Supramolecular Nanostructures Research Articles

Optical and supramolecular properties of cyclometalated palladium nanostructures with tumor targeting properties in living mice: a quantum mechanics interpretation.

The recent discovery that metallophilic interactions between cyclometalated palladium supramolecular nanostructures - with efficient tumour accumulation rate in a skin melanoma model - maintain excellent photodynamic properties even in a hypoxic microenvironment has inspired the present study focused on the theoretical predictions of optical properties of the bis-cyclometalated palladium compound in different contexts. More specifically, structural and UV/Vis absorption properties of both monomeric and dimeric forms of this anticancer drug are well reproduced with a Time-Dependent Density Functional Theoretical (TD-DFT) approach based on Exchange-Correlation (XC) hybrid functionals in conjunction with conductor-like and polarization solvation effects. A further novelty is represented by a fine investigation of the supramolecular interactions between the different subunits of the drug via dispersion force correction andQuantum Theory of Atoms in Molecules (QTAIM). This contribution while supporting the photoexcitation properties derived in laboratory following the self-assembly of monomeric units when passing from dimethyl sulfoxide (DMSO) to a H2O/DMSO mixture at 298K, shed some light on the nature of the chemical interactions modulating the formation of nano-size aggregates.

Supramolecular assemblies of amphiphilic donor-acceptor Stenhouse adducts as macroscopic soft scaffolds.

In the design of photoharvesting and photoresponsive supramolecular systems in aqueous medium, the fabrication of amphiphilic photoswitches enables a noninvasive functional response through photoirradiation. Although most aqueous supramolecular assemblies are driven by high-energy and biodamaging UV light, we have previously reported a design of amphiphilic donor-acceptor Stenhouse adducts (DASAs) controlled by white light. Herein, we present a series of DASA amphiphiles (DAs) with minor structural modifications on the alkyl linker chain length connecting the DASA motif with the hydrophilic moiety. The excellent photoswitchability in organic medium and the photoresponsiveness in aqueous medium, driven by visible light, were investigated by UV-vis absorption spectroscopy. The assembled supramolecular nanostructures were confirmed by electron microscopy, while the supramolecular packing was revealed by X-ray diffraction analysis. Upon visible-light irradiation, significant transformations of the DA geometry enabled transformations of the supramolecular assemblies on a microscopic scale, subsequently disassembling macroscopic soft scaffolds of DAs. The current work shows promising use for the fabrication of visible-light-controlled macroscopic scaffolds, offering the next generation of biomedical materials with visible-light-controlled microenvironments and future soft-robotic systems.

Supramolecular Self-Assembled Nanostructures Derived from Amplified Structural Isomerism of Zn(II)-Sn(IV)-Zn(II) Porphyrin Triads and Their Visible Light Photocatalytic Degradation of Pollutants.

Two structural isomeric porphyrin-based triads (Zn(II)porphyrin-Sn(IV)porphyrin-Zn(II)porphyrin) denoted as T1 and T2 were prepared from the reaction of meso-[5-(4-hydroxyphenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinato]zinc(II) (ZnL) with trans-dihydroxo-[5,10-bis(3-pyridyl)-15,20-bis(phenyl)porphyrinato]tin(IV) (SnP1) and trans-dihydroxo-[5,15-bis(3-pyridyl)-10,20-bis(phenyl)porphyrinato]tin(IV) (SnP2), respectively. All the compounds were characterized using UV-vis spectroscopy, emission spectroscopy, ESI-MS, 1H NMR spectroscopy, and FE-SEM. Most importantly, the two structurally isomeric porphyrin-based triads supramolecularly self-assembled into completely different nanostructures. T1 exhibits a nanosphere morphology, whereas T2 exhibits a nanofiber morphology. The amplified geometric feature in the structural isomeric porphyrin-based triads dictates the physical and chemical properties of the two triads. Both compounds showed the morphology-dependent visible light catalytic photodegradation of rhodamine B dye (74-97% within 90 min) and tetracycline antibiotic (44-71% within 45 min) in water. In both cases, the photodegradation efficiency of T2 was higher than that of T1. The present investigation can significantly contribute to the remediation of wastewater by tuning the conformational changes in porphyrin-based photocatalysts.

Lipidated DNA Nanostructures Target and Rupture Bacterial Membranes.

Chemistry has the power to endow supramolecular nanostructures with new biomedically relevant functions. Here it is reported that DNA nanostructures modified with cholesterol tags disrupt bacterial membranes to cause microbial cell death. The lipidated DNA nanostructures bind more readily to cholesterol-free bacterial membranes than to cholesterol-rich, eukaryotic membranes. These highly negatively charged, lipidated DNA nanostructures cause bacterial cell death by rupturing membranes. Strikingly, killing is mediated by clusters of barrel-shaped nanostructures that adhere to the membrane without the involvement of expected bilayer-puncturing barrels. These DNA nanomaterials may inspire the development of polymeric or small-molecule antibacterial agents that mimic the principles of selective binding and rupturing to help combat antimicrobial resistance.

Bioinspired on-off switchable multi-level responsiveness for ultralong fire-warning, super-sensitive solvent/humidity and light-driven behaviors

The prospects of endowing the omnipresent hazardous substances with sensitive, safe, and stable life-like behaviors poses significant for the development of on–off switchable smart materials. Herewith, based on material-structural synergistic design, a multi-level responsiveness smart structures (VBGO) inspired by phospholipid biomolecules is self-assembled through asymmetric swelling and smart supramolecular nano-structures. Due to the outstanding sensitive of fire-warning nano-hybrid of functionalized cyclodextrin-graphene and highly stable substrate of vermiculite, the designed VBGO exhibits the high-sensitively fire alarm time (only 0.17 s) and super-along sustained fire alarm time (up to 249 s). Moreover, the VBGO displays significant increment in thermal stability and film-forming properties. Besides, given the asymmetrical and self-assembled smart structures, the VBGO exhibits the unique fast responses in their surrounding environments like fire, heat, light, humidity, and solvent vapor. Additionally, the on–off switchable mechanisms of fire-warning responsiveness, solvent-/humidity-/light-driven, shape memory and environmental awareness are presented systematically. This work introduces a sensitive, safe, and stable approach to designing multi-level responsive smart materials by modifying fire-warning bioinspired structures.

Biomaterials for Targeting Endoplasmic Reticulum in Cancer.

Endoplasmic reticulum (ER) is one of the most important sub-cellular organelles which controls myriads of biological functions including protein biosynthesis with proper functional folded form, protein misfolding, protein transport into Golgi body for secretion, Ca2+ homeostasis and so on. Subsequently, dysregulation in ER function leads to ER stress followed by disease pathology like cancer. Hence, targeting ER in the cancer cells emerged as one of the futuristic strategies for cancer treatment. However, the major challenge is to selectively and specifically target ER in the sub-cellular milieu in the cancer tissues, due to the lack of ER targeting chemical moieties to recognize the ER markers. To address this, in the last decade, numerous biomaterials were explored to selectively impair and image ER in cancer cells to induce ER stress. This review outlines those biomaterials which consists of carbon and silicon materials, lipid nanoparticles (liposomes and micelles), supramolecular self-assembled nanostructures, cell membrane-coated nanoparticles and metallic nanoparticles. Moreover, we also discuss the challenges and possible solutions of this promising field to usher the readers towards next-generation ER targeted cancer therapy.

Expression of chiral molecular and supramolecular structure on enantioselective catalytic activity

Understanding the structure-function relationships encoded on chiral catalysts is important for investigating the fundamental principles of catalytic enantioselectivity. Herein, the synthesis and self-assembly of naphthalene substituted bis-l/d-histidine amphiphiles (bis-l/d-NapHis) in DMF/water solution mixture is reported. The resulting supramolecular assemblies featuring well-defined P/M nanoribbons (NRs). With combination of the (P/M)-NR and metal ion catalytic centers (Mn+ = Co2+, Cu2+, Fe3+), the (P)-NR-Mn+ as chiral supramolecular catalysts show catalytic preference to 3,4-dihydroxy-S-phenylalanine (S-DOPA) oxidation while the (M)-NR-Mn+ show enantioselective bias to R-DOPA oxidation. In contrast, their monomeric counterparts bis-l/d-NapHis-Mn+ display an inverse and dramatically lower catalytic selectivity in the R/S-DOPA oxidation. Among them, the Co2+-coordinated supramolecular nanostructures show the highest catalytic efficiency and enantioselectivity (select factor up to 2.70), while the Fe3+-coordinated monomeric ones show nearly racemic products. Analysis of the kinetic results suggests that the synergistic effect between metal ions and the chiral supramolecular NRs can significantly regulate the enantioselective catalytic activity, while the metal ion-mediated monomeric bis-l/d-NapHis were less active. The studies on association constants and activation energies reveal the difference in catalytic efficiency and enantioselectivity resulting from the different energy barriers and binding affinities existed between the chiral molecular/supramolecular structures and R/S-DOPA enantiomers. This work clarifies the correlation between chiral molecular/supramolecular structures and enantioselective catalytic activity, shedding new light on the rational design of chiral catalysts with outstanding enantioselectivity.

Unraveling the influence of aromatic endcaps in peptide self-assembly

Aromatic peptides are an emerging class of building units for molecular self-assembly and creation of functional biomaterials. The strength of aromatic association plays an essential role in the self-assembly of aromatic peptides. Here, we design a series of aromatic peptides with different hydrophobic domains but the same peptide sequence. The hydrophobicity and aromaticity can be carefully regulated by the number of benzene rings and the alkyl spacer between the benzene and peptide regions. Upon the continuous enhancement of aromaticity, diverse supramolecular nanostructures, including nanotubes, nanofibers, and short helical ribbons, were clearly observed. The peptide with diphenyl groups exhibits the highest regularity of molecular packing, due to the synergy of force balance between hydrogen bonding and π–π interactions. In addition, the incorporation of a spacer in between the aromatic and peptide regions facilitates the self-assembly capability, as the interference between aromatic association and hydrogen bonding is hindered. These dramatic results demonstrate that aromaticity serves as an effective and robust parameter in the molecular arrangement, providing a new perspective into the formation and evolution of supramolecular assembly.

Directed Chiral Self‐Assembly of Purely Organic Phosphors for Room‐Temperature Circularly Polarized Phosphorescence

AbstractCircularly polarized phosphorescence (CPP) is increasingly recognized in materials science for its unique applications in optoelectronic devices, chiral recognition, and bioimaging. This study underscores a novel directed chiral self‐assembly strategy of purely organic phosphors into supramolecular nanostructures to achieve bright room‐temperature circularly polarized phosphorescence (RT‐CPP). RT‐CPP molecules are built on an aromatic carbonyl structure having also Br to mix (n,π*) and (π,π*) characters and to enable the heavy atom effect. Side chains are rationally designed to have strong hydrogen bonding, van der Waals interactions, and a chiral center for directed chiral self‐assembly into supramolecular nanostructures. The tightly packed resulting supramolecular nanostructures also impower efficient suppression of molecular motions, thereby minimizing non‐radiative decay and facilitating bright CPP emission at room temperature. The developed self‐assembled supramolecular structures exhibit RT‐CPP with the dissymmetry factor (glum) of ≈10−3, a high phosphorescence quantum yield of 4.1%, and a rapid triplet decay time of 180 microseconds. The presented molecular design principle enabling RT‐CPP from purely organic phosphors may pave the way for novel photonic materials.

Atomic Scale Structure of Self-Assembled Lipidated Peptide Nanomaterials.

β-Peptides have great potential as novel biomaterials and therapeutic agents, due to their uniqueability to self-assemble into low dimensional nanostructures,and their resistance to enzymatic degradationin vivo. However, the self-assembly mechanisms of β-peptides, which possess increased flexibility due to the extra backbone methylene groups present within the constituent β-amino acids, are not well understood due to inherent difficulties of observing their bottom-up growth pathway experimentally. A computational approach is presented for the bottom-up modelling of the self-assembledlipidated β3-peptides, from monomers, to oligomers, to supramolecular low-dimensional nanostructures, in all-atom detail. The approach is applied to elucidate the self-assembly mechanisms of recently discovered, distinct structural morphologies of low dimensional nanomaterials, assembled from lipidated β3-peptide monomers. The resultant structures of the nanobelts and the twisted fibrils are stable throughout subsequent unrestrained all-atom molecular dynamics simulations, and these assemblies display good agreement with the structural features obtained from X-ray fiber diffraction and atomic force microscopy data.This is the first reported, fully-atomistic model of a lipidated β3-peptide-based nanomaterial, and the computational approach developed here, in combination with experimental fiber diffraction analysis and atomic force microscopy, will be useful in elucidating the atomic scale structure of self-assembled peptide-based and other supramolecular nanomaterials.

Donor-Acceptor Assembly of Amphiphilic Molecules Based on 9,10-Distyrylanthracene Derivatives with Terminal Naphthalene Groups.

Amphiphilic rod-coil compounds have excellent photophysical properties and can be assembled into supramolecular nanostructures of different sizes in water or polar solvents. Herein, we synthesized the amphiphilic compounds 2N-DSA, 4N-DSA, and 6N-DSA with 9,10-distyrylanthracene (DSA) as the core and a naphthalene unit as the terminal group that connected DSA through a tetraethylene glycol chain. These compounds have excellent aggregation-induced emission (AIE) properties in aqueous solution and are assembled into worm-like fragments or different sizes of spherical assemblies, defending the volume ratio of the rod to coil segments. Notably, the donor-acceptor interaction between DSA and electron- deficient compounds 2,4,6-trinitrophenol (TNP), 2,4,5,7-tetranitrofluorenone (TNF), and tetraethylene glycol dinitrobenzoate (TGDNB) forms a charge transfer complex, which can be used as a nanoreactor to improve the yield of the Suzuki coupling reaction about 8-10 times. The experimental results reveal that the synergy effect of the donor-acceptor, intermolecular π-π stacking, and hydrophobic-hydrophilic interactions significantly influences the morphology of aggregates and the efficiency of the nanoreactor.

Peptide Supramolecular Self-Assembly: Regulatory Mechanism, Functional Properties, and Its Application in Foods.

Peptide self-assembly, due to its diverse supramolecular nanostructures, excellent biocompatibility, and bright application prospects, has received wide interest from researchers in the fields of biomedicine and green life technology and the food industry. Driven by thermodynamics and regulated by dynamics, peptides spontaneously assemble into supramolecular structures with different functional properties. According to the functional properties derived from peptide self-assembly, applications and development directions in foods can be found and explored. Therefore, in this review, the regulatory mechanism is elucidated from the perspective of self-assembly thermodynamics and dynamics, and the functional properties and application progress of peptide self-assembly in foods are summarized, with a view to more adaptive application scenarios of peptide self-assembly in the food industry.

Engineering large nanoporous networks with size and shape selected by appropriate precursors

Large domains of two-dimensional supramolecular porous nanostructures are interesting for various applications from electronics to biology. Here, we investigate the formation of Cu-coordinated networks on Cu(111) using scanning tunneling microscopy and density functional theory (DFT). We consider two molecules with three pyridyl end groups connected to a central benzene ring by either one or two phenyl groups, namely 1,3,5-tris[4-(pyridin)phenyl]benzene (TPyPB) and 1,3,5-tris[4-(pyridin)-[1,1’-biphenyl]benzene (TPyPPB), respectively. Upon deposition of TPyPB at room temperature, a honeycomb nanostructure forms, which is stabilized by Cu adatoms, as previously seen. Upon deposition at 400 K, the growth dynamics change, and molecules become trapped in the hexagonal pores. In contrast, deposition of TPyPPB at room temperature leads to vitreous structures, which rearrange at 400 K forming a low-defect and extended ordered honeycomb phase, which is also stabilized only in the presence of Cu adatoms. The DFT calculations for both honeycomb phases show an impressive agreement with the experimental results, considering the size of such structures. After annealing at 420 K, a complex flower-like structure composed of a mix of two- and three-fold coordinated Cu centers emerges. Further annealing to above 420 K leads to another new phase composed of a high molecular density motif, the so-called diamond phase.

Bioinspired Self-Assembly of Metalloporphyrins and Polyelectrolytes into Hierarchical Supramolecular Nanostructures for Enhanced Photocatalytic H2 Production in Water.

Polypeptides, as natural polyelectrolytes, are assembled into tailored proteins to integrate chromophores and catalytic sites for photosynthesis. Mimicking nature to create the water-soluble nanoassemblies from synthetic polyelectrolytes and photocatalytic molecular species for artificial photosynthesis is still rare. Here, we report the enhancement of the full-spectrum solar-light-driven H2 production within a supramolecular system built by the co-assembly of anionic metalloporphyrins with cationic polyelectrolytes in water. This supramolecular photocatalytic system achieves a H2 production rate of 793 and 685 μmol h-1 g-1 over 24 h with a combination of Mg or Zn porphyrin as photosensitizers and Cu porphyrin as a catalyst, which is more than 23 times higher than that of free molecular controls. With a photosensitizer to catalyst ratio of 10000 : 1, the highest H2 production rate of >51,700 μmol h-1 g-1 with a turnover number (TON) of >1,290 per molecular catalyst was achieved over 24 h irradiation. The hierarchical self-assembly not only enhances photostability through forming ordered stackings of the metalloporphyrins but also facilitates both energy and electron transfer from antenna molecules to catalysts, and therefore promotes the photocatalysis. This study provides structural and mechanistic insights into the self-assembly enhanced photostability and catalytic performance of supramolecular photocatalytic systems.

Bioinspired Self‐Assembly of Metalloporphyrins and Polyelectrolytes into Hierarchical Supramolecular Nanostructures for Enhanced Photocatalytic H2 Production in Water

AbstractPolypeptides, as natural polyelectrolytes, are assembled into tailored proteins to integrate chromophores and catalytic sites for photosynthesis. Mimicking nature to create the water‐soluble nanoassemblies from synthetic polyelectrolytes and photocatalytic molecular species for artificial photosynthesis is still rare. Here, we report the enhancement of the full‐spectrum solar‐light‐driven H2 production within a supramolecular system built by the co‐assembly of anionic metalloporphyrins with cationic polyelectrolytes in water. This supramolecular photocatalytic system achieves a H2 production rate of 793 and 685 μmol h−1 g−1 over 24 h with a combination of Mg or Zn porphyrin as photosensitizers and Cu porphyrin as a catalyst, which is more than 23 times higher than that of free molecular controls. With a photosensitizer to catalyst ratio of 10000 : 1, the highest H2 production rate of >51,700 μmol h−1 g−1 with a turnover number (TON) of >1,290 per molecular catalyst was achieved over 24 h irradiation. The hierarchical self‐assembly not only enhances photostability through forming ordered stackings of the metalloporphyrins but also facilitates both energy and electron transfer from antenna molecules to catalysts, and therefore promotes the photocatalysis. This study provides structural and mechanistic insights into the self‐assembly enhanced photostability and catalytic performance of supramolecular photocatalytic systems.

Thermoresponsive Injectable Hydrogel To Mimic the Heat- and Strain-Stiffening Behavior of Biopolymers toward Muscle Cell Proliferation.

Injectable hydrogels with nonlinear mechanical attributes to emulate natural biopolymers hold paramount significance in tissue engineering, offering the potential to create scaffolds that seamlessly mimic the biomechanical intricacies of living tissues. Herein, we unveil a synthetic design strategy employing Schiff base chemistry to furnish a peptide-polymer hierarchical contractile injectable hydrogel network. This innovative design demonstrates cross-linking of supramolecular peptide nanostructures such as nanofibers, 1NF, and twisted bundles, 1TB, with a thermosensitive aldehyde-functionalized polymer, PCHO. These networks exhibit interesting nonlinear mechanical stiffening responses to temperature and external stress. Furthermore, the hydrogels transform into a gel state at physiological temperature to exhibit injectable behavior and demonstrate compression load-bearing capabilities. Finally, the hydrogel network exhibits excellent biocompatibility and cell proliferation toward fibroblast, L929, and myoblast, C2C12, to validate their use as potential extracellular matrix mimetic injectable scaffolds.

The effect of charge and albumin on cellular uptake of supramolecular polymer nanostructures.

Intracellular delivery of functional biomolecules by using supramolecular polymer nanostructures has gained significant interest. Here, various charged supramolecular ureido-pyrimidinone (UPy)-aggregates were designed and formulated via a simple "mix-and-match" method. The cellular internalization of these UPy-aggregates in the presence or absence of serum proteins by phagocytic and non-phagocytic cells, i.e., THP-1 derived macrophages and immortalized human kidney cells (HK-2 cells), was systematically investigated. In the presence of serum proteins the UPy-aggregates were taken up by both types of cells irrespective of the charge properties of the UPy-aggregates, and the UPy-aggregates co-localized with mitochondria of the cells. In the absence of serum proteins only cationic UPy-aggregates could be effectively internalized by THP-1 derived macrophages, and the internalized UPy-aggregates either co-localized with mitochondria or displayed as vesicular structures. While the cationic UPy-aggregates were hardly internalized by HK-2 cells and could only bind to the membrane of HK-2 cells. With adding and increasing the amount of serum albumin in the cell culture medium, the cationic UPy-aggregates were gradually taken up by HK-2 cells without anchoring on the cell membranes. It is proposed that the serum albumin regulates the cellular internalization of UPy-aggregates. These results provide fundamental insights for the fabrication of supramolecular polymer nanostructures for intracellular delivery of therapeutics.

Supramolecular assembly of isomeric SN-38 prodrugs regulated by conjugation sites.

Supramolecular polymers (SPs) are an emerging class of drug transporters employed to improve drug therapy. Through the rational design of self-assembling monomers, one can optimize the properties of the resulting supramolecular nanostructures, such as size, shape, surface chemistry, release, and, therefore, biological fates. This study highlights the design of isomeric SN38 prodrugs through the conjugation of hydrophilic oligo(ethylene glycol) (OEG) with hydroxyls at positions 10 and 20 on hydrophobic SN-38. Self-assembling prodrug (SAPD) isomers 10-OEG-SN38 and 20-OEG-SN38 can self-assemble into giant nanotubes and filamentous assemblies, respectively, via aromatic associations that dominate self-assembly. Our study reveales the influence of modification sites on the assembly behavior and ability of the SN38 SAPDs, as well as drug release and subsequent in vitro and in vivo antitumor effects. The SAPD modified at position 20 exhibits stronger π-π interactions among SN38 units, leading to more compact packing and enhanced assembly capability, whereas OEG at position 10 poses steric hindrance for aromatic associations. Importantly, owing to its higher chemical and supramolecular stability, 20-OEG-SN38 outperforms 10-OEG-SN38 and irinotecan, a clinically used prodrug of SN38, in a CT26 tumor model, demonstrating enhanced tumor growth inhibition and prolonged animal survival. This study presents a new strategy of using interactions among drug molecules as dominating features to create supramolecular assemblies. It also brings some insights into creating effective supramolecular drug assemblies via the engineering of self-assembling building blocks, which could contribute to the optimization of design principles for supramolecular drug delivery systems.

Super-tough self-healable multiphasic supramolecular plastic via sequence-biased statistical copolymerization

The complementary design of a multiphasic supramolecular nanostructure constructed via sequence-biased statistical copolymerization can provide a super-tough supramolecular plastic with a facile healing capability.

CO2-Responsive Rosin-Based Supramolecular Hydrogels: Diverse Chiral Nanostructures and Their Application in In Situ Synthesis of Chiral Gold Nanoparticles.

Natural small molecules have demonstrated tremendous potential for the construction of supramolecular chiral nanostructures owing to their unique molecular structures and chirality. In this study, novel CO2-responsive supramolecular hydrogels were constructed using a series of rosin-based surfactants (CnMPAN, n = 10, 12, and 14). The macroscopic properties, rheological properties, nanostructures, and intermolecular interactions of the hydrogels were investigated using differential scanning calorimetry, rotational rheometry, cryogenic transmission electron microscopy, and Fourier transform infrared spectroscopy. Interestingly, diverse nanostructures containing helical nanofibers, interwoven nanofibers, and twisted nanoribbons were formed in the hydrogels, which were rarely observed in reported supramolecular hydrogels, and the strength of the hydrogels was significantly enhanced by increasing the CnMPAN concentration and the alkyl chain length. The obtained hydrogels exhibited excellent CO2-responsiveness, with no obvious variation in the nanostructures and rheological properties after response to CO2/N2 for five cycles. Taking advantage of the chiral nanostructures of hydrogels, gold nanoparticles (GNPs) were further prepared. The average particle sizes of the resulting GNPs were as low as 2.5 nm, and the GNPs also had a chiral structure. It is worth noting that no additional reductants and UV-light irradiation were used during the reduction process of GNPs. This study emphasizes that the unique molecular structure and chirality of rosin are critical for the preparation of hydrogels with chiral nanostructures. In addition, this study enriches the applications of forest resources.