Jul 2026· Smart materials and structures (Print)· Vol 35, pp. 083001· 0 citations· 132 references
Physics
TL;DR
This review presents a comprehensive overview of the physical principles governing shape-memory behavior in PCL systems, emphasizing structure–property relationships that control switching temperature, recovery stress, and long-term stability.
Abstract
Poly(ϵ-caprolactone) (PCL)-based shape-memory materials have emerged as a versatile class of smart biomaterials that combine programmable mechanical behavior with biomedical functionality. In addition to biocompatibility, they exhibit adjustable thermal transitions, mechanical flexibility, and precisely controlled degradation characteristics. These materials exhibit reversible shape transformations driven by external stimuli. This facilitates their use in minimally invasive procedures and activation at the specific site within the body. This review presents a comprehensive overview of the physical principles governing shape-memory behavior in PCL systems, emphasizing structure–property relationships that control switching temperature, recovery stress, and long-term stability. Strategies to enhance performance through copolymerization, blending, and nanocomposite design are critically evaluated, alongside recent progress in additive manufacturing and 3D/4D printing that enables patient-specific architectures. Key applications include self-expanding stents, dynamic tissue-engineering scaffolds, microneedle systems, and smart drug-delivery implants, all biomedical uses of PCL-based SMPs. Furthermore, key issues like slow degradation, limited stimuli, mechanical challenges, and sterilization difficulties are identified and critically examined. Future research directions include multi-stimuli responsiveness, personalized implants, and sustainable polymer synthesis. Collectively, these innovations enhance the capabilities of PCL-based shape-memory systems, enabling them to become next-generation medical devices, advance regenerative therapies, and advance drug delivery technologies.
Background/Objectives: Shape-memory biodegradable scaffolds (4D scaffolds) represent promising platforms for minimally invasive tissue engineering and localized drug delivery. This study investigated how two different fabrication techniques, electrospinning (ES) and extrusion-based direct ink writing (DIW), influence the structural, thermal, mechanical, shape-memory, and drug-release properties of poly(L-lactide-co-caprolactone) (PLA/PCL 70:30) scaffolds loaded with dexamethasone (DXM). Methods: DXM-loaded PLA/PCL 70:30 scaffolds were fabricated by ES and DIW. The resulting matrices were characterized in terms of morphology, mass, thickness, drug-loading efficiency, thermal properties by differential scanning calorimetry, shape-memory performance, tensile mechanical properties, and in vitro DXM release. Results: Both fabrication techniques produced DXM-loaded matrices with comparable mass and thickness and high loading efficiencies (>82%). Glass transition temperatures ranged between 33 and 39 °C, supporting thermally induced shape recovery under physiologically relevant conditions, while ES processing was associated with higher polymer crystallinity. All scaffolds exhibited shape-memory behavior, with recovery ratios exceeding 90%. ES scaffolds displayed a microporous nanofibrous architecture, whereas DIW scaffolds showed a more open and highly porous structure. These morphological differences were reflected in their mechanical behavior: ES scaffolds exhibited higher tensile strength (up to 16.5 MPa vs. 1.9 MPa) and elongation at break (up to 320% vs. 243%). Drug-release profiles were also fabrication-dependent, with ES scaffolds reaching a plateau at approximately 80% DXM release, whereas DIW scaffolds showed near-complete release within 48 h. Conclusions: Both fabrication approaches preserved the thermoresponsive shape-memory behavior of PLA/PCL 70:30 but generated distinct scaffold architectures that strongly influenced mechanical performance and DXM-release kinetics.
Luigi Ruccolo, Aleksandra Evangelista, Francesco Andresini et al.· Pharmaceutics· 0 citations
Due to the tunable mechanical properties, degradation kinetics, and inherent compatibility with biological environments, biodegradable polymers have a considerable impact on bio‐interfaced technologies. Through the rational integration of active molecular motifs that impart electrical, physicochemical, and biological responsiveness, these materials evolve beyond passive structural roles into multifunctional platforms capable of signal transduction, adaptive mechanical behavior, controlled fabrication, and therapeutic intervention under physiological conditions. This review provides a comprehensive overview of recent advances in biodegradable and/or biocompatible functional polymers, with a focus on five representative material classes: conductive polymers, shape‐memory polymers, self‐healing polymers, photocurable polymers, and adhesive polymers. For each component, we discuss material design strategies, structure–property relationships, and a wide range of biomedical applications, and outline challenges and future directions for translating these materials into clinically relevant transient, bioresorbable platform technologies for next‐generation biomedical and bioelectronic systems.
Won Bae Han, Shuvra Mondal, Sungkeun Han et al.· Advanced Functional Material...· 0 citations
Regenerative medicine is vital for restoring tissue function and health; however, conventional biomaterials typically remain static or rely on external energy sources, limiting their functionality in dynamic biological environments. Here, we introduce a novel approach to fabricate dynamic, self-folding biomaterials via 4D printing, overcoming these limitations. Using an extrusion-based multi-material 4D printing technique, we engineer perfusable, shape-morphing hydrogel scaffolds composed of an alginate/methylcellulose system enhanced with carbonized alginate nanoparticles. These scaffolds exhibit programmed swelling-driven shape transformations and possess anti-oxidative, anti-inflammatory, and anti-thrombotic properties, promoting cell viability and mimicking complex vascular architectures.
In parallel, we develop solvent-cast chitosan films with enhanced aqueous stability and intrinsic piezoelectricity that autonomously convert biomechanical energy into electrical signals, stimulating cell proliferation and migration without external power. Despite chitosan being a well-known natural polymer, its piezoelectric application has been limited due to low piezoelectric coefficients and rapid degradation in aqueous environments. Our approach overcomes these challenges by alkaline cross-linking to improve stability and mechanical properties, enabling effective self-powered bioelectrical stimulation.
Together, these innovations establish a self-powered, dynamic biomaterial platform capable of mimicking native tissue mechanics and bioelectric cues, marking a significant advance toward next-generation tissue regeneration therapies.
Conventional static biomaterials possess relatively stable physicochemical properties after fabrication or implantation, which limits their ability to adapt to dynamically changing physiological microenvironments. In contrast, dynamic biomaterials can undergo controllable or programmable changes to regulate their physicochemical properties in response to external or endogenous stimuli, thereby providing improved spatiotemporal adaptability for biomedical applications. In this review, dynamic biomaterials are systematically discussed from a physical-cue-centered perspective, focusing on stimulus-responsive changes in stiffness, surface morphology, and shape programmability rather than classification solely by stimulus type or material composition. The responsive mechanisms, preparation strategies, and representative stimuli, including light, temperature, pH, ions, and magnetic fields, are summarized and critically analyzed. Recent biomedical applications in tissue engineering, drug delivery, minimally invasive therapy, and intelligent biomedical devices are further highlighted. Finally, current challenges involving long-term biosafety, mechanical durability, manufacturability, and clinical translation are discussed, together with future perspectives for multifunctional, multi-stimuli-responsive, and spatiotemporally programmable dynamic biomaterials.
Additive manufacturing has revolutionized the fabrication of functional metamaterials, offering unprecedented design freedom to program mechanical responses through geometric architecture. This review examines the recent advancements in 3D printed polymeric metamaterials for biomedical applications, specifically focusing on flexible systems that move beyond high-stiffness metallic or ceramic constructs with orthopedic applications. We provide a systematic overview of common metamaterial architectures and their implementation across five biomedical domains: (1) sensing and wearables, where lattices enhance sensitivity and linear range; (2) soft robotics and 4D printing, focusing on active, stimulus-responsive movement; (3) tissue simulation, utilizing architected tissue phantoms for medical training and device development; (4) tissue engineering, where porous scaffolds govern cellular behavior; and (5) drug delivery, leveraging increased surface-area-to-volume ratios for optimized release kinetics. This review highlights the various strategies employed by researchers to overcome the limitations of bulk polymers through innovative design and novel materials integration. Finally, we discuss future perspectives, including the role of inverse design and computational modeling, the integration of multi-modal sensory and actuation behaviors, and the need for long-term biocompatibility and fatigue characterization in clinical settings.
Adarsh Somayaji, A. Gong, Hamid Chalian et al.· Journal of Medical Devices· 0 citations
Additive manufacturing (AM) has expanded the design space of biomaterials for biomedical engineering, enabling patient-specific geometries, controlled porosity, multi-material constructs and cell-compatible fabrication. However, clinical translation remains constrained by a mismatch between fabrication capability and biological, mechanical and regulatory performance. Unlike reviews focused on individual material families, isolated AM routes or specific applications, this review interprets AM of biomaterials as an integrated biomaterial–process–structure–property–translation ecosystem. It examines how material chemistry, feedstock state, printing route, architecture, post-processing and biological response jointly determine the reliability of acellular and cellular constructs, with particular emphasis on clinically relevant performance, reproducibility and long-term safety. Metallic, ceramic, polymeric, hydrogel-based and composite biomaterials are analysed alongside binder jetting (BJ), directed energy deposition (DED), material extrusion (ME) and jetting (MJ), powder bed fusion (PBF), VAT photopolymerisation and bioprinting. The review identifies recurring challenges across routes, including restricted material–process compatibility, limited prediction of process–structure–property relationships, post-processing-induced changes in biological performance, insufficient standardisation of printability and biofunctionality metrics, incomplete validation of cell-laden and vascularised constructs and weak transfer of laboratory protocols to clinically robust workflows. The main conclusion is that progress will depend less on expanding printable geometries alone and more on integrated optimisation of materials, processing windows, structural fidelity, biological validation, quality assurance and translational readiness. This ecosystem-level perspective provides a framework for evaluating limitations and defining future priorities in AM-based biomaterials for regenerative medicine, implants and precision biomedical engineering.
A. Pedroso, Luciana Silva, Marta L. S. Barbosa et al.· Journal of Functional Biomat...· 0 citations