Editorial—Special Issue on the NCCR Bio‐Inspired Materials

The National Centre of Competence in Research (NCCR) Bio-Inspired Materials was established in June 2014 to create a Swiss research network dedicated to developing environmentally adaptive and stimuli-responsive materials inspired by nature. Throughout its twelve-year funding period, the centre has been guided by the vision of its main funders—the Swiss National Science Foundation and the University of Fribourg—to draw inspiration from biological systems to create stimuli-responsive materials, understand how these materials interact with living systems, and translate the this knowledge into real-world applications, in the fields of chemistry, physics, materials science, and biomedicine. The Centre is headquartered at the Adolphe Merkle Institute of the University of Fribourg (UniFr), with the École Polytechnique Fédérale de Lausanne (EPFL) and the Eidgenössische Technische Hochschule Zürich (ETHZ) as its primary partner institutions. Since its inception, a total of 30 research groups from six Swiss institutions and six other universities in the UK, Germany, Austria, Belgium, Finland, and the USA have participated in this venture. These groups work at the intersection of several disciplines, including chemistry, physics, biology, materials science, and medicine. The NCCR was initially launched under the directorship of UniFr professors Christoph Weder and Curzio Rüegg. In 2021, the directorship transitioned to UniFr professor Ullrich Steiner and EPFL professor Esther Amstad, who have since led the centre through the second half of its funding period. The Centre's research programme has traditionally been organised into three modules: mechanically responsive materials, photonic materials, and bio-interfaces. These three areas of research have shaped the NCCR's identity and informed its activities throughout its twelve-year funding period. At the same time, the NCCR has launched several other complementary research programmes. For instance, in 2018, an interdisciplinary programme combining microfluidics, sensing technologies, and cell biology was initiated to create a dynamic lab-on-a-chip platform for investigating cell–material interactions. Other examples include cross-disciplinary collaborative projects investigating long-standing challenges in cancer diagnosis, optical manipulation, and bio-inspired power conversion. In 2022, a new module was launched to support projects with translation potential. These projects focus on edible, bio-inspired colours, healable polymers, soft actuators, and carbon capture materials. The NCCR also offers Women in Science Fellowships, which have funded eleven projects led independently by female researchers. This programme has significantly advanced the careers of the fellows, with six of them transitioning to assistant professorships and equivalent positions worldwide. Since its launch, the NCCR has made significant contributions to its areas of activity. Research in the first module has resulted in the development of new families of mechanoresponsive polymers, polymersomes, nanoparticles, microcapsules, composites, and hydrogels, all of which exhibit unparalleled mechanical properties. The second module focuses on advanced photonics, creating novel optical materials based on patchy particles and investigating how order and disorder interact to control scattering and light transport. Fundamental studies have also been conducted on phase-separation-driven optical materials and DNA origami-based optical devices. The third module has produced new broad-spectrum antivirals and improved our understanding of nanoparticle-cell interactions. It has also developed DNA origami-based systems for the targeted detection and destruction of tumour cells, as well as new hydrogels for organoid morphogenesis. Other initiatives originating from the centre have produced organoid-on-a-chip prototypes and energy-converting membranes inspired by electric fish, as well as easily degradable plastics. Beyond its scientific achievements, an important mission of the NCCR has been to provide opportunities for young researchers and non-tenured, junior faculty members, supporting their career development. The centre has an excellent track record in this respect. Four of the nine NCCR Principal Investigators (PIs), who were initially assistant professors, have secured permanent positions: Alke Fink, Marco Lattuada, Stefano Vanni at the University of Fribourg, and Esther Amstad at the EPFL. Two others have secured permanent positions elsewhere: Nico Bruns, formerly at the University of Strathclyde, is now at TU Darmstadt; and Jovana Milic is at the University of Turku. Furthermore, 14 postdoctoral and senior researchers at the NCCR have moved directly into junior faculty positions at universities across 12 countries. Six more secured junior faculty positions after holding senior researcher positions elsewhere. The NCCR's Undergraduate Research Internship (URI) programme is one of its most successful initiatives for furthering the careers of young researchers. To date, it has brought over 180 students from 63 universities worldwide to NCCR laboratories to work on summer research projects. The programme has significantly strengthened the NCCR's network and boosted participants' careers, as evidenced by the 21 scientific articles co-authored by URI students in recent years. As the NCCR Bio-inspired Materials comes to a close with an international conference on bio-inspired materials at the University of Fribourg in Switzerland on 19–20 June, we would like to thank the Swiss National Science Foundation and the University of Fribourg for their generous support over the years. We would also like to thank all past and present Centre participants for their commitment and exceptional contributions. Finally, we would like to thank the authors who contributed to this special issue of Advanced Functional Materials, particularly Joseph Krumpfer, Jessica D'Lima, and Bernadette Gmeiner in the editorial office, for their hard work. This special issue contains 27 manuscripts, including contributions from current and former members of the NCCR Bio-Inspired Materials, as well as colleagues from the wider NCCR network. These works span several fields, showcasing the versatility of bio-inspired approaches for advanced materials design. The following summary groups these contributions by their alignment with the NCCR's three topical modules. Drawing inspiration from the intricate coupling of mechanical, chemical, and structural processes in living systems, this module focuses on designing synthetic polymers that translate external stimuli into functional responses, spanning sensing, actuation, and adaptation across multiple length scales. Kaur et al. (adfm.202532202) present a comprehensive review of strain-stiffening polymer networks, outlining how network architecture and chain semi-flexibility govern mechanical adaptation and establishing key design principles for biomimetic materials that respond to large deformations. Urban et al. (adfm.202526684) offer a perspective review on poly(ionic liquids), highlighting how molecular-level interactions and polymer topology can be harnessed to control hierarchical organisation in ways inspired by biological macromolecules, thereby linking molecular design to macroscopic function. Drawing on the use of dynamic, non-covalent interactions in biological materials to encode mechanical function, Clough and Weder et al. (adfm.202531535) employ supramolecular mechanophores as optical force probes in glassy polymers to detect and map pre-failure mechanical events and localised damage, while Korley et al. (adfm.202527307) engineer peptide-mediated matrix-filler interactions in polymer nanocomposites to direct self-assembly, stress transfer, and energy dissipation in hierarchical materials. Compartmentalised transport and spatially controlled chemical processes, characteristic of biological systems, are further explored by Rifaie-Graham et al. (adfm.202527008), who quantify small-molecule diffusion across light-responsive polymersome membranes, and by Andrieu-Brunsen and Bruns et al. (adfm.202522240), who achieve localised polymer growth via SI-bioATRP in mesoporous silica. At larger length scales, transport-coupled processes in biological systems enable the propagation of signals and the generation of functional responses across soft materials. Translating this concept to synthetic systems, Libanori et al. (adfm.202531953) develop adaptive hydrogels in which reaction-diffusion processes generate enzymatic pH waves, triggering localised stiffening, while Weder and Mayer et al. (adfm.202600031) harness coupled ion and water transport in mechanically robust hydrogels for electric-fish-inspired energy conversion. Finally, Weder and Formon et al. (adfm.202531442) show how dynamic bonds facilitate the repair and reprocessing of glycol-modified PET, and Stellacci and Slor et al. (adfm.202518059) introduce chemoselective polymerisation strategies for mixed plastic waste recycling, illustrating how precise control over bond reversibility and chemical selectivity, as exemplified by nature, can be leveraged to address sustainability challenges. Collectively, these contributions underscore the continued relevance of bioinspired design strategies that couple mechanical, chemical, and transport processes in advancing adaptive and functional polymer systems. Module 2 draws inspiration from the wide variety of colour-generating photonic structures found in living organisms. It also examines how macromolecules self-assemble to produce colour. Four contributions focus on the former. One of the greatest mysteries surrounding biogenic photonic colour is how the underlying 100 nm-scale structures develop biologically. In their article, B. Wilts and his colleagues address this question (adfm.202532173). They propose that mechanical instabilities play a significant role in the morphogenesis of photonic scales. According to their model, the outer epicuticular envelope buckles due to the secretion of the cuticle precursor through the associated plasma membrane. The authors suggest several experiments to verify their hypothesis. Saba and his colleagues address another fundamental issue: how seemingly disordered 100 nm morphologies found in nature give rise to a photonic signature. They developed a bond-switching Monte Carlo algorithm combined with an annealing protocol to deform an initially ordered photonic structure (adfm.202600037). By comparing a range of metrics with 3D tomograms from several organisms, they identified a subset of parameters that characterise the generated morphologies. This study lays the groundwork for discovering the relationship between these metrics and the resulting colour appearance. Wang and Wilts investigated the UV signature of the Graphium milon butterfly (adfm.202600049). By extracting bile pigments from the butterfly and incorporating them into structured polymer films, they elucidated the colour-generation mechanism and provided a new strategy for security printing. Dodero and his colleagues developed a cephalopod mimic based on the self-assembly of block copolymers (adfm.202528686). Emulsifying block copolymers with a carefully selected surfactant mixture yields elliptical microparticles measuring 100 nm with tunable internal morphologies. Incorporating magnetic nanoparticles into the layered internal structure enables colour switching in an external magnetic field. Acuña and his colleagues use DNA origami to customise the colour response of embedded plasmonic nanoparticles. In one study, they arranged fluorophores in close proximity to a silicon nanoparticle using DNA origami (adfm.202529955). This resulted in highly directional emission over a narrow wavelength range. In a second study (adfm.202532006), they employed a similar approach to position rhodium nanocube dimers, thereby creating programmable UV plasmonic nanoantennas. These nanoantennas were then used for label-free single-protein detection. Module 3 was dedicated to biointerfaces across scales, exploring interactions between living systems and materials. This issue features methodological and application-oriented contributions, including multimodal imaging, next-generation drug delivery systems, and scaffolds for tissue engineering and healing. Several contributions investigate bio-inspired materials using computational and experimental approaches. Vanni and coworkers report a fully automated Bayesian optimisation (BO) protocol (BACH) for the systematic parameterisation of coarse-grain force fields, and use it to systematically study a broad range of liquids (adfm.202532052). Moore and colleagues introduce a machine-learning workflow that accelerates the microfluidic formulation of nanomedicines by providing the most accurate predictions of nanomedicine attributes (adfm.202514387). Finally, Fink and Rothen-Rutishauser et al. introduce a multimodal imaging probe composed of a gold core surrounded by a fluorescently labelled silica shell (adfm.202527555), where fluorescence is maintained for more than 24 h in cell culture medium, even after uptake by macrophages. Notably, their approach resolves the long-standing trade-off between chemical robustness and fluorescence retention. This issue also features contributions focused on health-oriented materials and technologies. The Boesel group reports the synthesis of chlorhexidine-loaded silica particles that enable light-controlled release of antiseptic compounds to achieve on-demand drug delivery (adfm.202531727). The Maniura-Weber and Ren labs introduce ProΦGel, a pathogen-responsive dual-layer hydrogel designed to coordinate the sequential antibacterial activity of phages and probiotics, achieving significant eradication of P. aeruginosa and biofilm disruption in vitro and in an ex vivo human skin model (adfm.202527392). Since drug development is time-consuming and costly, and multidrug-resistant Gram-negative bacteria pose a growing medical threat, the group of Salentinig introduces a synthetic membrane (adfm.202532053), which includes human antimicrobial proteins that induce phase transitions in multilamellar vesicles. These findings provide valuable design guidelines for efficient peptide-integrated delivery vehicles. The therapeutic lifetime of large drug molecules is often limited by the body's immune response. Sousa et al. developed a poly(lactic-co-glycolic acid) (PLGA)-based delivery vehicle that significantly prolongs the lifetime of large self-amplifying RNA (adfm.202529443). In zebrafish xenograft tumour models, this system induced macrophage recruitment to the tumour site, indicating an early immunomodulatory response to the RNA treatment. To achieve better control over the timing of drug release, silica-based delivery vehicles enabling light-triggered release are introduced. For the coordinated release of different therapeutics, dual-layer hydrogel-based delivery systems in which each layer is functionalized with a different drug are also presented. The behaviour of epithelial cells depends strongly on substrate topography. Fink and Roten-Rutishauser et al. clarify how substrate feature size influences epithelial cell behaviour (adfm.202528452). In vitro cell culture is typically limited to environments that allow precise temperature control and easy nutrient replenishment. To expand their use to settings where these conditions cannot be readily maintained, such as integration into soft robots, Georgopoulou and coworkers present a hydrogel-based granular scaffold equipped with temperature sensing and a Joule heater for autonomous closed-loop temperature control and sustained nutrient release for up to 24 h (adfm.202530747). Bone healing is often a lengthy process, during which patients cannot fully load the injured structures and therefore frequently experience reduced mobility. Amstad and her colleagues aimed to shorten this period by introducing an enzyme-loaded granular paste that mineralises into load-bearing scaffolds within a few days (adfm.202526568), without requiring any sintering step. The porous structure of the resulting composites allows cells to infiltrate, creating opportunities for cellular remodelling of the synthetic scaffold and its gradual transformation into natural bone. Finally, Masania et al. present a strategy for producing living fungal-based materials (adfm.202530836). They achieve this by 3D-printing cross‑linkable hydrogels inoculated with mycelium, enabling spatially confined mycelial growth without inhibiting biological activity. This establishes mycelium as both a bio‑factory and a structural scaffold to produce adaptive, multifunctional living materials. The authors declare no conflicts of interest. Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.