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The development of fluorescence labeling techniques has attracted widespread interest in various fields, including biomedical science as it can facilitate high-resolution imaging and the spatiotemporal understanding of various biological processes. We report a supramolecular fluorescence labeling strategy using luminescent metal-phenolic networks (MPNs) constructed from metal ions, phenolic ligands, and common and commercially available dyes. The rapid labeling process (

Interfacial modular assembly has emerged as an adaptable strategy for engineering the surface properties of substrates in biomedicine, photonics, and catalysis. Herein, we report a versatile and robust coating (pBDT-TA), self-assembled from tannic acid (TA) and a self-polymerizing aromatic dithiol (i.e., benzene-1,4-dithiol, BDT), that can be engineered on diverse substrates with a precisely tuned thickness (5-40 nm) by varying the concentration of BDT used. The pBDT-TA coating is stabilized by covalent (disulfide) bonds and supramolecular (π-π) interactions, endowing the coating with high stability in various harsh aqueous environments across ionic strength, pH, temperature (e.g., 100 mM NaCl, HCl (pH 1) or NaOH (pH 13), and water at 100 °C), as well as surfactant solution (e.g., 100 mM Triton X-100) and biological buffer (e.g., Dulbecco's phosphate-buffered saline), as validated by experiments and simulations. Moreover, the reported pBDT-TA coating enables secondary reactions on the coating for engineering hybrid adlayers (e.g., ZIF-8 shells) via phenolic-mediated adhesion, and the facile integration of aromatic fluorescent dyes (e.g., rhodamine B) via π interactions without requiring elaborate synthetic processes.

Few synthetic hydrogels can mimic both the viscoelasticity and supramolecular fibrous structure found in the naturally occurring extracellular matrix (ECM). Furthermore, the ability to control the viscoelasticity of fibrous supramolecular hydrogel networks to influence cell culture remains a challenge. Here, we show that modular mixing of supramolecular architectures with slow and fast exchange dynamics can provide a suitable environment for multiple cell types and influence cellular aggregation. We employed modular mixing of two synthetic benzene-1,3,5-tricarboxamide (BTA) architectures: a small molecule water-soluble BTA with slow exchange dynamics and a telechelic polymeric BTA-PEG-BTA with fast exchange dynamics. Copolymerisation of these two supramolecular architectures was observed, and all tested formulations formed stable hydrogels in water and cell culture media. We found that rational tuning of mechanical and viscoelastic properties is possible by mixing BTA with BTA-PEG-BTA. These hydrogels showed high viability for both chondrocyte (ATDC5) and human dermal fibroblast (HDF) encapsulation (>80%) and supported neuronal outgrowth (PC12 and dorsal root ganglion, DRG). Furthermore, ATDC5s and human mesenchymal stem cells (hMSCs) were able to form spheroids within these viscoelastic hydrogels, with control over cell aggregation modulated by the dynamic properties of the material. Overall, this study shows that modular mixing of supramolecular architectures enables tunable fibrous hydrogels, creating a biomimetic environment for cell encapsulation. These materials are suitable for the formation and culture of spheroids in 3D, critical for upscaling tissue engineering approaches towards cell densities relevant for physiological tissues.

Soft, conformally shaped thermoplastic elastomer (TPE) hydrogels producible from a moldable precursor material are desirable in many biomedical, surgical, and pharmaceutical applications. An innovative class of hydrogel networks was developed by employing photocurable, moldable solutions of melt-assembled spherical micelles formed from ω-anthracenylpolystyrene-b-poly(ethylene oxide) diblock copolymer. Photoinduced [4 + 4] cycloaddition (λ = 365 nm) of terminal anthracene groups populating the hydrophilic corona of each micelle was used to produce polystyrene-b-poly(ethylene oxide)-b-polystyrene triblock copolymer tethers or network strands among adjacent micelles. Structural uniformity in the micelle population was confirmed by small-angle X-ray scattering (SAXS), cryogenic transmission electron microscopy (cryo-TEM), and dynamic light scattering (DLS). Homogeneous dispersal of the assembled micelle building blocks in water resulted in spreadable or moldable photoactive micelle solutions, studied for their stability in solution and ability to rapidly form elastomeric hydrogels once irradiated. Once in molds, these solutions of varied concentration were irradiated to form soft TPE hydrogels with dynamic shear modulus controllable with irradiation time (triblock copolymer content), exhibiting prescribed shape consistent with high-fidelity conformal fill.

Engineering coatings with precise physicochemical properties allows for control over the interface of a material and its interactions with the surrounding environment. However, assembling coatings with well-defined properties on different material classes remains a challenge. Herein, we report a co-assembly strategy to precisely control the structure and properties (e.g., thickness, adhesion, wettability, and zeta potential) of coatings on various materials (27 substrates examined) using quinone and polyamine building blocks. By increasing the length of the amine building blocks from small molecule diamines to branched amine polymers, we tune the properties of the films, including the thickness (from ca. 5 to ca. 50 nm), interfacial adhesion (0.05 to 5.54 nN), water contact angle (130 to 40°), and zeta potential (-42 to 28 mV). The films can be post-functionalized through the in situ formation of diverse nanostructures, including nanoparticles, nanorods, and nanocrystals. Our approach provides a platform for the rational design of engineered, substrate-independent coatings for various applications.

Patchy nanoparticles featuring tunable surface domains with spatial and chemical specificity are of fundamental interest, especially for creating three-dimensional (3D) colloidal structures. Guided assembly and regioselective conjugation of polymers have been widely used to manipulate such topography on nanoparticles; however, the processes require presynthesized specialized polymer chains and elaborate assembly conditions. Here, we show how small molecules can form 3D patches in aqueous environments in a single step. The patch features (e.g., size, number, conformation, and stereoselectivity) are modulated by a self-polymerizable aromatic dithiol and comixed ligands, which indicates an autonomous assembly mechanism involving covalent polymerization and supramolecular assembly. Moreover, this method is independent of the underlying nanoparticle material and dimension, offering a streamlined and powerful toolset to design heterogeneous patches on the nanoscale.

Multicomponent supramolecular polymers are a versatile platform to prepare functional architectures, but a few studies have been devoted to investigate their noncovalent synthesis. Here, we study supramolecular copolymerizations by examining the mechanism and time scales associated with the incorporation of new monomers in benzene-1,3,5-tricarboxamide (BTA)-based supramolecular polymers. The BTA molecules in this study all contain three tetra(ethylene glycol) chains at the periphery for water solubility but differ in their alkyl chains that feature either 10, 12 or 13 methylene units. C 10 BTA does not form ordered supramolecular assemblies, whereas C 12 BTA and C 13 BTA both form high aspect ratio supramolecular polymers. First, we illustrate that C 10 BTA can mix into the supramolecular polymers based on either C 12 BTA or C 13 BTA by comparing the temperature response of the equilibrated mixtures to the temperature response of the individual components in water. Subsequently, we mix C 10 BTA with the polymers and follow the copolymerization over time with UV spectroscopy and hydrogen/deuterium exchange mass spectrometry experiments. Interestingly, the time scales obtained in both experiments reveal significant differences in the rates of copolymerization. Coarse-grained simulations are used to study the incorporation pathway and kinetics of the C 10 BTA monomers into the different polymers. The results demonstrate that the kinetic stability of the host supramolecular polymer controls the rate at which new monomers can enter the existing supramolecular polymers.

Supramolecular fibers in water, micrometers long and several nanometers in width, are among the most studied nanostructures for biomedical applications. These supramolecular polymers are formed through a spontaneous self-assembly process of small amphiphilic molecules by specific secondary interactions. Although many compounds do not possess a stereocenter, recent studies suggest the (co)existence of helical structures, albeit in racemic form. Here, we disclose a series of supramolecular (co)polymers based on water-soluble benzene-1,3,5-tricarboxamides (BTAs) that form double helices, fibers that were long thought to be chains of single molecules stacked in one dimension (1D). Detailed cryogenic transmission electron microscopy (cryo-TEM) studies and subsequent three-dimensional-volume reconstructions unveiled helical repeats, ranging from 15 to 30 nm. Most remarkable, the pitch can be tuned through the composition of the copolymers, where two different monomers with the same core but different peripheries are mixed in various ratios. Like in lipid bilayers, the hydrophobic shielding in the aggregates of these disc-shaped molecules is proposed to be best obtained by dimer formation, promoting supramolecular double helices. It is anticipated that many of the supramolecular polymers in water will have a thermodynamic stable structure, such as a double helix, although small structural changes can yield single stacks as well. Hence, it is essential to perform detailed analyses prior to sketching a molecular picture of these 1D fibers.

The consequences of using saccharides versus tetra(ethyleneglycol) chains as water-compatible moieties on the morphology and dynamics of supramolecular polymers in aqueous solutions are investigated. The saccharides form many H-bonds with other saccharides within the polymer and with water, increasing the hydration of the fiber and changing its dynamics.

Polar cosolvents are commonly used to guide the self-assembly of amphiphiles in water. Here we investigate the influence of the cosolvent acetonitrile (ACN) on the structure and dynamics of a supramolecular polymer in water, which is based on the well-known benzene-1,3,5-tricarboxamide motif. Hydrogen/deuterium exchange mass spectroscopy measurements show that a gradual increase in the amount of ACN results in a gradual increase in the exchange dynamics of the monomers. In contrast, the morphology of the supramolecular polymers remains unchanged up to 15% of ACN, but then an abrupt change occurs and spherical aggregates are formed. Remarkably, this abrupt change coincides with the formation of micro-heterogeneity in the water-ACN mixtures. The results illustrate that in order to completely characterize supramolecular polymers it is important to add time-resolved measurements that probe their dynamic behavior, to the conventional techniques that are used to assess the morphology of the polymers. Subsequently we have used time-resolved measurements to investigate the influence of the concentration of ACN on the polymerization and depolymerization rates of the supramolecular polymers. Polymerization occurs within minutes when molecularly dissolved monomers are injected from ACN into water and is independent of the fraction of ACN up to 15%. In the depolymerization experiments - initiated by mixing equilibrated supramolecular polymers with dissolved monomers - the equilibration of the system takes multiple hours and does depend on the fraction of ACN. Interestingly, the longest equilibration time of the polymers is observed at a critical solvent composition of around 15% ACN. The differences in the timescales detected in the polymerization and depolymerization experiments are likely correlated to the non-covalent interactions involved, namely the hydrophobic effect and hydrogen-bonding interactions. We attribute the observed fast kinetics in the polymerization reactions to the hydrophobic effect, whereas the formation of intermolecular hydrogen bonds is the retarding factor in the equilibration of the polymers in the depolymerization experiments. Molecular dynamics simulations show that the latter is a likely explanation because ACN interferes with the hydrogen bonds and loosens the internal structure of the polymers. Our results highlight the importance of the solution conditions during the non-covalent synthesis of supramolecular polymers, as well as after equilibration of the polymers.

Intriguingly, little is known about the impact of dispersity on the crystallization driven self-assembly (CDSA) of amphiphilic block copolymers in aqueous media. Here, we investigate the influence of dispersity on the CDSA of ABA-type amphiphilic block co-oligomers (ABCOs). Two pairs of ABCOs are synthesized comprising discrete ( Đ = 1.00) or disperse ( Đ = 1.20) isotactic l-lactic acid 16-mers as the semicrystalline hydrophobic block and either oligo(ethylene glycol) methyl ether (MeOoEG) or oligo(tetraethylene glycol succinate) (oTEGSuc) as the discrete hydrophilic block. Self-assembly studies in water with 10% THF reveal uniform nanofibers/2D sheets for the discrete oligomers, but such structural regularity is largely compromised in the disperse oligomers. The results are corroborated by sharp melting transitions in both solution and bulk for the discrete ABCOs, unlike their disperse analogues that show a lack of crystallization. Interestingly, the discrete MeOoEG-LLA oligomer reveals crystallization driven gelation, illustrating the contrasting differences between the discrete oligomers and their disperse counterparts.

Biomimetic, strain‐stiffening materials are reported, made through self‐assembly and covalent fixation of small building blocks to form fibrous hydrogels that are able to stiffen by an order of magnitude in response to applied stress. The gels consist of semi‐flexible rodlike micelles of bisurea bolaamphiphiles with oligo(ethylene oxide) (EO) outer blocks and a polydiacetylene (PDA) backbone. The micelles are fibers, composed of 9–10 ribbons. A gelation method based on Cu‐catalyzed azide–alkyne cycloaddition (CuAAC), was developed and shown to lead to strain‐stiffening hydrogels with unusual, yet universal, linear and nonlinear stress–strain response. Upon gelation, the X‐ray scattering profile is unchanged, suggesting that crosslinks are formed at random positions along the fiber contour without fiber bundling. The work expands current knowledge about the design principles and chemistries needed to achieve fully synthetic, biomimetic soft matter with on‐demand, targeted mechanical properties.

Structural and kinetic exchange properties of supramolecular polymers composed of mono- and bivalent ureidopyrimidinone-based monomers are investigated in aqueous solutions. It is shown that exchange dynamics can be controlled by mixing different types of monomers. This tunability widens the scope in their design as biomaterials.

Polysaccharides present in the glycocalyx and extracellular matrix are highly important for a multitude of functions. Oligo- and polysaccharides-based biomaterials are being developed to mimic the glycocalyx, but the spatial functionalization of these polysaccharides represents a major challenge. In this paper, a series of benzene-1,3,5-tricarboxamide (BTA) based supramolecular monomers is designed and synthesized with mono- (BTA-β-d-glucose; BTA-Glc and BTA-α-d-mannose; BTA-Man) or disaccharides (BTA-β-d-cellobiose; BTA-Cel) at their periphery or a monosaccharide (BTA-OEG4-α-d-mannose; BTA-OEG4-Man) at the end of a tetraethylene glycol linker. These glycosylated BTAs have been used to generate supramolecular assemblies and it is shown that the nature of the carbohydrate appendage is crucial for the supramolecular (co)polymerization behavior. BTA-Glc and BTA-Man are shown to assemble into micrometers long 1D (bundled) fibers with opposite helicities, whereas BTA-Cel and BTA-OEG4-Man formed small spherical micelles. The latter two monomers are used in a copolymerization approach with BTA-Glc, BTA-Man, or ethylene glycol BTA (BTA-OEG4) to give 1D fibers with BTA-Cel or BTA-OEG4-Man incorporated. Consequently, the carbohydrate appendage influences both the assembly behavior and the internal order. Using this approach it is possible to create 1D-fibers with adjustable saccharide densities exhibiting tailored dynamic exchange profiles. Furthermore, hydrogels with tunable mechanical properties can be achieved, opening up possibilities for the development of multicomponent functional biomaterials.

[Image: see text] Structurally and functionally well-defined recombinant proteins are an interesting class of sequence-controlled macromolecules to which different crosslinking chemistries can be applied to tune their biological properties. Herein, we take advantage of a 571-residue recombinant peptide based on human collagen type I (RCPhC1), which we functionalized with supramolecular 4-fold hydrogen bonding ureido-pyrimidinone (UPy) moieties. By grafting supramolecular UPy moieties onto the backbone of RCPhC1 (UPy-RCPhC1), increased control over the polymer structure, assembly, gelation, and mechanical properties was achieved. In addition, by increasing the degree of UPy functionalization on RCPhC1, cardiomyocyte progenitor cells were cultured on “soft” (∼26 kPa) versus “stiff” (∼68–190 kPa) UPy-RCPhC1 hydrogels. Interestingly, increased stress fiber formation, focal adhesions, and proliferation were observed on stiffer compared to softer substrates, owing to the formation of stronger cell–material interactions. In conclusion, a bioinspired hydrogel material was designed by a combination of two well-known natural components, i.e., a protein as sequence-controlled polymer and UPy units inspired on nucleobases.

We introduce monosaccharides as versatile water-soluble units to compatibilise supramolecular polymers based on the benzene-1,3,5-tricarboxamide (BTA) moiety with water. A library of monosaccharide-based BTAs is evaluated, varying the length of the alkyl chain (hexyl, octyl, decyl and dodecyl) separating the BTA and saccharide units, as well as the saccharide units (α-glucose, β-glucose, α-mannose and α-galactose). In all cases, the monosaccharides impart excellent water compatibility. The length of the alkyl chain is the determining factor to obtain either long, one-dimensional supramolecular polymers (dodecyl spacer), small aggregates (decyl spacer) or molecularly dissolved (octyl and hexyl) BTAs in water. For the BTAs comprising a dodecyl spacer, our results suggest that a cooperative self-assembly process is operative and that the introduction of different monosaccharides does not significantly change the self- assembly behaviour. Finally, we investigate the potential of post-assembly functionalisation of the formed supramolecular polymers by taking advantage of dynamic covalent bond formation between the monosaccharides and benzoxaboroles. We observe that the supramolecular polymers readily react with a fluorescent benzoxaborole derivative permitting imaging of these dynamic complexes by confocal fluorescence microscopy.

Understanding the self-assembly of small molecules in water is crucial for the development of responsive, biocompatible soft materials. Here, a family of benzene-1,3,5-tricarboxamide (BTA) derivatives that comprise a BTA moiety connected to an amphiphilic chain is synthesised with the aim to elucidate the role of hydrophobic and hydrogen-bonding interactions in the self-assembly of these BTAs. The amphiphilic chain consists of an alkyl chain with a length of 10, 11, or 12 methylene units, connected to a tetraethylene glycol (at the periphery). The results show that an undecyl spacer is the minimum length required for these BTAs to self-assemble into supramolecular polymers. Interestingly, exchange studies reveal only minor differences in exchange rates between BTAs containing undecyl or dodecyl spacers. Additionally, IR spectroscopy provides the first experimental evidence that hydrogen-bonding is operative and contributes to the stabilisation of the supramolecular polymers in water.

In biology, polymorphism is a well-known phenomenon by which a discrete biomacromolecule can adopt multiple specific conformations in response to its environment. The controlled incorporation of polymorphism into noncovalent aqueous assemblies of synthetic small molecules is an important step toward the development of bioinspired responsive materials. Herein, we report on a family of carboxylic acid functionalized water-soluble benzene-1,3,5-tricarboxamides (BTAs) that self-assemble in water to form one-dimensional fibers, membranes, and hollow nanotubes. Interestingly, one of the BTAs with the optimized position of the carboxylic group in the hydrophobic domain yields nanotubes that undergo reversible temperature-dependent dynamic reorganizations. SAXS and Cryo-TEM data show the formation of elongated, well-ordered nanotubes at elevated temperatures. At these temperatures, increased dynamics, as measured by hydrogen-deuterium exchange, provide enough flexibility to the system to form well-defined nanotube structures with apparently defect-free tube walls. Without this flexibility, the assemblies are frozen into a variety of structures that are very similar at the supramolecular level, but less defined at the mesoscopic level.

A major challenge in supramolecular polymerization is controlling the stability of the polymers formed, that is, controlling the rate of monomer exchange in the equilibrium between monomer and polymer. The exchange dynamics of supramolecular polymers based on benzene-1,3,5-tricarboxamide (BTA) can be regulated by copolymerizing molecules with dendronized (dBTA) and linear (nBTA) ethylene glycol-based water-soluble side chains. Whereas nBTAs form long nanofibers in water, dBTAs do not polymerize, forming instead small spherical aggregates. The copolymerization of the two BTAs results in long nanofibers. The exchange dynamics of both the BTA monomers in the copolymer are significantly slowed down in the mixed systems, leading to a more stable copolymer, while the morphology and spectroscopic signature of the copolymers are identical to that of nBTA homopolymer. This copolymerization is the supramolecular counterpart of styrene/ maleic anhydride copolymerization.

A water-soluble benzene-1,3,5-tricarboxamide (BTA) derivative that self-assembles into one-dimensional, helical, supramolecular polymers is functionalised at the periphery with one L-proline moiety. In water, the BTA-derivative forms micrometre long supramolecular polymers, which are stabilised by hydrophobic interactions and directional hydrogen bonds. Furthermore, we co-assemble a catalytically inactive, but structurally similar, BTA with the L-proline functionalised BTA to create co-polymers. This allows us to assess how the density of the L-proline units along the supramolecular polymer affects its activity and selectivity. Both the supramolecular polymers and co-polymers show high activity and selectivity as catalysts for the aldol reaction in water when using p-nitrobenzaldehyde and cyclohexanone as the substrates for the aldol reaction. After optimisation of the reaction conditions, a consistent conversion of 92 ± 7%, deanti of 92 ± 3%, and eeanti of 97 ± 1% are obtained with a concentration of L-proline as low as 1 mol%.

Numerous self-assembling molecules have been synthesized aiming at mimicking both the structural and dynamic properties found in living systems. Here we show the application of hydrogen/deuterium exchange (HDX) mass spectrometry (MS) to unravel the nanoscale organization and the structural dynamics of synthetic supramolecular polymers in water. We select benzene-1,3,5-tricarboxamide (BTA) derivatives that self-assemble in H2O to illustrate the strength of this technique for supramolecular polymers. The BTA structure has six exchangeable hydrogen atoms and we follow their exchange as a function of time after diluting the H2O solution with a 100-fold excess of D2O. The kinetic H/D exchange profiles reveal that these supramolecular polymers in water are dynamically diverse; a notion that has previously not been observed using other techniques. In addition, we report that small changes in the molecular structure can be used to control the dynamics of synthetic supramolecular polymers in water., Understanding the dynamics of supramolecular architectures without using labels is crucial for developing advanced biosystems. Here, the authors show kinetic hydrogen/deuterium exchange profiles for a series of water-soluble supramolecular polymers.