Preparation Of Sprayable Photosensitive Cross-Linked Hydrogel Dressing For Diabetic Skin Wounds And Basic Research On Its Application

Objective:In order to solve the problem of difficult healing and scarring of diabetic wounds,we propose to synthesize a new sprayable hydrogel wound dressing,and explore the feasibility of the liquid dressing to promote diabetic wound healing and the mechanism of promoting scar-free healing,eventually providing relevant experimental data and theoretical support for the repair of clinical diabetic wounds.Methods:1)Sprayable methacrylic anhydride modified gelatin hydrogels（Gel MA）,zeolitic imidazolate frameworks（ZIF-8）,and ZIF-8 encapsulated with glucose oxidase（GOx）,chloroperoxidase（CPO）,and dual enzymes were prepared,named as gz,cz and gcz,respectively;the above nanoparticles were mixed with Gel MA hydrogels to prepare composite hydrogels,named as Ge Z,GZ,CZ,GCZ,respectively;atomic force microscopy（AFM）,transmission electron microscopy（TEM）,scanning electron microscopy（SEM）,Fourier infrared spectroscopy（FT-IR）,and X-ray diffraction（XRD）were used to characterize the surface morphology,particle size,chemical bonding,physical phase,and the properties of the hydrogels such as water content,swelling ratio,and degradation rate were tested.2)The loading amount of enzymes in gcz,gz and cz nanoparticles was measured and the HCl O produced amount by gcz nanoparticles was measured quantitatively.3)Antibacterial and biocompatibility tests of GCZ,GZ,CZ,Ge Z and Gel MA hydrogels were carried out.4)A type I diabetic rat model was established to investigate the ability of GCZ,GZ,CZ,Ge Z and Gel MA hydrogels to promote wound healing.5)The mechanism of hydrogel to promote scar-free wound healing was investigated by H＆E staining,Masson staining,PAS staining and immunohistochemical analysis.Results:1)AFM results show that the Gel MA hydrogel films have small surface roughness and uniform thickness.The TEM and SEM results showed that the successful synthesis of ZIF-8 nanoparticles and the enzyme loading of gcz,gz,and cz did not change the surface morphology of ZIF-8.FT-IR results showed the appearance of amide bonds in Gel MA hydrogels,indicating the successful introduction of methacrylamide groups into gelatin molecules.XRD patterns showed that the prepared ZIF-8 had a similar peak structure to the simulated ZIF-8,indicating that ZIF-8 was successfully synthesized.In addition,the diffraction peaks of gcz,gz and cz did not change significantly in comparison with ZIF-8.Secondly,the water content of all hydrogels was above 78.6%,which had a good swelling ratio,and the hydrogels were basically degraded after 28 days.2)The results of the enzyme loading showed that the enzyme loading of gcz,gz and cz were 9.24%,11.86% and 8.06%,respectively.The results of the HCl O generation test showed that the amount of HCl O produced after 2 days was about 56.41μM at 0.1% gcz solution according to the linear equation.3)The results of the antibacterial test showed that the 0.1% GCZ hydrogel has good ability to remove bacteria.Co-cultured with S.aureus,its antibacterial performance reached almost 100%.Co-cultured with E.coli,its antibacterial performance reached 100%.Regarding the biocompatibility of the hydrogels,we can find that the cellular activity of all experimental groups was higher than 80% during the whole co-culture process.4)Wound healing experiments in diabetic rats animals showed that at day 21,the treatment with GCZ group still had the highest wound healing rate compared to the other groups,which could reach 99.8%.5)The results of H＆E staining and Masson staining indicated less inflammatory cells in the wounds and massive formation of collagen fibers,indicating accelerated wound healing.The PAS staining results showed that glucose oxidase significantly reduced the glucose levels around the wounds.Immunohistochemical results showed lower levels of the three inflammatory factors IL-6,IL-1β and TNF-α in the GCZ group wounds,indicating a significant anti-inflammatory effect of GCZ hydrogel.Secondly,transforming growth factor-β（TGF-β）showed a trend of increasing and then decreasing,indicating a tendency of scar-free wound healing.Conclusions:We designed and validated an effective GCZ hydrogel with spraying,antiinflammatory,hypoglycemic,and antibacterial properties to promote diabetic wound healing.The designed GCZ hydrogel integrates antibacterial and hypoglycemic in a single platform,reduces the inflammatory response through synergistic effects,promotes the deposition of collagen fibers,and accelerates scar-free wound healing.It has potential applications in diabetic wound treatment.