In vitro tissue modelling has garnered significant interest because of its potential to enhance existing therapeutic approaches. The enduring challenge for researchers is the development of resilient tissue scaffolds that accurately replicate the morphology of natural tissues. Key factors to consider in the creation of an effective cell culture scaffold include material compatibility, biodegradability, hydrophilicity, capacity to incorporate growth factors, suitable pore size (e.g. 100–300 μm), and a sufficient local cell proliferation (reaching a cell density of 20–30 million cells/mL) to form a tissue [[1], [2], [3]].

Various methodologies have been employed to meet these prerequisites, including processing and removal of porogens through sublimation, evaporation, and melting, as well as 3D printing and electrospinning [[4], [5], [6], [7]]. Both 3D printing and electrospinning present promising avenues for the creation of robust porous structures with high overall porosity (70–90 %) and appropriate mechanical properties, such as the compressive modulus of scaffolds within the range of 0.1–1 MPa and the tensile strength above 3 MPa [8]. Solution electrospinning is a well-known method for creating nanofibrous structures that have been applied in a broad variety of industrial applications injectable biomaterials [9], and smart textiles [10]. However, only melt electrospinning has demonstrated the ability to accurately mimic the morphology of natural tissue, as it can form randomly oriented fibers without the need for additional techniques to enhance the porosity [11,12]. Melt electrospinning is a melt-based electrohydrodynamic polymer processing method that offers several advantages over the traditional solvent-based electrospinning techniques. Unlike solvent-based methods, which require volatile organic solvents that may leave residual traces, melt electrospinning entirely eliminates the need for solvents, resulting in scaffolds with higher biocompatibility [13]. This technique utilizes a high-voltage electric field to draw a polymer melt through a spinneret, ultimately forming ultrafine fibers that are collected on a grounded collector. The diameter and morphology of these fibers can be precisely controlled by adjusting parameters such as the voltage, flow rate, and distance between the spinneret and the collector [14]. One of the most significant advantages of melt electrospinning is its ability to produce scaffolds with well-defined architectures and high porosity, which are crucial for cellular infiltration and tissue integration [15,16].

Thermoplastic polymers such as polycaprolactone (PCL), polylactic acid (PLA), and poly(lactic-co-glycolic acid) (PLGA) are frequently used in melt electrospinning [17]. PCL is particularly suitable because of its favorable mechanical properties, biocompatibility, biodegradability, and low melting point (60 °C) ([18]. Recent studies have illustrated the versatility and potential applications of poly[ε]caprolactone (PCL) scaffolds in tissue engineering, such as the enhancement of mechanical properties and antibacterial capabilities [19], the use in bone substitutes for femoral fractures [20], and modifications to improve antithrombogenic properties [21], providing a context for our investigation into the effects of alkaline hydrolysis on PCL scaffold performance. Despite the suitability of semicrystalline polymers for 3D melt electrospinning, they exhibit hydrophobicity, that is, a water contact angle in the range of 118–140° [22,23] and a lack of functional groups to enhance wettability and bind growth factors necessary for cell growth. Common growth factors include transforming growth factor-β (TGF-β), insulin-like growth factor-1 (IGF-1), and fibroblast growth factor (FGF) [24]. TGF- β3 is frequently used in cell treatment, as it fosters an optimal environment for health and growth. Specifically, TGF- β3 plays a crucial role in chondrogenesis by promoting the differentiation of mesenchymal stem cells (MSCs) into chondrocytes and enhancing the synthesis of cartilage-specific extracellular matrix components [25]. Additionally, TGF- β3 has been shown to suppress inflammatory responses, further creating a conducive environment for tissue regeneration [26]. Its ability to modulate cellular activities, combined with its chondroprotective effects, makes TGF- β3 an invaluable factor in cartilage tissue engineering and regenerative medicine [27]. These growth factors can be incorporated into the scaffold, attached to it, or added to the cell culture medium [[28], [29], [30]], however their application is often complicated and expensive.

The surface properties of PCL can be modified by several techniques such as surface coating, alkaline hydrolysis, plasma etching, and laser treatment [17,31,32]. Methods that only alter the physical properties of the surface, such as laser treatment, are not ideal, as they do not introduce new functional groups. Conversely, plasma treatment and alkaline hydrolysis provide an oxidative environment, and are thus considered effective for modifying chemical properties.

As the number of functional groups (hydroxyl and carboxyl) increases, the wettability of the material improves, favoring cell attachment [33]. However, these methods have a drawback: the prolonged treatment can compromise the mechanical properties of the structure [34,35]. Thus, selection of an appropriate treatment duration is crucial. Alkaline hydrolysis surpasses plasma treatment when applied to 3D structures because it ensures a uniform treatment across the entire scaffold [36].

Recent advances in tissue engineering highlight the importance of scaffold surface characteristics in influencing cellular responses crucial for tissue regeneration. Our study focuses on enhancing poly[ε]caprolactone (PCL) scaffolds using alkaline hydrolysis, a technique that improves hydrophilicity and introduces functional groups to support tissue ingrowth. The primary research question addressed in this study is: What is the impact of alkaline hydrolysis duration on the physicochemical properties, morphology, and biocompatibility of poly[ε]caprolactone (PCL) scaffolds in chondrocyte cultures? Based on preliminary data, we hypothesize that a short-duration alkaline hydrolysis treatment (5 min) significantly enhances the scaffold's characteristics related to cell culture applications without compromising mechanical integrity. We advance existing methodologies by optimizing alkaline hydrolysis to tailor scaffold properties specifically for bone and cartilage repair, concentrating on adjustments like pore size reduction and surface roughness enhancement. This approach links physical modifications directly to improved biological performance, particularly in chondrogenic and osteogenic potentials. While existing studies have explored general effects of scaffold enhancements, detailed impacts of specific hydrolysis durations remain underexplored. Our research addresses this by demonstrating that short-duration treatments can significantly enhance scaffold efficiency, facilitating cartilage regeneration without the need for expensive growth factors. This approach shows that control over scaffold modifications can lead to significant improvements in bone and cartilage tissue engineering, suggesting new directions for developing advanced scaffold designs.