Adaptive liquid interfaces induce neuronal differentiation of mesenchymal stem cells through lipid raft assembly

Localized assembly in biological activity: Origin of life and future of nanoarchitectonics

The concept of nanoarchitectonics has emerged as a post-nanotechnology paradigm in the field of functional materials development. This concept entails the construction of functional material systems at the nanoscale, based on the knowledge acquired from nanotechnology. In biological systems, advanced nanoarchitectonics is achieved through precise structural organization governed by spatial localization, a process facilitated by localized assembly mechanisms. A thorough understanding of the principles of localized assembly is crucial for the creation of complex, asymmetric, hierarchical organizations that are similar in structure and function to living organisms. This review explores the concept of localized assembly, highlighting its biological inspiration, providing representative examples, and discussing its contributions to nanoarchitectonics. Key examples include assemblies using biological materials, those mimicking cellular functions, and those occurring within cells. Additionally, the role of interfacial interactions and liquid-liquid phase separation in localized assembly is emphasized. Particularly, the utilization of liquid-liquid phase separation demonstrates a remarkable capacity for forming intricate compartmentalized structures without discernible membranes, paving the way for multifunctional, localized systems. These localized assemblies are fundamental to essential biological functions and provide valuable insights into the molecular mechanisms underlying the origin of cells and life. Such understanding holds significant promise for advancing materials nanoarchitectonics, particularly in biomedical applications.

Assembly and Functionality of 2D Protein Arrays

Among the unique classes of 2D nanomaterials, 2D protein arrays garner increasing attention due to their remarkable structural stability, exceptional physiochemical properties, and tunable electronic and mechanical attributes. The interest in mimicking and surpassing the precise architecture and advanced functionality of natural protein systems drives the field of 2D protein assembly toward the development of sophisticated functional materials. Recent advancements deepen the understanding of the fundamental principles governing 2D protein self-assembly, accelerating the creation of novel functional biomaterials. These developments encompass biological, chemical, and templated strategies, facilitating the self-organization of proteins into highly ordered and intricate 2D patterns. Consequently, these 2D protein arrays create new opportunities for integrating diverse components, from small molecules to nanoparticles, thereby enhancing the performance and versatility of materials in various applications. This review comprehensively assesses the current state of 2D protein nanotechnology, highlighting the latest methodologies for directing protein assembly into precise 2D architectures. The transformative potential of 2D protein assemblies in designing next-generation biomaterials, particularly in areas such as biomedicine, catalysis, photosystems, and membrane filtration is also emphasized.

Cascade of phase transitions in a dipeptide supramolecular assembly triggered by a single fatty acid

Significant progress has been achieved with diversity of short peptide supramolecular assemblies. However, their programmable phase modulation by single stimulus remains a great challenge. Herein, we demonstrate a dipeptide supramolecular system undergoes sequentially coupled phase transitions upon hydrogen bonding association and dissociation triggered by a single fatty acid. To be specific, fatty acid at a low specific ratio mediates gel-crystal transformation of the dipeptide supramolecular assembly by rearrangement of hydrogen bonding interactions. Moreover, fatty acid at a high specific ratio induces crystal-sol transition by protonation of the dipeptide, generating strong electrostatic repulsion to cleave hydrogen bonding interactions. Remarkably, the cascade of phase transitions enables spontaneous solid-liquid separation of the dipeptide from one dispersion phase and further dissolution in another in a capture and release fashion. In contrast, it is not facilitated by individual phase transition. Our work creates competitive pathways to achieve integration of phase transitions in a simple dipeptide supramolecular system. It is useful to deeply understand the dynamic and complex biomolecular condensates in nature and with important implications for efficient collection of biomolecules.

Lateral nanoarchitectonics from nano to life: ongoing challenges in interfacial chemical science

Lateral nanoarchitectonics is a method of precisely designing functional materials from atoms, molecules, and nanomaterials (so-called nanounits) in two-dimensional (2D) space using knowledge of nanotechnology. Similar strategies can be seen in biological systems; in particular, biological membranes ingeniously arrange and organise functional units within a single layer of units to create powerful systems for photosynthesis or signal transduction and others. When our major lateral nanoarchitectural approaches such as layer-by-layer (LbL) assembly and Langmuir-Blodgett (LB) films are compared with biological membranes, one finds that lateral nanoarchitectonics has potential to become a powerful tool for designing advanced functional nanoscale systems; however, it is still rather not well-developed with a great deal of unexplored possibilities. Based on such a discussion, this review article examines the current status of lateral nanoarchitectonics from the perspective of in-plane functional structure organisation at different scales. These include the extension of functions at the molecular level by on-surface synthesis, monolayers at the air-water interface, 2D molecular patterning, supramolecular polymers, macroscopic manipulation and functionality of molecular machines, among others. In many systems, we have found that while the targets are very attractive, the research is still in its infancy, and many challenges remain. Therefore, it is important to look at the big picture from different perspectives in such a comprehensive review. This review article will provide such an opportunity and help us set a direction for lateral nanotechnology toward more advanced functional organization.

Interfacial mechanics of β-casein and albumin mixed protein assemblies at liquid-liquid interfaces

Protein emulsifiers play an important role in formulation science, from food product development to emerging applications in biotechnologies. The impact of mixed protein assemblies on surface composition and interfacial shear mechanics remains broadly unexplored, in comparison to the impact that formulation has on dilatational mechanics and surface tension or pressure. In this report, we use interfacial shear rheology to quantify the evolution of interfacial shear moduli as a function of composition in bovine serum albumin (BSA)/β-casein mixed assemblies. We present the pronounced difference in mechanics of these two protein, at oil interfaces, and observe the dominance of β-casein in regulating interfacial shear mechanics. This observation correlates well with the strong asymmetry of adsorption of these two proteins, characterised by fluorescence microscopy. Using neutron reflectometry and fluorescence recovery after photobleaching, we examine the architecture of corresponding protein assemblies and their surface diffusion, providing evidence for distinct morphologies, but surprisingly comparable diffusion profiles. Finally, we explore the impact of crosslinking and sequential protein adsorption on the interfacial shear mechanics of corresponding assemblies. Overall, this work indicates that, despite comparable surface densities, BSA and β-casein assemblies at liquid-liquid interfaces display almost 2 orders of magnitude difference in interfacial shear storage modulus and markedly different viscoelastic profiles. In addition, co-adsorption and sequential adsorption processes are found to further modulate interfacial shear mechanics. Beyond formulation science, the understanding of complex mixed protein assemblies and mechanics may have implications for the stability of emulsions and may underpin changes in the mechanical strength of corresponding interfaces, for example in tissue culture or in physiological conditions.

Nanoarchitectonics of Vesicle Microreactors for Oscillating ATP Synthesis and Hydrolysis

We construct a compartmentalized nanoarchitecture to regulate bioenergy level. Glucose dehydrogenase, urease and nicotinamide adenine dinucleotide are encapsulated inside through liquid-liquid phase separation. ATPase and glucose transporter embedded in hybrid liposomes are attached at the surface. Glucose is transported and converted to gluconic acid catalyzed by glucose dehydrogenase, resulting in an outward proton gradient to drive ATPase for ATP synthesis. In parallel, urease catalyzes hydrolysis of urea to generate ammonia, which leads to an inward proton gradient to drive ATPase for ATP hydrolysis. These processes lead to a change of the direction of proton gradient, thus achieving artificial ATP oscillation. Importantly, the frequency and the amplitude of the oscillation can be programmed. The work explores nanoarchitectonics integrating multiple components to realize artificial and precise oscillation of bioenergy level.

Data-driven optimization of the in silico design of ionic liquids as interfacial cell culture fluids

As an alternative to conventional plastic dishes, the interface between water-immiscible hydrophobic fluids, such as perfluorocarbons and silicones, permits cell adhesion and growth. Thus, it is expected to replace the petroleum-derived products in a sustainable society. However, most hydrophobic fluids are cytotoxic, which limits the range of mechanical and chemical cues exposed to the cells. Using a data-driven approach, this study aimed to identify non-cytotoxic ionic liquids (ILs) as fluid culture platforms to take advantage of their 'designer' nature for broadening the possible physicochemical ranges exposed to cells and their repeated use owing to their high heat stability before their biological applications. The new candidates within the readily synthesized ammonium-type ILs were identified through the active cycle of regression and a limited number of cytotoxicity tests. Structure - cytotoxicity analysis indicated that the presence of multiple long alkyl branches was critical for low cytotoxicity. Particularly, we successfully cultured human mesenchymal stem cells (hMSCs) at the trihexylethylammonium trifluoromethylsulfonylimide interface and repeated their use after solvent extraction and heat sterilization. This study identified non-cytotoxic ILs that fulfill plastics' 3 R (Reduce, Recycle, and Replace) requirements and opens new avenues for hMSC fate manipulation through mechanotransduction.

Liquid-Liquid Interfacial Nanoarchitectonics

Science in the small world has become a crucial key that has the potential to revolutionize materials technology. This trend is embodied in the postnanotechnology concept of nanoarchitectonics. The goal of nanoarchitectonics is to create bio-like functional structures, in which self-organized and hierarchical structures are working efficiently. Liquid-liquid interface like environments such as cell membrane surface are indispensable for the expression of biological functions through the accumulation and organization of functional materials. From this viewpoint, it is necessary to reconsider the liquid-liquid interface as a medium where nanoarchitectonics can play an active role. In this review, liquid-liquid interfacial nanoarchitectonics is classified by component materials such as organic, inorganic, carbon, and bio, and recent research examples are discussed. Examples discussed in this paper include molecular aggregates, supramolecular polymers, conductive polymers film, crystal-like capsules, block copolymer assemblies, covalent organic framework (COF) films, complex crystals, inorganic nanosheets, colloidosomes, fullerene assemblies, all-carbon π-conjugated graphite nanosheets, carbon nanoskins and fullerphene thin films at liquid-liquid interfaces. Furthermore, at the liquid-liquid interface using perfluorocarbons and aqueous phases, cell differentiation controls are discussed with the self-assembled structure of biomaterials. The significance of liquid-liquid interfacial nanoarchitectonics in the future development of materials will then be discussed.

Strong Elastic Protein Nanosheets Enable the Culture and Differentiation of Induced Pluripotent Stem Cells on Microdroplets

Advances in stem cell technologies, revolutionizing regenerative therapies and advanced in vitro testing, require novel cell manufacturing pipelines able to cope with scale up and parallelization. Microdroplet technologies, which have transformed single cell sequencing and other cell-based assays, are attractive in this context, but the inherent soft mechanics of liquid-liquid interfaces is typically thought to be incompatible with the expansion of induced pluripotent stem cells (iPSCs), and their differentiation. In this work, the design of protein nanosheets stabilizing liquid-liquid interfaces and enabling the adhesion, expansion and retention of stemness by iPSCs is reported. Microdroplet microfluidic chips are used to control the formulation of droplets with defined dimensions and size distributions. The resulting emulsions sustain high expansion rates, with excellent retention of stem cell marker expression. iPSCs cultured in such conditions retain the capacity to differentiate into cardiomyocytes. This work provides clear evidence that local nanoscale mechanics, associated with interfacial viscoelasticity, provides strong cues able to regulate and maintain pluripotency, as well as to support commitment in defined differentiation conditions. Microdroplet technologies appear as attractive candidates to transform cell manufacturing pipelines, bypassing significant hurdles paused by solid substrates and microcarriers.

Building Functional Liquid-Based Interfaces: From Mechanism to Application

Functional liquid-based interfaces, with their inhomogeneous regions that emphasize the functionalized liquids, have attracted much interest as a versatile platform for a broad spectrum of applications, from chemical manufacturing to practical uses. These interfaces leverage the physicochemical characteristics of liquids, alongside dynamic behaviors induced by macroscopic wettability and microscopic molecular exchange balance, to allow for tailored properties within their functional structures. In this Minireview, we provide a foundational overview of these functional interfaces, based on the structural investigations and molecular mechanisms of interaction forces that directly modulate functionalities. Then, we discuss design strategies that have been employed in recent applications, and the crucial aspects that require focus. Finally, we highlight the current challenges in functional liquid-based interfaces and provide a perspective on future research directions.

Formulate Adaptive Biphasic Scaffold via Sequential Protein-Instructed Peptide Co-Assembly

To ensure compositional consistency while mitigating potential immunogenicity for stem cell therapy, synthetic scaffolds have emerged as compelling alternatives to native extracellular matrix (ECM). Substantial progress has been made in emulating specific natural traits featuring consistent chemical compositions and physical structures. However, recapitulating the dynamic responsiveness of the native ECM involving chemical transitions and physical remodeling during differentiation, remains a challenging endeavor. Here, the creation of adaptive scaffolds is demonstrated through sequential protein-instructed molecular assembly, utilizing stage-specific proteins, and incorporating in situ assembly technique. The procedure is commenced by introducing a dual-targeting peptide at the onset of stem cell differentiation. In response to highly expressed integrins and heparan sulfate proteoglycans (HSPGs) on human mesenchymal stem cell (hMSC), the peptides assembled in situ, creating customized extracellular scaffolds that adhered to hMSCs promoting osteoblast differentiation. As the expression of alkaline phosphatase (ALP) and collagen (COL-1) increased in osteoblasts, an additional peptide is introduced that interacts with ALP, initiating peptide assembly and facilitating calcium phosphate (CaP) deposition. The growth and entanglement of peptide assemblies with collagen fibers efficiently incorporated CaP into the network resulting in an adaptive biphasic scaffold that enhanced healing of bone injuries.

Liquid-Liquid and Liquid-Solid Interfacial Nanoarchitectonics

Nanoscale science is becoming increasingly important and prominent, and further development will necessitate integration with other material chemistries. In other words, it involves the construction of a methodology to build up materials based on nanoscale knowledge. This is also the beginning of the concept of post-nanotechnology. This role belongs to nanoarchitectonics, which has been rapidly developing in recent years. However, the scope of application of nanoarchitectonics is wide, and it is somewhat difficult to compile everything. Therefore, this review article will introduce the concepts of liquid and interface, which are the keywords for the organization of functional material systems in biological systems. The target interfaces are liquid-liquid interface, liquid-solid interface, and so on. Recent examples are summarized under the categories of molecular assembly, metal-organic framework and covalent organic framework, and living cell. In addition, the latest research on the liquid interfacial nanoarchitectonics of organic semiconductor film is also discussed. The final conclusive section summarizes these features and discusses the necessary components for the development of liquid interfacial nanoarchitectonics.

Ultimately Adaptive Fluid Interfacial Phospholipid Membranes Unveiled Unanticipated High Cellular Mechanical Work

Living cells actively interact biochemically and mechanically with the surrounding extracellular matrices (ECMs) and undergo dramatic morphological and dimensional transitions, concomitantly remodeling ECMs. However, there is no suitable method to quantitatively discuss the contribution of mechanical interactions in such mutually adaptive processes. Herein, a highly deformable "living" cellular scaffold is developed to evaluate overall mechanical energy transfer between cell and ECMs. It is based on the water-perfluorocarbon interface decorated with phospholipids bearing a cell-adhesive ligand and fluorescent tag. The bioinert nature of the phospholipid membranes prevents the formation of solid-like protein nanofilms at the fluid interface, enabling to visualize and quantify cellular mechanical work against the ultimately adaptive model ECM. A new cellular wetting regime is identified, wherein interface deformation proceeds to cell flattening, followed by its eventual restoration. The cellular mechanical work during this adaptive wetting process is one order of magnitude higher than those reported with conventional elastic platforms. The behavior of viscous liquid drops at the air-water interface can simulate cellular adaptive wetting, suggesting that overall viscoelasticity of the cell body predominates the emergent wetting regime and regulates mechanical output. Cellular-force-driven high-energy states on the adaptive platform can be useful for cell fate manipulation.

Liquid Interfacial Gating of Superhydrophobic Plasmonic Metal-Organic Frameworks for Three-in-One Separation, Enrichment, and Recognition in Bacterial Quorum Sensing

Poor adsorption properties of nonadsorbing targets and competing adsorption of nontargets at a liquid interface always hamper the development of interface sensing techniques. There is a need to fabricate materials that are applicable to various interface assemblies and, meanwhile, could be employed as interfacial gating to improve the performance of interface sensing by separating, enriching, and recognizing targets at the liquid interface. Here, superhydrophobic zeolite imidazole frameworks-8@gold nanoparticles-1H,1H,2H,2H-perfluorodecanethiol (ZIF-8@GNPs-PFDT) with a static water contact angle (WCA) of 155° was constructed via electrostatic self-assembly and surface graft modification. The plasmonic metal-organic framework (PMOF) nanohybrid realized all-purpose self-assembly at air/liquid and liquid/liquid interfaces and also facilely assembled on the surface of liquid droplets, hydrogels, and foams. The self-assembled porous materials displayed the capability for separating, enriching, and recognizing analytes at various oil/water interfaces and thus could be used to adsorb nonadsorbing targets and block the competing adsorption of nontargets. The self-assembled ZIF-8@GNPs-PFDT structures were employed as a three-in-one interfacial gating to endow the excellent surface-enhanced Raman scattering (SERS) sensing capability and has become a promising tool for dye molecular analysis, oil/water separation, organic phase identification, and in situ cultivation and monitoring of bacterial quorum sensing (QS).

Tailoring the Heterogeneous Structure of Macro-Fibers Assembled by Bacterial Cellulose Nanofibrils for Tissue Engineering Scaffolds

Bacterial cellulose/oxidized bacterial cellulose nanofibrils (BC/oxBCNFs) macro-fibers are developed as a novel scaffold for vascular tissue engineering. Utilizing a low-speed rotary coagulation spinning technique and precise solvent control, macro-fibers with a unique heterogeneous structure with dense surface and porous core are created. Enhanced by a polydopamine (PDA) coating, these macro-fibers offer robust mechanical integrity, high biocompatibility, and excellent cell adhesion. When cultured with endothelial cells (ECs) and smooth muscle cells (SMCs), the macro-fibers support healthy cell proliferation and exhibit a unique spiral SMC alignment, demonstrating their vascular suitability. This innovative strategy opens new avenues for advances in tissue engineering.

Ionic Liquid Interface as a Cell Scaffold

In sharp contrast to conventional solid/hydrogel platforms, water-immiscible liquids, such as perfluorocarbons and silicones, allow the adhesion of mammalian cells via protein nanolayers (PNLs) formed at the interface. However, fluorocarbons and silicones, which are typically used for liquid cell culture, possess only narrow ranges of physicochemical parameters and have not allowed for a wide variety of cell culturing environments. In this paper, it is proposed that water-immiscible ionic liquids (ILs) are a new family of liquid substrates with tunable physicochemical properties and high solvation capabilities. Tetraalkylphosphonium-based ILs are identified as non-cytotoxic ILs, whereon human mesenchymal stem cells are successfully cultured. By reducing the cation charge distribution, or ionicity, via alkyl chain elongation, the interface allows cell spreading with matured focal contacts. High-speed atomic force microscopy observations of the PNL formation process suggest that the cation charge distribution significantly altered the protein adsorption dynamics, which are associated with the degree of protein denaturation and the PNL mechanics. Moreover, by exploiting dissolution capability of ILs, an ion-gel cell scaffold is fabricated. This enables to further identify the significant contribution of bulk subphase mechanics to cellular mechanosensing in liquid-based culture scaffolds.

Light-triggered AND logic tetrapeptide dynamic covalent assembly

We demonstrate light-triggered dynamic covalent assembly of a linear short tetrapeptide containing two terminal cysteine residues in an AND logic manner. A photobase generator is introduced to accomplish light-mediated pH regulation to increase the reduction potential of thiols in the tetrapeptide, which activates its oxidative polymerization through disulfide bonds. Interestingly, it is elucidated that under light irradiation, mere co-existence of photobase generator and the oxidizing agent permits the polymerization performance of this tetrapeptide. Hence, a light-triggered AND logic dynamic covalent assembly of a tetrapeptide is achieved. Further, upon redox response, the reversible aggregation and disaggregation can be transformed for numerous times due to the dynamic covalent feature of disulfide bond. As a comparison, no assembly occurs for a short peptide containing one terminal cysteine residue under the same stimuli condition. This work offers a new approach to remotely control programmable molecular assembly of short linear peptides based on dynamic covalent bond, holding great potential in wide bioapplications.

A novel strategy to facilitate uniform epithelial cell maturation using liquid-liquid interfaces

Epithelial tissue forms and maintains a critical barrier function in the body. A novel culture design aimed at promoting uniform maturation of epithelial cells using liquid materials is described. Culturing Madin-Darby canine kidney (MDCK) cells at the liquid-liquid interface yielded reduced migration and stimulated active cell growth. Similar to solid-liquid interfaces, cells cultured on a fibronectin-coated liquid-liquid interface exhibited active migration and growth, ultimately reaching a confluent state. These cells exhibited reduced stress fiber formation and adopted a cobblestone-like shape, which led to their even distribution in the culture vessel. To inhibit stress fiber formation and apoptosis, the exposure of cells on liquid-liquid interfaces to Y27632, a specific inhibitor of the Rho-associated protein kinase (ROCK), facilitated tight junction formation (frequency of ZO-2-positive cells, FZ = 0.73). In Y27632-exposed cells on the liquid-liquid interface, the value obtained by subtracting the standard deviation of the ratio of nucleus densities in each region that compartmentalized a culture vessel from 1, denoted as HLN, was 0.93 ± 0.01, indicated even cell distribution in the culture vessel at t = 72 h. The behavior of epithelial cells on liquid-liquid interfaces contributes to the promotion of their uniform maturation.

Nanoarchitectonics with a Membrane-Embedded Electron Shuttle Mimics the Bioenergy Anabolism of Mitochondria

Enhanced bioenergy anabolism through transmembrane redox reactions in artificial systems remains a great challenge. Here, we explore synthetic electron shuttle to activate transmembrane chemo-enzymatic cascade reactions in a mitochondria-like nanoarchitecture for augmenting bioenergy anabolism. In this nanoarchitecture, a dendritic mesoporous silica microparticle as inner compartment possesses higher load capacity of NADH as proton source and allows faster mass transfer. In addition, the outer compartment ATP synthase-reconstituted proteoliposomes. Like natural enzymes in the mitochondrion respiratory chain, a small synthetic electron shuttle embedded in the lipid bilayer facilely mediates transmembrane redox reactions to convert NADH into NAD+ and a proton. These facilitate an enhanced outward proton gradient to drive ATP synthase to rotate for catalytic ATP synthesis with improved performance in a sustainable manner. This work opens a new avenue to achieve enhanced bioenergy anabolism by utilizing a synthetic electron shuttle and tuning inner nanostructures, holding great promise in wide-range ATP-powered bioapplications.

2D Materials Nanoarchitectonics for 3D Structures/Functions

It has become clear that superior material functions are derived from precisely controlled nanostructures. This has been greatly accelerated by the development of nanotechnology. The next step is to assemble materials with knowledge of their nano-level structures. This task is assigned to the post-nanotechnology concept of nanoarchitectonics. However, nanoarchitectonics, which creates intricate three-dimensional functional structures, is not always easy. Two-dimensional nanoarchitectonics based on reactions and arrangements at the surface may be an easier target to tackle. A better methodology would be to define a two-dimensional structure and then develop it into a three-dimensional structure and function. According to these backgrounds, this review paper is organized as follows. The introduction is followed by a summary of the three issues; (i) 2D to 3D dynamic structure control: liquid crystal commanded by the surface, (ii) 2D to 3D rational construction: a metal-organic framework (MOF) and a covalent organic framework (COF); (iii) 2D to 3D functional amplification: cells regulated by the surface. In addition, this review summarizes the important aspects of the ultimate three-dimensional nanoarchitectonics as a perspective. The goal of this paper is to establish an integrated concept of functional material creation by reconsidering various reported cases from the viewpoint of nanoarchitectonics, where nanoarchitectonics can be regarded as a method for everything in materials science.

Crucial Factors Influencing the Involvement of Odontogenic Exosomes in Dental Pulp Regeneration

Recent progress in exosome based studies has revealed that they possess several advantages over cells, including "cell-free" properties, low immunogenicity and ethical controversy, high biological safety and effective action. These characteristics confer exosomes significant advantages that allow them to overcome the limitations associated with traditional "cell therapy" by circumventing the issues of immune rejection, scarcity of donor cells, heterogeneity, and ethical concerns. Identification of a complete and effective radical treatment for irreversible pulpal disease, a common clinical problem, continues to pose challenges. Although traditional root canal therapy remains the primary clinical treatment, it does not fully restore the physiological functions of pulp. Although stem cell transplantation appears to be a relatively viable treatment strategy for pulp disease, issues such as cell heterogeneity and poor regeneration effects remain problematic. Dental pulp regeneration strategies based on "cell-free" exosome therapies explored by numerous studies appear to have shown significant advantages. In particular, exosomes derived from odontogenic stem cells have demonstrated considerable potential in tooth tissue regeneration engineering, and continue to exhibit superior therapeutic effects compared to non-odontogenic stem cell-derived exosomes. However, only a few studies have comprehensively summarised their research results, particularly regarding the critical factors involved in the process. Therefore, in this study, our purpose was to review the effects exerted by odontogenic exosomes on pulp regeneration and to analyse and discus crucial factors related to this process, thereby providing scholars with a feasible and manageable new concept with respect to regeneration schemes.

Bioactive and chemically defined hydrogels with tunable stiffness guide cerebral organoid formation and modulate multi-omics plasticity in cerebral organoids

Organoids are an emerging technology with great potential in human disease modelling, drug development, diagnosis, tissue engineering, and regenerative medicine. Organoids as 3D-tissue culture systems have gained special attention in the past decades due to their ability to faithfully recapitulate the complexity of organ-specific tissues. Despite considerable successes in culturing physiologically relevant organoids, their real-life applications are currently limited by challenges such as scarcity of an appropriate biomimetic matrix. Peptide amphiphiles (PAs) due to their well-defined chemistry, tunable bioactivity, and extracellular matrix (ECM)-like nanofibrous architecture represent an attractive material scaffold for organoids development. Using cerebral organoids (COs) as exemplar, we demonstrate the possibility to create bio-instructive hydrogels with tunable stiffness ranging from 0.69 kPa to 2.24 kPa to culture and induce COs growth. We used orthogonal chemistry involving oxidative coupling and supramolecular interactions to create two-component hydrogels integrating the bio-instructive activity and ECM-like nanofibrous architecture of a laminin-mimetic PAs (IKVAV-PA) and tunable crosslinking density of hyaluronic acid functionalized with tyramine (HA-Try). Multi-omics technology including transcriptomics, proteomics, and metabolomics reveals the induction and growth of COs in soft HA-Tyr hydrogels containing PA-IKVAV such that the COs display morphology and biomolecular signatures similar to those grown in Matrigel scaffolds. Our materials hold great promise as a safe synthetic ECM for COs induction and growth. Our approach represents a well-defined alternative to animal-derived matrices for the culture of COs and might expand the applicability of organoids in basic and clinical research. STATEMENT OF SIGNIFICANCE: Synthetic bio-instructive materials which display tissue-specific functionality and nanoscale architecture of the native extracellular matrix are attractive matrices for organoids development. These synthetic matrices are chemically defined and animal-free compared to current gold standard matrices such as Matrigel. Here, we developed hydrogel matrices with tunable stiffness, which incorporate laminin-mimetic peptide amphiphiles to grow and expand cerebral organoids. Using multi-omics tools, the present study provides exciting data on the effects of neuro-inductive cues on the biomolecular profiles of brain organoids.

Manipulating the Dynamic Adaptivity of a Fluid Interface to Maintain the Multipotency of Mesenchymal Stromal Cells

The native extracellular matrix is highly dynamic with continuous mutual feedback between cells being responsible for many important cell function regulators. However, establishing bidirectional interaction between complex adaptive microenvironments and cells remains elusive. Herein an adaptive biomaterial based on lysozyme monolayers self-assembled at a perfluorocarbon FC40-water interface is reported. The dynamic adaptivity of interfacially assembled protein nanosheets is modulated independently of bulk mechanical properties by covalent crosslinking. This provides a scenario to establish bidirectional interactions of cells with liquid interfaces of varying dynamic adaptivity. This is found that growth and multipotency of human mesenchymal stromal cells (hMSCs) are enhanced at the highly adaptive fluid interface. The multipotency retention of hMSCs is mediated by low cell contractility and metabolomic activity involving the continuous mutual feedback between the cells and materials. Consequently, an understanding of the cells' response to dynamic adaptivity has substantial implications for regenerative medicine and tissue engineering.

Probing the Interfacial Properties of Oil-Water Interfaces Decorated with Ionizable, pH Responsive Silica Nanoparticles

Particle-stabilized emulsions (Pickering emulsions) have recently attracted significant attention in scientific studies and for technological applications. The interest stems from the ease of directly assembling the particles at interfaces and modulating the interfacial properties. In this paper, we demonstrate the formation of stable, practical emulsions leveraging the assembly of ionizable, pH responsive silica nanoparticles, surface-functionalized by a mixture of silanes containing amine/ammonium groups, which renders them positively charged. Using pH as the trigger, the assembly and the behavior of the emulsion are controlled by modulating the charges of the functional groups of the nanoparticle and the oil (crude oil). In addition to their tunable charge, the particular combination of silane coupling agents leads to stable particle dispersions, which is critical for practical applications. Atomic force microscopy and interfacial tension (IFT) measurements are used to monitor the assembly, which is controlled by both the electrostatic interactions between the particles and oil and the interparticle interactions, both of which are modulated by pH. Under acidic conditions, when the surfaces of the oil and the nanoparticles (NPs) are positively charged, the NPs are not attracted at the interface and there is no significant reduction in the IFT. In contrast, under basic conditions in which the oil carries a high negative charge and the amine groups on the silica are deprotonated while still positively charged because of the ammonium groups, the NPs assemble at the interface in a closely packed configuration yielding a jammed state with a high dilatational modulus. As a result, two oil droplets do not coalesce even when pushed against each other and the emulsion stability improves significantly. The study provides new insights into the directed assembly of nanoparticles at fluid interfaces relevant to several applications, including environmental remediation, catalysis, drug delivery, food technology, and oil recovery.