Skin-Adaptable, Long-Lasting Moisture, and Temperature-Tolerant Hydrogel Dressings for Accelerating Burn Wound Healing without Secondary Damage

Abstract

Developing multifunctional wound dressings, possessing not only skin-like mechanical properties and adaptability, long-lasting moisture, and temperature tolerance that maximally mimics the human skin but also on-demand adhesion without unnecessary bleeding and secondary damage upon peeling, is necessary but remains a challenge. Herein, a novel dual cross-linked and multifunctional hydrogel, termed PSNC hydrogel for polymerized sulfobetaine methacrylate (SBMA), N-(2-amino-2oxyethyl)acrylamide (NAGA), and 1-carboxy-N-methyl-N-di(2methacryloyloxy-ethyl)methanaminium inner salt (CBMAX), was fabricated as a wound dressing for burn injuries via one-pot radical polymerization in glycerine (GLY)/H 2 O solvent. The dual crosslinked network of the PSNC hydrogel combined the double hydrogen bonding of N-(2-amino-2-oxyethyl)acrylamide (NAGA) with a covalently cross-linked zwitterionic network, endowing the hydrogel with skin−like mechanical properties with a high stretchability of 1613.8 ± 79.8%, a tensile strength of 77.5 ± 1.8 kPa, and a tensile modulus of 1.9 ± 0.1 kPa. Moreover, the hydrogel with well-developed adaptability can withstand skin deformation without breaking or debonding attributed to its good tissue adhesiveness and self-healing ability. Further, the utilization of the GLY/H 2 O binary solvent effectively prevented the crystallization and evaporation of free water, endowing the hydrogel with not only longlasting moisture but also excellent temperature tolerance in a wide range from −20 to 60 °C. More importantly, the PSNC hydrogel could effectively accelerate wound healing of burn injuries and could be easily removed on-demand with saline without causing secondary damage due to intense hydration. Such a novel PSNC zwitterionic hydrogel could be a promising candidate for the treatment of burn wounds and tissue regeneration.

Recent Advances in Mechanical Reinforcement of Zwitterionic Hydrogels

“…The copolymer with a strong hydrogen bond can provide hydrogen bond interaction and hydrogen bond–dipole interaction for hydrogels, and the hydrated layer on a copolymer can also provide nonspecific protein adsorption resistance, leading to a low-fouling hydrogel. Huangfu et al [ 99 ] prepared the copolymer hydrogel with 16 mm/mm tensile strain, 77.5 KPa tensile stress and 1.9 KPa tensile modulus using a strong hydrogen bond monomer N-(2-amino-2-oxyethyl)acrylamide (NAGA) and zwitterionic SB 3 MA 2 as a wound dressing ( Figure 5 a1–a3). The introduction of NAGA enables the hydrogel to produce sufficient adhesion with the skin wound and accelerates the wound healing.…”

“…The dipole–dipole interaction between zwitterionic units and the hydrogen bond interaction between NAGA units synergistically promote the mechanical properties and self-healing ability of hydrogels ( a1 ), leading to stretchable, tough ( a2 ) and rapid self-healing ( a3 ). Reproduced with permission from [ 99 ]. Copyright 2021, American Chemical Society; ( b1 – b3 ) zwitterionic hydrogel prepared with MPBA as a copolymerization component.…”

Highly transparent, mechanical, and self-adhesive zwitterionic conductive hydrogels with polyurethane as a cross-linker for wireless strain sensors

“…However, it remains a significant challenge to prepare hydrogel sensors with excellent mechanical properties, tissue adhesion, and electrical conductivity, which seriously hinders their widespread application. [7][8][9] Currently, zwitterionic hydrogels are promising candidate materials for wearable hydrogel sensors due to their excellent biocompatibility and adhesion, and inherent ionic conductivity. [10][11][12][13] In addition, due to the high light transmittance, zwitterionic hydrogels can be used to prepare visible sensors for the next generation smart displays of transparent electronic devices in the fields of aerospace, automotive, and biomedicine.…”

“…17 Yini Huangfu et al prepared a hydrogel with a double crosslinking network by combining a double hydrogen bond of N-(2-amino-2-oxyethyl) acrylamide (NAGA) with a zwitterionic covalent-crosslinked network, which has excellent tissue adhesion, excellent self-healing ability, and high stretchability (1613.8 AE 79.8%), but the tensile strength is only 77.5 AE 1.8 kPa. 8 Therefore, there is an urgent need to improve the mechanical properties of zwitterionic hydrogels.…”

“…However, it remains a significant challenge to prepare hydrogel sensors with excellent mechanical properties, tissue adhesion, and electrical conductivity, which seriously hinders their widespread application. 7–9…”