11.3.4　Antibacterial fiber dressings

Bacterial infections seriously threaten the wound healing process，and preventing bacterial infections is essential to complete wound healing.The addition of inorganic，organic，or metal antibacterial agents to electrospun fibers has always been an important strategy for obtaining antibacterial fiber dressings.

At present，in clinical operations，systemic antibiotics are often used to treat wound infections.The long-term use of antibiotics with strong potency and rapid sterilization will bring bacterial resistance.If the release concentration is less than the minimum inhibitory concentration，the adverse consequences of resistance will be aggravated.Therefore，controlling a reasonable antibiotic release concentration has always been an important aspect of antibacterial fiber dressings.He et al.loaded enrofloxacin antibiotics into PVDF electrospun nanofibers.Within 0-12 h，the drug release showed a burst behavior，and the cumulative release reached 60％，which can quickly kill bacteria，and then the residual drug continued to release up to 3 days.The sustainable release of the loaded drugs can effectively inhibit the proliferation of bacteria.

In addition，many studies have shown that loading inorganic antibacterial agents including Ag，Zn，and carbon-based nanomaterials，into fibers can kill bacteria，reduce inflammation，or promote epithelial proliferation and regeneration.Some researchers used PVA as a reducing agent to prepare Ag-NPs loaded PVA electrospun fibers.The fibers showed inhibitory effects on E.coli and S.aureus，and the antibacterial efficiency was much higher than that of wound dressings loaded with silver nitrate.(https://www.daowen.com)

Chang et al.synthesized zinc-doped hollow mesoporous silica nanospheres（HMZS）by the sol-gel method and loaded them into polycaprolactone（PCL）electrospun fiber to prepare a new type of wound healing dressing.As shown in Figure 11-16，the composite electrospun fiber dressing can promote angiogenesis and skin regeneration by releasing Si ions，and enhance hair follicle regeneration and inhibit bacterial growth by releasing zinc ions.

Besides these inorganic materials，some organic polymers，such as quaternary ammonium salts，guanidine group-containing polymers，or antibacterial peptides，also have excellent antibacterial properties.Loading these motifs into the electrospun fiber membranes can even overcome multidrug resistance（MDR）bacterial infections.Recently，Lei et al.developed an elastic，photoluminescence，and antibacterial hybrid polypeptide-based nanofiber matrix as a multifunctional platform for inhibiting MDR bacteria and enhancing wound healing（Figure 11-17）.The hybrid nanofiber matrix is composed of poly（citrate）-εpolylysine（PCE）and polycaprolactone（PCL）.The PCL-PCE hybrid nanofiber matrix exhibits biomimetic elastic behavior，strong antibacterial activity（including the ability to kill MDR bacteria）and excellent biocompatibility，and can effectively prevent wound infections caused by MDR bacteria and enhance wound healing and skin regeneration.