polarization
A central therapeutic strategy involves steering macrophage polarization from the pro-inflammatory M1 phenotype to the pro-healing M2 phenotype. Hydrogels with tunable network dynamics and faster stress relaxation activate epithelial integrin-FAK signaling to promote this transition. Sulfated alginate hydrogels function as "molecular sinks," sequestering inflammatory chemokines such as IL-8 and MCP-1 to reduce immune cell infiltration. When combined with Prussian blue nanozymes for ROS scavenging, this multi-pronged approach enhanced neovascularization in burn models.
Heparin-based hydrogels cross-linked with 4-arm star-shaped PEG and loaded with Cu5.4O ultrasmall nanozymes employ a dual-action "weeding and uprooting" strategy that breaks the inflammation-ROS feedback loop in chronic diabetic wounds. Single-cell RNA sequencing has confirmed enrichment of pro-repair macrophage subtypes following such treatments.
Targeting Ferroptosis, Senescence, and Angiogenesis
Beyond inflammation, recent research has identified ferroptosis—iron-dependent cell death—as a key factor in diabetic wound healing. Baicalein-loaded hydrogels protect endothelial cells from ferroptosis, while phytic acid-releasing PVA hydrogels inhibit this pathway in corneal burn models.
Cellular senescence, another hallmark of chronic wounds, is addressed by hydrogels releasing Panax notoginseng saponins (PNS) and IGF-1, which suppress senescence markers and restore endothelial cell function by inhibiting the NF-κB (搜索) pathway. For angiogenesis, NIR-controlled nitric oxide release from encapsulated polymeric nanoparticles combats bacterial infection while promoting new blood vessel formation.
Theranostic Platforms and Closed-Loop Systems
The integration of diagnostic sensing with therapeutic delivery represents the next frontier. Self-powered bioadhesive patches with conductive hydrogel-sponge architectures function as pressure sensors, wirelessly transmitting data to prevent pressure ulcers (搜索) while redistributing mechanical stress. Multifunctional Nd-Ca-Si glass particle hydrogels provide photothermal therapy with real-time temperature sensing via NIR fluorescence, preventing overheating while released silicate and neodymium ions promote angiogenesis through VEGF (搜索) and KDR upregulation.
Multi-layered systems enable programmed, sequential therapy aligned with wound healing phases. Dual-layered hydrogels first release bacteria-responsive photosensitizers followed by pro-regenerative nanovesicles. Concentric hydrogels provide burst-release of antibacterial copper followed by sustained release of pro-angiogenic zinc.
Translational Barriers and Future Directions
Despite promising preclinical results, significant barriers to clinical adoption remain. "Many advanced hydrogel systems, particularly those involving DNA, peptides, or complex nanocomposites, are expensive and difficult to produce on a large scale," the reviewers caution. Terminal sterilization methods such as gamma irradiation and autoclaving can degrade hydrogel polymers and their bioactive payloads. Smart hydrogels often fall into the complex regulatory category of combination products—material plus drug plus device—facing stringent requirements without standardized testing pipelines.
The global wound care market, estimated at approximately $50 billion annually in the United States alone as of 2023, is projected to exceed $30 billion globally by 2032, reflecting strong translational and commercial interest. Future directions include AI-driven material design, closed-loop theranostics with wearable electronics, and patient-stratified wound care with diagnostic readouts tailored to specific populations such as burn patients, diabetic ulcer patients, and those with pressure injuries.
"The most effective hydrogel dressings are those that integrate multiple functionalities in a spatiotemporally controlled manner, addressing the dynamic needs of the healing wound," the authors conclude. "By addressing these challenges and embracing emerging technologies like AI-driven design and closed-loop theranostics, smart hydrogel dressings have the potential to revolutionize the treatment of complex wounds, moving from generalized care to truly personalized and adaptive therapy."