Abstract:

Objective Electrospun membranes have great potential as advanced wound dressings by virtue of their high specific surface area, porous structure and good permeability. These attributes facilitate wound exudate absorption and create a moisture-permeable microenvironment for tissue repair. Developing multifunctional membranes with inherent antibacterial properties is crucial for preventing infection and promoting healing. Therefore, a crosslinked polysuccinimide/cinnamaldehyde (PSI/CA) electrospun fibrous membrane was prepared for antibacterial dressing, using PSI as electrospinning polymer matrix and CA as a functional agent.

Method PSI was synthesized by thermal polymerization of L-aspartic acid. Electrospinning solutions were prepared by dissolving PSI and varying amounts of CA (0%, 3%, 5%, and 10% by mass of PSI) in dimethylformamide (DMF). PSI/CA solutions were electrospun into fiber membranes, and then crosslinked with ethylenediamine vapor. The electrospun fiber membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FT-IR), water absorption test, mechanical property test, antibacterial assays, cytotoxicity analysis and drug release studies.

Results The PSI/CA electrospun fiber membranes exhibited smooth surfaces and a uniform diameter distribution. The addition of CA had no significant effect on fiber diameter. After crosslinking, the fibers display slight bending and agglomeration, with a minor increase in diameter. FT-IR analysis confirmed the opening of the succinimide rings in PSI and formation of amide bonds via crosslinking. In the uncrosslinked state, the PSI/CA electrospun fiber membranes demonstrated a water absorption capacity of 19.0-21.6 g/g, which significantly decreased to 12.8-14.6 g/g after crosslinking due to increased packing density. The CA addition also showed little effect on water absorption properties. Crosslinking notably improved the mechanical strength of the PSI/CA electrospun fiber membranes. With increasing CA loading, the mechanical strength of crosslinked PSI/CA electrospun fiber membranes exhibited a peak of (1.41±0.19) MPa at 3% CA content. All crosslinked PSI/CA electrospun fiber membranes containing CA demonstrated good antibacterial activity. The inhibition rate against both Escherichia coli and Staphylococcus aureus achieved 100%, and the crosslinked pure PSI membrane also showed considerable intrinsic antibacterial activity, with the inhibition rate of 98.5% against Escherichia coli and 87.3% against Staphylococcus aureus, respectively. Cytotoxicity assay revealed good cell compatibility for all membranes, with cell viability remaining above 95%, and a slight promotion of proliferation was observed for CA-loaded PSI/CA electrospun fibrous membranes, with cell viability rate over 98%. In drug release studies, CA displayed an initial burst release within the first 24 h, followed by a sustained release profile. The CA release process conforms to the first-order kinetic model, and the release mechanism was dominated by Fickian diffusion. The CA release behavior was closely related to the CA content in the PSI/CA electrospun fibrous membranes.

Conclusion The PSI loaded with CA is successfully electrospun into fiber membranes. After crosslinking modification, PSI/CA electrospun fiber membranes still retain fiber morphology, along with improved mechanical properties, excellent antibacterial activity and good cell compatibility. The CA release process conformed to the first-order kinetic model, and the release mechanism is dominated by Fickian diffusion. These integrated properties enable the crosslinked PSI/CA electrospun fiber membranes to meet key requirements for advanced wound dressing applications.

Key words: medical dressing, polysuccinimide, cinnamaldehyde, antibacterial activity, electrospun fiber membrane, crosslinking modification