Fungal Engineered Living Materials: The Viability of Pure Mycelium Materials with Self-Healing Functionalities

Engineered living materials (ELMs) composed entirely of fungal cells offer significant potential due to their functional properties such as self-assembly, sensing, and self-healing. Alongside rapid developments in the ELM field, there is significant and growing interest in mycelium materials, which are made from the vegetative part of filamentous fungi, as a potential source of advanced functional materials. In order to advance the development of fungal ELMs that utilize the organism's ability to regenerate as self-repair, new methods for controlling and optimizing mycelium materials are needed, as well as a better understanding of the biological mechanisms behind regeneration. In this study, pure mycelium materials are fabricated for use as leather substitutes, and it is found that chlamydospores, thick-walled vegetative cells formed at the hyphal tip, may be the key to the material's self-healing properties. The results suggest that mycelium materials can survive in dry and oligotrophic environments, and self-healing is possible with minimal intervention after a two-day recovery period. Finally, the study characterizes the mechanical recovery and physical properties of damaged and healed samples, allowing for the first characterization of fungal ELMs.     

Self‐Assembling Peptides as Cell‐Interactive Scaffolds

Cell and tissue engineering therapies for regenerative medicine as well as cell‐based assays require an understanding of the interactions between cells with the surrounding microenvironment at the nanoscale. Engineering a cell‐interactive scaffold therefore entails control over the nanostructure of the biomaterial. Peptides that are able to self‐assemble into 3D scaffolds have emerged as interesting biomaterials for directing cell behavior, with desirable properties such as the capability of tuning the nanostructure by modulating the amino acid composition. Here, an overview of the development of self‐assembling peptide hydrogels as functional cell scaffolds is presented, highlighting recent work on incorporating features such as bioactive ligands, growth factor delivery, controlled degradation, and formulation into microgels for defined cell microenvironments.     

Electrospun Extracellular Matrix: Paving the Way to Tailor‐Made Natural Scaffolds for Cardiac Tissue Regeneration

Biomimetic scaffolds generally aim at structurally and compositionally imitating native tissue, thus providing a supportive microenvironment to the transplanted or recruited cells in the tissue. Native decellularized porcine extracellular matrix (ECM) is becoming the ultimate bioactive material for the regeneration of different organs. Particularly for cardiac regeneration, ECM is studied as a patch and injectable scaffolds, which improve cardiac function, yet lack reproducibility and are difficult to control or fine‐tune for the desired properties, like most natural materials. Seeking to harness the natural advantages of ECM in a reproducible, scalable, and controllable scaffold, for the first time, a matrix that is produced from whole decellularized porcine cardiac ECM using electrospinning technology, is developed. This unique electrospun cardiac ECM mat preserves the composition of ECM, self‐assembles into the same microstructure of cardiac ECM ,and ,above all, preserves key cardiac mechanical properties. It supports cell growth and function, and demonstrates biocompatibility in vitro and in vivo. Importantly, this work reveals the great potential of electrospun ECM‐based platforms for a wide span of biomedical applications, thus offering the possibility to produce complex natural materials as tailor‐made, well‐defined structures.     

A Bionanozyme with Ultrahigh Activity Enables Spatiotemporally Controlled Reactive Oxygen Species Generation for Cancer Therapy

Nanozymes hold great potential in nanomedicine, yet biotoxicity limits their clinical translation because of their uncontrolled catalytic activity, artificial inorganic components, and harsh synthesis conditions. Herein, a peroxidase-like bionanozyme with ultrahigh and photocontrolled catalytic activity through the self-assembly of biomolecules, hemin, and in situ polymerization of pyrrole in an aqueous solution is reported. Such bionanozymes leverage the specific cues of the tumor microenvironment and precise light-induced photothermal heating for spatiotemporally controlled reactive oxygen species generation in tumors. The tunable catalytic activity and excellent biocompatibility of the bionanozyme result in high cancer cell apoptosis and tumor growth inhibition in murine models with negligible biotoxicity. This work highlights the potential of biomolecule-based nanozymes for cancer-specific therapy. Bionanozymes with ultrahigh and tunable catalytic activity may lay the important foundation for more advanced nanomedicine and biosensing.     

Emerging Plasmonic Assemblies Triggered by DNA for Biomedical Applications

Plasmonic gold nanocrystal represents plasmonic metal nanomaterials, and has a variety of unique and beneficial properties, such as optical signal enhancement, catalytic activity, and photothermal properties tuned by local temperature, which are useful in physical, chemical, and biological applications. In addition, the inherent properties of predictable programmability, sequence specificity, and structural plasticity provide DNA nanostructures with precise controllability, spatial addressability, and targeting recognition, serving as ideal ligands to link or position building blocks during the self-assembly process. Self-assembly is a common technique for the organization of prefabricated and discrete nanoparticle blocks for the construction of extremely sophisticated nanocomposites. To this end, the integration of DNA nanotechnology with Au nanomaterials, followed by assembly of DNA-functionalized Au nanomaterials can form novel functional Au nanomaterials that are difficult to obtain through conventional methods. Here, recent progress in DNA-assembled Au nanostructures of various shapes is summarized, and their functions are discussed. The fabrication strategies that employ DNA for the self-assembly of Au nanostructures, including dimers, tetramers, satellites, nanochains, and other nanostructures with more complex geometric configurations are first described. Then, the characteristic optical properties and applications of biosensing, bioimaging, drug delivery, and therapy are discussed. Finally, the remaining challenges and prospects are elucidated.     

自组装——自底而上的纳米制造方法

介绍了“自底而上”的自组装纳米制造方法中的一些关键技术。利用自组装技术将成形的或未成形的材料淀积在大面积基底上,制造出纳米结构和分子局域自组装装置,并通过由自组装技术发展而来的原子操作和蘸水笔纳米加工技术,以构建纳米尺度的图形。描述了与这些技术相关的原理和工艺过程以及其当前的应用和潜在的应用前景。     

Protein Corona Influences Cell–Biomaterial Interactions in Nanostructured Tissue Engineering Scaffolds

Biomaterials are extensively used to restore damaged tissues, in the forms of implants (e.g., tissue engineered scaffolds) or biomedical devices (e.g., pacemakers). Once in contact with the physiological environment, nanostructured biomaterials undergo modifications as a result of endogenous proteins binding to their surface. The formation of this macromolecular coating complex, known as “protein corona,” onto the surface of nanoparticles and its effect on cell–particle interactions are currently under intense investigation. In striking contrast, protein corona constructs within nanostructured porous tissue engineering scaffolds remain poorly characterized. As organismal systems are highly dynamic, it is conceivable that the formation of distinct protein corona on implanted scaffolds might itself modulate cell–extracellular matrix interactions. Here, it is reported that corona complexes formed onto the fibrils of engineered collagen scaffolds display specific, distinct, and reproducible compositions that are a signature of the tissue microenvironment as well as being indicative of the subject's health condition. Protein corona formed on collagen matrices modulated cellular secretome in a context‐specific manner ex vivo, demonstrating their role in regulating scaffold–cellular interactions. Together, these findings underscore the importance of custom‐designing personalized nanostructured biomaterials, according to the biological milieu and disease state. The use of protein corona as in situ biosensor of temporal and local biomarkers is proposed.     

Microphysiological Systems as Enabling Tools for Modeling Complexity in the Tumor Microenvironment and Accelerating Cancer Drug Development

Tumor cell heterogeneity with distinct phenotypes, genotypes, and epigenetic states as well as the complex tumor microenvironment is major challenges for cancer diagnosis and treatment. There have been substantial advances in our knowledge of tumor biology and in the capabilities of available biological analysis tools; however, the absence of physiologically relevant in vitro testing platforms limits our ability to gain an in‐depth understanding of the role of the tumor microenvironment in cancer pathology. In this review, recent advances in engineered tumor microenvironments to advance cancer research and drug discovery are presented, including tumor spheroids, microfluidic chips, paper scaffolds, hydrogel‐based engineered tissues, 3D bioprinted scaffolds, and multiscale topography. Furthermore, how these technologies address the specific characteristics of the native tumor microenvironment is described. Through the comparison of these biomimetic 3D tumor models to conventional 2D culture models, the validity and physiological relevance of these platforms for fundamental in vitro studies of the tumor biology, as well as their potential use in drug screening applications, is also discussed.     

The Implications of Polymer Selection in Regenerative Medicine: A Comparison of Amorphous and Semi‐Crystalline Polymer for Tissue Regeneration

Biodegradable polymeric scaffolds are being investigated as scaffolding materials for use in regenerative medicine. While the in vivo evaluation of various three‐dimensional (3D), porous, biodegradable polymeric scaffolds has been reported, most studies are ≤3 months in duration, which is typically prior to bulk polymer degradation, a critical event that may initiate an inflammatory response and inhibit tissue formation. Here, a 6 month in vitro degradation and corresponding in vivo studies that characterized scaffold changes during complete degradation of an amorphous, 3D poly(lactide‐co‐glycolide)(3D‐PLAGA) scaffold and near‐complete degradation of a semi‐crystalline3D‐PLAGA scaffold are reported. Using sintered microsphere matrix technology, constructs were fabricated in a tubular shape, with the longitudinal axis void and a median pore size that mimicked the architecture of native bone. Long‐term quantitative measurements of molecular weight, mechanical properties, and porosity provided a basis for theorization of the scaffold degradation process. Following implantation in a critical size ulnar defect model, histological analysis and quantitative microCT indicated early solubilization of the semi‐crystalline polymer created an acidic microenvironment that inhibited mineralized tissue formation. Thus, the use of amorphous over semi‐crystalline PLAGA materials is advocated for applications in regenerative medicine.     

Polymer Fiber Scaffolds for Bone and Cartilage Tissue Engineering

Successful regeneration of weight‐bearing bone defects and critical‐sized cartilage defects remains a major challenge in clinical orthopedics. In the past decades, biodegradable polymer materials with biomimetic chemical and physical properties have been rapidly developed as ideal candidates for bone and cartilage tissue engineering scaffolds. Due to their unique advantages over other materials of high specific‐surface areas, suitable mechanical strength, and tailorable characteristics, scaffolds made of polymer fibers have been increasingly used for the repair of bone and cartilage defects. This Review summarizes the preparation and compositions of polymer fibers, as well as their characteristics. More importantly, the applications of polymer fiber scaffolds with well‐designed structures or unique properties in bone, cartilage, and osteochondral tissue engineering have been comprehensively highlighted. On the whole, such a comprehensive summary affords constructive suggestions for the development of polymer fiber scaffolds in bone and cartilage tissue engineering.     

SACs on Non-Carbon Substrates: Can They Outperform for Water Splitting?

Non-carbon-supported single-atom electrocatalysts (SACs) have attracted tremendous research interest for water splitting, owning to their remarkable differences in bond and coordination, and better and tunable catalytic performance, compared with those carbon-supported SACs and commercial catalysts. The electrocatalytic performance of these non-carbon-supported SACs is intimately related to the structure, surficial chemical groups, and vacancy defects of non-carbon host materials, as well as the physico-chemical properties and population of single atoms. The much widened range of host materials and types of single atoms create virtually limitless opportunities in the design of SACs with tunable structures and electrocatalysis behaviors. In this review, the recent progress of non-carbon-supported SACs for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is visited, where the unique local structures, electrocatalytic performance, catalytic centers and key preparation processes are presented. The characterizations down to atomic scales that can reveal the key local structures and catalytic mechanism are also investigated. New insights into the correlations between the structural evolution of these SACs during electrocatalytic reactions and their catalytic performance are examined. Finally, the major challenges faced by these new SACs are summarized, together with future perspectives on the rational design of superior non-carbon-supported SACs.     

Silica‐Gelatin Hybrids with Tailorable Degradation and Mechanical Properties for Tissue Regeneration

Nature has evolved mechanisms to create a diversity of specialized materials through nanoscale organization. Inspired by nature, hybrid materials are designed with highly tailorable properties, which are achieved through careful control of their nanoscale interactions. These novel materials, based on a silica‐gelatin hybrid system, have the potential to serve as a platform technology for human tissue regeneration. Covalent interactions between the inorganic and organic constituents of the hybrid are essential to enable the precise control of mechanical and dissolution properties. Furthermore, hybrid scaffold porosity is found to highly influence mechanical properties, to the extent where scaffolds of particular strength could be specified based on their porosity. The hybrids also demonstrate a non‐cytotoxic effect when mesenchymal stem cells are cultured on the material. Cytoskeletal proteins of the cells are imaged using actin and vimentin staining. It is envisaged these hybrid materials will find a diverse application in both hard and soft tissue regenerating scaffolds.     

Hybrid Materials: Silica‐Gelatin Hybrids with Tailorable Degradation and Mechanical Properties for Tissue Regeneration (Adv. Funct. Mater. 22/2010)

Nature has evolved mechanisms to create a diversity of specialized materials through nanoscale organization. Inspired by nature, hybrid materials are designed with highly tailorable properties, which are achieved through careful control of their nanoscale interactions. These novel materials, based on a silica‐gelatin hybrid system, have the potential to serve as a platform technology for human tissue regeneration. Covalent interactions between the inorganic and organic constituents of the hybrid are essential to enable the precise control of mechanical and dissolution properties. Furthermore, hybrid scaffold porosity is found to highly influence mechanical properties, to the extent where scaffolds of particular strength could be specified based on their porosity. The hybrids also demonstrate a non‐cytotoxic effect when mesenchymal stem cells are cultured on the material. Cytoskeletal proteins of the cells are imaged using actin and vimentin staining. It is envisaged these hybrid materials will find a diverse application in both hard and soft tissue regenerating scaffolds.     

Tissue Regeneration through Cyber-Physical Systems and Microbots

Tissue engineering is a systematic approach of assembling cells onto a 3D scaffold to form a functional tissue in the presence of critical growth factors. The scaffolding system guides stem cells through topological, physiochemical, and mechanical cues to differentiate and integrate to form a functional tissue. However, cellular communication during tissue formation taking place in a reactor needs to be understood properly to enable appropriate positioning of the cells in a 3D environment. Hence, sensors and actuators integrated with cyber-physical system (CPS) may be able to sense the tissue microenvironment and direct cells/cellular aggregates to an appropriate position, respectively. This can facilitate better cell-to-cell communication and cell–extracellular matrix communication for proper tissue morphogenesis. Advancements are made in the field of smart scaffolds that can morph cells/cellular aggregates after sensing the cellular microenvironment in a desired 3D architecture by providing appropriate cues. Recent scientific developments in the additive manufacturing technology have enabled the fabrication of smart scaffolds to create structural and functional tissue constructs. Sensors/actuators, cyber-systems, smart materials, and additive manufacturing put together is expected to lead to improved tissue-engineered medical products. The present review aims to highlight the possibilities of advancement of BioCPS for tissue engineering and regenerative medicine.     

Artificial Helical Screws of 2D Materials with Archimedean Spiral Arrangement

Helix structures, which are frequently observed in nature, act as versatile structural templates for complex functionalities with asymmetry and anisotropy. However, atomically thin 2D materials, including graphene, transition metal dichalcogenides (TMDs), and MXenes, do not have inherent chirality in their planar geometry and cannot easily form such a structure. This study presents the macroscopic self-assembly of 2D materials for helical screws with an Archimedean spiral arrangement. The naturally triggered spontaneous rotation upon the 1D fiber assembly of 2D materials forms helical screws consisting of multiple helices and perversions. For a clear understanding of the morphological evolution of helical screws, variations in the helical pitch and angle are systematically analyzed considering thermodynamic and kinetic conditions. Subsequently, the influence of spontaneous helix formation on the properties of the 2D assembled fibers is investigated in terms of the solvent-driven actuator performance and electrical and electrothermal properties. The suggested approach provides a new perspective on the directed self-assembly of inherently achiral 2D materials toward chiral helix formation.     

Healing DNA Self-Assemblies Using Punctures

In self-assembly, individual components (commonly referred to as tiles) have sufficient infor mation to build templates for structures such as lat tices for two-dimensional scaffolds. Tile sets that can heal (fully or partially) an erroneous DNA assembly have been proposed. Healing requires growth to be restarted such that erroneous tiles can be removed and the correct tiles can bind to the aggregate. Punctures have been proposed for this purpose; in this paper, a puncture is intentionally induced in the self-assembly to restart the growth process. The goal of this paper is to characterize an intentionally induced puncture (and its relevant properties) on an erroneous tile site in the grown crystal as part of a healing process. This allows to propagate any newly generated error away from the source of growth (i.e. the seed tile), such that self-assembly can continue along specific directions. Different types of puncture are considered with respect to healing and related features, such as growth direction, error and aggregate types. Punctures are analyzed using a new characterization and metric; different tile sets are investigated in detail for healing of a DNA self-assembly.

Recent Advances in Electrospun Nanofibrous Scaffolds for Cardiac Tissue Engineering

Cardiovascular diseases remain the leading cause of human mortality worldwide. Some severe symptoms, including myocardial infarction and heart failure, are difficult to heal spontaneously or under systematic treatment due to the limited regenerative capacity of the native myocardium. Cardiac tissue engineering has emerged as a practical strategy to culture functional cardiac tissues and relieve the disorder in myocardium when implanted. In cardiac tissue engineering, the design of a scaffold is closely relevant to the function of the regenerated cardiac tissues. Nanofibrous materials fabricated by electrospinning have been developed as desirable scaffolds for tissue engineering applications because of the biomimicking structure of protein fibers in native extra cellular matrix. The versatilities of electrospinning on the polymer component, the fiber structure, and the functionalization with bioactive molecules have made the fabrication of nanofibrous scaffolds with suitable mechanical strength and biological properties for cardiac tissue engineering feasible. Here, an overview of recent advances in various electrospun scaffolds for engineering cardiac tissues, including the design of advanced electrospun scaffolds and the performance of the scaffolds in functional cardiac tissue regeneration, is provided with the aim to offer guidance in the innovation of novel electrospun scaffolds and methods for improving their potential for cardiac tissue engineering applications.     

Colloid-Mediated Fabrication of a 3D Pollen Sponge for Oil Remediation Applications

There is tremendous interest in developing 3D scaffolds from natural materials for a wide range of healthcare, energy, photonic, and environmental science applications. To date, most natural materials that are used to make 3D scaffolds consist of fibril structures; however, it would be advantageous to explore the development of scaffolds from natural materials with distinct supramolecular structures. Herein, the fabrication of a mechanically responsive pollen sponge that exhibits tunable 3D scaffold properties and is useful for oil remediation applications is reported. By using pollen-based microgel particles as colloidal building blocks, the sponge fabrication process is optimized by tuning the processing conditions during freeze-drying and thermal annealing steps. Stearic acid functionalization transforms the pollen sponge into a hydrophobic scaffold that can readily and repeatedly absorb oil and other organic solvents from contaminated water sources, with similar performance levels to commercial, synthetic polymer-based absorbents and an improved environmental footprint.     

3D Printed Enzyme-Functionalized Scaffold Facilitates Diabetic Bone Regeneration

Patients with diabetes mellitus (DM) suffer from a high risk of fractures and poor bone healing ability. Surprisingly, no effective therapy is available to treat diabetic bone defect in clinic. Here, a 3D printed enzyme-functionalized scaffold with multiple bioactivities including osteogenesis, angiogenesis, and anti-inflammation in diabetic conditions is proposed. The as-prepared multifunctional scaffold is constituted with alginate, glucose oxidase (GOx), and catalase-assisted biomineralized calcium phosphate nanosheets (CaP@CAT NSs). The GOx inside scaffolds can alleviate the hyperglycemia environment by catalyzing glucose and oxygen into gluconic acid and hydrogen peroxide (H₂O₂). Both the generated H₂O₂ as well as the overproduced H₂O₂ in DM can be scavenged by CaP@CAT NSs, while the initiated hypoxic microenvironment stimulates neovascularization. Moreover, the incorporation of CaP@CAT NSs not only enhance the mechanical property of the scaffolds, but also facilitate bone regeneration by the degraded Ca²⁺ and PO₄³⁻ ions. The remarkable in vitro and in vivo outcomes demonstrate that enzymes functionalized scaffolds can be an effective strategy for enhancing bone tissue regeneration in diabetic conditions, underpinning the potential of multifunctional scaffolds for diabetic bone regeneration.     

Triple Enzyme-Regulated Molecular Hydrogels for Carrier-Free Delivery of Lonidamine

Cancerous cells exhibit overexpression of multiple enzymes in various cellular compartments. These enzymes are often undruggable, yet display unique advantages in regulating intracellular self-assembly and dis-assembly of small molecules for cancer targeting. Herein, a self-assembling molecule (LND-1p-ES) for carrier-free delivery of lonidamine specifically to cancerous cells is designed, where LND-1p-ES executes as both a drug and a carrier with combined benefits thereof. Under the precise regulation of phosphatase (ALP) and esterase (CES), LND-1p-ES is capable of self-assembling intracellularly in a spatiotemporal manner, to confer lonidamine-borne nanofibers with enhanced cellular uptake. These nanofibers also facilitate controlled drug release with the aid of cellular proteases. Taking advantages of overexpressing ALP and CES as well as proteases in cancerous cells, the LND-1p-ES formulation demonstrates enhanced potency and selectivity against melanoma cells A375 in vitro and in vivo. In comparison, none/single enzyme responsive compounds fail to show a similar potency or selectivity, further confirming the indispensable roles of these enzymes in the delivery system. Collectively, the research provides a viable strategy to utilize multiple enzymes in cancerous cells for regulation of intracellular self-assembly, which can be expanded to design smart soft materials responsive to multiple biologically relevant biomolecules for enhanced therapeutic efficacy.