Injectable, self-healing hyaluronic acid-based hydrogels for spinal cord injury repair.

The cystic cavity that develops following spinal cord injury is a major obstacle for repairing spinal cord injury (SCI). The injectable self-healing biomaterials treatment is a promising strategy to enhance tissue repair after traumatic spinal cord injury. Herein, a natural extracellular matrix (ECM) biopolymer hyaluronic acid-based hydrogel was developed based on multiple dynamic covalent bonds. The hydrogels exhibited excellent injectable and self-healing properties, could be effectively injected into the injury site, and filled the lesion cavity to accelerate the tissue repair of traumatic SCI. Moreover, the hydrogels were compatible with cells and various tissues and possessed proper stiffness matched with nervous tissue. Additionally, when implanted into the injured spinal cord site, the hyaluronic acid-based hydrogel promoted axonal regeneration and functional recovery by accelerating remyelination, axon regeneration, and angiogenesis. Overall, the injectable self-healing hyaluronic acid-based hydrogels are ideal biomaterials for treating traumatic SCI.

Flexible dual-functionalized hyaluronic acid hydrogel adhesives formed in situ for rapid hemostasis.

Hydrogel adhesives integrating both rapid and strong adhesion to blooding tissues and biocompatibility are highly desired for fast hemostasis. Herein, a flexible hyaluronic acid hydrogel adhesive is fabricated via photocrosslinking of the solution originating from dopamine-conjugated maleic hyaluronic acid (DMHA) in situ. The introduction of acrylate groups with high substitutions into the hydrogel matrix endows the adhesive with rapid gelation and strong tissue adhesion properties through photopolymerization. Moreover, the high substitution of catechol groups with unoxidized state can not only induce red blood cell aggregation and platelets adhesion but also adhere to wound tissue to further enhance hemostasis. Based on its bio-adhesion and procoagulant activity, the DMHA hydrogel formed in situ reveals superior hemostatic performance in the rat liver injury model and noncompressible hemorrhage model, and rabbit femoral artery puncture model, compared to commercial products (gauze, absorbable gelatin sponge) and oxidized DMHA (SMHA) hydrogel. Besides, the hydrogel exhibited good adaptability, biodegradability, and superior cytocompatibility as well as negligible inflammation. This hydrogel adhesive is a promising biological adhesive for hemorrhage control.

SWCNTs/PEDOT:PSS-Modified Microelectrode Arrays for Dual-Mode Detection of Electrophysiological Signals and Dopamine Concentration in the Striatum under Isoflurane Anesthesia.

Accurate detection of the degree of isoflurane anesthesia during a surgery is important to avoid the risk of overdose isoflurane anesthesia timely. To address this challenge, a four-shank implantable microelectrode array (MEA) was fabricated for the synchronous real-time detection of dual-mode signals [electrophysiological signal and dopamine (DA) concentration] in rat striatum. The SWCNTs/PEDOT:PSS nanocomposites were modified onto the MEAs, which significantly improved the electrical and electrochemical performances of the MEAs. The electrical performance of the modified MEAs with a low impedance (16.20 ± 1.68 kΩ) and a small phase delay (-27.76 ± 0.82°) enabled the MEAs to detect spike firing with a high signal-to-noise ratio (> 3). The electrochemical performance of the modified MEAs with a low oxidation potential (160 mV), a low detection limit (10 nM), high sensitivity (217 pA/µM), and a wide linear range (10 nM-72 µM) met the specific requirements for DA detection in vivo. The anesthetic effect of isoflurane was mediated by inhibiting the spike firing of D2_SPNs (spiny projection neurons expressing the D2-type DA receptor) and the broadband oscillation rhythm of the local field potential (LFP). Therefore, the spike firing rate of D2_SPNs and the power of LFP could reflect the degree of isoflurane anesthesia together. During the isoflurane anesthesia-induced death procedure, we found that electrophysiological activities and DA release were strongly inhibited, and changes in the DA concentration provided more details regarding this procedure. The dual-mode recording MEA provided a detection method for the degree of isoflurane anesthesia and a prediction method for fatal overdose isoflurane anesthesia.