Bioinspired Supramolecular Hydrogel from Design to Applications

Deceptive Ceropegia sandersonii uses an arabinogalactan for trapping its fly pollinators

Many plant species have evolved surfaces that reduce insect attachment. Among such plants are deceptive trap flowers of Ceropegia. Their gliding zones consist of convex epidermal cells, each with a bristle-like central protuberance and a single small liquid droplet on its tip. So far, the molecular and physical mechanisms controlling the function of these droplets are unknown. We analyzed the droplets of Ceropegia sandersonii flowers by microscopic approaches, studied how they behave when getting in contact with the feet of fly pollinators, and analyzed their chemical composition. The droplets contaminate the insect feet, on which they solidify. As its main component, a negatively charged polysaccharide containing a β1,3-galactan backbone and Rha-α1,4-GlcA-β1,6-[Araf-α1,3-]Gal-β1,6 side chains or truncated versions of it was identified. The chemical structure represents a rudimentary version of an arabinogalactan, which is supported by its binding to β-d-glucosyl Yariv reagent. Candidates of arabinogalactan proteins were identified to which the polysaccharide might be connected. The high amount of GlcA in the polysaccharide helps to explain the unusual physical characteristics of the droplets, like viscoelasticity and hygroscopy. We add a new function to arabinogalactans and discuss why the identified polymer is well suited for catching and temporarily trapping pollinators.

MXene/Doxorubicin Complex-Loaded Supramolecular Hydrogels for Near Infrared-Triggered Synergistic Cancer Therapy

Photothermal therapy (PTT) has attracted great interest due to the high spatial precision and reduced general toxicity compared to conventional cancer therapies. However, PTT often faces challenges such as incomplete tumor eradication and collateral damage to healthy tissues. Here, we report an injectable MXene-doxorubicin (MD) complex-loaded supramolecular hydrogel (MDGel) for dual synergistic cancer therapy of near-infrared (NIR) PTT and chemotherapy. MDGel is prepared by the host-guest interaction between gelatin-cyclodextrin (GE-CD) and hyaluronic acid-adamantane (HA-AD), facilitating the efficient dispersion of MD complexes in the hydrogel. NIR irradiation triggers the PTT and the release of doxorubicin with increasing temperature. In vitro therapeutic effect is confirmed by achieving nearly 80% cancer cell death via the synergistic effect, compared to the single-modality treatment. In vivo tumor inhibition (68.9% volume reduction) is further validated in skin cancer-bearing model mice with no substantial negative side effect. With its prolonged retention, NIR light-controlled release, and localized therapeutic effect, the MDGel system would provide a notable paradigm as a versatile platform for dual synergistic cancer therapy.

Advances in cellulose-based hydrogels: tunable swelling dynamics and their versatile real-time applications

Cellulose-derived hydrogels have emerged as game-changing materials in biomedical research, offering an exceptional combination of water absorption capacity, mechanical resilience, and innate biocompatibility. This review explores the intricate mechanisms that drive their swelling behaviour, unravelling how molecular interactions and network architectures work synergistically to enable efficient water retention and adaptability. Their mechanical properties are explored in depth, with a focus on innovative chemical modifications and cross-linking techniques that enhance strength, elasticity, and functional versatility. The versatility of cellulose-based hydrogels shines in applications such as wound healing, precision drug delivery, and tissue engineering, where their biodegradability, biocompatibility, and adaptability meet the demands of cutting-edge healthcare solutions. By weaving together recent breakthroughs in their development and application, this review highlights their transformative potential to redefine regenerative medicine and other biomedical fields. Ultimately, it emphasizes the urgent need for continued research to unlock the untapped capabilities of these extraordinary biomaterials, paving the way for new frontiers in healthcare innovation.

Smart core-shell microneedles for psoriasis therapy: In situ self-assembly of calcium ion-coordinated dexamethasone hydrogel

Psoriasis is a prevalent relapsing dermatological condition that often necessitates lifelong treatment. The distinctive thickening of the stratum corneum presents a challenge to drug penetration. The employment of microneedles has been demonstrated to enhance the transdermal drug delivery efficacy by creating multiple microchannels in the skin. Nevertheless, polymeric microneedles often encounter difficulties in meeting the requirements for sustained drug release. It is imperative to acknowledge that sustained-release hydrogel microneedles are invariably fabricated under harsh crosslinking conditions. In addressing these challenges, a core-shell microneedles (CSMNs) system was customized at a facile, accessible process, enabling the in situ formation of supramolecular microhydrogels within the skin. This concept was realized by leveraging the interaction between the therapeutic drug dexamethasone sodium phosphate (DexP) and calcium chloride (CaCl2), combined with the differential biphasic release technology (DexP HMNs). Upon insertion into the skin, the core of the microneedles rapidly released CaCl2, which diffused to the shell and formed a hydrogel with DexP, creating multiple reservoirs for the sustained release of DexP. In vitro transdermal permeation experiments demonstrated that DexP HMNs greatly prolonged the skin retention time of DexP. In the context of psoriasis treatment, DexP HMNs were demonstrated to be more effective than DexP CSMNs in inhibiting keratinocyte proliferation and significantly reducing the levels of inflammatory factors and immune cell infiltration at the lesion site. This study provides a new direction for the development of intelligent microneedle drug delivery systems for sustained drug release and enhanced management of chronic skin diseases.

Pyruvate Kinase M2-Responsive Release of Paclitaxel and Indoleamine 2,3-Dioxygenase Inhibitor for Immuno-Chemotherapy of Nonsmall Cell Lung Cancer

Paclitaxel (PTX) is a first-line chemotherapeutic drug for non-small cell lung cancer (NSCLC) but it can induce indoleamine 2,3-dioxygenase (IDO) activation, which severely lowers down its immuno-chemotherapeutic effect. To address this issue, a smart peptide hydrogelator Nap-Phe-Phe-Phe-Lys-Ser-Thr-Gly-Gly-Lys-Ala-Pro-Arg-OH (Nap-T), which co-assembles with PTX and an IDO inhibitor GDC0919 to form a hydrogel GP@Gel Nap-T, is rationally designed. Upon specific phosphorylation by pyruvate kinase M2 (PKM2), an overexpressed biomarker of NSCLC, Nap-T is gradually converted to Nap-Phe-Phe-Phe-Lys-Ser-Thr(H2PO3)-Gly-Gly-Lys-Ala-Pro-Arg-OH (Nap-Tp), leading to dehydrogelation and sustained release of PTX and GDC0919 within NSCLC tissues. The released PTX exerts chemotherapy on NSCLC cells as well as immunogenic cell death induction, while GDC0919 promotes the immuno-chemotherapeutic effect of PTX through IDO inhibition. We find that GP@Gel Nap-T enhances the infiltration of tumor-infiltrating immune cells and reduces the number of immunosuppressive cells in either tumor tissues or tumor-draining lymph nodes, thus enhancing the immuno-chemotherapy of PTX toward NSCLC. With this PKM2-responsive drug release strategy, the smart peptide hydrogel platform might be applied for NSCLC treatment in clinic in near future.

Chiral Engineered Biomaterials: New Frontiers in Cellular Fate Regulation for Regenerative Medicine

Chirality, the property of objects that are nonsuperimposable on their mirror images, plays a crucial role in biological processes and cellular behaviors. Chiral engineered biomaterials have emerged as a promising approach to regulating cellular fate in regenerative medicine. However, few reviews provide a comprehensive examination of recent advancements in chiral biomaterials and their applications in cellular fate regulation. Herein, various fabrication techniques available for chiral biomaterials, including the use of chiral molecules, surface patterning, and self‐assembly are discussed. The mechanisms through which chiral biomaterials influence cellular responses, such as modulation of adhesion receptors, intracellular signaling, and gene expression, are explored. Notably, chiral biomaterials have demonstrated their ability to guide stem cell differentiation and augment tissue‐specific functions. The potential applications of chiral biomaterials in musculoskeletal disorders, neurodegenerative diseases, cardiovascular diseases, and wound healing are highlighted. Challenges and future perspectives, including standardization of fabrication methods and translation to clinical settings, are addressed. In conclusion, chiral engineered biomaterials offer exciting prospects for precisely controlling cellular fate, advancing regenerative medicine, and enabling personalized therapeutic strategies.

Ultrahard and Ultraflexible Supramolecular Hydrogel with Superenergy Dissipating Structure for Biomimetic Skin

How to integrate the "soft" (flexibility and self-healing properties) and "hard" (shape retention) into the supramolecular hydrogel system is an attractive challenge. In this work, a supramolecular hydrogel with an energy dissipation structure is designed and prepared for intelligent biomimetic skin. Lignin molecules with disulfide bonds of fracture and healing activities are introduced into the hydrogel system through covalent bonds. A large number of hydrophobic interactions and ionic bonds constitute the cross-linking structure of this supramolecular hydrogel. These supramolecular cross-linking structures endow the hydrogel with "soft" properties with 1200% of elongation at break and 92.5% of self-healing rate. The disulfide bonds between lignin macromolecules give the hydrogel with "hard" properties and can effectively absorb the work of external forces on the supramolecular hydrogel system, thus maintaining the chemical structure, shape, and resistivity. Furthermore, this supramolecular hydrogel shows good biocompatibility, antibacterial properties, tissue fluid removal properties, wound healing promoting properties, and sensing output characteristics. This covalent binding structure of biomass-based macromolecules and disulfide bonds has an important reference value for the design of supramolecular hydrogels with both "hard" and "soft" properties.

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.

Hydration effect and molecular geometry conformation as critical factors affecting the longevity stability of G4-structure-based supramolecular hydrogels

Nucleoside-derived supramolecular hydrogels based on G4-structures have been extensively developed in the biomedical sector and recognized for superior excellent biocompatibility and biodegradability. However, limited longevity and stability present a significant challenge. Chemical modifications in the molecular structure have been shown to enhance the longevity stability of G4-structure-based supramolecular hydrogels, but the precise way in which the molecular structure impacts the stability of the G4-structures and consequently affects the properties of the hydrogel remains to be elucidated. This issue represents a notable challenge in the field, which restricts their further applications to some extent. In this study, single crystals of Gd, αGd and αGd* were cultivated and compared with G. Notably, before this study, the single crystal structures of all natural nucleosides, with the exception of Gd, had been determined. The investigation into the molecular structure and supramolecular self-assembly properties of four guanosine analogs at the atomic scale revealed that the formation of G-quartets is critical for their ability to form hydrogels. The stability of the sugar ring geometry conformation (an intrinsic factor) and the disorder and strength of the hydration effect (extrinsic factors) are vital for maintaining the stability of the G4-structures. The rapid cooling changes the molecular geometry conformation, and the organic solvent changes the hydration effect, which can improve the longevity stability of G4-structure-based supramolecular hydrogels instead of chemical modifications. Consequently, the lifespan of the hydrogels was extended from 2 h to over one week. This advancement is expected to offer significant insights for future research in designing and developing G4-structure-based supramolecular hydrogels.

An Integrated All-Natural Conductive Supramolecular Hydrogel Wearable Biosensor with Enhanced Biocompatibility and Antibacterial Properties

Conductive hydrogels exhibit tremendous potential for wearable bioelectronics, biosensing, and health monitoring applications, yet concurrently enhancing their biocompatibility and antimicrobial properties remains a long-standing challenge. Herein, we report an all-natural conductive supramolecular hydrogel (GT5-DACD2-B) prepared via the Schiff base reaction between the biofriendly dialdehyde cyclodextrin and gelatin. The potent antibacterial agent fusidic acid (FA) is incorporated through host-guest inclusion, enabling 100% inhibition of Staphylococcus aureus proliferation. The biocompatibility of our hydrogel is bolstered with tannic acid (TA) facilitating antibacterial effects through interactions with gelatin, while borax augments conductivity. This supramolecular hydrogel not only exhibits stable conductivity and rapid response characteristics but also functions as a flexible sensor for monitoring human movement, facial expressions, and speech recognition. Innovatively integrating biocompatibility, antimicrobial activity, and conductivity into a single system, our work pioneers a paradigm for developing multifunctional biosensors with integrated antibacterial functionalities, paving the way for advanced wearable bioelectronics with enhanced safety and multifunctionality.

Mechanochemistry: Fundamental Principles and Applications

Mechanochemistry is an emerging research field at the interface of physics, mechanics, materials science, and chemistry. Complementary to traditional activation methods in chemistry, such as heat, electricity, and light, mechanochemistry focuses on the activation of chemical reactions by directly or indirectly applying mechanical forces. It has evolved as a powerful tool for controlling chemical reactions in solid state systems, sensing and responding to stresses in polymer materials, regulating interfacial adhesions, and stimulating biological processes. By combining theoretical approaches, simulations and experimental techniques, researchers have gained intricate insights into the mechanisms underlying mechanochemistry. In this review, the physical chemistry principles underpinning mechanochemistry are elucidated and a comprehensive overview of recent significant achievements in the discovery of mechanically responsive chemical processes is provided, with a particular emphasis on their applications in materials science. Additionally, The perspectives and insights into potential future directions for this exciting research field are offered.

Exploring a Solvent Dependent Strategy to Control Self-Assembling Behavior and Cellular Interaction in Laminin-Mimetic Short Peptide based Supramolecular Hydrogels

Self-assembled hydrogels, fabricated through diverse non-covalent interactions, have been extensively studied in regenerative medicines. Inspired from bioactive functional motifs of ECM protein, short peptide sequences have shown remarkable abilities to replicate the intrinsic features of the natural extracellular milieu. In this direction, we have fabricated two short hydrophobic bioactive sequences derived from the laminin protein i. e., IKVAV and YIGSR. Based on the substantial hydrophobicity of these peptides, we selected a co-solvent approach as a suitable gelation technique that included different concentrations of DMSO as an organic phase along with an aqueous solution containing 0.1 % TFA. These hydrophobic laminin-based bioactive peptides with limited solubility in aqueous physiological environment showed significantly enhanced solubility with higher DMSO content in water. The enhanced solubility resulted in extensive intermolecular interactions that led to the formation of hydrogels with a higher-order entangled network along with improved mechanical properties. Interestingly, by simply modulating DMSO content, highly tunable gels were accessed in the same gelator domain that displayed differential physicochemical properties. Further, the cellular studies substantiated the potential of these laminin-derived hydrogels in enhancing cell-matrix interactions, thereby reinforcing their applications in tissue engineering.

Stimulus-Responsive Hydrogels as Drug Delivery Systems for Inflammation Targeted Therapy

Deregulated inflammations induced by various factors are one of the most common diseases in people's daily life, while severe inflammation can even lead to death. Thus, the efficient treatment of inflammation has always been the hot topic in the research of medicine. In the past decades, as a potential biomaterial, stimuli-responsive hydrogels have been a focus of attention for the inflammation treatment due to their excellent biocompatibility and design flexibility. Recently, thanks to the rapid development of nanotechnology and material science, more and more efforts have been made to develop safer, more personal and more effective hydrogels for the therapy of some frequent but tough inflammations such as sepsis, rheumatoid arthritis, osteoarthritis, periodontitis, and ulcerative colitis. Herein, from recent studies and articles, the conventional and emerging hydrogels in the delivery of anti-inflammatory drugs and the therapy for various inflammations are summarized. And their prospects of clinical translation and future development are also discussed in further detail.