Hemostasis is a complex physiological response to prevent blood loss from injured vessels. Initially, platelets adhere to the vascular injury, become activated, and form a platelet plug that seals the injury (primary hemostasis). Fibrin produced by the blood coagulation systems stabilizes the clot (secondary hemostasis). The hemostatic machinery, which includes both pathways that interact simultaneously in the process of primary and secondary hemostasis, stops bleeding from minor wounds and contributes to wound healing [
1]. However, severe trauma associated with major vascular injury can result in life-threatening blood loss [
2]. In particular, patients with hereditary or acquired hemostatic disorders are at increased risk of bleeding and require immediate and specific treatment. Similarly, patients on anticoagulant medications have impaired hemostatic capacity and are prone to persistent local bleeding [
3]. In recent years, new types of anticoagulants have been introduced. However, their impact on spontaneous and post-operative bleeding has not been fully elucidated. Therefore, in an ageing society where both the number of surgical interventions and the number of patients being treated with oral anticoagulants are increasing, efficient strategies for local support of hemostasis are needed. The rapid and efficient administration of potent topical medications for hemostasis is hence becoming increasingly important for surgical patients, especially during anticoagulant therapy [
3]. Post-interventional bleeding is frequently observed as an adverse complication in oral surgery [
4]. Oral wounds are particularly susceptible to bleeding due to dense blood supply, mechanical stress from chewing, breathing and articulation. In addition, they are exposed to fluids such as saliva and the physiological oral microbiome. Furthermore, the tissue of the upper gastrointestinal tract has a high fibrinolytic activity and thus an increased capability to dissolve already formed blood clots during hemostasis [
5]. Overall, the specific oral environment has a strong influence on hemostasis and wound healing. The recently published guideline of the German Society for Dental, Oral and Maxillofacial Medicine (DGZMK) emphasizes the advantages of local topical hemostasis in oral surgery, especially for patients taking anticoagulant drugs [
6]. In contrast, intervention with systemic hemostasis by administration of pro-coagulant or anti-fibrinolytic drugs remains under debate [
6]. Treatment strategies for oral bleedings include bypass agents, such as recombinant factor VIIa (rFVIIa), activated prothrombin complex concentrates (aPCC, e.g., Factor VIII Inhibitor Bypassing Activity [FEIBA]), or fibrin sealants (fibrin glue). The latter reproduce the final stage of the coagulation cascade and subsequently the formation of a fibrin clot [
7]. While these agents have potent hemostatic capacity and interfere with bleeding, the administration of current topical hemostatic medications is associated with an array of adverse side effects, including compromised local wound healing [
8,
9], local inflammation [
8‐
11], anaphylactic reactions [
8,
11,
12], formation of heat that can lead to burn injuries [
13], risk of disease transmission [
14] and high costs [
8,
9]. Overall, post-operative local hemostasis remains a challenge in patients undergoing oral surgery, especially while receiving anticoagulation therapy or when hemostatic abnormalities are present. To date, none of the currently available topical hemostatic agents meet the criteria for a low-risk, effective, and safe local hemostasis. Polyphosphate (polyP) is an inorganic, negatively charged polymer composed of orthophosphate residues linked by phosphoanhydride bonds. PolyP is abundant in nature, regulated by phosphate-homeostasis [
15], non-immunogenic, degraded in plasma by endogenous phosphatases with a half-life of about 90 min, is inexpensive, and is easy to store and apply. Recently, the polymer has gained interest with regard to local hemostasis. PolyP is a procoagulant by several fibrin-forming mechanisms. In vivo, polyP contact-activates factor XII (FXII) to activated FXII (FXIIa) which in turn triggers the “intrinsic” pathway of blood coagulation [
16‐
18]. Animal studies and experiments with human plasma have shown that the pharmacological inhibition of FXIIa and its activator polyP is associated with thromboprotection without increased clinical bleeding [
19‐
22]. Moreover, in vitro studies suggest that polyP contributes to fibrin formation by accelerating thrombin-dependent activation of factor XI and factor V, as well as von Willebrand factor binding. It also decreases fibrinolysis and stabilizes the fibrin clot [
23]. PolyP is produced in bulk form as a powder. For utilization as a local hemostatic agent in routine clinical practice, an improved method for defined application is required, e.g., a carrier material must be coated with polyP. In recent years, silk fibroin has gained importance in regenerative medicine research and is currently being investigated in various forms such as sponges, hydrogels, electrospun fibers, tubes or membranes [
24]. Due to its mechanical versatility and high cytocompatibility [
25‐
27] silk appears to be a suitable carrier for hemostatic agents. The aim of this feasibility study is to evaluate the potential of silk membranes coated with polyP for local hemostasis in vitro.