Curcumin-loaded keratin-chitosan hydrogels for enhanced peripheral nerve regeneration.

Peripheral nerve injury often leads to symptoms of motor and sensory impairment, and slow recovery of nerves after injury and limited treatment methods will aggravate symptoms or even lead to lifelong disability. Curcumin can promote peripheral nerve regeneration, but how to accurately deliver the appropriate concentration of curcumin in the local peripheral nerve remains to be solved. In this study, we designed a human hair keratin/chitosan (C/K) hydrogel with sodium tripolyphosphate ions crosslinked to deliver curcumin topically. Chitosan improves the mechanical properties of hydrogels and keratin improves the biocompatibility of hydrogels. C/K hydrogel showed good cytocompatibility, histocompatibility and degradability. In vitro experiments showed that hydrogels can continuously release curcumin for up to 10 days. In addition, a comprehensive analysis of behavioral, electrophysiological, histology, and target organ recovery results in animal experiments showed that locally delivered curcumin can enhance nerve regeneration in addition to hydrogels. In short, we provide a new method that combines the advantages of human hair keratin, chitosan, and curcumin for nerve damage repair.

Topological Hydrogels for Long-Term Brain Signal Monitoring, Neuromodulation, and Stroke Treatment.

Stroke is the primary cause of disability without effective rehabilitation methods. Emerging brain-machine interfaces offer promise for regulating brain neural circuits and promoting the recovery of brain function disorders. Implantable probes play key roles in brain-machine interfaces, which are subject to two irreconcilable tradeoffs between conductivity and modulus match/transparency. In this work, mechanically interlocked polyrotaxane is incorporated into topological hydrogels to solve the two tradeoffs at the molecular level through the pulley effect of polyrotaxane. The unique performance of the topological hydrogels enables them to acquire brain neural information and conduct neuromodulation. The probe is capable of continuously recording local field potentials for eight weeks. Optogenetic neuromodulation in the primary motor cortex to regulate brain neural circuits and control limb behavior is realized using the probe. Most importantly, optogenetic neuromodulation is conducted using the probe, which effectively reduces the infarct regions of the brain tissue and promotes locomotor function recovery. This work exhibits a significant scientific advancement in the design concept of neural probes for developing brain-machine interfaces and seeking brain disease therapies.

Electron Conductive and Transparent Hydrogels for Recording Brain Neural Signals and Neuromodulation.

Recording brain neural signals and optogenetic neuromodulations open frontiers in decoding brain neural information and neurodegenerative disease therapeutics. Conventional implantable probes suffer from modulus mismatch with biological tissues and an irreconcilable tradeoff between transparency and electron conductivity. Herein, a strategy is proposed to address these tradeoffs, which generates conductive and transparent hydrogels with polypyrrole-decorated microgels as cross-linkers. The optical transparency of the electrodes can be attributed to the special structures that allow light waves to bypass the microgel particles and minimize their interaction. Demonstrated by probing the hippocampus of rat brains, the biomimetic electrode shows a prolonged capacity for simultaneous optogenetic neuromodulation and recording of brain neural signals. More importantly, an intriguing brain-machine interaction is realized, which involves signal input to the brain, brain neural signal generation, and controlling limb behaviors. This breakthrough work represents a significant scientific advancement toward decoding brain neural information and developing neurodegenerative disease therapies.

Self-Healing and Shape-Editable Wearable Supercapacitors Based on Highly Stretchable Hydrogel Electrolytes.

Shape editability combined with a self-healing capability and long-term cycling durability are highly desirable properties for wearable supercapacitors. Most wearable supercapacitors have rigid architecture and lack the capacity for editability into desirable shapes. Through sandwiching hydrogel electrolytes between two electrodes, a suite of wearable supercapacitors that integrate desirable properties namely: repeated shape editability, excellent self-healing capability, and long-term cycling durability is demonstrated. A strategy is proposed to enhance the long-term cycling durability by utilizing hydrogel electrolytes with unique cross-linking structures. The dynamic crosslinking sites are formed by quadruple H bonds and hydrophobic association, stabilizing the supercapacitors from inorganic ion disruption during charge-discharge processes. The fabricated supercapacitors result in the capacitance retention rates of 99.6% and 95.8% after 5000 and 10 000 charge-discharge cycles, respectively, which are much higher than others reported in the literature. Furthermore, the supercapacitor sheets can be repeatedly processed into various shapes without any capacitance loss. The supercapacitors exhibit a 95% capacitance retention rate after five cutting/self-healing cycles, indicative of their excellent self-healing performance. To demonstrate real-life applicability, the wearable supercapacitors are successfully used to power a light-emitting diode and an electronic watch.

Highly Stretchable Hydrogels as Wearable and Implantable Sensors for Recording Physiological and Brain Neural Signals.

Recording electrophysiological information such as brain neural signals is of great importance in health monitoring and disease diagnosis. However, foreign body response and performance loss over time are major challenges stemming from the chemomechanical mismatch between sensors and tissues. Herein, microgels are utilized as large crosslinking centers in hydrogel networks to modulate the tradeoff between modulus and fatigue resistance/stretchability for producing hydrogels that closely match chemomechanical properties of neural tissues. The hydrogels exhibit notably different characteristics compared to nanoparticles reinforced hydrogels. The hydrogels exhibit relatively low modulus, good stretchability, and outstanding fatigue resistance. It is demonstrated that the hydrogels are well suited for fashioning into wearable and implantable sensors that can obtain physiological pressure signals, record the local field potentials in rat brains, and transmit signals through the injured peripheral nerves of rats. The hydrogels exhibit good chemomechanical match to tissues, negligible foreign body response, and minimal signal attenuation over an extended time, and as such is successfully demonstrated for use as long-term implantable sensory devices. This work facilitates a deeper understanding of biohybrid interfaces, while also advancing the technical design concepts for implantable neural probes that efficiently obtain physiological information.

Mechanistic Investigation on Copper-Arylacetylide Polymerization and Sensing Applications.

Exploration of new polymerization reactions is very intriguing in fundamental and practical research, which will advance reaction theories and produce various functional materials. Herein, we report a new polymerization method based on the reaction of CuI and arylacetylide, which generates linear polymers with high molecular weight and low polydispersity index of molecular weight. The Cu-arylacetylide polymerization exhibits different characteristics with traditional polymerizations such as mild reaction temperature, air atmosphere reaction, high molecular weight, fast polymerization rate, and imprecise molar ratio between monomers. The bond formation path and activation energy of each step was investigated by density functional theory calculations to understand the reaction mechanism. The poly(Cu-arylacetylide)s exhibit strong fluorescence emission and inherent semiconductive properties, which have been used to fabricate an electronic device for streptavidin sensing.