Experimental Study Of Peptide-modified Hydrogel Microneedles For The Treatment Of Pain In Mice

Objective.Local anesthesia a commonly clinical analgesic method,and plays an necessary role in the treatment of pain by causing local anesthetic drugs to bind to ion channels in cell membranes,temporarily blocking nerve conduction functions to produce anesthesia.However,the duration and application of local anesthesia is still very limited due to the toxic side effects,physicochemical properties and other factors that limit the applications of local anesthetic drugs.When the source of pain is cutaneous or subcutaneous,it is difficult to achieve satisfactory results despite the use of multimodal analgesia by clinicians to relieve the patient’s pain,and for patients suffering from pain,repeated visits to the doctor and the side effects of oral medication often cause a lot of inconvenience and compromise the patient’s physical and mental health.Microneedles can physically penetrate the stratum corneum and form micron-sized pores on the skin surface.The use of soluble microneedles instead of traditional surface anesthesia can speed up the onset of drug action and increase the efficiency of drug delivery,but due to their size,there are often problems such as short release times and sudden drug release.Studies have shown that there are interactions such as hydrogen bonding between some local anesthetic drugs and specific peptide structures on sodium channels,and researchers have used this interaction to construct peptide-tetrodotoxin self-assembled nanomicelles,which in turn enable long-lasting sciatic nerve blocks based on slow release of drugs.In this study,hydrogel microneedles loaded with lidocaine hydrochloride were prepared by modifying methacrylic anhydride modified hyaluronic acid using peptides with which lidocaine interacts,in the hope of providing a safer and more convenient means of local anesthetic drug analgesia.Methods.1.Microneedles preparation: Hyaluronic acid was modified with methacrylic anhydride,then modified with peptides by the carbodiimide method,and the material obtained after modification was used as a carrier to prepare microneedles and gels loaded with lidocaine hydrochloride.The material composition was examined using the Fourier infrared spectroscopy,and nuclear magnetic resonance spectroscopy,the microneedles’ morphology and gel pores were observed under the cold-field scanning electron microscopy,and the mechanical properties of the microneedles were examined by mass spectrometry.2.In vitro drug release by a transdermal diffusion cell and in vivo drug release in mice,and comparison of drug release from peptide modified microneedles and unmodified microneedles using an enzyme marker.3.Animals experiments: C57 male mice were used for 4-8 weeks(weight 18-20 g)and subjected to SNI mode and treated with microneedles on the third day after successful operation in the following groups: 2% lidocaine hydrochloride solution injection group(Lid/Sol),methacrynic anhydride acid modified hyaluronic acid hydrogel microneedle group loaded with lidocaine hydrochloride(Lid/MHA),peptide modified microneedles loaded with lidocaine hydrochloride(Lid/MHA-P),methacrynic anhydride-modified hyaluronic acid hydrogel microneedle group loaded with lidocaine hydrochloride(Blank/MHA-P),methacrynic anhydride-modified hyaluronic acid hydrogel microneedle group loaded with peptide modified with lidocaine hydrochloride(Blank/MHA-P),and phosphate buffer control(PBS),and the analgesic effect was measured by plantar prick pain meter.MHA-P hydrogel microneedle was applied to the back of the mice for 1h,and the mice were executed24 h after microneedle removal.4.Cytotoxicity of microneedles: PC-12 cells were treated with microneedle material in Hacat cell medium and tested for cytotoxicity using the CCK-8 kit in the following groups: lidocaine hydrochloride solution group(Lid/Sol),methacrynic anhydride modified hyaluronic acid hydrogel microneedle group loaded with lidocaine hydrochloride(Lid/MHA),peptide modified methacrynic anhydride modified hyaluronic acid loaded with lidocaine hydrochloride methacrynic anhydride modified hyaluronic acid hydrogel microneedle group(Lid/MHA-P),blank peptide modified methacrynic anhydride modified hyaluronic acid hydrogel microneedle group(Blank/MHA-P),and phosphate buffer control(NC).Results.1.the microneedles made from the peptide modified material showed little difference in morphology and mechanical properties from those made from the unmodified material,and were able to penetrate the mice skin.2.The hydrogel microneedles were able to slow down the release of lidocaine hydrochloride,and the peptide-modified hydrogel microneedles significantly slowed down the release of the drug in vitro and in vivo compared with that before the modification,which effectively relieved the sudden release phenomenon.3.The peptide-modified hydrogel microneedles could significantly prolong the analgesic time of lidocaine hydrochloride in the feet of SNI mice,and the peptide-modified hydrogel microneedles could achieve 11 h foot analgesia in mice with less impact on local tissues.4.The hydrogel microneedles loaded with lidocaine hydrochloride had better biocompatibility and lower cytotoxicity compared with lidocaine hydrochloride solution.Conclusion:1.Hydrogel microneedles can slow release lidocaine hydrochloride and effectively improve sudden release.2.The use of microneedles for slow release of lidocaine hydrochloride significantly prolonged the analgesic duration in the feet of SNI mice.3.The hydrogel microneedle loaded with lidocaine hydrochloride has good biocompatibility.Highlight:1.For improving the sudden release of drugs by exploiting the specific interaction between sodium channel proteins and lidocaine for the first time.2.A long-acting and slow-release analgesic microneedle was constructed,which can sustain analgesia for 11 h in a mouse model.