Temperature/near-infrared light-responsive conductive hydrogels for controlled drug release and real-time monitoring

Stimuli-responsive hydrogels with adaptable physical properties show great potential in the biomedical field. In particular, the collection of electrical signals is essential for precision medicine. Here, a simple strategy is demonstrated for achieving controlled drug release and real-time monitoring using an interpenetrating binary network consisting of a graphene aerogel and a poly(N-isopropylacrylamide) hydrogel with incorporated polydopamine nanoparticles (PDA-NPs). Owing to the good physical properties of graphene and the embedded PDA-NPs, the hybrid hydrogel shows enhanced mechanical properties and good electrical conductivity. In addition, the hybrid hydrogel also shows dual thermo- and near-infrared light responsiveness, as revealed by the controlled release of a model drug. In addition, as the hydrogel exhibits detectable changes in resistance during drug release, the drug-release behavior of the hydrogel can be monitored in real time using electrical signals. Moreover, owing to the abundance of catechol groups on the PDA-NPs, the hybrid hydrogel shows good tissue adhesiveness, as demonstrated using in vivo experiments. Thus, the developed hybrid hydrogel exhibits considerable practical applicability for drug delivery and precision medicine.

A Highly Stretchable and Real-Time Healable Supercapacitor

In addition to a high specific capacitance, a large stretchability and self-healing properties are also essential to improve the practicality and reliability of supercapacitors in portable and wearable electronics. However, the integration of multiple functions into one device remains challenging. Here, the construction of a highly stretchable and real-time omni-healable supercapacitor is demonstrated by sandwiching the polypyrrole-incorporated gold nanoparticle/carbon nanotube (CNT)/poly(acrylamide) (GCP@PPy) hydrogel electrodes with a CNT-free GCP (GP) hydrogel as the electrolyte and chemically soldering an Ag nanowire film to the hydrogel electrode as the current collector. The newly developed dynamic metal-thiolate (M-SR, M = Au, Ag) bond-induced integrated configuration, with an intrinsically powerful electrode and electrolyte, enables the assembled supercapacitor to deliver an areal capacitance of 885 mF cm^-2 and an energy density of 123 µWh cm^-2 , which are among the highest-reported values for stretchable supercapacitors. Notably, the device exhibits a superhigh stretching strain of 800%, rapid optical healing capability, and significant real-time healability during the charge-discharge process. The exceptional performance combined with the facile assembly method confirms this multifunctional device as the best performer among all the flexible supercapacitors reported to date.

All-in-One Cellulose Nanocrystals for 3D Printing of Nanocomposite Hydrogels

Cellulose nanocrystals (CNCs) with >2000 photoactive groups on each can act as highly efficient initiators for radical polymerizations, cross-linkers, as well as covalently embedded nanofillers for nanocomposite hydrogels. This is achieved by a simple and reliable method for surface modification of CNCs with a photoactive bis(acyl)phosphane oxide derivative. Shape-persistent and free-standing 3D structured objects were printed with a mono-functional methacrylate, showing a superior swelling capacity and improved mechanical properties.