Supramolecular Hydrogels Research Articles

Multi‐Solvent‐Induced Gradient Aggregation Rendered Superstrong, Tough, Stretchable, and Fatigue‐Resistant Lignin‐Based Supramolecular Hydrogels

AbstractA hydrogel that is expected as a biomedical load‐bearing material remains a substantial challenge. In this work, a multi‐solvent‐induced gradient aggregation state strategy is developed to construct lignin‐based supramolecular hydrogels that feature superstrong, tough, stretchable, and fatigue‐resistant properties. The multi‐solvent high‐temperature annealing induces the gradient crystallization of polyvinyl alcohol and the self‐assembly of lignin. The interior strong hydrogen‐binding and the external weak non‐covalent‐binding forms a gradient aggregation state microstructure and compact macrostructure, where lignin acts as an interfacial molecular bridge. By sharing interconnection points to collaboratively dissipate energy, the developed hydrogels demonstrate high modulus (74.4 MPa), toughness (90 MJ m−3), tear (34,000 J m−2), tensile (24.8 MPa), and compressive strength (60 MPa). Moreover, such lignin‐based supramolecular hydrogels also exhibit extraordinary fatigue resistance, biocompatibility, and reactive oxygen species scavenging activity. This gradient non‐covalent conjoined‐network caused by multi‐solvent high‐temperature annealing provides a new design strategy and potential for developing biomaterials that mimic biomedical load‐bearing materials (e.g., natural tendons and ligaments).

Biochemical Signal-Induced Supramolecular Hydrogelation for Structured Free-Standing Soft Material Formation.

Cells coordinate their activity and regulate biological processes in response to chemical signals. Mimicking natural processes, control over the formation of artificial supramolecular materials is of high interest for their application in biology and medicine. Supramolecular material that can form in response to chemical signals is important for the development of autonomously responsive materials. Herein, a supramolecular hydrogel system is reported enabling in situ generation of hydrogelators in response to a specific chemical signal. Using self-immolative chemistry, spatial control over the formation of supramolecular hydrogel material and structured free-standing hydrogel objects via providing H2O2 locally is demonstrated. In addition, a hybrid system is developed enabling in situ generation of the H2O2 by the action of an enzyme and glucose, providing an extra handle for the development of an intelligent soft material. This generic design should enable the use of various (chemical)stimuli that can be obtained via coupling different stimuli and various chemical and/or biological markers and appears a versatile approach for the design of smart artificial soft materials that can find application in theranostic purposes.

Intrinsic PD-L1 Degradation Induced by a Novel Self-Assembling Hexapeptide for Enhanced Cancer Immunotherapy.

Programmed death-ligand 1 (PD-L1) is a critical immune checkpoint protein that facilitates tumor immune evasion. While antibody-based PD-1/PD-L1 inhibitors have shown promise, their limitations necessitate the development of alternative therapeutic strategies. This work addresses these challenges by developing a hexapeptide, KFM (Lys-Phe-Met-Phe-Met-Lys), capable of both directly downregulating PD-L1 and self-assembling into a ROS-responsive supramolecular hydrogel. This dual functionality allows Gel KFM to function as a localized drug delivery system and a PD-L1 inhibitor. Loading the hydrogel with mitoxantrone (MTX) and metformin (MET) further enhances the therapeutic effect by combining chemotherapy with PD-L1 downregulation. In vitro and in vivo studies demonstrate significant tumor growth inhibition, increased CD8+ T cell infiltration, and reduced intratumoral PD-L1 expression following peritumoral administration. Mechanistically, KFM promotes PD-L1 degradation via a ubiquitin-dependent pathway. This "carrier-free" delivery system expands the role of supramolecular hydrogels beyond passive carriers to active immunotherapeutic agents, offering a promising new strategy for cancer therapy.

Biocompatible supramolecular hydrogels based on polysaccharide-modified hyaluronic acid for targeted delivering of doxorubicin

ABSTRACT In this paper, Biocompatible supramolecular hydrogels, composed of β-cyclodextrin-modified hyaluronic acid, pluronic F127, α-cyclodextrin and doxorubicin, were constructed, which can be employed for targeted delivery system. The chemical composition and rheological properties of the obtained hydrogels were fully characterised. Considering the controlled complexation between DOX and the hydrogel skeletons, the controlled release of hydrogel G[5, 10, 5] was investigated to exhibit a better pH- and temperature-controlled release behavior. The data of DOX release kinetic was fitted well with Higuchi and Korsmeyer-Peppas models. Moreover, the cellular toxicity experiments indicated that the hydrogel DOX@G[5, 10, 5] exhibited a similar anticancer ability in comparison with free DOX. Due to the hyaluronic acid-targeted effects, the cytotoxicity of the hydrogel DOX@G[5,10,5] to HepG2 cells was lower than that to SKOV-3 cells upon increasing the concentration. Therefore, these hydrogels may act as a potential prospect for the targeting release of anticancer drugs.

Extracellular matrix mimetic supramolecular hydrogels reinforced with covalent crosslinked mesoporous silica nanoparticles.

The extracellular matrix (ECM) is a dynamic environment that is primarily built up from fibrous proteins (e.g., elastins, fibronectins, collagens, and laminins) and plays a vital role in tissue regeneration processes. Therefore, the development of supramolecular hydrogels that can mimic the ECM's dynamicity and fibrous structure is of great interest in regenerative medicine. However, such hydrogels generally have weak mechanical properties and poor structural stability, which significantly limits their potential applications. To overcome this drawback, we developed a new type of hybrid network composed of supramolecular assemblies with covalent nanoparticle-based crosslinkers. The ECM mimetic hydrogels were created through UV-initiated thiol-ene crosslinking between norbornene functionalized benzene-1,3,5-tri carboxamide (NBTA) macromonomers and thiol functionalized mesoporous silica nanoparticles (MSN). We hypothesized that the MSN would improve the mechanical properties by crosslinking the NBTA supramolecular fibrous hydrogels. Notably, the covalent incorporation of MSNs did not disrupt the fibrous morphology of the resulting NBTA-MSN nanocomposites. Furthermore, these supramolecular nanocomposites demonstrated higher structural stability and elasticity compared to pristine NBTA hydrogels. Rheology studies showed that the mechanical properties of NBTA-MSN hydrogels could be tuned by adjusting MSN wt%. Interestingly, NBTA-MSN nanocomposites exhibited self-healing and injectability despite the covalent crosslinking of MSNs. In vitro studies confirmed that NBTA-MSN nanocomposites showed good cytocompatibility and maintained the viability of encapsulated MG63 cells. As a proof of concept, we also demonstrated that MSNs could act as ion reservoirs for calcium and phosphate within the hydrogel networks in addition to being covalent crosslinkers. Taken together, our work offers a promising strategy to create hybrid, biomimetic supramolecular nanocomposite materials for various applications such as injectable materials for bone tissue engineering, and reinforced bioinks for 3D printing applications.

Effect of supramolecular peptide hydrogel scaffold charge on HepG2 viability and spheroid formation.

Supramolecular bioinspired self-assembling peptide hydrogel (SAPH) scaffolds represent a class of fully defined synthetic materials whose chemical and mechanical properties can be finely engineered. In this study, the relationship between SAPHs physicochemical properties and HepG2 cells viability, spheroid formation and function are discussed. We first report that negatively charged SAPHs promote hepatocyte proliferation and spheroids formation in vitro 3D culture while positively charged SAPHs lead to hepatocyte death irrespective of the hydrogel mechanical properties. More specifically HepG2 cultured in 3D in E(FKFE)2 negatively charged SAPH maintained a differentiated phenotype and assembled into well-defined spheroids with strong cell-cell interactions. Furthermore, HepG2 spheroids responded to acetaminophen exposure with upregulation of key CYP450 enzymes expression clearly showing their potential for drug toxicity testing. These findings demonstrate how fine-tuned functional SAPH scaffolds can be used to identify key scaffolds parameters affecting cells. In this case we demonstrated the potential of negatively charged SAPHs for the 3D culture of HepG2 with potential applications in drug screening.

One-pot fabrication of sodium deoxycholate based supramolecular self-healing antibacterial double network hydrogels

Double network (DN) hydrogels have emerged as a significant technology for enhancement of mechanical strength of weak supramolecular gels. In the present study, we report the one-pot route for design of a low molecular weight gelator based DN hydrogel wherein sodium deoxycholate (NaDC) forms the primary network entangled with agar matrix. Various compositions of the reported agar-NaDC hydrogels were examined through FTIR, sol-gel transition temperature (Tsg), XRD, circular dichroism (CD), scanning electron microscopy (SEM), hydrophobicity probe studies, Zeta potential studies and rheology measurements. Analysis of all studies together reveal that 1 mg/ml agar-NaDC DN hydrogel is the optimum composition that exhibits dense networking with primarily β-sheet like structure, highest mechanical strength as well as self-healing characteristics with reversed optical activity and highest Tsg. Antibacterial activity studied using inhibition zone method suggests that 1 mg/ml agar-NaDC gel demonstrates significant bactericidal effect unlike the pure gel with an inhibition zone of ∼25 mm against E.coli after 24 h and ∼32 mm after 48 h incubation. The antibacterial activity was unique for this composition of the DN hydrogel which is attributed to its reversal in optical activity exhibiting positive cotton effect resulting in stronger interaction with the bacterial cell wall. Additionally, nearly 2 times reduced water absorption capacity of the 1 mg/ml agar-NaDC DN hydrogel compared to pure NaDC hydrogel ensures the retention of its mechanical strength as well as other properties in high moisture containing environment. Hence, the 1 mg/ml agar-NaDC DN hydrogel holds appreciable potential as a novel strong supramolecular self-healing antibacterial hydrogel with sustained release characteristics primarily important for biomedical applications.

Patterned glycopeptide-based supramolecular hydrogel promotes the alignment and contractility of iPSC-derived cardiomyocytes

The functional restoration of a damaged cardiac tissue relies on a synchronized contractile capacity of exogenous and/or endogenous cardiomyocytes, which is challenging to achieve. Here, we explored the potential of the short glycopeptide diphenylalanine glucosamine-6-sulfate (FFGlcN6S) conjugated with an aromatic moiety, namely fluorenylmethoxycarbonyl (Fmoc), to enhance cardiac tissue regeneration. At physiological conditions, Fmoc-FFGlcN6S assembles into nanofibrous hydrated meshes, i.e., matrix mimicking hydrogels. These hydrogels can be further micropatterned allowing co-existence of hierarchical structures at different lenght. The patterned hydrogels support the culture of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and promote their alignment. The cultured iPSC-CMs exhibit anisotropic synchronized contractions, indicating maturation and electrical interconnectivity. Moreover, the cultures express specific cardiac markers including, connexin-43 and sarcomeric-α-actinin, confirming enhanced cell-cell crosstalk, spontaneous contractility, and efficient transmission of electrical signals. Our results showcase the potential of short amphiphilic glycopeptides to mimic physical and biochemical cues that are essential for cardiomyocytes functionality and thus, these conjugates can be used in cardiac tissue engineering and regeneration.

Supramolecular Self-Assembled Hydrogel for Antiviral Therapy through Glycyrrhizic Acid-Enhanced Zinc Absorption and Intracellular Accumulation.

Respiratory syncytial virus (RSV) is a common pathogen that causes respiratory infections in infants and children worldwide, significantly impacting hospitalization rates in this age group. Zinc ions are considered to have broad-spectrum antiviral potential against RNA viruses, including RSV. However, poor organism absorption and low intracellular accumulation of zinc require repeated high-dose supplementation, which may lead to unnecessary toxic side effects. In this research, a Zn2+-mediated glycyrrhizinic acid (GA)-based hydrogel (ZnGA Gel) was introduced and potentially developed to be a clinically available drug candidate for RSV therapy. ZnGA Gel was fabricated based on the cooperation of two potential RSV inhibiting molecules (Zn2+ and GA), where Zn2+ promoted self-assembly of GA and reduced its gel concentration and GA promoted zinc absorption and distribution in lung tissue in vivo. The facile construction of supramolecular hydrogel by the self-assembled coordination complex made it an injectable, temperature-sensitive, and pH-responsive controlled-release drug delivery for Zn2+. Most importantly, GA was observed to enhance organism absorption and intracellular accumulation of Zn2+ and was identified as a zinc ionophore for the first time. GA can colonize on the cell membrane and disturb cell membrane potential, resulting in an enhanced cell membrane permeability. In the presence of GA, more than 4.7-fold increasing Zn2+ concentrations materialized in the intracellular cytoplasm, compared to Zn2+ alone administration. This intracellular Zn2+ accumulation directly boosted the antiviral activities through improved inhibition of RSV replication-associated proteins and significantly inhibited RSV replication. Oral administration of ZnGA Gel on the RSV-infected mice model achieved an ideal therapeutic effect by effectively lowering viral load in the lungs, alleviating lung injury symptoms, and reducing inflammatory cell infiltration at pathological sites. The mechanism involved the inhibition of RSV replication-related proteins, aligning with our in vitro results. Additionally, ZnGA Gel had demonstrated biocompatibility, and reasonable supplementation of zinc was acceptable and effective for infants and children in clinical practice. Hence, the ZnGA Gel developed by us holds promise as an effective anti-RSV medicine in the future.

Supramolecular Conductive Hydrogels for Tissue Engineering Applications.

Owing to their unique attributes, including reversibility, specificity, directionality, and tunability, supramolecular biomaterials have evolved as an excellent alternative to conventional biomaterials like polymers, ceramics, and metals. Supramolecular hydrogels, in particular, have garnered significant interest because their fibrous architecture, high water content, and interconnected 3D network resemble the extracellular matrix to some extent. Consequently, supramolecular hydrogels have been used to develop biomaterials for tissue engineering. Supramolecular conductive hydrogels combine the advantages of supramolecular soft materials with the electrical properties of metals, making them highly relevant for electrogenic tissue engineering. Given the versatile applications of these hydrogels, it is essential to periodically review high-quality research in this area. In this review, we focus on recent advances in supramolecular conductive hydrogels, particularly their applications in tissue engineering. We discuss the conductive components of these hydrogels and highlight notable reports on their use in cardiac, skin, and neural tissue engineering. Additionally, we outline potential future developments in this field.

Efficiency Enhancement in Peptide Hydrogelators: The Crucial Role of Side Chain Hydrogen Bonding Over Aromatic π-π Interactions.

Short peptide assemblies that form supramolecular hydrogels are stabilized by both intermolecular noncovalent interactions among amino acid side chains and hydrogen bonding between peptide backbone amides. Previous research has emphasized the inclusion of aromatic amino acids in short peptide sequences, positing that aromatic π-π interactions contribute significantly to inducing efficient hydrogelation i.e., at low minimum gelation concentrations (MGCs). However, herein, we demonstrate that additional hydrogen bonding interactions from amino acid side chains play a more pivotal role in the efficiency of peptide hydrogelation compared to aromatic π-π interactions. We investigated two sets of Fluorenylmethoxycarbonyl (Fmoc)-functionalized α-synuclein and human islet amyloid peptide fragments [Fmoc-NVGGAVVT (Syn-N) and Fmoc-NFGAIL (IAP-N)], substituting asparagine (N) with phenylalanine (Syn-F/IAP-F), alanine (Syn-A/IAP-A), and glutamine (Syn-Q/IAP-Q). This allowed us to explore the effects of aromatic (π-system), aliphatic (hydrophobic), and hydrogen bonding effects with varying chain lengths on hydrogel formation. Our results reveal that Syn-N and Syn-Q exhibit MGC of 0.03 and 0.05 wt %, respectively, classifying them as super hydrogelators (MGC < 0.1 wt %). These values are 4.0-6.6-fold lower than Syn-F and Syn-A, with Syn-N demonstrating greater efficiency than Syn-Q. Similarly, IAP-N exhibited a substantial decrease in MGC by 8.75, 3.75, and 2.5 folds compared to IAP-A, IAP-F, and IAP-Q, respectively. Experimental evidence and molecular dynamic simulation suggest that -CO-NH2 of asparagine side chains effectively engaged in hydrogen bonding, thereby immobilizing water molecules at low gelator concentrations. Although glutamine shares similar -CO-NH2 functionality, its hydrogelation efficiency is less pronounced compared to asparagine, likely due to its longer alkyl chain, which may hinder the formation of a hydrogen bonding network in the self-assembled structure compared to asparagine-containing peptides. These findings offer valuable insights for designing efficient peptide hydrogelators or lowering MGCs by substituting amino acids with asparagine/glutamine in peptide sequences. Additionally, modifying peptide properties through asparagine/glutamine substitution could optimize hydrogel properties for specific applications.

3D Cryo-Electron Microscopy Reveals the Structure of a 3-Fluorenylmethyloxycarbonyl Zipper Motif Ensuring the Self-Assembly of Tripeptide Nanofibers.

Short peptide-based supramolecular hydrogels appeared as highly interesting materials for applications in many fields. The optimization of their properties relies mainly on the design of a suitable hydrogelator through an empirical trial-and-error strategy based on the synthesis of various types of peptides. This approach is in part due to the lack of prior structural knowledge of the molecular architecture of the various families of nanofibers. The 3D structure of the nanofibers determines their ability to interact with entities present in their surrounding environment. Thus, it is important to resolve the internal structural organization of the material. Herein, using Fmoc-FFY tripeptide as a model amphiphilic hydrogelator and cryo-EM reconstruction approach, we succeeded to obtain a 3.8 Å resolution 3D structure of a self-assembled nanofiber with a diameter of approximately 4.1 nm and with apparently "infinite" length. The elucidation of the spatial organization of such nano-objects addresses fundamental questions about the way short amphiphilic N-Fmoc peptides lacking secondary structure can self-assemble and ensure the cohesion of such a lengthy nanostructure. This nanofiber is organized into a triple-stranded helix with an asymmetric unit composed of two Fmoc-FFY peptides per strand. The three identical amphiphilic strands are maintained together by strong lateral interactions coming from a 3-Fmoc zipper motif. This hydrophobic core of the nanofiber is surrounded by 12 phenyl groups from phenylalanine residues, nonplanar with the six Fmoc groups. Polar tyrosine residues at the C-term position constitute the hydrophilic shell and are exposed all around the external part of the assembly. This fiber has a highly hydrophobic central core with an internal diameter of only 2.4 Å. Molecular dynamics simulations highlight van der Waals and hydrogen bonds between peptides placed on top of each other. We demonstrate that the self-assembly of Fmoc-FFY, whether induced by annealing or by the action of a phosphatase on the phosphorylated precursor Fmoc-FFpY, results in two nanostructures with minor differences that we are unable to distinguish.

A strategy for introducing biopotency-enhanced chirality coating on bio-magnesium

Biomedical magnesium alloys (Mg) are often considered potential metallic materials for bone repair scaffolds due to their excellent biomechanical properties, biocompatibility, and biodegradability. However, their rapid degradation behavior is insufficient to support the rapid growth and repair of living tissues. The new surface modification methods to slow down the degradation rate of Mg scaffolds and promote the rapid growth of living tissues is urgent. Here, we developed a chiral-enhanced composite functional coating on the surface of biomedical magnesium. Specifically, a chiral supramolecular hydrogel with graphene oxide (GO) was used to simulate the chiral environment of biological systems, enhancing the adsorption of osteogenic growth factors. Additionally, the silane layers cleverly crosslink traditional silane chains with supramolecular chiral fibers through a hydrogen bond network, which allows the bonding strength (critical loads) of the composite coating to be maintained between 245–275 mN and retains structural integrity when soaked in SBF for 7 days. It was found that both MC3T3-E1 cells growth and BMP-2 adhesion were significantly enhanced by GO-added left-handed chiral coatings, which exhibit superior bone growth-promoting effects. In summary, incorporating chiral features into functional coatings represents a transformative approach in the design and application of bone defect repair materials.

Volumetric printing and non-destructive drug quantification of water-soluble supramolecular hydrogels.

Vat photopolymerisation 3D printing is being actively explored for manufacturing personalised medicines due to its high dimensional accuracy and lack of heat application. However, several challenges have hindered its clinical translation, including the inadequate printing speeds, the lack of resins that give soluble matrices, and the need for non-destructive quality control measures. In this study, for the first time, a rapid approach to producing water-soluble vat photopolymerised matrices and a means of non-destructively verifying their drug content were investigated. Volumetric printing, a novel form of vat photopolymerisation, was used to fabricate personalised warfarin-loaded 3D-printed tablets (printlets). Eight different formulations containing varying amounts of warfarin (0.5-6.0% w/w) were used to print two different sized torus-shaped printlets within 6.5 to 11.1s. Nuclear magnetic resonance (NMR) spectroscopy revealed the presence of only trace amounts of unreacted acrylate monomers, suggesting that the photopolymerisation reaction had occurred to near completion. All printlets completely solubilised and released their entire drug load within 2.5 to 7h. NIR spectroscopy (NIRS) was used to non-destructively verify the dose of warfarin loaded into the vat photopolymerised printlets. The partial least square regression model built showed strong linearity (R2 = 0.980), and high accuracy in predicting the drug loading of the test sample (RMSEP = 0.205%). Therefore, this study advances pharmaceutical vat photopolymerisation by demonstrating the feasibility of producing water-soluble printlets via volumetric printing and quantifying the drug load of vat photopolymerised printlets with NIRS.

Design and Applications of Supramolecular Peptide Hydrogel as Artificial Extracellular Matrix.

Supramolecular peptide hydrogels (SPHs) consist of peptides containing hydrogelators and functional epitopes, which can first self-assemble into nanofibers and then physically entangle together to form dynamic three-dimensional networks. Their porous structures, excellent bioactivity, and high dynamicity, similar to an extracellular matrix (ECM), have great potential in artificial ECM. The properties of the hydrogel are largely dependent on peptides. The noncovalent interactions among hydrogelators drive the formation of assemblies and further transition into hydrogels, while bioactive epitopes modulate cell-cell and cell-ECM interactions. Therefore, SPHs can support cell growth, making them ideal biomaterials for ECM mimics. This Review outlines the classical molecular design of SPHs from hydrogelators to functional epitopes and summarizes the recent advancements of SPHs as artificial ECMs in nervous system repair, wound healing, bone and cartilage regeneration, and organoid culture. This emerging SPH platform could provide an alternative strategy for developing more effective biomaterials for tissue engineering.

Dynamic Micelle-Hydrogels for 3D-Architected Transition Metal Sulfides.

Additive manufacturing of transition metal sulfides (TMS) enables the creation of complex 3D structures, significantly expanding their applications. However, preparing 3D-structured TMS remains challenging due to difficulties in developing suitable inks. In this study, a supramolecular micelle hydrogel as the ink to fabricate 3D-structured TMS is utilized. Initially, the hydrogels are printed and infused with metal salt solutions to stabilize the structures, which are then calcined to convert into miniaturized 3D-TMS replicas. The micellar hydrogels crosslink via hydrophobic interactions, with sodium dodecyl sulfonate (SDS) micelles providing both a hydrophobic environment and sulfur sources. During calcination, the decomposed sulfur precursors coordinate with metal ions to form various TMS, including FeS2, Cu2S, Ni3S2, and Co9S8, along with several metal sulfides like PbS and SnS. Additionally, the method also allows for the preparation of transition metal dichalcogenides such as MoS2 and WS2. The formation mechanism is demonstrated using Ni3S2 as an example which exhibits notable catalytic activity in oxygen evolution reactions (OER) and hydrogen evolution reactions (HER). Given its simplicity and versatility, this dynamic micellar hydrogel-derived strategy offers a promising pathway for creating advanced TMS materials.

Supported Supramolecular Hydrogel Nanoarchitectonics for Tunable Biocatalytic Flow Activity.

Enzymatically-active polyelectrolyte multilayers containing n layers of phosphatase (APn-PEM) induce the formation of supported biocatalytic supramolecular hydrogels when brought in contact with the precursor tripeptide Fmoc-FFpY (Fmoc = N-fluorenylmethyloxycarbonyl; F = Phenylalanine; Y = Tyrosine; p = phosphate group). APn-PEM triggers the spatially-localized hydrogelation reaching 2, 17 and 350µm of thickness for n = 1, 2 and 3, respectively. As observed by cryo scanning electron microscopy, a dense nanofibrous network underpinning the hydrogel shows parallelly orientated Fmoc-FFY peptide-based fibrils, perpendicular to the substrate. For the gel generated by the AP3-PEM, fluorescence confocal microscopy images show that during the peptide self-assembly, some enzymes are distributed in the hydrogel, preferentially located in few dozens of micrometers above the substrate. In addition, a self-assembly growth rate of 5µmmin-1 is determined when the hydrogelation starts. Through transmission electron microscopy immuno-labelling experiments on self-assemblies generated in solution, we observe that AP are decorating the Fmoc-FFY nanofibers. It is observed both a long-term stability and a higher biocatalytic activity of the so AP-encapsulated hydrogel compared to the bare APn-PEM. This bioactivity can be tuned by the number n in batch and under continuous flow conditions. To illustrate the versatility of this enzyme-supported strategy, multi-catalytic transformations in continuous flow conditions have been successfully carried out using supported supramolecular hydrogel.

Supramolecular Luminescent Hydrogel Based on Glycine/Terbium Complex and Fluorescent Dyes for Visual Temperature Monitoring

AbstractThe development of smart synthetic materials that are sensitive, accurate, and visually responsive to changes in temperature is vital. Herein, a supramolecular luminescent hydrogel based on a glycine/terbium (Gly/Tb) complex, rhodamine B (RB), and gelatin is reported. The hydrogel exhibits responsive luminescence and undergoes a temperature‐induced phase transformation from hydrogel to sol. The electrospray ionization time‐of‐flight mass spectra, Fourier‐transform infrared spectra, and simulation results verifiy the coordination mode of the Gly/Tb complex. The Gly/Tb complex and RB emit green and orange luminescence, respectively. When the Gly/Tb complex and RB are co‐doped into the gel network of gelatin, the obtained Gly/Tb/RB hydrogel displays steady yellow luminescence by virtue of luminescence resonance energy transfer. Subsequently, a luminescent switch is constructed owing to the sensitive and reversible luminescence responsiveness of the Gly/Tb/RB hydrogel to temperature stimuli. Remarkably, the Gly/Tb/RB hydrogel undergoes a visual phase transformation from hydrogel to sol above 35 °C, allowing the ambient temperature variation to be monitored. This study establishes a novel and effective route for the construction of smart optical materials and visual temperature monitors.

Hydrogel Embedding Enables Enhanced Leaf Deposition and Bioavailability of Fe-Based Engineered Nanoparticles.

Nanofertilizers comprising engineered nanoparticles (ENPs) have great potential in sustainable agriculture due to their strong capabilities of improving crop yields. As an effective fertilization strategy, foliar spraying could lead to broken and splashed ENP droplets, resulting in inaccurate leaf targeting and potential environmental contamination. Herein, we propose embedding Fe-based ENPs into a supramolecular hydrogel to effectively enhance the deposition amount on leaves and thus the bioavailability. The proper rheological properties of the hydrogel droplets and their robust interaction with soybean leaf simultaneously reduce the droplet rebound and fragmentation, especially under elevated impact speeds, resulting in up to 168.9% more droplet deposition compared to the ENP suspension. Computational fluid dynamics simulation analysis suggests that the contact angle is a key sensitive factor influencing the dynamic deposition behavior of the hydrogel droplet. A 15% reduction in the contact angle results in a 14% reduction of the highest bouncing height. The incorporation of ENPs enhances the viscous dissipation rate by 7.4% in comparison with pure hydrogel droplets. The hydrogel embedding also causes a 1.5-fold increase in ENP uptake compared to that of the ENP suspension. The hydrogel embedding delivers a reduction of 80% in the ENP application amount, compared to ENP suspensions, while achieving a 28% increase in the fresh weight of soybean seedlings. This work provides an effective method to enhance the deposition of ENPs during foliar application.

9-Fluorenylmethoxycarbonyl (Fmoc)-modified taurine as a hydrogelator bearing sulfonate group

Abstract Here, we report that a 9-fluorenylmethoxycarbonyl (Fmoc)-modified taurine (Fmoc-Tau) can act as a hydrogelator. The supramolecular hydrogels of Fmoc-Tau were constructed through the self-assembly to form fibrous structures under physiologically relevant aqueous conditions. Fluorescence microscopy was employed to investigate the accumulation of basic fibroblast growth factors along the self-assembled fibrous structures.