RESUMO
The high prevalence of acquiring skin wounds, along with the emergence of antibiotic-resistant strains that lead to infections, impose a threat to the physical, mental, and socioeconomic health of society. Among the wide array of wound dressings developed, hydrogels are regarded as a biomimetic soft matter of choice owing to their ability to provide a moist environment ideal for healing. Herein, neutral glycol chitosan (GC) was cross-linked via imine bonds with varying concentrations of dibenzaldehyde-terminated polyethylene glycol (DP) to give glycol chitosan/dibenzaldehyde-terminated polyethylene glycol hydrogels (GC/DP). These dynamic Schiff base linkages (absorption peak at 1638 cm-1) within the hydrogel structure endowed their ability to recover from damage as characterized by high-low strain exposure in continuous step strain rheology. Along with their good injectability and biodegradability, the hydrogels exhibited remarkable inhibition against E. coli, P. aeruginosa, and S. aureus. GC/DP hydrogels demonstrated high LC50 values in vivo using zebrafish embryos as a model system due to their relative biocompatibility and a remarkable 93.4 ± 0.88% wound contraction at 30-dpw against 49.1 ± 3.40% of the control. To the best of our knowledge, this is the first study that developed injectable glycol chitosan/dibenzaldehyde-terminated polyethylene glycol self-healing hydrogels for application in wound healing with intrinsic bacteriostatic properties against the three bacteria.
Assuntos
Escherichia coli , Staphylococcus aureus , Animais , Biomimética , Peixe-Zebra , Cicatrização , Materiais Biocompatíveis/farmacologia , Polietilenoglicóis/química , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Antibacterianos/química , Hidrogéis/químicaRESUMO
BACKGROUND: Protease-activated receptors (PARs) can be stimulated by thrombin and other proteases generated by periodontal pathogens. Activation of PARs in gingival fibroblasts (GFs) can modulate wound healing and inflammatory responses in gingival tissues. METHODS: The mRNA expression of PARs and early responsive genes in GFs and other oral cells was studied by reverse transcription-polymerase chain reaction. Western blotting was used to study the activation of p38 and cAMP responsive element binding protein (CREB)/activating transcription factor (ATF)-1 as well as Ras. RESULTS: GFs, dental pulp cells, and buccal mucosal fibroblasts expressed PAR-1 and -3 receptors, whereas gingival keratinocytes expressed PAR-1 and -2 receptors. Stimulation of GFs by thrombin rapidly activated Ras signaling and the phosphorylation of CREB/ATF-1 and p38. Thrombin also stimulated the expression of c-fos in GFs within 1 hour of exposure. Stimulation of c-jun mRNA expression showed biphasic responses with two peaks after 1 and 8 hours of exposure. Elevated c-myc expression in GFs by thrombin was noted after 2 hours of exposure. Moreover, the stimulation of c-fos and c-myc mRNA expression by thrombin can be attenuated by D-Phe-Pro-ArgCH(2)Cl, a serine-proteinase inhibitor. CONCLUSIONS: PAR activation during gingival wounding or inflammation may stimulate Ras-CREB/ATF-1 signaling and c-fos, c-jun, and c-myc expression. This might be due to the proteinase activity of thrombin. These signaling events are important for wound healing and inflammatory responses in gingival tissues.