Preparation Of GelMA-ACNM Hydrogel Microneedles And Its Promotion Of Chronic Infection Wound Repair

Objective:Chronic infected wounds are often difficult to heal due to the presence of bacterial biofilm,and both long-term infection and inflammation may induce persistent local neuropathic pain,which is one of the most difficult chronic pain conditions to treat pharmacologically or surgically.The current traditional therapeutic approaches suffer from single function,toxic side effects and poor permeability to bacterial biofilms,and there is an urgent need to develop new therapeutic strategies with antimicrobial,healing-promoting and chronic neuropathic pain treatment.Peptides are usually safer and more effective as therapeutic agents for chronic infected wounds than small molecules because of their higher selectivity and effective post-action metabolism.However,the use of peptides for the treatment of chronically infected wounds also faces the problems of delivery and preservation.In this study,a double network(DN)Gel MA-ACNM hydrogel with excellent biocompatibility was constructed by physicochemical co-crosslinking,and vancomycin and CGRP8-37 were encapsulated into the Gel MA-ACNM hydrogel to build a multifunctional drug-carrying DN microneedle patch with antibacterial properties to promote wound healing and treat chronic neuropathic pain,which provides a potential treatment for chronic infected wounds.It provides a promising therapeutic strategy for the treatment of chronic infected wounds.Methods:A double-network Gel MA-ACNM hydrogel with natural biocompatibility and biodegradability was constructed by introducing ACNM into Gel MA for physicochemical co-crosslinking.The drug loading performance and biocompatibility were verified by SEM observation,mechanical tests,drug loading and biocompatibility tests to explore its potential as a microneedle matrix material.Double network microneedles(DN MNs)with a biphasic drug release pattern and effective retention of drug activity during drug release were fabricated by a two-step template replication method using Gel MA-ACNM hydrogels.The performance of DN MNs was analyzed by mechanical property tests,in vitro drug release experiments and tissue biocompatibility tests.Based on the above study,vancomycin and CGRP 8-37 were encapsulated into Gel MA-ACNM hydrogel using DN MNs as a delivery platform,thereby preparing multifunctional DN MNs with antibacterial and analgesic functions for the treatment of chronic infected wounds.Then,the therapeutic effects of multifunctional DN MNs were verified by in vitro antimicrobial,in vivo analgesia and wound healing experiments.Results:The SEM observation,drug loading and biocompatibility test results of the double network Gel MA-ACNM hydrogels showed that Gel MA-ACNM hydrogels have interconnected porous microstructures.The mechanical strength of Gel MA-ACNM hydrogels increased with the increase in concentration.After UV irradiation,95.2 ± 6.3%of CGRP II loaded by Gel MA-ACNM hydrogels remained stable and the residual amount of CGRP II after 7 days of storage at 26°C was 87.5% ± 9.0%.MTT and livedead cell staining results showed no cytotoxicity of Gel MA-ACNM hydrogels.DN MNs tips prepared from Gel MA-ACNM hydrogels contained about 5.5 μg ± 0.9 μg of CGRP II.Compared to CN MNs with single chemical cross-linked network and PN MNs with physical cross-linked network,the DN MNs were released at a high rate within the first 2 days and continued to be released at subsequent times,exhibiting a biphasic release characteristic of rapid pre-release and slow post-release.There was no trend of increase in OD600 value of S.aureus solution after 16 h co-incubation with multifunctional DN MNs loaded with vancomycin and CGRP 8-37,and no colony growth after plate coating.In addition,DN MNs had a significant bacteriostatic ring.In chronic neuropathic pain model rats,the mechanical pain thresholds of rats with multifunctionally loaded DN MNs recovered to 29.3 ± 9.1% after 4 h of treatment.Chronic infected wounds experiments showed that rats in the multifunctional DN MNs group had a 91% ± 3.4% wound healing rate at day 7.Histological and immunofluorescence staining results showed that multifunctional DN MNs could promote collagen deposition,epithelial tissue regeneration and alleviate the inflammatory response,thus improving the healing of chronically infected wounds.Conclusion:The double network Gel MA-ACNM hydrogels have suitable mechanical properties and porosity,and are capable of loading and protecting peptide drugs with excellent biocompatibility.DN MNs prepared by a two-step template replication method can concentrate drugs at the needle tip and have sufficient mechanical properties to penetrate the skin for a biphasic release combining rapid and slow release,thus meeting the therapeutic needs for different periods of time.Moreover,by selecting different ACMs as functional molecular carriers,DN MNs have the potential to be further optimized for different application needs.Multifunctional DN MNs loaded with vancomycin and CGRP 8-37 can exert bactericidal effects as well as treat chronic neuropathic pain,providing a promising therapeutic strategy for the treatment of chronically infected wounds.