A biomimetic spore nanoplatform for boosting chemodynamic therapy and bacteria-mediated antitumor immunity for synergistic cancer treatment

Bacterial-based antitumor immunity has become a promising strategy to activate the immune system for fighting cancer.However,the potential application of bacterial therapy is hindered by the presence of instability and susceptibility to infections within bacterial populations.Furthermore,monotherapy is ineffective in completely eliminating complex cancer with multiple contributing factors.In this study,based on our discovery that spore shell(SS)of Bacillus coagulans exhibits excellent tumor-targeting ability and adjuvant activity,we develop a biomimetic spore nanoplatform to boost bacteria-mediated antitumor therapy,chemodynamic therapy and antitumor immunity for synergistic cancer treatment.In detail,SS is separated from probiotic spores and then attached to the surface of liposome(Lipo)that was loaded with hemoglobin(Hb),glucose oxidase(GOx)and JQ1to construct SS@Lipo/Hb/GOx/JQ1.In tumor tissue,highly toxic hydroxyl radicals(·OH)are generated via sequential catalytic reactions:GOx catalyzing glucose into H_(2)O_(2)and Fe^(2+)in Hb decomposing H_(2)O_(2)into·OH.The combination of·OH and SS adjuvant can improve tumor immunogenicity and activate immune system.Meanwhile,JQ1-mediated down-regulation of PD-L1 and Hb-induced hypoxia alleviation synergistically reshape immunosuppressive tumor microenvironment and potentiate immune response.In this manner,SS@Lipo/Hb/GOx/JQ1 significantly suppresses tumor growth and metastasis.To summarize,the nanoplatform represents an optimum strategy to potentiate bacteria-based cancer immunotherapy.

Biomimetic 3D printing of composite structures with decreased cracking

The development of tissue engineering and regeneration research has created new platforms for bone transplantation.However,the preparation of scaffolds with good fiber integrity is challenging,because scaffolds prepared by traditional printing methods are prone to fiber cracking during solvent evaporation.Human skin has an excellent natural heat-management system,which helps to maintain a constant body temperature through perspiration or blood-vessel constriction.In this work,an electrohydrodynamic-jet 3D-printing method inspired by the thermal-management system of skin was developed.In this system,the evaporation of solvent in the printed fibers can be adjusted using the temperature-change rate of the substrate to prepare 3D structures with good structural integrity.To investigate the solvent evaporation and the interlayer bonding of the fibers,finite-element analysis simulations of a three-layer microscale structure were carried out.The results show that the solvent-evaporation path is from bottom to top,and the strain in the printed structure becomes smaller with a smaller temperaturechange rate.Experimental results verified the accuracy of these simulation results,and a variety of complex 3D structures with high aspect ratios were printed.Microscale cracks were reduced to the nanoscale by adjusting the temperature-change rate from 2.5 to 0.5℃s-1.Optimized process parameters were selected to prepare a tissue engineering scaffold with high integrity.It was confirmed that this printed scaffold had good biocompatibility and could be used for bone-tissue regeneration.This simple and flexible 3D-printing method can also help with the preparation of a wide range of micro-and nanostructured sensors and actuators.

Confined cobalt single-atom catalysts with strong electronic metal-support interactions based on a biomimetic self-assembly strategy

Designing high-performance and low-cost electrocatalysts for oxygen evolu-tion reaction(OER)is critical for the conversion and storage of sustainable energy technologies.Inspired by the biomineralization process,we utilized the phosphorylation sites of collagen molecules to combine with cobalt-based mononuclear precursors at the molecular level and built a three-dimensional(3D)porous hierarchical material through a bottom-up biomimetic self-assembly strategy to obtain single-atom catalysts confined on carbonized biomimetic self-assembled carriers(Co SACs/cBSC)after subsequent high-temperature annealing.In this strategy,the biomolecule improved the anchoring efficiency of the metal precursor through precise functional groups;meanwhile,the binding-then-assembling strategy also effectively suppressed the nonspecific adsorption of metal ions,ultimately preventing atomic agglomeration and achieving strong electronic metal-support interactions(EMSIs).Experimental characterizations confirm that binding forms between cobalt metal and carbonized self-assembled substrate(Co–O_(4)–P).Theoretical calculations disclose that the local environment changes significantly tailored the Co d-band center,and optimized the binding energy of oxygenated intermediates and the energy barrier of oxygen release.As a result,the obtained Co SACs/cBSC catalyst can achieve remarkable OER activity and 24 h durability in 1 M KOH(η10 at 288 mV;Tafel slope of 44 mV dec-1),better than other transition metal-based catalysts and commercial IrO_(2).Overall,we presented a self-assembly strategy to prepare transition metal SACs with strong EMSIs,providing a new avenue for the preparation of efficient catalysts with fine atomic structures.

Biomimetic Erythrocyte-Like Particles from Microfluidic Electrospray for Tissue Engineering

Microparticles have demonstrated value for regenerative medicine.Attempts in this field tend to focus on the development of intelligent multifunctional microparticles for tissue regeneration.Here,inspired by erythrocytes-associated self-repairing process in damaged tissue,we present novel biomimetic erythrocyte-like microparticles(ELMPs).These ELMPs,which are composed of extracellular matrix-like hybrid hydrogels and the functional additives of black phosphorus,hemoglobin,and growth factors(GFs),are generated by using a microfluidic electrospray.As the resultant ELMPs have the capacity for oxygen delivery and near-infrared-responsive release of both GFs and oxygen,they would have excellent biocompatibility and multifunctional performance when serving as microscaffolds for cell adhesion,stimulating angiogenesis,and adjusting the release profile of cargoes.Based on these features,we demonstrate that the ELMPs can stably overlap to fill a wound and realize controllable cargo release to achieve the desired curative effect of tissue regeneration.Thus,we consider our biomimetic ELMPs with discoid morphology and cargo-delivery capacity to be ideal for tissue engineering.

Crystalline-magnetism action in biomimetic mineralization of calcium carbonate

The influence of minor environmental factors,such as the geomagnetic field,on the biomineralization of nacres,is often ignored but a great deal of research has confirmed its important role in the normal mineralization of calcium carbonate.Although the geomagnetic field is weak,its cumulative effects need to be considered given that the biomineralization process can take years.Accordingly,the authors of this paper have investigated the effects of weak magnetic fields(25 Gs or 50 Gs)on calcium carbonate mineralization and analyzed the mechanism involved.The results show that even a weak magnetic field conduces to the formation of vaterite or aragonite,in the induction order of precursor→vaterite→aragonite.The stronger the magnetic field and the longer the time,the more obvious the induction effect.The effect of a magnetic field is strongest in the aging stage and weakest in the solution stage.Inductions by egg-white protein and by a magnetic field inhibit each other,but they both restrict particle growth.These findings highlight the importance of minor environmental factors for biomineralization and can serve as a reference for biomimetic preparation of a CaCO_(3)nacre-like structure and for anti-scale technology for circulating cooling water.

Effect of an Artificial Caudal Fin on the Performance of a Biomimetic Fish Robot Propelled by Piezoelectric Actuators

This paper addresses the design of a biomimetic fish robot actuated by piezoeeramic actuators and the effect of artificial caudal fins on the fish robot＇s performance. The limited bending displacement produced by a lightweight piezocomposite actuator was amplified and transformed into a large tail beat motion by means of a linkage system. Caudal fins that mimic the shape of a mackerel fin were fabricated for the purpose of examining the effect of caudal fm characteristics on thrust production at an operating frequency range. The thickness distribution of a real mackerel＇s fin was measured and used to design artificial caudal fins. The thrust performance of the biomimetic fish robot propelled by fins of various thicknesses was examined in terms of the Strouhal number, the Froude number, the Reynolds number, and the power consumption. For the same fm area and aspect ratio, an artificial caudal fin with a distributed thickness shows the best forward speed and the least power consumption.

Effects of Biomimetic Surface Designs on Furrow Opener Performance

The effects of biomimetic designs of tine furrow opener surface on equivalent pressure and pressure in the direction of motion on opener surface against soil were studied by finite element method (FEM) simulation and the effects of these designs on tool force and power requirements were examined experimentally.Geometrical structures of the cuticle surfaces of dung beetle (Copris ochus Motschulsky) were examined by stereoscopy.The structures of the cuticle surfaces and Ultra High Mo- lecular Weight Polyethylene (UHMWPE) material were modeled on surface of tine furrow opener as biomimetic designs.Seven furrow openers were analyzed in ANSYS program (a FEM simulation software).The biomimetic furrow opener surfaces with UHMWPE structures were found to have lower equivalent pressure and pressure in the direction of motion as compared to the conventional surface and to the biomimetic surfaces with textured steel-35 structures.It was found that the tool force and power were increased with the cutting depth and operating speed and the biomimetic furrow opener with UHMWPE tubular section ridges showed the lowest resistance and power requirement against soil..

A Biomimetic Climbing Robot Based on the Gecko

The excellent climbing performance of the gecko is inspiring engineers and researchers for the design of artificial systems aimed at moving on vertical surfaces. Climbing robots could perform many useful tasks such as surveillance, inspection, repair, cleaning, and exploration. This paper presents and discusses the design, fabrication, and evaluation of two climbing robots which mimic the gait of the gecko. The first robot is designed considering macro-scale operations on Earth and in space. The second robot, whose motion is controlled using shape memory alloy actuators, is designed to be easily scaled down for micro-scale applications. Proposed bionic systems can climb up 65 degree slopes at a speed of 20 mm·s^-1.

Biomimetic Shoulder Complex Based on 3-PSS/S Spherical Parallel Mechanism

The application of the parallel mechanism is still limited in the humanoid robot fields, and the existing parallel humanoid robot joint has not yet been reflected the characteristics of the parallel mechanism completely, also failed to solve the problem, such as small workspace, effectively. From the structural and functional bionic point of view, a three degrees of freedom（DOFs） spherical parallel mechanism for the shoulder complex of the humanoid robot is presented. According to the structure and kinetic characteristics analysis of the human shoulder complex, 3-PSS/S（P for prismatic pair, S for spherical pair） is chosen as the original configuration for the shouder complex. Using genetic algorithm, the optimization of the 3-PSS/S spherical parallel mechanism is performed, and the orientation workspace of the prototype mechanism is enlarged obviously. Combining the practical structure characteristics of the human shouder complex, an offset output mode, which means the output rod of the mechanism turn to any direction at the point a certain distance from the rotation center of the mechanism, is put forward, which provide possibility for the consistent of the workspace of the mechanism and the actual motion space of the human body shoulder joint. The relationship of the attitude angles between different coordinate system is derived, which establishs the foundation for the motion descriptions under different conditions and control development. The 3-PSS/S spherical parallel mechanism is proposed for the shoulder complex, and the consistence of the workspace of the mechanism and the human shoulder complex is realized by the stuctural parameter optimization and the offset output design.

A Biomimetic Study of Discontinuous-Constraint Metamorphic Mechanism for Gecko-Like Robot

Locomotion ability, efficiency and reliability are key targets for a good robot. The linkage mechanism for robot locomotion is a discontinuous-constraint metamorphic mechanism. Here we set up equations to present the discontinuous-constraint, point out that driving and controlling are the key points to improve the performance and efficiency of the linkage mechanism. Inspired by controlling strategy of the motor nervous system in peripheral vertebrae to the locomotion, we draw off motor control and drive strategy.

Biologically Inspired Self-assembling Synthesis of Bone-like Nano-hydroxyapatite/PLGA-(PEG-ASP)_n Composite: A New Biomimetic Bone Tissue Engineering Scaffold Material

A new biomimetic bone tissue engineering scaffold material, nano-HAI PLGA-（ PEG-Asp ）n composite, was synthesized by a biologically inspired self-assembling approach. A novel biodegradable PLGA- （ PEG-Asp ）n copolymer with pendant amine functional groups and enhanced hydrophilicity woo synthesized by bulk ring-opening copolymerization by DL-lactide（ DLLA） and glycolide（ GA ） with Aspartic acid （ Asp ）-Polyethylene glycol（PEG） alt-prepolymer. A Three-dimensional, porous scaffold of the PLGA-（ PEG- Asp）n copolymer was fabricated by a solvent casting , particulate leaching process. The scaffold woo then incubated in modified simulated body fluid （naSBF）. Growth of HA nanocrystals on the inner pore surfaces of the porous scaffold is confirmed by calcium ion binding analyses, SEM , mass increooe meoourements and quantification of phosphate content within scaffolds. SEM analysis demonstrated the nucleation and growth of a continuous bonelike, low crystalline carbonated HA nanocrystals on the inner pore surfaces of the PLGA- （ PEG-Asp ）n scaffolds. The amount of calcium binding, total mass and the mass of phosphate on experimental PLGA- （ PEG-Asp ） n scaffolds at different incubation times in mSBF was significantly greater than that of control PLGA scaffolds. This nano-HA/ PLGA-（ PEG- Asp ）n composite stunts some features of natural bone both in main composition and hierarchical microstrueture. The Asp- PEG alt-prepolymer modified PleA copolymer provide a controllable high surface density and distribution of anionic functional groups which would enhance nucleation and growth of bonelike mineral following exposure to mSBF. This biomimetic treatment provides a simple method for surface functionalization and sabsequent mineral nucleation and self-oosembling on bodegradable polymer scaffolds for tissue engineering.

Wetting Behaviours of a Single Droplet on Biomimetic Micro Structured Surfaces

Natural surfaces with super hydrophobic properties often have micro or hierarchical structures.In this paper, the wettingbehaviours of a single droplet on biomimetic micro structured surfaces with different roughness parameters are investigated.Atheoretical model is proposed to study wetting transitions.The results of theoretical analysis are compared with those of experimentindicating that the proposed model can effectively predict the wetting transition.Furthermore, a numerical simulationbased on the meso scale Lattice Boltzmann Method （LBM） is performed to study dynamic contact angles, contact lines, andlocal velocity fields for the case that a droplet displays on the micro structured surface.A spherical water droplet with r= 15 μmfalls down to a biomimetic square-post patterned surface under the force of gravity with an initial velocity of 0.01 m·sand aninitial vertical distance of 20 μm from droplet centre to the top of pots.In spite of a higher initial velocity, the droplet can stillstay in a Cassie state; moreover, it reaches an equilibrium state at t≈17.5 ms, when contact angle is 153.16° which is slightlylower than the prediction of Cassie-Baxter’s equation which gives θ=154.40°.

The fabrication of biomimetic biphasic CAN-PAC hydrogel with a seamless interfacial layer applied in osteochondral defect repair

Cartilage tissue engineering based on biomimetic scaffolds has become a rapidly developing strategy for repairing cartilage defects. In this study, a biphasic CAN-PAC hydrogel for osteochondral defect(OCD)regeneration was fabricated based on the density difference between the two layers via a thermally reactive,rapid cross-linking method. The upper hydrogel was cross-linked by CSMA and NIPAm, and the lower hydrogel was composed of PECDA, AAm and PEGDA. The interface between the two layers was first grafted by the physical cross-linking of calcium gluconate and alginate, followed by the chemical cross-linking of the carbon-carbon double bonds in the other components. The pore sizes of the upper and lower hydrogels were ~ 187.4 and ~ 112.6 μm, respectively. The moduli of the upper and lower hydrogels were ~ 0.065 and~ 0.261 MPa. This prepared bilayer hydrogel exhibited the characteristics of mimetic composition, mimetic structure and mimetic stiffness, which provided a microenvironment for sustaining cell attachment and viability. Meanwhile, the biodegradability and biocompatibility of the CAN-PAC hydrogel were examined in vivo. Furthermore, an osteochondral defect model was developed in rabbits, and the bilayer hydrogels were implanted into the defect. The regenerated tissues in the bilayer hydrogel group exhibited new translucent cartilage and repaired subchondral bone, indicating that the hydrogel can enhance the repair of osteochondral defects.

Plants as concept generators for biomimetic light-weight structures with variable stiffness and self-repair mechanisms

Plants possess many structural and functional properties that have a high potential to serve as concept generators for the production of biomimetic technical materials and structures. We present data on two features of plants (variable stiffness due to pressure changes in cellular structures and rapid self-repair functions) that may be used as models for biomimetic projects.

Influence of Dimensions of UHMW-PE Protuberances on Sliding Resistance and Normal Adhesion of Bangkok Clay Soil to Biomimetic Plates

A number of investigations into application of polymers for macro-morphological modification of tool surface have been carried out. These researches, with extensive stress on convex or domed protuberations as one of the widely used construction units, have tried to harness benefits from using polymers in agriculture. Ultra high molecular weight polyethylene （UHMW-PE） has proved an emerging polymer in its application to reduce soil adhesion. This research was conducted to study the effect of shape （flat, semi-spherical, semi-oblate, semi short-prolate and semi long-prolate） and dimensions （base diameter and dome height） on sliding resistance and normal adhesion of biomimetic plates. To incorporate both shape and size, a dimensionless ratio of height to diameter （HDR） was introduced to characterize the effect of construction unit＇s physique. Experiments were conducted in Bangkok clay soil with dry （ 19.8% d.b.）, sticky （36.9% d.b.） and flooded （60.1% d.b.） soil conditions respectively. Soil at sticky limit exhibited the highest sliding resistance （77.8 N） and normal adhesion （3 kPa to 7 kPa）, whereas these values were 61.7 N and 〈0.2 kPa in dry, and 53.7 N and 0.5 kPa to 1.5 kPa in flooded soil conditions. Protuberances with HDR ≤ 0.5 lowered sliding resistance by 10% - 30% and the same reduced normal adhesion by 10% - 60%. The amount of reduction in both sliding resistance and normal adhesion was higher in flooded soil. Lighter normal loads obviously produced lesser resistance and adhesion.

Biomimetic flexible plate actuators are faster and more efficient with a passive attachment

Using three-dimensional computer simulations, we probe biomimetic free swimming of an internally actuated flexible plate in the regime near the first natural frequency. The plate is driven by an oscillating internal moment approximating the actuation mechanism of a piezoelectric macro fiber composite (MFC) bimorph. We show in our simulations that the addition of a passive attachment increases both swimming velocity and efficiency. Specifically, if the active and passive sections are of similar size, the overall performance is the best. We determine that this optimum is a result of two competing factors. If the passive section is too large, then the actuated portion is unable to generate substantial deflection to create sufficient thrust. On the other hand, a large actuated section leads to a bending pattern that is inefficient at generating thrust especially at higher frequencies.

Friction and Wear Study on Friction Pairs with a Biomimetic Non-smooth Surface of 316L Relative to CF/PEEK under a Seawater Lubricated Condition

Current studies of a seawater axial piston pump mainly solve the problems of corrosion and wear in a slipper pair by selecting materials with corrosion resistance, self-lubrication, and wear resistance. In addition, an appropriate biomimetic non-smooth surface design for the slipper pair can further improve the tribological behavior. In this paper, 316 L stainless steel and CF/PEEK were selected to process the upper and bottom specimens, and the biomimetic non-smooth surface was introduced into the interface between the friction pair. The friction and wear tests were performed on a MMD-5 A tester at a rotation speed of 1000 r/min and load of 200 N under seawater lubricated condition. The results indicate that the main friction form of the smooth surface friction pair corresponds to abrasive wear and adhesive wear and that it exhibits a friction coe cient of 0.05–0.07, a specimen temperature of 56 ℃, a high wear rate, and surface roughness. Pits on the non-smooth surface friction pairs produced hydrodynamic lubrication and reduced abrasive wear, and thus the plowing e ect is their main friction form. The non-smooth surface friction pairs exhibit a friction coe cient of 0.03–0.04, a specimen temperature of 48 ℃, a low wear rate, and surface roughness. The study has important theoretical significance for enriching the lubrication, friction, and wear theory of a seawater axial piston pump, and economic significance and military significance for promoting the marine development and the national defense military.

Advantages of a Biomimetic Stiffness Profile in Pitching Flexible Fin Propulsion

The use of oscillating flexible fins in propulsion has been the subject of several studies in recent years, but attention israrely paid to the specific role of stiffness profile in thrust production.Stiffness profile is defined as the variation in localchordwise bending stiffness (EI) of a fin, from leading to trailing edge.In this study, flexible fins with a standard NACA0012shape were tested alongside fins with a stiffness profile mimicking that of a Pumpkinseed Sunfish (Lepomis gibbosus).The finswere oscillated with a pitching sinusoidal motion over a range of frequencies and amplitudes, while torque, lateral force andstatic thrust were measured.Over the range of oscillation parameters tested, it was shown that the fin with a biomimetic stiffness profile offered a significantimprovement in static thrust, compared to a fin of similar dimensions with a standard NACA0012 aerofoil profile.Thebiomimetic fin also produced thrust more consistently over each oscillation cycle.A comparison of fin materials of different stiffness showed that the improvement was due to the stiffness profile itself, andwas not simply an effect of altering the overall stiffness of the fin.Fins of the same stiffness profile were observed to follow thesame thrust-power curve, independent of the stiffness of the moulding material.Biomimetic fins were shown to produce up to26% greater thrust per watt of input power, within the experimental range.

3D printing biomimeticmaterials and structures for biomedical applications

Over millions of years of evolution,nature has created organisms with overwhelming performances due to their unique materials and structures,providing us with valuable inspirations for the development of next-generation biomedical devices.As a promising new technology,3D printing enables the fabrication of multiscale,multi-material,and multi-functional threedimensional(3D)biomimetic materials and structures with high precision and great flexibility.The manufacturing challenges of biomedical devices with advanced biomimetic materials and structures for various applications were overcome with the flourishing development of 3D printing technologies.In this paper,the state-of-the-art additive manufacturing of biomimetic materials and structures in the field of biomedical engineering were overviewed.Various kinds of biomedical applications,including implants,lab-on-chip,medicine,microvascular network,and artificial organs and tissues,were respectively discussed.The technical challenges and limitations of biomimetic additive manufacturing in biomedical applications were further investigated,and the potential solutions and intriguing future technological developments of biomimetic 3D printing of biomedical devices were highlighted.

Directional sliding of water:biomimetic snake scale surfaces

Bioinspired superhydrophobic surfaces have attracted many industrial and academic interests in recent years.Inspired by unique superhydrophobicity and anisotropic friction properties of snake scale surfaces,this study explores the feasibility to produce a bionic superhydrophobic stainless steel surface via laser precision engineering,which allows the realization of directional superhydrophobicity and dynamic control of its water transportation.Dynamic mechanism of water sliding on hierarchical snake scale structures is studied,which is the key to reproduce artificially bioinspired multifunctional materials with great potentials to be used for water harvesting,droplet manipulation,pipeline transportation,and vehicle acceleration.