During the last decades polymeric networks containing dynamic covalent bonds have received high interest as a result of the possibility of increasing their lifetimes by self-healing, reprocessing or recycling upon triggering the reversibility or exchange between their dynamic bonds by different stimuli (heat, pH, UV, ox.-red. agents) without or with relatively low loss of their original mechanical properties and stability [1].
In this work, linear and star-shaped poly(ε-caprolactone-co-α-methylene-γ-butyrolactone) P(CL-co-MBL) copolyesters with a pendant functional double bond of MBL comonomer were used as polymeric precursor for organo-gels formation [2]. Crosslinking was carried out by light-initiated thia-Michael reaction using 1,5-pentanedithiol or pentaerythritol tetrakis(3-mercaptopropionate). The gel content and the crosslinking density varied based on MBL comonomer and crosslinker content and were highest for slight thiol to double bond molar excess (SH/vinyl; 2/1). The thermal and rheological properties investigation of the obtained materials was performed employing DSC, TGA and using frequency and temperature sweeps rheological measurements. Formed thioether bond within the network were not reversible up to 150 °C as it was found based on temperature sweep rheology. PCL segments provides toughness into the material at r.t. while material becomes malleable after melting of this physical crosslinks at 50 °C. Following, the activation and conversion of thioether bonds into trialkylsulfonium salts was attained through the alkylation. The dynamic nature of the transalkylation at 150 °C allowed network rearrangement, which was proved by stress relaxation and creep recovery experiments[3] (Figure).

Acknowledgment: The authors acknowledge the financial support through grants VEGA 2/0153/25, SAS-NSTC-JRP-2023-02 „MULTICOMP“ and APVV-21-0297.

Self-assembling scaffolds enhance shape adaptation to the human body environment thanks to the dynamic response to external stimuli. Due to their flexibility, additive manufacturing techniques, such as melt electrowriting (MEW), are powerful approaches to fabricating these scaffolds. Dual-head MEW allows high-precision simultaneous deposition of diverse materials. This research focuses on multimaterial self-assembling scaffolds fabricated using dual-head MEW. Square and triangular structures were designed with a fiber-to-fiber distance of 300 μm. The scaffolds consisted of two parts with different swelling properties, where the fiber orientation and layer thickness varied. Polycaprolactone (PCL) or poly(ethylene oxide terephthalate)/poly(butylene terephthalate) with molecular weight of the poly(ethylene oxide) equal to 300 (PEOT-PBT 300) was used as more hydrophobic layer, while PEOT-PBT 1000 was used as more hydrophilic layer. The optimization of printing parameters was performed. The fabricated scaffolds were processed with oven treatment to enhance the connections between fibers. The microstructure of scaffolds was characterized by optical and confocal microscopy. The tensile strength of fabricated scaffolds was also assessed. The self-assembling properties were investigated by observing the rolling behavior after placing the scaffolds in PBS. The difference in swelling properties between the printed materials enabled self-assembly of the construct. The self-rolling behavior depended on the material combination, the orientation of hydrophobic fibers, as well as on the way of placing scaffolds in PBS. The conducted research shows successful integration of two different materials into one MEW process. The fabricated self-rolling scaffolds are promising solutions in vascular tissue engineering applications, which will be further investigated.

3D printing of pharmaceuticals is a potential manufacturing solution for distributed healthcare offering unparalleled personalisation and sustainability[1]. 3D printed polypills can accommodate personalised doses of different drugs of varied functions and allow synergistic effects to improve treatments[2]. However, precise control of drug release relies on rational design of polypills[3]. Here, we present a parametric study of polypill microstructure design in terms of their dimensional precision and mechanical integrity. By direct control of optimised toolpaths, we designed a capsule polypill model with continuous and consistent extrusion to ensure the microstructures are predictably consistent. The polypill models consist of single-filament walls of variable wall thickness, since the wall erosion can be controlled by the geometry of the printed filaments[4], the basic building unit for 3D printing (Figure 1 a). Greater wall thickness (0.8 mm versus 0.4 mm) showed fewer interlayer geometric defects, which are usually regarded as the weakness point for mechanical and chemical attack. Additionally, greater wall thickness exhibited more rigid with greater compression force than thinner walls (Figure 1 b). We 3D-printed pharmaceutical-grade polymers and demonstrated a thickness-dependent model for rapid and slow release (Figure 1 c). This study highlights the importance of controlled deposition and microstructures of 3D printed polypills and provides new knowledge about structure-dependent drug release models.

This study is part of a comprehensive project focused on developing a multimodal wound dressing composed of biodegradable polymers to provide mechanical protection, gas permeability, antimicrobial and immunomodulatory properties, and enhanced cell adhesion. The dressing is designed to support the early to mid-stages of wound healing while minimizing the need for intensive medical intervention.
The presented work specifically investigates the fabrication and characterization of a coaxial fiber-based mid-layer engineered for controlled drug release, imparting antimicrobial and immunomodulatory properties. The fiber core consists of polyethylene oxide (PEO) loaded with clindamycin and diclofenac, while the shell is composed of a specially synthesized polylactic acid (PLA) optimized for sustained drug release. Coaxial electrospinning was used for fiber fabrication, with process optimization conducted by design of experiments (DOE) using Taguchi approach. This method systematically varies key formulation and electrospinning parameters—including polymer solution concentration, flow rate, and applied voltage—to evaluate their influence on fiber properties and drug release kinetics. An L9 orthogonal array was employed to identify the optimal conditions for controlled drug release and fiber biodegradability. Data analysis using signal-to-noise (S/N) ratios determined the most influential parameters.
The results demonstrate that the optimized fibers exhibit controlled drug release, high biodegradability, and strong antimicrobial efficacy, making them highly suitable for biomedical applications, particularly in advanced wound-healing devices.
This work is part of the NATO SPS Project (SPS G6031): Wearable Smart Patches for Multimodal Wound Healing – DRESWOUTRE.

Chronic wounds, burns, and surgical sites are prone to infections that delay healing and cause complications. Therefore, developing advanced wound dressings with antibacterial and regenerative properties is essential to accelerate recovery and reduce healthcare burdens.
Electrospinning is a versatile technique for fabricating polymeric nanofibers and nonwoven mats using high electrostatic forces. Due to their high surface area-to-volume ratio and extensive surface functionality, nanofibrous electrospun materials are widely explored for biomedical applications, especially wound healing. In recent years, our research group has demonstrated that combining electrospinning with photoinduced crosslinking enhances the physicochemical properties of fibrous materials while enabling precise morphological control and the tuning of chemical composition to create (multi)functional materials.¹⁻⁴ Moreover, other photoinduced reactions such as photo-grafting and photo-reduction can allow the design of specific functional features.
In this study, we present electrospun membranes as innovative wound dressing materials, consisting of photocrosslinked poly(ethylene oxide) (PEO) nanofibers modified through: i) in situ-generated silver nanoparticles (Ag NPs) via photo-reduction,⁵ and ii) photo-chemically grafted eugenol. The structural, morphological, and mechanical properties of the electrospun membranes were analyzed, and the effects of additive concentration were evaluated. The cytocompatibility and antibacterial activity of the materials were assessed using direct and indirect assays on fibroblasts and both Gram-positive and Gram-negative bacterial strains. Additionally, the regenerative potential of the patches was evaluated in monolayer cultures and using a commercial 3D reconstructed human epidermis model. The results demonstrated that these PEO-based nanofibrous mats exhibit both antibacterial activity and pro-regenerative properties, confirming their potential as effective wound dressing materials.