Intelligent skinlike materials have recently attracted tremendous research interests for employing in electronic skin, soft robotics, and wearable devices. Because the traditional soft matters are restricted in unsatisfactory mechanical performances or short-term usage, these materials are adverse to practical applications. Here, intriguing conductive hydrogel materials with multifunctionality (MFHs) are fabricated by using poly­(acrylic acid) (PAA), dopamine-functionalized hyaluronic acid (DHA), and Fe3+ as ionic cross-linker. The mussel-inspired networks with delicate combination of physical and chemical cross-linking possess synergistic features of inherent viscoelasticity, high stretchability (800%), and durable self-adhesiveness to various substrates. Owing to the abundant hydrogen bonds and multiple metal coordination interactions between Fe3+, catechol, and carboxylic groups, the matrix reveals repeatable thermoplasticity and autonomous self-healing property both mechanically and electrically (98% recovery in 2 s). When served as strain sensors, the MFHs can distinctly perceive complex body motions from tiny physiological signal (breathing) to large movements (knee bending) as human motion detecting devices. Moreover, the MFHs were explored as ideal material for circuit repairing, programming, and switches constructing because of their excellent properties. Consequently, these eco-friendly hydrogel ionotronic devices can be promising candidates for next-generation intelligent wearable devices and human–machine interfaces.

No abstract

The constant and noninvasive tracking of the distribution and degradation of engineered hydrogel scaffolds using fluorescent probes is considered to be one of the important research studies. Conventional fluorophores were simply mixed into hydrogels by physical doping, and they suffered from photoinstability or UV–vis light excitation, which usually led to the potential leak of the fluorescent tag and imprecise tracking results. In this article, upconversion nanoparticles, NaGdF4:Yb3+,Er3+@NaGdF4 (UCNPs) with near-infrared light (NIR) excitation, were synthesized and were coated with polydopamine (PDA). A biodegradable composite hydrogel OSA-I-CMCS-I-UCNPs@PDA (“I” means “linked-by”) was constructed by the UCNPs@PDA, serving as both the construction unit and NIR-excited fluorescent probe, where carboxymethyl chitosan (CMCS) was used as the cross-linker to chemically cross-link UCNPs@PDA and oxidized sodium alginate (OSA) based on dynamic covalent Schiff-base linkages. It is demonstrated that the composite hydrogels possess enhanced mechanical strength, excellent self-healing capacity, injectable performance, and good biocompatibility with the tissue. In addition, the composite hydrogels possess a deep penetrating ability from UCNPs@PDA in vitro through about 10 mm thick chicken strips. A mimetic lysozyme biodegradation test was performed for 108 h in vitro for evaluating the feasibility and accuracy of UCNPs@PDA in tracking the hydrogel degradation. The degradation signals were obtained by the decrease in fluorescence intensity, which were well consistent with the weight changes in composite hydrogels, suggesting the accuracy of the UCNPs@PDA in consecutively monitoring the hydrogel degradation in vitro. With these superior properties, the composite hydrogels are expected to be promising candidates for various biomedical fields, for example, as tissue engineering or delivery carriers in vivo.

No abstract

No abstract

No abstract

No abstract

No abstract