A supramolecular polymer as a self-assembling polyvalent scaffold

Using Chemistry To Recreate the Complexity of the Extracellular Matrix: Guidelines for Supramolecular Hydrogel-Cell Interactions

Hydrogels have emerged as a promising class of extracellular matrix (ECM)-mimicking materials in regenerative medicine. Here, we briefly describe current state-of-the-art of ECM-mimicking hydrogels, ranging from natural to hybrid to completely synthetic versions, giving the prelude to the importance of supramolecular interactions to make true ECM mimics. The potential of supramolecular interactions to create ECM mimics for cell culture is illustrated through a focus on two different supramolecular hydrogel systems, both developed in our laboratories. We use some recent, significant findings to present important design principles underlying the cell-material interaction. To achieve cell spreading, we propose that slow molecular dynamics (monomer exchange within fibers) is crucial to ensure the robust incorporation of cell adhesion ligands within supramolecular fibers. Slow bulk dynamics (stress-relaxation─fiber rearrangements, τ1/2 ≈ 1000 s) is required to achieve cell spreading in soft gels (<1 kPa), while gel stiffness overrules dynamics in stiffer gels. Importantly, this resonates with the findings of others which specialize in different material types: cell spreading is impaired in case substrate relaxation occurs faster than clutch binding and focal adhesion lifetime. We conclude with discussing considerations and limitations of the supramolecular approach as well as provide a forward thinking perspective to further understand supramolecular hydrogel-cell interactions. Future work may utilize the presented guidelines underlying cell-material interactions to not only arrive at the next generation of ECM-mimicking hydrogels but also advance other fields, such as bioelectronics, opening up new opportunities for innovative applications.

Interfacial Preparation of Polyoxometalate-Based Hybrid Supramolecular Polymers by Orthogonal Self-Assembly

The construction of organic-inorganic hybrid supramolecular polymers using polyoxometalate (POM) as building block is expected to bring new opportunities to the functionalization of supramolecular polymers and the development of novel POM-based soft materials. Here, by using the orthogonal self-assembly based on host-guest interactions and metal-ligand interactions, we report the in situ construction of a novel POM-based hybrid supramolecular polymer (POM-SP) at the oil-water interface, while the redox and competitive responsiveness can be triggered independently. Moreover, the binding energy of POM-SP at the interface is sufficiently strong so that the assembly of POM-SP jams, allowing the stabilization of liquids in nonequilibrium shapes, offering the possibility of fabricating all-liquid constructs with reconfigurability.

Synthesis, Photophysical Properties and Self-Assembly of a Tetraphenylethylene-Naphthalene Diimide Donor-Acceptor Molecule

The development of new π-conjugated molecular structures with controlled self-assembly and distinct photophysical properties is crucial for advancing applications in optoelectronics and biomaterials. This study introduces the synthesis and detailed self-assembly analysis of tetraphenylethylene (TPE) functionalized naphthalene diimide (NDI), a novel donor-acceptor molecular structure referred to as TPE-NDI. The investigation specifically focuses on elucidating the self-assembly behavior of TPE-NDI in mixed solvents of varying polarities, namely chloroform: methylcyclohexane (CHCl3 : MCH) and chloroform: methanol (CHCl3 : MeOH). Employing a several analytical methodologies, including UV-Vis absorption and fluorescence emission spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS), these self-assembled systems have been comprehensively examined. The results reveal that TPE-NDI manifests as distinct particles in CHCl3 : MCH (fMCH =90 %), while transitioning to flower-like assemblies in CHCl3 : MeOH (fMeOH =90 %). This finding underscores the critical role of solvent polarity in dictating the morphological characteristics of TPE-NDI self-assembled aggregates. Furthermore, the study proposes a molecular packing mechanism, based on SEM data, offering significant insights into the design and development of functional supramolecular systems. Such advancements in understanding the molecular self-assembly new π-conjugated molecular structures are anticipated to pave the way for novel applications in material science and nanotechnology.

Merging Solid-Phase Peptide Synthesis and Automated Glycan Assembly to Prepare Lipid-Peptide-Glycan Chimeras

Biomaterials with improved biological features can be obtained by conjugating glycans to nanostructured peptides. Creating peptide-glycan chimeras requires superb chemoselectivity. We expedite access to such chimeras by merging peptide and glycan solid-phase syntheses employing a bifunctional monosaccharide. The concept was explored in the context of the on-resin generation of a model α(1→6)tetramannoside linked to peptides, lipids, steroids, and adamantane. Chimeras containing a β(1→6)tetraglucoside and self-assembling peptides such as FF, FFKLVFF, and the amphiphile palmitoyl-VVVAAAKKK were prepared in a fully automated manner. The robust synthetic protocol requires a single purification step to obtain overall yields of about 20 %. The β(1→6)tetraglucoside FFKLVFF chimera produces micelles rather than nanofibers formed by the peptide alone as judged by microscopy and circular dichroism. The peptide amphiphile-glycan chimera forms a disperse fiber network, creating opportunities for new glycan-based nanomaterials.

Upper Critical Solution Temperature Polyvalent Scaffolds Aggregate and Exterminate Bacteria

Specific recognition and strong affinities of bacteria receptors with the host cell glycoconjugates pave the way to control the bacteria aggregation and kill bacteria. Herein, using aggregation-induced emission (AIE) molecules decorated upper critical solution temperature (UCST) polyvalent scaffold (PATC-GlcN), an approach toward visualizing bacteria aggregation and controlling bacteria-polyvalent scaffolds affinities under temperature stimulus is described. Polyvalent scaffolds with diblocks, one UCST block PATC of polyacrylamides showing a sharp UCST transition and typical AIE behavior, the second bacteria recognition block GlcN of hydrophilic glucosamine modified polyacrylamide, are prepared through a reversible addition and fragmentation chain transfer polymerization. Aggregated chain conformation of polyvalent scaffolds at temperature below UCST induces the aggregation of E. coli ATCC8739, because of the high density of glucosamine moieties, whereas beyond UCST, the hydrophilic state of the scaffolds dissociates the bacteria aggregation. The sweet-talking of bacteria toward the polyvalent scaffolds can be visualized by the fluorescent imaging technique, simultaneously. Due to the specific recognition of polyvalent scaffolds with bacteria, the photothermal agent IR780 loaded PATC-GlcN shows the targeted killing ability toward E. coli ATCC8739 in vitro and in vivo under NIR radiation.

Self-assembled plasmonic nanoarrays for enhanced bacterial identification and discrimination

The rapid and accurate bacterial testing is a critical step for the management of infectious diseases, but challenges remain largely due to a lack of advanced sensing tools. Here we report the development of highly plasmon-active, biofunctional nanoparticle arrays for simultaneous capture, identification, and differentiation of bacteria by surface-enhanced Raman scattering (SERS). The nanoarrays were facilely prepared through an electrostatic mechanism-controlled self-assembly of metallic nanoparticles at liquid-liquid interfaces, and exhibited high SERS sensitivity beyond femtomole, good reproducibility (relative standard deviation of 2.7%) and stability. Modification of the nanoarrays with concanavalin A allowed to effective capture of both Gram-positive and Gram-negative bacteria (bacterial-capture efficiency maintained beyond 50%) at bacterial concentrations ranging from 50 to 2000 CFU mL^-1, as determined by the plate-counting method. Moreover, single-cell Raman fingerprinting and discrimination of eight different bacteria species with high signal-to-noise ratio, excellent spectral reproducibility, and a total assay time of 1.5 h was achieved under fairly mild conditions (24 μW, acquisition time: 1 s). Collectively, we believe that our biofunctionalized, SERS-based self-assembled nanoarrays have great potential to help in rapid and label-free bacterial diagnosis and phenotyping study.

Introducing Hyaluronic Acid into Supramolecular Polymers and Hydrogels

The use of supramolecular polymers to construct functional biomaterials is gaining more attention due to the tunable dynamic behavior and fibrous structures of supramolecular polymers, which resemble those found in natural systems, such as the extracellular matrix. Nevertheless, to obtain a biomaterial capable of mimicking native systems, complex biomolecules should be incorporated, as they allow one to achieve essential biological processes. In this study, supramolecular polymers based on water-soluble benzene-1,3,5-tricarboxamides (BTAs) were assembled in the presence of hyaluronic acid (HA) both in solution and hydrogel states. The coassembly of BTAs bearing tetra(ethylene glycol) at the periphery (BTA-OEG₄) and HA at different ratios showed strong interactions between the two components that led to the formation of short fibers and heterogeneous hydrogels. BTAs were further covalently linked to HA (HA-BTA), resulting in a polymer that was unable to assemble into fibers or form hydrogels due to the high hydrophilicity of HA. However, coassembly of HA-BTA with BTA-OEG₄ resulted in the formation of long fibers, similar to those formed by BTA-OEG₄ alone, and hydrogels were produced with tunable stiffness ranging from 250 to 700 Pa, which is 10-fold higher than that of hydrogels assembled with only BTA-OEG₄. Further coassembly of BTA-OEG₄ fibers with other polysaccharides showed that except for dextran, all polysaccharides studied interacted with BTA-OEG₄ fibers. The possibility of incorporating polysaccharides into BTA-based materials paves the way for the creation of dynamic complex biomaterials.

Assembly of Dynamic Supramolecular Polymers on a DNA Origami Platform

Biological processes rely on transient interactions that govern assembly of biomolecules into higher order, multi-component systems. A synthetic platform for the dynamic assembly of multicomponent complexes would provide novel entries to study and modulate the assembly of artificial systems into higher order topologies. Here, we establish a hybrid DNA origami-based approach as an assembly platform that enables dynamic templating of supramolecular architectures. It entails the site-selective recruitment of supramolecular polymers to the platform with preservation of the intrinsic dynamics and reversibility of the assembly process. The composition of the supramolecular assembly on the platform can be tuned dynamically, allowing for monomer rearrangement and inclusion of molecular cargo. This work should aid the study of supramolecular structures in their native environment in real-time and incites new strategies for controlled multicomponent self-assembly of synthetic building blocks.

Exploring the Potential of Benzene-1,3,5-tricarboxamide Supramolecular Polymers as Biomaterials

The fast dynamics occurring in natural processes increases the difficulty of creating biomaterials capable of mimicking Nature. Within synthetic biomaterials, water-soluble supramolecular polymers show great potential in mimicking the dynamic behavior of these natural processes. In particular, benzene-1,3,5-tricaboxamide (BTA)-based supramolecular polymers have shown to be highly dynamic through the exchange of monomers within and between fibers, but their suitability as biomaterials has not been yet explored. Herein we systematically study the interactions of BTA supramolecular polymers bearing either tetraethylene glycol or mannose units at the periphery with different biological entities. When BTA fibers were incubated with bovine serum albumin (BSA), the protein conformation was only affected by the fibers containing tetraethylene glycol at the periphery (BTA-OEG₄). Coarse-grained molecular simulations showed that BSA interacted with BTA-OEG₄ fibers rather than with BTA-OEG₄ monomers that are present in solution or that may exchange out of the fibers. Microscopy studies revealed that, in the presence of BSA, BTA-OEG₄ retained their fiber conformation although their length was slightly shortened. When further incubated with fetal bovine serum (FBS), both long and short fibers were visualized in solution. Nevertheless, in the hydrogel state, the rheological properties were remarkably preserved. Further studies on the cellular compatibility of all the BTA assemblies and mixtures thereof were performed in four different cell lines. A low cytotoxic effect at most concentrations was observed, confirming the suitability of utilizing functional BTA supramolecular polymers as dynamic biomaterials.

Mechanisms of nanotoxicity - biomolecule coronas protect pathological fungi against nanoparticle-based eradication

Whereas nanotoxicity is intensely studied in mammalian systems, our knowledge of desired or unwanted nano-based effects for microbes is still limited. Fungal infections are global socio-economic health and agricultural problems, and current chemical antifungals may induce adverse side-effects in humans and ecosystems. Thus, nanoparticles are discussed as potential novel and sustainable antifungals via the desired nanotoxicity but often fail in practical applications. In our study, we found that nanoparticles' toxicity strongly depends on their binding to fungal spores, including the clinically relevant pathogen Aspergillus fumigatus as well as common plant pests, such as Botrytis cinerea or Penicillum expansum. Employing a selection of the model and antimicrobial nanoparticles, we found that nanoparticle-spore complex formation is influenced by the NM's physicochemical properties, such as size, identified as a key determinant for our silica model particles. Biomolecule coronas acquired in pathophysiologically and ecologically relevant environments, protected fungi against nanoparticle-induced toxicity as shown by employing antimicrobial ZnO, Ag, or CuO nanoparticles as well as dissolution-resistant quantum dots. Mechanistically, dose-dependent corona-mediated resistance was conferred via reducing the physical adsorption of nanoparticles to fungi. The inhibitory effect of biomolecules on nano-based toxicity of Ag NPs was further verified in vivo, using the invertebrate Galleria mellonella as an alternative non-mammalian infection model. We provide the first evidence that biomolecule coronas are not only relevant in mammalian systems but also for nanomaterial designs as future antifungals for human health, biotechnology, and agriculture.

Divergent Self-Assembly Pathways to Hierarchically Organized Networks of Isopeptide-Modified Discotics under Kinetic Control

Natural proteins traverse complex free energy landscapes to assemble into hierarchically organized structures, often through stimuli-directed kinetic pathways in response to relevant biological cues. Bioinspired strategies have sought to emulate the complexity, dynamicity, and modularity exhibited in these natural processes with synthetic analogues. However, these efforts are limited by many factors that complicate the rational design and predictable assembly of synthetic constructs, especially in aqueous environments. Herein, a model discotic amphiphile gelator is described that undergoes pathway-dependent structural maturation when exposed to varying application rates of a pH stimulus, investigated by electron microscopy, spectroscopy, and X-ray scattering techniques. Under the direction of a slowly changing pH stimulus, complex hierarchical assemblies result, characterized by mesoscale elongated "superstructure" bundles embedded in a percolated mesh of narrow nanofibers. In contrast, the assembly under a rapidly applied pH stimulus is characterized by homogeneous structures that are reminiscent of the superstructures arising from the more deliberate path, except with significantly reduced scale and concomitantly large increases in bulk rheological properties. This synthetic system bears resemblance to the pathway complexity and hierarchical ordering observed for native structures, such as collagen, and points to fundamental design principles that might be applied toward enhanced control of the properties of supramolecular self-assembly across length scales.

Galactose-Grafted 2D Nanosheets from the Self-Assembly of Amphiphilic Janus Dendrimers for the Capture and Agglutination of Escherichia coli

High aspect ratio, sugar-decorated 2D nanosheets are ideal candidates for the capture and agglutination of bacteria. Herein, the design and synthesis of two carbohydrate-based Janus amphiphiles that spontaneously self-assemble into high aspect ratio 2D sheets are reported. The unique structural features of the sheets include the extremely high aspect ratio and dense display of galactose on the surface. These structural characteristics allow the sheet to act as a supramolecular 2D platform for the capture and agglutination of E. coli through specific multivalent noncovalent interactions, which significantly reduces the mobility of the bacteria and leads to the inhibition of their proliferation. Our results suggest that the design strategy demonstrated here can be applied as a general approach for the crafting of biomolecule-decorated 2D nanosheets, which can perform as 2D platforms for their interaction with specific targets.

Multivalent Ultrasensitive Interfacing of Supramolecular 1D Nanoplatforms

Multivalent display on linear platforms is used by many biomolecular systems to effectively interact with their corresponding binding partners in a dose-responsive and ultrasensitive manner appropriate to the biological system at hand. Synthetic supramolecular multivalent displays offer a matching approach for the modular and bottom-up construction and systematic study of dynamic 1D materials. Fundamental studies into multivalent interactions between such linear, 1D materials have been lacking because of the absence of appropriate modular nanoplatforms. In this work we interfaced two synthetic multivalent linear nanoplatforms based on a dynamic supramolecular polymer, formed by hybrid discotic-oligonucleotide monomers, and a series of complementary DNA-duplex-based multivalent ligands, also with appended short oligonucleotides. The combination of these two multivalent nanoplatforms provides for the first time entry to study multivalent effects in dynamic 1D systems, of relevance for the conceptual understanding of multivalency in biology and for the generation of novel multivalent biomaterials. Together the two nanoscaffolds provide easy access to libraries of multivalent ligands with tunable affinities. The DNA scaffold allows for exact control over valency and spatial ligand distribution, and the discotic supramolecular polymer allows for dynamic adaptation and control over receptor density. The interaction between the two nanoplatforms was studied as a function of ligand interaction strength, valency, and density. Usage of the enhancement parameter β allowed quantification of the effects of ligand valency and affinity. The results reveal a generalized principle of additive binding increments. Receptor density is shown to be crucially and nonlinearly correlated to complex formation, leading to ultrasensitive responses. The results reveal that, not unlike biomolecular signaling, high density multivalent display of receptors is crucial for functionally increased affinities.

Fabrication of Emulsion-Templated Poly(vinylsulfonic acid)-Ag Nanocomposite Beads with Hierarchical Multimodal Porosity for Water Cleanup

Emulsion templating has emerged as a cutting-edge technique to prepare a wide array of porous polymer-metal nanocomposites with intriguing properties. Using this strategy, we set out to prepare novel hierarchically porous poly(vinylsulfonic acid) beads, which were then used for the in situ production of silver nanoparticles to obtain poly(vinylsulfonic acid)-Ag nanocomposite beads via a facile approach. Owing to their multimodal macro-meso-/microporosity that accounts for their decent BET surface areas (170.75-197.74 m²/g) and easier mass diffusion and transport together with the synergistic benefits of very small silver nanoparticles (down to ∼3.77 nm), the nanocomposite beads are found effective to remove Hg(II) and RhB and to kill Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. The adsorption capacities (167.98-190.58 mg/g) of these materials for Hg(II) surpass some recently reported benchmark materials. The larger size (1.56 ± 0.20-1.50 ± 0.14 mm) of the beads that helps favor the handling and subsequent recovery for recycling is also very useful to further broaden the horizons of these materials to develop decentralized water treatment systems.

Elucidating the Ordering in Self-Assembled Glycocalyx Mimicking Supramolecular Copolymers in Water

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.

Light-Responsive Arylazopyrazole Gelators: From Organic to Aqueous Media and from Supramolecular to Dynamic Covalent Chemistry

Versatile photoresponsive gels based on tripodal low molecular weight gelators (LMWGs) are reported. A cyclohexane-1,3,5-tricarboxamide (CTA) core provides face-to-face hydrogen bonding and a planar conformation, inducing the self-assembly of supramolecular polymers. The CTA core was substituted with three arylazopyrazole (AAP) arms. AAP is a molecular photoswitch that isomerizes reversibly under alternating UV and green light irradiation. The E isomer of AAP is planar, favoring the self-assembly, whereas the Z isomer has a twisted structure, leading to a disassembly of the supramolecular polymers. By using tailor-made molecular design of the tripodal gelator, light-responsive organogels and hydrogels were obtained. Additionally, in the case of the hydrogels, AAP was coupled to the core through hydrazones, so that the hydrogelator and, hence, the photoresponsive hydrogel could also be assembled and disassembled by using dynamic covalent chemistry.

Insights into the Kinetics of Supramolecular Comonomer Incorporation in Water

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. C₁₀BTA does not form ordered supramolecular assemblies, whereas C₁₂BTA and C₁₃BTA both form high aspect ratio supramolecular polymers. First, we illustrate that C₁₀BTA can mix into the supramolecular polymers based on either C₁₂BTA or C₁₃BTA by comparing the temperature response of the equilibrated mixtures to the temperature response of the individual components in water. Subsequently, we mix C₁₀BTA 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 C₁₀BTA 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.

Future of Supramolecular Copolymers Unveiled by Reflecting on Covalent Copolymerization

Supramolecular copolymers are an emerging class of materials, and in the last years their potential has been demonstrated on a broad scale. Implementing noncovalent polymers with multiple components can bring together useful features such as dynamicity and new functionalities. However, mastering and tuning the microstructure of these systems is still an open challenge. In this Perspective, we aim to trace the general principles of supramolecular copolymerization by analyzing them through the lens of the well-established field of covalent copolymerization. Our goal is to delineate guidelines to classify and analyze supramolecular copolymers in order to create a fruitful platform to design and investigate new multicomponent systems.

Resistance to Nano-Based Antifungals Is Mediated by Biomolecule Coronas

Fungal infections are a growing global health and agricultural threat, and current chemical antifungals may induce various side-effects. Thus, nanoparticles are investigated as potential novel antifungals. We report that nanoparticles' antifungal activity strongly depends on their binding to fungal spores, focusing on the clinically important fungal pathogen Aspergillus fumigatus as well as common plant pathogens, such as Botrytis cinerea. We show that nanoparticle-spore complex formation was enhanced by the small nanoparticle size rather than the material, shape or charge, and could not be prevented by steric surface modifications. Fungal resistance to metal-based nanoparticles, such as ZnO-, Ag-, or CuO-nanoparticles as well as dissolution-resistant quantum dots, was mediated by biomolecule coronas acquired in pathophysiological and ecological environments, including the lung surfactant, plasma or complex organic matters. Mechanistically, dose-dependent corona-mediated resistance occurred via reducing physical adsorption of nanoparticles to fungal spores. The inhibitory effect of biomolecules on the antifungal activity of Ag-nanoparticles was further verified in vivo, using the invertebrate Galleria mellonella as an A. fumigatus infection model. Our results explain why current nanoantifungals often show low activity in realistic application environments, and will guide nanomaterial designs that maximize functionality and safe translatability as potent antifungals for human health, biotechnology, and agriculture.

Biomolecule-corona formation confers resistance of bacteria to nanoparticle-induced killing: Implications for the design of improved nanoantibiotics

Multidrug-resistant bacterial infections are a global health threat. Nanoparticles are thus investigated as novel antibacterial agents for clinical practice, including wound dressings and implants. We report that nanoparticles' bactericidal activity strongly depends on their physical binding to pathogens, including multidrug-resistant primary clinical isolates, such as Staphylococcus aureus, Klebsiella pneumoniae or Enterococcus faecalis. Using controllable nanoparticle models, we found that nanoparticle-pathogen complex formation was enhanced by small nanoparticle size rather than material or charge, and was prevented by 'stealth' modifications. Nanoparticles seem to preferentially bind to Gram-positive pathogens, such as Listeria monocytogenes, S. aureus or Streptococcus pyrogenes, correlating with enhanced antibacterial activity. Bacterial resistance to metal-based nanoparticles was mediated by biomolecule coronas acquired in pathophysiological environments, such as wounds, the lung, or the blood system. Biomolecule corona formation reduced nanoparticles' binding to pathogens, but did not impact nanoparticle dissolution. Our results provide a mechanistic explanation why nano-sized antibiotics may show reduced activity in clinically relevant environments, and may inspire future nanoantibiotic designs with improved and potentially pathogen-specific activity.

Mutually Exclusive Cellular Uptake of Combinatorial Supramolecular Copolymers

The cellular uptake of self-assembled biological and synthetic matter results from their multicomponent properties. However, the interplay of the building block composition of self-assembled materials and uptake mechanisms urgently requires addressing. It is shown here that supramolecular polymers that self-assemble in aqueous media, are a modular and controllable platform to modulate cellular delivery by the introduction of small ligands or cationic moieties, with concomitantly different cellular uptake kinetics and valence dependence. A library of supramolecular copolymers revealed stringent mutually exclusive uptake behavior in which either of the uptake pathways dominated, with sharp compositional transition. Supramolecular biomaterial engineering thus provides for adaptive platforms with great potential for efficient tuning of multivalent and multicomponent systems interfacing with biological matter.

Small Meets Smaller: Effects of Nanomaterials on Microbial Biology, Pathology, and Ecology

As functionalities and levels of complexity in nanomaterials have increased, unprecedented control over microbes has been enabled, as well. In addition to being pathogens and relevant to the human microbiome, microbes are key players for sustainable biotechnology. To overcome current constraints, mechanistic understanding of nanomaterials' physicochemical characteristics and parameters at the nano-bio interface affecting nanomaterial-microbe crosstalk is required. In this Perspective, we describe key nanomaterial parameters and biological outputs that enable controllable microbe-nanomaterial interactions while minimizing design complexity. We discuss the role of biomolecule coronas, including the problem of nanoantibiotic resistance, and speculate on the effects of nanomaterial-microbe complex formation on the outcomes and fates of microbial pathogens. We close by summarizing our current knowledge and noting areas that require further exploration to overcome current limitations for next-generation practical applications of nanotechnology in medicine and agriculture.

Mannose-Decorated Multicomponent Supramolecular Polymers Trigger Effective Uptake into Antigen-Presenting Cells

A modular route to prepare functional self-assembling dendritic peptide amphiphiles decorated with mannosides, to effectively target antigen-presenting cells, such as macrophages, is reported. The monomeric building blocks were equipped with tetra(ethylene glycol)s (TEGs) or labeled with a Cy3 fluorescent probe. Experiments on the uptake of the multifunctional supramolecular particles into murine macrophages (Mφs) were monitored by confocal microscopy and fluorescence-activated cell sorting. Mannose-decorated supramolecular polymers trigger a significantly higher cellular uptake and distribution, relative to TEG carrying bare polymers. No cytotoxicity or negative impact on cytokine production of the treated Mφs was observed, which emphasized their biocompatibility. The modular nature of the multicomponent supramolecular polymer coassembly protocol is a promising platform to develop fully synthetic multifunctional vaccines, for example, in cancer immunotherapy.

Dual-Input Regulation and Positional Control in Hybrid Oligonucleotide/Discotic Supramolecular Wires

The combination of oligonucleotides and synthetic supramolecular systems allows for novel and long‐needed modes of regulation of the self‐assembly of both molecular elements. Discotic molecules were conjugated with short oligonucleotides and their assembly into responsive supramolecular wires studied. The self‐assembly of the discotic molecules provides additional stability for DNA‐duplex formation owing to a cooperative effect. The appended oligonucleotides allow for positional control of the discotic elements within the supramolecular wire. The programmed assembly of these hybrid architectures can be modulated through the DNA, for example, by changing the number of base pairs or salt concentration, and through the discotic platform by the addition of discotic elements without oligonucleotide handles. These hybrid supramolecular‐DNA structures allow for advanced levels of control over 1D dynamic platforms with responsive regulatory elements at the interface with biological systems.

Templated Formation of Luminescent Virus-like Particles by Tailor-Made Pt(II) Amphiphiles

Virus-like particles (VLPs) have been created from luminescent Pt(II) complex amphiphiles, able to form supramolecular structures in water solutions, that can be encapsulated or act as templates of cowpea chlorotic mottle virus capsid proteins. By virtue of a bottom-up molecular design, icosahedral and nonicosahedral (rod-like) VLPs have been constructed through diverse pathways, and a relationship between the molecular structure of the complexes and the shape and size of the VLPs has been observed. A deep insight into the mechanism for the templated formation of the differently shaped VLPs was achieved, by electron microscopy measurements (TEM and STEM) and bulk analysis (FPLC, DLS, photophysical investigations). Interestingly, the obtained VLPs can be visualized by their intense emission at room temperature, generated by the self-assembly of the Pt(II) complexes. The encapsulation of the luminescent species is further verified by their higher emission quantum yields inside the VLPs, which is due to the confinement effect of the protein cage. These hybrid materials demonstrate the potential of tailor-made supramolecular systems able to control the assembly of biological building blocks.

Supramolecular self-assemblies for bacterial cell agglutination driven by directional charge-transfer interactions

Two supramolecular amphiphiles are fabricated through directional charge-transfer interactions, which self-assemble into nanofibers and nanoribbons. Due to the existence of galactose on their surface, these self-assemblies act as a cell glue to agglutinate E. coli, benefiting from multivalent interactions.

Phase Behavior of a New Class of Anthraquinone-Based Discotic Liquid Crystals

Five novel columnar liquid crystalline compounds (4.1-4.5) consisting of a central anthraquinone core carrying four alkoxy chains (R = n-C₆H₁₃, n-C₈H₁₇, n-C₁₀H₂₁, n-C₁₂H₂₅, and 3,7-dimethyl octyl) with two diagonally opposite 1-ethynyl-4-pentylbenzene units were synthesized, and their phase transitions were investigated between changes in the molecular structure and their self-assembly into the columnar mesophases. Small and wide-angle X-ray scattering (SAXS/WAXS) studies were performed to deduce the exact nature of the mesophases, and their corresponding electron density maps were derived from the intensities of the peaks observed in the diffraction patterns. A comparison of compounds with different alkoxy chains indicated that the soft crystal columnar rectangular (Cr_colrec) phase was stable at lower temperature for the shortest peripheral alkoxy chain (4.1; R = n-C₆H₁₃) and was found to exhibit the columnar hexagonal (Col_h) phase and then the discotic nematic (N_D) phase with increasing temperature. In contrast, increasing the peripheral chain length to n-C₈H₁₇ or the branched one (4.2 and 4.5) stabilized the Col_h phase at lower temperature and showed the N_D phase at higher temperature. Further increase in chain length (4.3 and 4.4; n-C₁₀H₂₁, n-C₁₂H₂₅) demonstrated the formation of the N_D phase. Conductivity measurement in the Col_h mesophase was found to be almost 10 times higher in magnitude than the corresponding Cr_colrec phase. The HOMO-LUMO band gap of all the compounds was found to be in the range from 2.79 to 2.82 eV, which is quite less and comparable with the optical energy band gap.

Sulfated glycopeptide nanostructures for multipotent protein activation

Biological systems have evolved to utilize numerous proteins with capacity to bind polysaccharides for the purpose of optimizing their function. A well-known subset of these proteins with binding domains for the highly diverse sulfated polysaccharides are important growth factors involved in biological development and tissue repair. We report here on supramolecular sulfated glycopeptide nanostructures, which display a trisulfated monosaccharide on their surfaces and bind five critical proteins with different polysaccharide-binding domains. Binding does not disrupt the filamentous shape of the nanostructures or their internal β-sheet backbone, but must involve accessible adaptive configurations to interact with such different proteins. The glycopeptide nanostructures amplified signalling of bone morphogenetic protein 2 significantly more than the natural sulfated polysaccharide heparin, and promoted regeneration of bone in the spine with a protein dose that is 100-fold lower than that required in the animal model. These highly bioactive nanostructures may enable many therapies in the future involving proteins.

Morphological control of self-assembled multivalent (SAMul) heparin binding in highly competitive media

Shape control – self-assembly of ligands into different morphologies directs their ability to bind heparin.

Last-Step Enzymatic [(18) F]-Fluorination of Cysteine-Tethered RGD Peptides Using Modified Barbas Linkers

We report a last-step fluorinase-catalyzed [(18) F]-fluorination of a cysteine-containing RGD peptide. The peptide was attached through sulfur to a modified and more hydrophilic variant of the recently disclosed Barbas linker which was itself linked to a chloroadenosine moiety via a PEGylated chain. The fluorinase was able to use this construct as a substrate for a transhalogenation reaction to generate [(18) F]-radiolabeled RGD peptides, which retained high affinity to cancer-cell relevant αv β3 integrins.

Electrostatic binding of polyanions using self-assembled multivalent (SAMul) ligand displays - structure-activity effects on DNA/heparin binding

This paper reports that modifying the ligands in self-assembled multivalent (SAMul) displays has an impact on apparent binding selectivity towards two nanoscale biological polyanions - heparin and DNA. For the nanostructures assayed here, spermidine ligands are optimal for heparin binding but spermine ligands are preferred for DNA. Probing subtle differences in such nanoscale binding interfaces is a significant challenge, and as such, several experimental binding assays - competition assays and isothermal calorimetry - are employed to confirm differences in affinity and provide thermodynamic insights. Given the dynamic nature and hierarchical binding processes involved in SAMul systems, we employed multiscale modelling to propose reasons for the origins of polyanion selectivity differences. The modelling results, when expressed in thermodynamic terms and compared with the experimental data, suggest that DNA is a shape-persistent polyanion, and selectivity originates only from ligand preferences, whereas heparin is more flexible and adaptive, and as such, actively reinforces ligand preferences. As such, this study suggests that inherent differences between polyanions may underpin subtle binding selectivity differences, and that even simple electrostatic interfaces such as these can have a degree of tunability, which has implications for biological control and regulation on the nanoscale.

Agglutination of bacteria using polyvalent nanoparticles of aggregation-induced emissive thiophthalonitrile dyes

A novel class of aggregation-induced emissive bis(phenylthio)phthalonitrile dyes were synthesized. These dyes assembled into nanoparticles that were equipped with mannose units. The nanoparticles underwent selective interactions with lectins and bacteria. The bright fluorescent aggregates aid in the visualization of the agglutination of bacteria.

Enhancement of TFO Triplex Formation by Conjugation with Pyrene via Click Chemistry

This paper reports the preparation of 14-mer triplex-forming oligonucleotides (TFOs) containing a 2-O-methyl-1-β-phenyl-α-propargyl-ribose unit, which was conjugated with azide-modified molecules via a click reaction. Modification of these TFOs with pyrene assisted triplex formation, improving the stability of the triplex DNA and the anti-proliferative effects against A549 cells.

Switching of carbohydrate nanofibers for regulating cell proliferation

We report switchable, fluorescent carbohydrate nanofibers formed through the self-assembly of aromatic rod amphiphiles with a combination of mannose epitopes and thermoresponsive oligoether dendrons. The carbohydrate nanofibers undergo reversible switching between carbohydrate-exposed and hidden states on their surface in response to a thermal signal, and have the ability to regulate cell proliferation.

Solution Behavior of Amphiphilic Glycodendrimers with a Rod-Like Core

Glycodendrimers based on aromatic cores have an amphiphilic character and have been reported to generate supramolecuar assemblies in water. A new group of glycodendrimers with an aromatic rod-like core were recently described as potent antagonists of DC-SIGN-mediated viral infections. A full characterization of the aggregation properties of these materials is presented here. The results show that these compounds exist mostly as monomers in water solution, in dynamic equilibrium with small aggregates (dimers or trimers). Larger aggregates observed by dynamic light scattering and transmission Electron Microscopy for some of the dendrimers are found to be portions of materials not fully solubilized and can be removed either by optimizing the dissolution protocol or by centrifugation of the samples.

A toolbox for controlling the properties and functionalisation of hydrazone-based supramolecular hydrogels

In situ multicomponent hydrogelator formation enables straightforward chemical functionalisation of supramolecular hydrogels.

Probing the self-assembly and stability of oligohistidine based rod-like micelles by aggregation induced luminescence

The synthesis and self-assembly of a new C₂-symmetric oligohistidine amphiphile equipped with an aggregation induced emission luminophore is reported.

Tuning of glyconanomaterial shape and size for selective bacterial cell agglutination

Acting as veritable glue, 1D-coated mannose carbon nanotubes efficiently and selectively regulate the agglutination and proliferation of the enterobacteriaEscherichia colitype 1 fimbriae, much better than the mannose coated 3D-micelles.

Carbohydrates in Supramolecular Chemistry

Carbohydrates are involved in a variety of biological processes. The ability of sugars to form a large number of hydrogen bonds has made them important components for supramolecular chemistry. We discuss recent advances in the use of carbohydrates in supramolecular chemistry and reveal that carbohydrates are useful building blocks for the stabilization of complex architectures. Systems are presented according to the scaffold that supports the glyco-conjugate: organic macrocycles, dendrimers, nanomaterials, and polymers are considered. Glyco-conjugates can form host-guest complexes, and can self-assemble by using carbohydrate-carbohydrate interactions and other weak interactions such as π-π interactions. Finally, complex supramolecular architectures based on carbohydrate-protein interactions are discussed.

Multivalency at Interfaces: Supramolecular Carbohydrate-Functionalized Graphene Derivatives for Bacterial Capture, Release, and Disinfection

A supramolecular carbohydrate-functionalized two-dimensional (2D) surface was designed and synthesized by decorating thermally reduced graphene sheets with multivalent sugar ligands. The formation of host-guest inclusions on the carbon surface provides a versatile strategy, not only to increase the intrinsic water solubility of graphene-based materials, but more importantly to let the desired biofunctional binding groups bind to the surface. Combining the vital recognition role of carbohydrates and the unique 2D large flexible surface area of the graphene sheets, the addition of multivalent sugar ligands makes the resulting carbon material an excellent platform for selectively wrapping and agglutinating Escherichia coli (E. coli). By taking advantage of the responsive property of supramolecular interactions, the captured bacteria can then be partially released by adding a competitive guest. Compared to previously reported scaffolds, the unique thermal IR-absorption properties of graphene derivatives provide a facile method to kill the captured bacteria by IR-laser irradiation of the captured graphene-sugar-E. coli complex.