Information recording and encryption/decryption functions are essential due to the prevalence of counterfeiting activities and information leakage in the current age. However, the development of high-resolution information recording and multistage information protection systems to achieve high data security levels, such as self-erasing encrypted data and time-controlled data handling, remains limited. Herein, inspired by the information-recording structure of paper, a multiresponsive nanofiber-reinforced poly(N-isopropylacrylamide) (PNIPAM) hydrogel (NCPN hydrogel) with improved mechanical properties, solvent-induced high-resolution reversible information recording, self-encryption, and multi-decryption capabilities, is proposed. Due to the unique hydrophilic and hydrophobic structures of the hydrogel matrix, ethanol and other polar analogs can be applied as special inks to record information by changing the lower critical solution temperature to achieve the repeatable transmittance variation. The recorded information can be erased via water wiping or ethanol volatilization. Additionally, self-encryption can be achieved and adjusted based on the ethanol volatilization time and concentration difference, and confidential information can be further decrypted in a water environment or under a thermal stimulus. Furthermore, several stable, repeatable, and fast-response hydrogel-based information-recognition systems are designed and investigated. Therefore, the designed hydrogel-based informational platform provides a universal information-handling system allowing for the reversible recording of information, with self-encryption and multidecryption capabilities.
Dynamic full-thickness skin wound healing remains an intricate problem due to the humid environment and frequent exercise. Recently, multifunctional hydrogels have a great promise in wound repair. However, traditional hydrogels only keep the wound moist, protect the wound from bacterial infection, and cannot actively drive dynamic wound closure. Inspired by embryo wound active closure, we constructed a double-sided thermoresponsive mechanoactive (DTM) hydrogel that combines good flexibility, self-healing, wet-tissue adhesion, and antibacterial functions. The strong adhesion of the hydrogel to biological tissues is attributed to "multiple hydrogen bonding clusters" without any chemical reaction. The contraction force triggered by temperature is quickly transmitted to dynamic wound edges to resist external mechanical forces and drive wound closure, which can effectively avoid damage to surrounding healthy tissue and reduce the risk of scarring, infection, and inflammation caused by sutures, staples, or clips. Strikingly, in vivo, this hydrogel bandage actively enhanced wound repair in a full-thickness skin defect model by promoting collagen deposition, facilitating angiogenesis, and accelerating wound re-epithelialization. This mechanoactive biological method will provide a facile strategy for joint wound management and demonstrates strong potential in tissue remodeling.
Ionic conductive hydrogels used as flexible wearable sensor devices have attracted considerable attention because of their easy preparation, biocompatibility, and macro/micro mechanosensitive properties. However, developing an integrated conductive hydrogel that combines high mechanical stability, strong adhesion, and excellent mechanosensitive properties to meet practical requirements remains a great challenge owing to the incompatibility of properties. Herein, we prepare a multifunctional ionic conductive hydrogel by introducing high-modulus bacterial cellulose (BC) to form the skeleton of double networks, which exhibit great mechanical properties in both tensile (83.4 kPa, 1235.9% strain) and compressive (207.2 kPa, 79.9% strain) stress–strain tests. Besides, the fabricated hydrogels containing high-concentration Ca2+ show excellent anti-freezing (high ionic conductivities of 1.92 and 0.36 S/m at room temperature and −35 ∘C, respectively) properties. Furthermore, the sensing mechanism based on the conductive units and applied voltage are investigated to the benefit of the practical applications of prepared hydrogels. Therefore, the designed and fabricated hydrogels provide a novel strategy and can serve as candidates in the fields of sensors, ionic skins, and soft robots.
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