Biomaterials

Three-dimensional printed protein-based robotic structures are actuated by exoskeleton-like coats of molecular motor assemblies upon the spatially targeted release of chemical fuel, resulting in micrometre-scale shape-morphing activity.

Fabrication of semiconductor heterojunctions typically involves a complex process and often leads to bioincompatibility. Here, the authors propose a porous heterojunction in p-type silicon via simple stain etching at ambient conditions, and apply it in optically induced biomodulation.

This Perspective reviews the complementary developments in synthetic biology and biomaterials and discusses how convergence of these two fields creates a promising design strategy for the fabrication of tailored living materials for medicine and biotechnology.

Wiring photosynthetic biomachineries to electrodes is promising for sustainable bio-electricity and fuel generation, but designing such interfaces is challenging. Aerosol jet printing is now used to generate hierarchical pillar array electrodes using indium tin oxide nanoparticles for high-performance semi-artificial photosynthesis.

Lignocellulosic waste is transformed into fungal–bacterial biocomposites that can be processed into recyclable, human-scale structural objects with biosynthetic and sensing–reporting functionalities.

The influence of stress relaxation of the extracellular matrix on the formation of intestinal organoids was investigated. It was shown that a stress-relaxing synthetic matrix promotes crypt budding through increased symmetry breaking and niche cell formation.

The large-scale fabrication of cellulose nanocrystal photonic films in a roll-to-roll device is achieved by careful optimization of the cellulose nanocrystal formulation and its controlled deposition and drying on a substrate. Once dry, these photonic films can be peeled and milled into effect pigments, highlighting the potential of cellulose nanocrystals as a sustainable material for industrial photonic applications.

A synthetic hydrogel has been developed to mimic the physicochemical properties of pancreatic tissue and is shown to support the culture of pancreatic cancer organoids, revealing the role of laminin–integrin interactions in their growth.

This Review summarizes limitations in the current techniques used for patient-derived cancer organoid culture and highlights recent advancements and future opportunities for their standardization.

A functional interfacial material has been developed for soft integration of bioelectronic devices with biological tissues. This has been applied in battery-free optoelectronic systems for deep-brain optogenetics and subdermal phototherapy as well as wireless millimetre-scale pacemakers and flexible multielectrode epicardial arrays.

Silica beads encapsulating DNA information and functionalized with DNA labels create an alternative DNA data storage system, where direct random access and data retrieval are enabled by complementary fluorescent strands that identify beads for separation in fluorescence-activated sorting.

An approach integrating molecular dynamics-based computer-aided engineering with computer-aided design allows for the rapid construction of large three-dimensional DNA assemblies and control over their geometry, mechanics and dynamics.

Patterned contracting networks composed of biomolecular motors and filaments achieve millimetre-scale actuation of mechanical structures with light-triggered molecular stimuli.

It is now shown that cells migrate robustly on soft, viscoelastic substrates with fast stress relaxation using a migration mode marked by a rounded cell morphology and filopodia protrusions extending at the leading edge.

Ionizable phospholipid nanoparticles have been designed to efficiently destabilize endosomal membranes and mediate organ-selective mRNA delivery and CRISPR–Cas9 gene editing.

A symbiotic culture of bacteria and yeast is used to fabricate bacterial cellulose-based living materials that respond to external cues and adapt their structural and functional properties, with implications for sensing and catalytic applications.

Extrusion-based bioprinting has been shown to rapidly and reproducibly generate kidney organoids from a cell-only paste, with the number and maturation of functional units within the kidney tissue capable of being further improved by bioprinting tissue sheets.

This Review provides an overview of bioengineering technologies that can be harnessed to facilitate the culture, self-organization and functionality of human pluripotent stem cell-derived organoids.

Microporous annealed-particle degradable scaffolds have been developed and shown to induce type 2 innate and adaptive immune response that facilitated skin wound healing.

A 3D bioprinting approach has been developed to facilitate tissue morphogenesis by directly depositing organoid-forming stem cells in an extracellular matrix, with the ability to generate intestinal epithelia and branched vascular tissue constructs.

Wnt3a protein has been immobilized on a biocompatible bandage and is now shown to induce oriented asymmetric cell division of human skeletal stem cells and can also promote bone tissue repair in vivo.

Type-1 innate lymphoid cells have been shown to drive intestinal epithelial proliferation and extracellular matrix remodelling through TGF-β1 secretion, which could exacerbate inflammatory bowel disease comorbidities such as cancer and fibrosis.

Shear-aligned keratin protofibres are used to fabricate shape-memory fibres and three-dimensional scaffolds that respond to water.

A coating made from densely packed hydroxyapatite particles in an organic matrix endows the dactyl club of mantis shrimps with high stiffness and energy damping.

Protein-based materials for soft robotics that self-heal within a second while maintaining the high strength of the damaged area are reported.

A cell culture interfacing an organic neuromorphic device in a microfluidic system reversibly modifies the device synaptic weight through chemical reactions mediated by the release of dopamine, a neurotransmitter used in biological synapses.

Atomic force microscopy indentation measurements of cells cultured on soft substrates may result in an underestimation of cell stiffness. A model has now been developed that takes this soft substrate effect into account, revealing that cortical cell stiffness is largely independent of substrate mechanics.

Dendritic cells concentrated in vivo within a hydrogel have been metabolically tagged with azido groups to enable tracking as well as delivery of antigens, adjuvants and cytokines, thereby facilitating targeted immunomodulation.

The polarity of primary hepatocytes has now been shown to be inducible at the single-cell level by passive artificial micro-niches, indicating that the early development of polarity occurs largely independently of the types and response of the neighbouring cells.

Biocompatible and degradable silk materials with programmable mechanical properties can be directly obtained from regenerated amorphous silk using thermal moulding.

The generation of aligned extracellular matrices by fibroblasts is shown to depend on cell reorientation following collision, leading to closer alignment of the cells’ long axes. This cell collision guidance depends on the transcription factor TFAP2C and localized regulation of actomyosin contractility.

Epithelial tissues behave as pre-tensed viscoelastic sheets that can buffer against compression and rapidly recover from buckling. Epithelial mechanical properties define a tissue-intrinsic buckling threshold that dictates the compressive strain above which tissue folds become permanent.

A RAB5A-mediated, epidermal growth factor-dependent activation of endosomal ERK1/2 is identified as a key molecular route for a solid-to-liquid-like phase transition, sufficient to overcome kinetic and proliferation arrest in normal mammary epithelial assemblies and to promote collective invasion in breast carcinoma.

Kirigami metamaterials show significant terahertz circular dichroism and are adopted as tunable optical elements in the terahertz region.

Foreign body response can result in failure of biomaterials in vivo. Solvent-free crystals containing anti-fibrotic drugs now show the potential for long-term inhibition of fibrosis on a number of implantable devices in rodents and non-human primates.

High-spatial-resolution mechanical imaging reveals that intracellular forces generate cellular nanoscale stiffness patterns.

The Alx3 transcription factor, expressed in prenatal tooth development, is shown to revitalize adult progenitor cells in decellularized scaffolds, leading to enhanced parenchymal dental pulp and vascularized stroma regeneration in vivo.

A modular approach of photoreversible patterning of macromolecules with high spatiotemporal resolution within hydrogels is employed to generate biomaterials with controllable cell activity through site-specific immobilization of proteins.

Molten salts are used as a reaction medium to protect carbide, nitride and boride powders from oxidation during high-temperature synthesis in air, thus avoiding the need to carry out these processes in a vacuum or inert environment.

The extracellular matrix surrounding cells plays a significant role in their behaviour. The spreading, mechanosensing and differentiation of mesenchymal stem cells are shown to be dependent on the early deposition and remodelling of local nascent proteins within degradable and viscoelastic hydrogels.

Neural probes mimicking the size and mechanical properties of neurons interpenetrate the brain tissue, allowing stable single-unit recordings from implantation up to at least three months, and acting as scaffolds for the migration of new-born neurons.

A method to accelerate the generation of kidney organoids from human pluripotent stem cells cultured in a three-dimensional environment and exposed to inductive stimuli has been developed, with the organoids capable of recapitulating kidney organogenesis.

Microparticle wear debris from prosthetic implants following patient revision surgery is observed to induce a potent type 2 inflammatory response involving cytokine secretion by macrophages through a Bruton’s tyrosine kinase-dependent signalling pathway.

A vaccine platform has been developed from a polymeric glyco-adjuvant conjugated to an antigen, and is now shown to target dendritic cells via mannose-binding receptors and generate potent cellular and humoral immune response against malaria.

Elastomer sheets with programmable air channel organization swiftly shape into complex three-dimensional structures upon the application of pressure.

A protein-based material with temperature-modulated mechanical properties and function is achieved by the rational incorporation of structural ordering and disordering elements into its polypeptide sequence.

Protocells are synthetic cell-like entities that mimic distinct cellular functions. A synthetic prototissue based on an interlinked protein–polymer protocells community that shows reversible contractibility is now reported.

Ultrafast water transport in the surface of Sarracenia trichome is reported and demonstrated in synthetic bioinspired materials, where nano- and microchannels induce high-speed sliding of droplets on top of a thin water film.

The gastrointestinal tract is a therapeutic target for type-2 diabetes. An orally deliverable sucralfate-based material is shown to form a physical coating in the gut, capable of limiting glucose uptake and also administering drugs to the gut lining.