Special issue: Surface and interface engineering in biomedical applications: Harnessing nature's design

Biological systems offer a remarkable blueprint for engineering innovation. Over millions of years, nature has evolved intricate surface and interface structures to optimize interaction with dynamic environments—capabilities that are now being emulated in the development of advanced biomedical solutions. This special issue, “Surface and Interface Engineering in Biomedical Applications: Harnessing Nature's Design,” explores how bioinspired principles are being translated into next-generation materials and devices that address persistent challenges in medicine.

Surface and interface properties play a pivotal role in determining how synthetic materials interact with biological systems. From initial contact to long-term integration, the chemical and physical cues presented by a material's surface influence biocompatibility, immune responses, tissue regeneration, and more. Drawing inspiration from natural micro- and nanostructures—such as the self-cleaning wings of butterflies or the underwater adhesion mechanisms of marine mussels—researchers are developing novel strategies for surface modification that combine functional performance with biological compatibility.

This special issue brings together recent advances at the intersection of bioinspired design and biointerface engineering. The collection spans a wide spectrum of topics, including adhesive coatings, hierarchical and nanostructured surface patterning, and cell-material interactions, all aimed at enhancing diagnostics, therapeutics, and regenerative medicine.

A central focus is the development of bioactive surfaces through either chemical coatings or morphological modifications. As comprehensively reviewed by Lee et al., both approaches offer complementary pathways for enhancing surface functionality in biologically meaningful ways [1].

One particularly promising class of coating materials draws inspiration from the adhesive capabilities of marine mussels. Catechol-rich compounds such as polydopamine and catechol-grafted biopolymers have emerged as versatile coatings with strong adhesion to diverse substrates, along with inherent antioxidant, antibacterial, and anti-inflammatory properties. For example, Li et al. demonstrated that polydopamine-coated bioactive glass effectively alleviated inflammation and supported odontogenic differentiation, highlighting its potential in vital pulp therapy [2]. In another study, Shi et al. developed a composite polydopamine–microarc oxidation coating on magnesium-based scaffolds, which enhanced bone regeneration by activating the CPZ/Wnt4 osteogenic signaling pathway [3]. Furthermore, Wang et al. fabricated catechol-rich gelatin microspheres as biodegradable implants [4]. These microspheres not only prevented seroma formation but also promoted subcutaneous wound healing, illustrating the multifunctionality of catechol-based systems.

In addition to catechols, plant-derived polyphenols have attracted attention as nature-inspired coating agents. Among these, metal–phenolic networks (MPNs) offer a modular framework for multifunctional biointerfaces. Wang et al. provided a comprehensive review of MPNs in bone tissue engineering, emphasizing their roles in immunoregulation, osteogenesis, and angiogenesis [5]. In a related study, Zhou et al. developed a copper-based MPN hydrogel incorporating polyvinyl alcohol and chitosan, which proved effective in promoting healing in both acute and infected wounds [6].

Other notable contributions in this issue highlight diverse approaches to functional coatings. Pan et al. introduced a hydrogel coating that catalyzes therapeutic nitric oxide (NO) release through the incorporation of bivalirudin and selenocystamine [7]. This coating demonstrated anticoagulant, antifouling, and corrosion-resistant properties when applied to magnesium-based alloys, underscoring its broad biomedical applicability. Meanwhile, a review by Graván et al. discussed the direct coating of nanomaterials with cell membranes—a strategy that mimics the natural cellular environment and enables stealth-like behavior in vivo, thereby reducing immune recognition [8].

Beyond chemical coatings, morphological patterning plays a critical role in spatially guiding cellular behavior. Nagase et al. fabricated striped patterns of polyacrylamide (PAAm) grafted onto temperature-responsive PNIPAAm substrates, resulting in aligned mesenchymal stem cell (MSC) sheets [9]. These aligned sheets secreted significantly higher levels of therapeutic cytokines—such as VEGF, HGF, and TGF-β—compared to non-aligned controls, demonstrating their enhanced potential for cell sheet-based therapies. Similarly, Kato et al. engineered anisotropic nanospike arrays on titanium surfaces via electric-field-guided microparticle deposition [10]. These nanostructures exhibited potent anti-biofouling and mechano-bactericidal properties, attributed to the enhanced electrical reactivity of the patterned surfaces. Araya et al. further advanced the translational relevance of bioinspired surface design by evaluating microstructured Ti64 implants fabricated using Powder Bed Fusion–Laser Beam (PBF–LB) in large-animal (horse) models [11]. Their in vivo and ex vivo studies provided valuable insights into the biological performance of such engineered implants at clinically relevant scales.

Collectively, these studies demonstrate the power of bioinspired surface and interface engineering in enhancing the performance of materials for biomedical applications. By mimicking and adapting nature's design principles, researchers are creating surfaces that are not only biologically compatible, but also actively therapeutic and regenerative.

As guest editor, I would like to express my sincere gratitude to all the authors who contributed their outstanding work to this issue. I also thank the reviewers for their rigorous and thoughtful feedback, and the editorial team at Materials Today Bio for their continued support throughout this process.

We hope this special issue serves both as a snapshot of current innovation and a catalyst for future research and interdisciplinary collaboration. By harnessing the elegance of nature's design, we believe the future of biomedical surfaces lies in functional, responsive, and biologically intelligent interfaces.

Seonki Hong

Guest Editor, Materials Today Bio