# Antigate Melt-Electrowritten Biodegradable Mesh Implants for Enhanced Pelvic Organ Prolapse Repair
## 1 Introduction  
Pelvic organ prolapse (POP) is a condition in which pelvic organs descend due to weakened support structures such as muscles, ligaments, and fascia [1, 2, 3]. It affects nearlyhalf of women over 50 years who have had vaginal childbirth, and its prevalence is expected to increase with population aging [4; 5; 6; 7]. While conservative treatments exist, many advanced cases require surgical intervention, with up to 15% of women undergoing POP surgery during their lifetime [8]. Synthetic meshes, initially designed for hernia repair [9], were introduced for POP treatment in the early 2000s [10]. However, their poor mechanical compatibility with vaginal tissue, along with complications such as inflammation, erosion, and excessive stiffness, led to safety concerns [8; 11]. In 2019, the FDA banned transvaginal mesh products for POP repair in the U.S., highlighting the need for alternative, tissue-compatible solutions [12]. These limitations have driven the development of new, more compatible solutions for POP repair. Additive manufacturing, particularly melt electrowritten (MEW), has emerged as a promising strategy to fabricate customized biodegradable meshes with high resolution and precise control over fiber architecture. MEW enables the production of scaffolds with tunable geometry, porosity, and fiber alignment, mimicking the microstructure of native tissue [13; 14]. Polycaprolactone (PCL) is widely used in MEW [15; 16] due to its biocompatibility, mechanical stability, and slow degradation rate [17; 18; 19; 20]. Unlike solvent-based techniques, MEW allows solvent-free processing by melting and extruding PCL directly, which is advantageous for biomedical applications [21]. Although medical-grade PCL is more expensive than technical-grade versions, it ensures greater purity, reproducibility, and printing precision [19], which are critical factors for clinical translation. Prior studies have demonstrated its use in FDA-approved devices and its ability to enhance tissue regeneration without increasing local stiffness [22]. Antistatic agents are amphiphilic molecules commonly used to reduce surface charge accumulation, which can destabilize the electrohydrodynamic jet during MEW. Their inclusion enhances surface conductivity by attracting moisture and increasing ion concentration at the polymer-air interface [23], resulting in improved jet stability and finer fiber formation. Hostastat(r) FA 38 (HT), a commercial antistatic additive [24], has previously demonstrated potential to reduce fiber diameter and improve ionic conductivity in melt electrospun systems [25]. However, such additives may also affect biocompatibility, making cytotoxicity testing essential when targeting biomedical applications [26]. Mixing HT with PCL via melt blending enables homogeneous distribution, potentially influencing both mechanical performance and cell compatibility [27]. Ensuring implant sterility is a critical step in biomedical device development [28]. Sterilization and disinfection techniques such as ultraviolet (UV) light and ethanol (EtOH) immersion are commonly used for polymeric materials due to their accessibility and low cost. However, these methods can potentially alter polymer structure, especially when used in combination [29]. Therefore, assessing the cytocompatibility of sterilization and disinfection protocols with PCL/HT meshes is essential to ensure safety and performance. Additionally, incorporating additives such as HT may influence the thermal behavior of the polymer. Differential scanning calorimetry (DSC) is a valuable tool for characterizing melting behavior and crystallinity, helping determine whether the additive alters the material's thermal stability--an important factor for processing and degradation in vivo [30]. Beyond material selection, the structural design of the mesh, particularly fiber geometry, orientation, and pore architecture, plays a critical role in its mechanical behavior and biological integration.