Natural materials and bioinspired biomaterials

Biominerals contain trace elements that can give important environmental information, but the mechanism by which these are incorporated into the structure is not well understood. Here, the authors explore the crystallization pathways involved in the formation of nacre, and how these affect the incorporation of trace elements.

Collagen is an important structural protein in connective tissue, but the effect of location and type of micro-ruptures in the structure on the overall tissue is not well understood. Here, the authors use scale-bridging simulations to determine the breakage points in collagen, and how the failure mode helps to prevent material ageing

The genetic basis of spider major ampullate (Ma) gland silk production remains unknown. Hu et al. unveil a molecular atlas of this gland for the golden orb-weaving spider combining genome assembly and multiomics, revealing the single-cell spatial architecture of silk production in the Ma gland.

Animals precisely control the morphology and assembly of guanine crystals to produce diverse optical phenomena but little is known about how organisms regulate crystallization to produce optically useful morphologies. Here, the authors demonstrate that pre-assembled, fibrillar sheets in developing scallop eyes template nucleation and direct the growth and orientation of plate-like guanine crystals showing a striking resemblance to melanosome morphogenesis.

By following morphological changes in supramolecular assemblies of silkworm silk, the authors find that while the initial steps of secretion and storage inside the silk gland follow the micelle theory of silk assembly, a phase rearrangement occurs inside microscale spherical structures that gives rise to the formation of nanoscale spherical assemblies.

Collagen is known to play a key role in the fracture resistance of bone. Here, in situ synchrotron tomography during the mechanical testing of bone is combined with deep learning to mitigate radiation damage, revealing that a compromised collagen network lowers the efficacy of crack deflection.

Engineering ceramic foams are often limited for non-structural usages due to their brittleness. Here the authors elucidate the structural design strategies of echinoderm stereo as a biological ceramic cellular solid for achieving simultaneous high strength and damage tolerance.

Chirality transfer across length-scales is an intriguing phenomenon but connecting the properties of individual building blocks to the emergent features of their resulting large-scale structure remains challenging. Here, the authors investigate the origins of mesophase chirality in cellulose nanocrystal suspensions, whose self-assembly into chiral photonic films has attracted significant interest.

Bioinspired materials require an understanding of how biomaterials achieve the materials properties. Here, the authors report on the load-bearing shell of Discinisca tenuis and explore how hydration changes the dry shell from hard and stiff to soft and flexible within minutes by reorganisation caused by organic matrix swelling.

Biomineral armour is known in a number of diverse creatures but has not previously been observed in insects. Here, the authors report on the discovery and characterization of high-magnesium calcite armour which overlays the exoskeletons of leaf-cutter ants.

The hierarchical structure of nacre is known to contribute to its high strength and toughness, providing inspiration for many biomimetic materials. Here, co-oriented 20 µm stacks of aragonite platelets are shown to contribute to the toughness of nacre, defining a new characteristic length scale.

Spider silk is well known for its high toughness. Here, a comprehensive study of the simultaneous effect of strain rate and humidity on toughness is reported, revealing that toughness is highest under mildly humid conditions and at high strain rates, similar conditions to those in nature.

Underwater adhesive proteins greatly inspired the development of underwater glue but except for specific proteins it is believed that abundant common proteins cannot be converted into underwater glue. Here, the authors demonstrate, using bovine serum albumin as model protein, that unfolded common proteins exhibit high affinity to surfaces and strong internal cohesion via amyloid-like aggregation in water.

Demand for plant proteins is increasing, but these often give an astringent sensation due to poor lubrication performance. Here, the authors report the development of plantprotein microgels with improved lubricity with potential in sustainable foods.

Natural adhesives have received a lot of attention recently. Here, the authors develop a natural biological adhesive from snail mucus that can adhere to wet tissue and be used to accelerate healing of skin wounds.

Bacteriophage are natural antibiotic agents and provide natural building blocks for living biomaterials. Here, the authors crosslink self-organised bacteriophages to make sprayable microgels which preserves the natural antibacterial action, have tuneable auto-fluorescence and demonstrate application in food decontamination.

Controlling the dynamics of natural soft photonic systems is challenging due to difficulties in sourcing and stimulating them. Here, natural bovine tapetum is used to investigate soft biophotonic crystals and dynamically control their response, providing insight into the development of displays and dynamic light management.

Naturally derived biopolymers attracted great interest to construct photonic materials but traditional processing commonly results in non-uniform organization across largescale areas. Here, the authors report a uniform biophotonic organization of cellulose nanocrystals decorated with superparamagnetic nanoparticles enabling transformation from helicoidal cholesteric to uniaxial nematic phase with near-perfect orientation.

Developing effective treatments for noncompressible hemorrhages remains a challenge. Here the authors engineer alkylated chitosan sponges with highly interconnective microchannels and demonstrate anti-infective activity, as well as higher pro-coagulant, hemostatic and wound healing capacities compared to clinically-used materials in rat and pig liver models.

Green use of plant derived proteins in functional materials has been limited by inefficient methods to control micro and nanoscale structure. Here, the authors use nanoscale assembly of water-insoluble plant proteins to make meter scale films with comparable properties to conventional plastics.

Making environmentally responsive materials often requires the use of multi-material devices. Here, the authors report on the use of electric field patterning of alginate hydrogels to make environmentally responsive actuators and demonstrate a range of applications in response to ionic triggers.

Bovine serum albumin proteins are used to fabricate antifouling coatings, but it is unclear which of these give the best coatings. Here, bovine serum albumin proteins from different purification processes are investigated, revealing that fatty acid-free proteins give superior antifouling properties.

Counterfeit medicines are a threat to patient health and public safety. Here, the authors use random patterns formed by fluorescent silk microparticles with various excitation and emission pairs as an edible physical unclonable function that can directly be attached onto the surface of medicines.

The design and manufacture of materials that replicate the form, function, and sustainability of biological solutions remains difficult. Here, key challenges and promising approaches to materials development informed by biology are identified.

Polymeric vesicles are promising candidates for use in a range of applications including drug delivery and cell mimics, however, control over the shape is still a challenge. Here, the authors report control over local curvature formation by addition of salt ions and stimuli responsive polymer to modulate its interaction with polymeric membrane.

Architected materials are known for high stiffness-to-weight behavior but bending-dominated lattices are of interest for their energy absorption performance. Here, an interwoven lattice with decoupled nodes shows significantly higher compliance at similar volume fractions to traditional lattices

High-yield production of well-performing protein materials is challenging due to their high molecular weights and repetitive sequences. Here the authors develop a method to boost the strength of low molecular-weight protein materials by bi-terminal fusion of intrinsically-disordered mussel foot protein fragments, while achieving high yield.

Nacre structure is used as inspiration in the design of impact resistant materials yet natural nacre is overcome by high impact speed attacks from predators. Here, the authors perform a range of testing and demonstrate superior energy dissipation of nacre-like structures at low impact velocities which is lost at higher impact velocities.

The highest tensile strength biomaterial known exists in limpet teeth and replicating this material is of interest. Here, the authors report on the ex vivo growth of teeth and use of isolated limpet tissue and cells providing foundations for the development of this high-tensile biomaterial.

Bioinspired architectures are desired to achieve improved mechanical properties, but challenging to achieve in metallic systems. Here the authors fabricate a Mg-Ti interpenetrating phase composite with brick-and-mortar, Bouligand, and crossed-lamellar architectures by pressureless infiltrating method.

Bio-inspired materials are an intense area of study as researchers try to adapt biomaterials for other applications. Here, the authors report on the processing of protein materials derived from the byssal thread of scallops to create high-extensibility materials with self-recovery under wet conditions.

Piezoelectric materials which are non-toxic and eco-friendly are of interest. Here, the authors report on the creation of collagen-mimetic peptides which can be self-assembled into piezoelectric materials and study the design characteristics required for optimized power generation.

The creation of biomaterials which are resorbable and have biomimetic mechanical properties is key to successful tissue engineering. Here the authors report on the creation of a new biopolymer where the mechanical properties can be tuned by changing the ratios of cis:trans double bonds in the backbone.

Replicating biological patterns is promising for designing materials with multifaceted properties but replication of twisted cholesteric liquid crystal patterns found in insects is extremely difficult. Here, the authors use liquid crystal oligomers to reproduce the textural, structural and color properties of biological liquid crystals.

Corals have evolved as finely tuned light collectors. Here, the authors report on the 3D printing of coral-inspired biomaterials, that mimic the coral-algal symbiosis; these bionic corals lead to dense microalgal growth and can find applications in algal biotechnology and applied coral science.

Interest in protein-based fibers is driven by their unique properties, including biocompatibility and biodegradability. This Review summarizes the synthesis and properties of biomimetic protein fibers, such as keratin, collagen, elastin and silk fibers, and their application in energy, air and water treatment, and biomedical uses.

Response by mechanical deformation to give actuation is essential in the design of soft robots. Here, the authors demonstrate that combining organic molecular crystals with polymers makes it possible to create materials with susceptible properties to changes in temperature and humidity.

Recapitulating the native architecture of myocardium is crucial to engineering functional cardiac tissues. Here, the authors develop a leaf-venation-directed strategy for macroscale cardiac constructs with tissue-like structural, mechanical, and electrophysiological properties.

Salvinia molesta plant has the ability to maintain a stable air layer when submerged underwater due to its specific form. The authors propose here a soft lithography fabrication method of artificial Salvinia leaf assisted with capillary-force induced clustering of micropillar array, for hydrodynamic drag reduction.

Current spread hampers the efficacy of neuromodulation, while existing animal, in vitro and in silico models have failed to give patient-centric insights. Here the authors employ 3D printing and machine learning to advance clinical predictions of current spread for cochlear implant patients.

Cell encapsulation into biomaterials for transplantation is currently limited by inadequate oxygenation. Here the authors present a biomimetic scaffold featuring internal continuous air channels endowed with 10,000-fold higher O2 diffusivity than hydrogels and demonstrate correction of diabetes in immunocompetent mice using rat islets for over 6 months.

Armored fish exoskeletons combine flexibility and protection from predators and territorial attacks. Here, using modeling, 3D printing, and experimental testing, the mechanical origin of anisotropic bending stiffness in fish scale architectures is revealed, providing design guidelines for biomimetics.

Minimally invasive drug delivery is of wide interest and oral tissue is an attractive target for this. Here, the authors report on the creation of mussel-inspired films for retention on the wet oral tissue for the delivery of drugs by diffusion and transport though the mucosal tissue.

It is desirable yet challenging to develop sustainable structural materials to replace petroleum-based plastics. Here, the authors report a facile assembly method for manufacturing high-performance structural materials with a unique combination of high strength, toughness and stiffness.