Introducing Metal–Organic Frameworks to Melt Electrowriting: Multifunctional Scaffolds with Controlled Microarchitecture for Tissue Engineering Applications

Scaffolds with multiple advantageous biological and structural properties are still a challenge in the field of tissue engineering. The convergence of advanced fabrication techniques and functional materials is key to fulfill this need. Melt electrowriting (MEW) is an additive manufacturing technique that enables the fabrication of microfibrous scaffolds with precisely defined microarchitectures. Here, it is proposed to exploit metal–organic frameworks (MOFs) to efficiently introduce multifunctionalities by combining polycaprolactone (PCL), the gold standard material in MEW, with a silver-/silver-chloride-decorated iron-based MOF (NH₂-MIL-88B(Fe)). This results in highly ordered constructs with antibacterial properties and magnetic resonance imaging (MRI) visibility. Scaffolds with up to 20 wt% MOF are successfully melt-electrowritten with a fiber diameter of 50 µm. Among these, 5 wt% MOF proves to be the optimal concentration as it exhibits silver-induced sustained antibacterial efficacy while maintaining PCL cytocompatibility and in vitro immune response. The iron component of the MOF (Fe(III) nodes) renders the composite visible with MRI, thereby enabling scaffold monitoring upon implantation with a clinically accepted method. The combination of MEW and MOFs as tunable additives and cargo carriers opens the way for designing advanced multifunctional scaffolds with a wide range of applications in, e.g., tissue engineering, biosensing and drug delivery.