Extracellular Matrix-Inspired Electrospun Nanofiber-Coated 3D-Printed Polylactic Acid Scaffolds for Bone Regeneration

Three-Dimensional Printing of Polycaprolactone Scaffolds with Multiscale Porosity for Bone Tissue Engineering.

This study provides a practical framework for creating intrafilamentary porosity into 3D-printed PCL scaffolds with improved surface-mediated biological performance.

Hybrid 3D Printing of Interfacial Polyelectrolyte Complex Formed between Hyaluronic Acid and Poly-L-lysine Hydrogels

Hyaluronic acid (HA), a principal component of the extracellular matrix (ECM), exhibits excellent biocompatibility, high water-retention capacity, and inherent biodegradability. α-Poly-L-lysine (PLL), a cationic polypeptide with favorable biocompatibility, is widely employed for surface modification to promote cell adhesion and proliferation. Electrostatic interactions between oppositely charged polyelectrolytes enable the formation of interfacial polyelectrolyte complexes (IPC) in the absence of chemical cross-linking agents. In this study, IPC hydrogels were fabricated from HA and PLL and processed via a combination of hybrid and gravity-compensated embedded three-dimensional (3D) printing techniques to generate both two-dimensional (2D) and 3D scaffolds for tissue engineering applications. Using this approach, anisotropic 2D membranes with submicrometer groove topographies were produced, together with mechanically stable 3D fibrous architectures. The resulting IPC hydrogels retained structural integrity under aqueous conditions, demonstrating high morphological controllability and highlighting their substantial potential as scaffolding materials in tissue engineering.

Mechanical and Biological Properties of 3D-Printed Magnetic Mesoporous Bioactive Glass Scaffolds via Chitosan/MWCNTs Coating

Functionalization of Electrospun Fibers and Hydrogel Integration: Tailoring Scaffolds for Tissue-Specific Regeneration

Electrospinning has emerged as a versatile technique for fabricating nanofibrous scaffolds for biomedical applications, as their structure perfectly biomimics the native extracellular matrix (ECM). Recent advances in biofunctionalization of electrospun fibers, such as coating with natural proteins, enable improved control of cell interaction. Furthermore, advanced spinning techniques, such as coaxial electrospinning, allow incorporation of active ingredients and their controlled release. Even specific requirements of distinct cell types, such as electrical stimulation of neurons in regenerating tissue, can be addressed by the fabrication of conductive scaffolds. Many more applications arise when moving beyond the usage of fibers as conventional two-dimensional scaffolds, toward three-dimensional constructs. The development of regenerative biomaterials by integrating electrospun fibers into hydrogels combines the attractiveness of the fibrous structures with the shape and size flexibility of hydrogels, resulting in a versatile tool for in vitro test systems and for tissue-specific regeneration. Thus, in this review, the functionalization options for electrospun fibers are discussed regarding their implementation methods and resulting cell biological impact. Furthermore, the integration of such fibers into hydrogels is addressed as a promising strategy to modulate electrospun biomaterials and examples are given for tissue-specific biomedical applications.

Cryogenic 3D-printed gelatin-chondroitin sulfate scaffold embedded with PCA/Cu2+/ε-polylysine-functionalized chitosan microspheres for simultaneous antibacterial, anti-inflammatory, angiogenic, and osteogenic bone regeneration.

3D-printed gelatin scaffolds are widely explored for bone regeneration due to their excellent biocompatibility and biodegradability, yet their clinical translation is severely hindered by several inherent defects, including weak mechanical stability, fast in vivo biodegradation, limited osteogenic capability, and the absence of anti-infective functions. Globally, it remains a key challenge in bone tissue engineering to develop integrated scaffold systems that simultaneously satisfy mechanical matching, long-term biological activity, and anti-pathogenic requirements. To address this challenge, a multifunctional CHm/PCA/Cu2+/ε-PL@Gel-OCS scaffold with enhanced mechanical properties, outstanding antibacterial, anti-inflammatory, pro-vascularization and osteogenic activities was developed via cryogenic 3D printing of a gelatin (Gel)/oxidized chondroitin sulfate (OCS) composite ink loaded with chitosan microspheres surface-functionalized by protocatechuic aldehyde (PCA), copper ions (Cu2+) and ε-polylysine (ε-PL). Scanning electron microscopy and energy-dispersive X-ray analysis confirmed uniform dispersion of the microspheres and sustained release of therapeutic agents as the scaffold degraded. Rheological and mechanical testing demonstrated excellent print fidelity, interconnected porosity (161 ± 37 μm pores), and compressive strengths (100-200 MPa) suitable for cortical bone repair. Such porous structure and mechanical performance are highly compatible with human cortical bone microenvironment, which facilitates cell infiltration, nutrient exchange and mechanical load bearing. In vitro release studies revealed a sequential sustained release profile (OCS > Cu2+ > ε-PL), ensuring a sustainable osteogenic, angiogenic, anti-inflammatory and antibacterial activity. The scaffold achieved 100% bactericidal efficiency against both Staphylococcus aureus and Escherichia coli, suppressed protein denaturation (anti-inflammation), and promoted neovascularization in a chick chorioallantoic membrane assay. Biocompatibility assays using MC3T3-E1 osteoblasts showed enhanced cell adhesion, proliferation, and live/dead viability over 5 days. Osteogenic potential was significantly elevated on the multifunctional scaffold, as evidenced by time-dependent increases in ALP activity, mineral deposition (Alizarin Red S), and upregulated expression of ALP, RUNX2, OPN, and OCN genes compared with Gel and Gel-OCS controls. Taken together, our cryogenic 3D-printed Gel-OCS scaffold incorporating PCA/Cu2+/ε-PL-functionalized chitosan microspheres provides a single-step, customizable platform that combines robust mechanical properties with multi-modal therapeutic functionalities. Different from conventional single-function bone scaffolds reported in most international studies, this multi-component synergistic design successfully realizes the integration of mechanical reinforcement, antibacterial, anti-inflammatory, vascularization and osteogenesis functions in one system. These promising preclinical results highlight a novel therapeutic strategy for bone defect regeneration, it solves the common bottlenecks of traditional gelatin-based bone scaffolds, provides a feasible and universal fabrication strategy for high-performance multifunctional bone repair materials, and offers new insights for the global development and clinical translation of 3D-printed bone tissue engineering scaffolds.

A REVIEW OF NANOFIBER & 3D PRINT SCAFFOLDS FOR TISSUE ENGINEERING APPLICATIONS

Tissue engineering aims to develop biological substitutes that restore, maintain, or improve tissue function, with a central challenge being the fabrication of scaffolds that replicate the complex structural and physicochemical properties of the native extracellular matrix. Over the past decades, a wide array of fabrication methods and polymers has been explored to create optimal scaffolds that support cell adhesion, proliferation, and differentiation, while promoting the regeneration of damaged tissues. Among these, electrospinning and three-dimensional printing have emerged as particularly promising technologies. Electrospinning enables the production of nanofibrous matrices that closely mimic the natural tissue topography, whereas three-dimensional printing offers unprecedented control over macroscopic scaffold architecture and porosity. However, each technique possesses inherent limitations; electrospun scaffolds often lack sufficient mechanical strength and hinder cellular infiltration, while three dimensional printed constructs typically fail to replicate the nano scale fibrous environment essential for cell matrix interactions. This review systematically explores the synergistic potential of integrating electrospun nanofibers with three dimensional printed frameworks to create hierarchical hybrid scaffolds. We critically examine the fabrication strategies, material considerations, and application specific outcomes of such combined approaches in regenerating tissues such as bone, cartilage, and skin. Finally, we discuss current challenges and future directions for this converging manufacturing paradigm, highlighting its capacity to bridge the multi scale gap in tissue engineering.