Hydrogels are soft materials used in an array of biomedical applications. However, the in situ formation of hydrogels at target sites, particularly in dynamic in vivo environments, usually requires a prolonged gelation time and results in poor adhesion. These limitations cause considerable loss of both hydrogel mass and encapsulated therapeutic cargoes, thereby compromising treatment outcomes. Here, we report the development of a hydrogel based on thiourea-catechol reaction to enhance the bioadhesion. Compared with classical bioadhesive hydrogels, our hydrogels show enhanced mechanical properties, exceedingly short curing time, and pH-independent gelation with a much lower oxidant concentration. We further report the robust adhesion of our hydrogels to acidic gastric tissues and easy delivery to the porcine stomach via endoscopy. The delivered hydrogels adhered to ulcer sites in vivo for at least 48 hours. Hydrogel treatment of gastric ulcers in rodent and porcine models accelerated ulcer healing by suppressing inflammation and promoting re-epithelization and angiogenesis. The improved retention of proregenerative growth factors and reduced exposure to external catabolic factors after hydrogel application may contribute to the observed therapeutic outcomes. Our findings reveal a promising biomaterial-based approach for treating gastrointestinal diseases.
Liying Wu,Yongbo Yu,Qian Zhang,Junming Hong,Ji Wang,Yuecheng She
Through direct and indirect radical mechanism of peroxymonosulfate (PMS) activation, novel CoFe 2 O 4−x catalysts were successfully developed via hydrogen calcination to overcome popular disadvantages of the dependence on pH. Bisphenol A (BPA) was selected as the model pollutant to decipher the mechanism of catalysts for peroxymonosulfate (PMS) activation. Possible degradation pathways of Bisphenol A were proposed via analysis of liquid chromatograph mass spectrometer (LC-MS). The findings indicated that catalytic activation of CoFe 2 O 4−x was not dependent upon the initial pH, as the direct and indirect radicals seemed to be generated in parallel. FTIR analysis confirmed that surface hydroxyl groups were actively involved in the activation of PMS under alkaline conditions. During the reaction, the oxygen defects promoted electron transfer and participated in the redox cycle from Co 3+ /Fe 3+ to Co 2+ /Fe 2+ to generate 1 O 2 and O 2 − . Hydroxyl (OH ) and sulfate (SO 4 − ) radicals were generated on the surface of CoFe 2 O 4−x by the synergistic interactions among oxygen defects, transition metal, and surface hydroxyl groups. To the best of our knowledge, this combined mechanism of direct and indirect radical generation for advanced oxidation was a first-attempt study to be disclosed in public domain.
Development of efficient and highly active non-noble metal electrocatalysts to replace Pt-based catalysts for achieving pH-dependent electrochemical hydrogen generation on a large scale is extremely significant. In this study, a B-doped molybdenum carbide nanocrystal confined in a porous N-doped carbon nanostructure (B–MoC) was synthesized and evaluated as a pH-independent electrocatalyst for the hydrogen evolution reaction (HER). B-doping could modify the electronic structure of MoC by introducing electron deficiency, which resulted in excess electron transfer to MoC nanoparticles , thereby generating many proton adsorption sites and improving the electrocatalytic performance. B-doping could also increase the electrochemical surface area of the catalyst and lower its resistance. Moreover, B–MoC could participate in charge transfer processes and prevent the agglomeration of MoC nanoparticles . B–MoC showed a low overpotential of 285 mV at a current density of 10 mA cm −2 , as well as excellent stability for 1000 cycles in an acidic medium. Such remarkable improvements in the activity and stability of B–MoC toward HER were also observed in alkaline and neutral media.
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