With the improvement of living standards, the changes in diet structure, and the aging of the population, the prevalence of diabetes is also increasing. The chronic diabetic wound is one of the serious complications of diabetes. Diabetic patients, who are often in a state of hyperglycemia, experience damage to their microvascular, nervous, and immune systems to varying degrees, resulting in a complex pathological mechanism. Therefore, the causes of diabetic chronic wounds are complex, including venous insufficiency, peripheral vascular diseases, systemic diseases, traumatic scars, and infection [1]. Once the local wound occurs in diabetic patients, it often isn't easy to heal [2,3].

Wound dressing is a temporary skin substitute that can protect wound [4]. An ideal wound dressing should have air permeability and biocompatibility, keeping wound moist and protecting it from bacterial contamination, etc. [5,6]. Nanofiber dressing prepared by electrospinning technology is a new type of wound dressing that could have strong absorption and good air permeability. It can also absorb exudation from wound tissue [7,8]. Additionally, nanofiber dressing have high porosity, which could be benefit for facilitating cell respiration and gas exchange, thereby maintaining wound wettability and preventing microbial invasion [9,10].

The CS/PLA nanofiber functional dressings containing astragaloside IV (AS) were prepared by an electrostatic spinning process in this study. The dressing comprised of two kinds of polymer materials, chitosan (CS) and polylactic acid (PLA). CS is biocompatible, low toxicity, and biodegradable [11,12]. It also has properties required by general wounds, such as hemostasis and antibacterial effects, making it a potential wound healing accelerator [13,14]. However, CS has some problems, such as poor mechanical properties, difficult electrospinning, and solubility only in acidic solutions [15,16]. Therefore, CS is often co-spun with other polymers to improve its applicability [17]. PLA has good mechanical properties and biocompatibility, and can be absorbed by the human body. It has high compliance and permeability for dressing and also has anti-inflammatory and wetting functions [[18], [19], [20]]. However, PLA has poor cell affinity and hydrophilicity [21]. Therefore, in this study the combination of CS and PLA not only improved the hydrophilicity and cell affinity of PLA but also improved the poor mechanical properties of CS.

Astragaloside IV(AS) is the main component of Astragaloside, which has the functions of regulating body immunity, anti-inflammation, anti-virus, anti-apoptosis, and lowering blood sugar [22,23]. According to some relevant literature reports, in the treatment of diabetic wounds, some traditional Chinese medicines played a great role in the proliferation of fibroblasts, the formation of new blood vessels, and the secretion of cytokines [24]. In our previous experiments, AS displayed a good property in promoting diabetic chronic wound in rats. Therefore, we developed a novel nanofibers functional wound dressing based on CS, PLA and AS, and hope they could play their advantages to promote diabetic chronic wound together.