Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

Biocompatible fluorescent carbon nanoparticles as nanocarriers for targeted delivery of tamoxifen for regression of Breast carcinoma

Breast cancer (BC) is the most common malignancy among females worldwide, and its high metastasis rates are the leading cause of death just after lung cancer. Currently, tamoxifen (TAM) is a hydrophobic anticancer agent and a selective estrogen modulator (SERM), approved by the FDA that has shown potential anticancer activity against BC, but the non-targeted delivery has serious side effects that limit its ubiquitous utility. Therefore, releasing anti-cancer drugs precisely to the tumor site can improve efficacy and reduce the side effects on the body. Nanotechnology has emerged as one of the most important strategies to solve the issue of overdose TAM toxicity, owing to the ability of nano-enabled formulations to deliver desirable quantity of TAM to cancer cells over a longer period of time. In view of this, use of fluorescent carbon nanoparticles in targeted drug delivery holds novel promise for improving the efficacy, safety, and specificity of TAM therapy. Here, we synthesized biocompatible carbon nanoparticles (CNPs) using chitosan molecules without any toxic surface passivating agent. Synthesized CNPs exhibit good water dispersibility and emit intense blue fluorescence upon excitation (360 nm source). The surface of the CNPs has been functionalized with folate using click chemistry to improve the targeted drug uptake by the malignant cell. The pH difference between cancer and normal cells was successfully exploited to trigger TAM release at the target site. After six hours of incubation, CNPs released ∼ 74 % of the TAM drug in acidic pH. In vitro, studies have also demonstrated that after treatment with the synthesized CNPs, significant inhibition of the tumor growth could be achieved.

High performances of cellulose nanocrystal based bicomponent supramolecular hydrogel lubricant

To improve the limitations of water-based lubricants, a novel cellulose nanocrystal based supramolecular hydrogel (CNC/x-DG/y) was prepared by mixing cellulose nanocrystal (CNC) and diglycerol (DG) into deionized water (DW). The hydrogel was characterized to determine its material ratio and gelation mechanism. When DW was fixed at 1 mL, CNC content should be no <2.4 wt% and DG content 0.1-1.3 mL. The gelification was driven by the multiple H-bond network between CNC and DG, which immobilized water molecules. The rheological performances, the anti-rust property and the volatilization behaviour of the hydrogel were further studied. The results showed that the hydrogel had satisfactory viscoelasticity, excellent thermal stability, strong creep recovery, high anti-rust performance and low volatilization rate, which were exactly its advantages for use as lubricant. A typical representative of the hydrogel, namely CNC/2.4-DG/0.1, was selected to evaluate the tribological performances, and the resulting worn surfaces were analyzed. CNC/2.4-DG/0.1 exhibited a lower friction coefficient of 0.059 and a smaller wear volume of 0.81 × 10-3 mm3, compared to DW(1 mL) + CNC(2.4 wt%) and DW(1 mL) + DG(0.1 mL). The outstanding tribological performances of CNC/2.4-DG/0.1 were reasonably attributed to the synergistic mending effect of CNC and DG and the dissipative effect of H-bonds between the two.

Effect of oxidized Bletilla striata polysaccharide on fibrin hydrogel formation and its application in wound healing dressing

Wound healing is influenced by various factors, including oxidative damage, bacterial infection, and inadequate angiogenesis, which collectively contribute to a protracted healing process. In this work, we designed innovative multifunctional hydrogels based on fibrin integrated with Bletilla striata polysaccharides (BSP) or oxidated Bletilla striata polysaccharides (OBSP) for use as wound dressings. The preliminary structure and bioactivity of BSP and OBSP were investigated. The effect of polysaccharides on the self-assembly process of fibrin hydrogels were also evaluated. BSP and OBSP significantly altered the initial fibrin fibrillogenesis and the ultimate structure of the fibrin network. Relative to pure fibrin hydrogel, the incorporation of BSP and OBSP enhanced water swelling and retention, and decelerated the degradation of hydrogels in PBS. Furthermore, BSP and OBSP augmented the antioxidant, antibacterial, and anti-inflammatory properties of fibrin hydrogels, with OBSP demonstrating superior performance in these aspects. Through the development of a murine wound model, it was observed that the wound healing efficacy of hydrogels incorporating BSP and OBSP surpassed that of the pure fibrin group. Notably, the hydrogel formulated with 25 mg/mL OBSP exhibited the most pronounced therapeutic effect, achieving a healing rate approaching 100 %. Consequently, fibrin-OBSP composite hydrogels demonstrate significant potential as wound dressings.

Antifreezing/Antiswelling Hydrogels: Synthesis Strategies and Applications as Flexible Motion Sensors

Hydrogels are excellent materials for fabricating flexible electronic devices, such as flexible sensors. However, obtaining hydrogels with superior swelling capacity and good hydrophilicity suitable for use under extreme environments, such as cold and underwater conditions, is still challenging due to the occurrence of freezing and excessive swelling. Alternatively, hydrogels with antifreezing and antiswelling capacities exhibit minimal changes in their physical and chemical properties under extreme conditions with retained original performance, such as mechanical properties, conductivity, and adhesiveness, making them suitable for various applications. Accordingly, various multifunctional antifreezing/antiswelling hydrogels meeting practical application requirements have been developed thanks to the advancement of hydrogel technology. Examples include flexible sensors for monitoring various motion signals, such as changes during sports events. However, comprehensive reviews describing these hydrogels in terms of synthesis and application in sensors are still lacking. Herein, the design and synthetic strategies of antifreezing/antiswelling hydrogels reported in recent years are comprehensively analyzed along with their mechanisms and applications in flexible motion sensors. This review aims to provide a comprehensive understanding of the research of antifreezing/antiswelling hydrogels and offer valuable insights for researchers engaged in the development of advanced materials suitable for practical applications.

Engineering supramolecular peptide nanofibers for in vivo platelet-hitchhiking beyond ligand-receptor recognition

Ex vivo or in vivo cell-hitchhiking has emerged as a potential means for efficient drug delivery and various disease therapies. However, many challenges remain, such as the complicated engineering process and dependence on ligand-receptor interaction. Here, we present a simple in vivo platelet-hitchhiking strategy based on self-assembling peptides without ligand modification. The engineered peptide nanofibers can hitchhike ultrafast (<5 s) and efficiently on both resting and activated platelets in a receptor-independent and species-independent manner. Mechanistic studies showed that unique secondary structure of nanofibers, which lead to surface exposure of hydrophobic and hydrogen bond-forming groups, might primarily contribute to the selective and efficient platelet-hitchhiking behavior. After intravenous injection, these peptide nanofibers hitchhiked in situ on circulating platelets and achieved almost 20-fold lung accumulation. Our study provides not only a different paradigm of in vivo platelet-hitchhiking beyond ligand-receptor recognition but also a potential strategy for lung-targeted drug delivery and pulmonary disease therapy.

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 15-crown-5-ether-based supramolecular hydrogel with selection ability for potassium cations via gelation and colour change

We developed a novel supramolecular hydrogelator possessing a benzo-15-crown-5 (B15C5) moiety. The hydrogelator can detect colourless potassium cations (K+) via easily readable gelation and colour change arising from a change in the molecular assembling ability through host-guest interactions between B15C5 and K+, which afford a B15C5/K+/B15C5 sandwich complex.

Injectable self-assembling peptide hydrogel as a promising vitreous substitute

Vitreoretinal diseases pose significant threats to vision, often requiring vitrectomy and substitution of vitreous humor to restore ocular structure and visual function. However, existing substitutes have limitations that compromise patient outcomes. Supramolecular hydrogels, particularly peptide-based formulations, have emerged as promising alternatives due to their superior optical clarity, biocompatibility, and viscoelasticity. In this study, we designed and evaluated two peptide hydrogels, 3K-OX and 3E-OX, bearing positive and negative charges, respectively, as potential vitreous substitutes. Our in vitro findings revealed that the physicochemical properties of the negatively charged peptide hydrogel, 3E-OX, closely resembled those of the native vitreous body, exhibiting optimal light transmittance, refractive index, molecular permeability, and biocompatibility. Animal studies further confirmed the safety and biocompatibility of 3E-OX as a promising vitreous substitute. Notably, we introduced optical coherence tomography for retinal microvascular detection in non-pigmented rabbits, presenting a novel approach to evaluate the performance of intraocular tamponade materials. This work not only expands the utility of peptide hydrogels but also provides valuable insights into the design of vitreous substitutes.

Long Stability of Atomically Precise Red Emissive Copper Nanoclusters within the Gel and Their Use As a Potential Catalyst and Fluorescent Ink

Herein, an amphiphile-based hydrogel (with 5% DMF) containing natural amino acid residue has been used to prepare and stabilize red-emitting CuNCs for several months. Though different methods have been attempted, amphiphile and 4-mercaptobenzoic acid (4-MBA)-containing hydrogels are pinpointed to be the base medium to stabilize this new Cu-cluster. From a MALDI-TOF MS analysis it was found that it is a Cu8-atom cluster stabilized by three 4-MBA ligands. Copper acetate monohydrate (Cu(CH3COO)2·H2O) has been used as a copper precursor, and l-ascorbic acid has been used as a reducing agent. FEG-TEM analysis shows that the Cu cluster has an average size of 2.83 nm. Interestingly, these clusters can be used as a fluorescent ink with a visibility of the solid state under a UV-lamp with an excitation of 365 nm. This envisaged applying these CuNCs for anticounterfeiting. These Cu-clusters show an excitation of 420 nm with an emission of 620 nm, as is evident from the fluorescence spectroscopic analysis. Based on our knowledge, this is the first example of making and consequently stabilizing Cu-clusters using hydrogel as a template for a few months. Moreover, these CuNCs can also be used as a catalyst for the reduction of nitro derivatives to their amine derivatives in aqueous medium.

Novel aerogels based on supramolecular G-quadruplex assembly with intrinsic flame retardancy and thermal insulation

The construction of supramolecular aerogels still faces great challenges. Herein, we present a novel bio-based supramolecular aerogel derived from G-Quadruplex self-assembly of guanosine (G), boric acid (B) and sodium alginate (SA) and the obtained GBS aerogels exhibit superior flame-retardant and thermal insulating properties. The entire process involves environmentally friendly aqueous solvents and freeze-drying. Benefiting from the supramolecular self-assembly and interpenetrating dual network structures, GBS aerogels exhibit unique structures and sufficient self-supporting capabilities. The resulting GBS aerogels exhibit overall low densities (36.5-52.4 mg/cm3), and high porosities (>95 %). Moreover, GBS aerogels also illustrate excellent flame retardant and thermal insulating properties. With an oxygen index of 47.0-51.1 %, it can easily achieve a V-0 rating and low heat, smoke release during combustion. This work demonstrates the preparation of intrinsic flame-retardant aerogels derived from supramolecular self-assembly and dual cross-linking strategies, and is expected to provide an idea for the realization and application of novel supramolecular aerogel materials.

Self-Assembled Peptide with Morphological Structure for Bioapplication

Peptide materials, such as self-assembled peptide materials, are very important biomaterials. Driven by multiple interaction forces, peptide molecules can self-assemble into a variety of different macroscopic forms with different properties and functions. In recent years, the research on self-assembled peptides has made great progress from laboratory design to clinical application. This review focuses on the different morphologies, including nanoparticles, nanovesicles, nanotubes, nanofibers, and others, formed by self-assembled peptide. The mechanisms and applications of the morphology transformation are also discussed in this paper, and the future direction of self-assembled nanomaterials is envisioned.

Synthesis and characterization of self-healable supramolecular hydrogel based on carboxymethyl cellulose for biomedical applications

Hydrogels have been widely used in biomedical fields including tissue engineering, drug delivery and cell delivery and 3D cell delivery due to abundant water content in their hydrophilic three-dimensional networks and having soft tissue similar to the human body. In recent years, supramolecular hydrogels (SHG) formed by the inclusion complex between polyethylene glycol (PEG) and macrocycles such as cyclodextrin (CD) have attracted much interest due to their excellent biocompatibility and great potential in biomedical. In this research, a carboxymethyl cellulose (CMC)-based graft copolymer was prepared by using acrylic acid (AA) and maleic anhydride functionalized β-CD (β-CD-MA) as comonomers and ammonium persulfate (APS) as initiator. Then, a self-healable supramolecular hydrogel was synthesized by formation of a host-guest inclusion complex between CMC-g-poly (AA-co-β-CD-MA) as host molecule and cytosine- and guanine-modified PEG as guest molecules. The prepared hydrogel was characterized by Scanning Electron Microscope (SEM), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (1H NMR). The thermal stability of hydrogel was also determined by thermal gravimetric (TGA) and differential scanning calorimetry (DSC) methods. In addition, the loading and release profiles of metformin hydrochloride (MH) drug as a model on hydrogel was investigated. The results indicated that the drug release from the hydrogel peaks around 360 min and aligns with the Ritger-Peppas model. The hydrogel's self-healing property was examined at ambient temperature and 37 °C. It showed 70 % healing in 1.5 h and completed recovery after 9 h.

Supramolecular nanomedicine in the intelligent cancer therapy: recent advances and future

In recent years, the incidence of cancer has been increasing year by year, and the burden of the disease and the economic burden caused by it has been worsening. Although chemotherapy, immunotherapy, targeted therapy and other therapeutic means continue to progress, they still inevitably have problems such as high toxicity and side effects, susceptibility to drug resistance, and high price. Photothermal therapy and photodynamic therapy have demonstrated considerable advantages in cancer imaging and treatment due to their minimally invasive and selective nature. However, their development has been constrained by challenges related to drug delivery. In recent times, drug delivery systems constructed based on supramolecular chemistry have been the subject of considerable interest, particularly in view of their compatibility with the high permeability and long retention effect of tumors. Furthermore, the advantage of dissociating the active ingredient under pH, light and other stimuli makes them unique in cancer therapy. This paper reviews the current status of supramolecular nanomedicines in cancer therapy, elucidating the challenges faced and providing a theoretical basis for the efficient and precise treatment of malignant tumors.

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 350 µm 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 5 µm min-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.

Gelation Dynamics steering Frontiers in Technology: Unraveling Hotspots and Research Trends through Scientometric insights

The serendipitous occurrence of gels in science has been a milestone for further industrial revolutionization. The controlled formation and disassembly of gels coupled with their viscoelastic properties and their ability to undergo extensive structural modification to suit different applications have led to the widespread use of gelation technology in different domains of science such as sensing, material chemistry and physics, medicine, food and nutrition, ecology, and more. With the rising interest in gelators and gels applications, accurately depicting the current status of gelation and associated technology is of paramount importance for researchers and scholars already immersed in gel technology as well as those aiming to delve into this field. Utilizing bibliometrics offers a systematic approach to analyze trends, citation patterns, and the impact of research, providing crucial insights for advancing knowledge and innovation in gel technology. By performing a comprehensive bibliometric analysis of scientific publications, using Vosviewer, Citespace, and Biblioshiny, in terms of co-authorship and co-citations of publications, and also the co-occurrence analysis of countries, institutions, authors, and keywords Research frontiers and hotspots in gelation and associated technologies in 21st century can be assessed. The result indicated a research frontier in the discipline of ecology, earth, and marine for gelator application and current hotspots within the research field of gelation technology in; catalysis, eutectogels development as an alternative for ionic liquid gels, gelators in drug delivery for antibacterial activity, oleogels in the food industry, low molecular weight hydrogels for tissue repair and 4D printing and gelators application for oil spill remediation and dye removal. This work, although not assessing fully the qualitative aspect of a research field, gives a broad quantitative analysis and direction of research within a research field. The result of this work will provide a comprehensive overview of the evolution of research in the field of gelation technology and a global understanding of research frontiers, hotspots, and drawbacks within the field to researchers and scholars willing to work in this research area.

Recent Advances in Self-Assembling Peptide-Based Nanomaterials for Enhanced Photodynamic Therapy

Self-assembling peptide-based materials with ordered nanostructures possess advantages such as good biocompatibility and biodegradability, superior controllability, and ease of chemical modification. Through covalent conjugation or non-covalent encapsulation, photosensitizers (PSs) can be carried by self-assembling peptide-based nanomaterials for targeted delivery towards tumor tissues. This improves the stability, solubility, and tumor accumulation of PSs, as well as reduces their dark toxicity. More importantly, these nanomaterials can be tailored with responsiveness to tumor microenvironment, which enables smart release of PSs for precise and enhanced photodynamic therapy (PDT). In this review, the self-assembly of peptide from the perspective of driving forces is first described, and various self-assembling peptide materials with zero to 3D nanostructures are subsequently highlighted for PDT of cancers in recent years. Finally, an outlook in this field is provided to motivate fabrication of advanced PDT nanomaterials.

Model to rationalize and predict the formation of organic patterns originating from an enzyme-assisted self-assembly Liesegang-like process of peptides in a host hydrogel

Recently, we have investigated the enzyme-assisted self-assembly of precursor peptides diffusing in an enzyme-containing host gel, leading to various self-assembly profiles within the gel. At high enzyme concentrations, the reaction-diffusion self-assembly processes result in the formation of a continuous non-monotonous peptide self-assembly profile. At low enzyme concentrations, they result in the formation of individual self-assembled peptide microglobules and at intermediate enzyme concentrations both kinds of self-assembled structures coexist. Herein, we develop a Liesegang-type model that considers four major points: (i) the diffusion of the precursor peptides within the host gel, (ii) the diffusion of the enzymes in the gel, (iii) the enzymatic transformation of the precursor peptides into the self-assembling ones and (iv) the nucleation of these building blocks as the starting point of the self-assembly process. This process is treated stochastically. Our model predicts most of the experimentally observed features and in particular (i) the transition from a continuous to a microglobular pattern of self-assembled peptides through five types of patterns by decreasing the enzyme concentration in the host hydrogel. (ii) It also predicts that when the precursor peptide concentration decreases, the enzyme concentration at which the continuous/microglobules transition appears increases. (iii) Finally, it predicts that for peptides whose critical self-assembly concentration in solution decreases, the peptide concentration at which the continuous-to-microglobular transition decreases too. All these predictions are observed experimentally.

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.

From self-Assembly to healing: Engineering ultra-Small peptides into supramolecular hydrogels for controlled drug release

The aim of this study was the evaluation of suitability of novel mucoadhesive hydrogel platforms for the delivery of therapeutics useful for the management of disorders related to the gastrointestinal tract (GI). At this purpose, here we describe the preparation, the physicochemical characterization and drug delivery behaviour of novel hydrogels, based on self-assembling lipopeptides (MPD02-09), obtained by covalently conjugating lauric acid (LA) to SNA's peptide derivatives gotten by variously combining D- and L- amino acid residues. LA conjugation was aimed at improving the stability of the precursor peptides, obtaining amphiphilic structures, and triggering the hydrogels formation through the self-assembling. Budesonide (BUD), an anti-inflammatory drug, was selected as model because of its use in the treatment in GI disorders. Preliminary studies were performed to correlate the chemical structure of the conjugates with the key physicochemical properties of the materials for drug delivery. Two lipopeptides, MPD03 and MPD08, were found to form hydrogels (MPD03h and MPD08h, respectively) with characteristics suitable for drug delivery. These materials showed mucoadhesiveness of about 60 %. In vitro studies carried out with BUD loaded hydrogels showed about 70 % drug release within 6 h. Wound healing assessed in Caco-2 and HaCaT cells, showed reduction of cell-free area to values lower than 10 %. Taking together these results MPD03h and MPD08h have been shown to be excellent candidates for BUD delivery.

New Supramolecular Hydrogels Based on Diastereomeric Dehydrotripeptide Mixtures for Potential Drug Delivery Applications

Self-assembly of peptide building blocks offers unique opportunities for bottom-up preparation of exquisite nanostructures, nanoarchitectures, and nanostructured bulk materials, namely hydrogels. In this work we describe the synthesis, characterization, gelation, and rheological properties of new dehydrotripeptides, Cbz-L-Lys(Cbz)-L,D-Asp-∆Phe-OH and (2-Naph)-L-Lys(2-Naph)-L,D-Asp-∆Phe-OH, containing a N-terminal lysine residue Nα,ε-bis-capped with carboxybenzyl (Cbz) and 2-Naphthylacetyl (2-Naph) aromatic moieties, an aspartic acid residue (Asp), and a C-terminal dehydrophenylalanine (∆Phe) residue. The dehydrotripeptides were obtained as diastereomeric mixtures (L,L,Z and L,D,Z), presumably via aspartimide chemistry. The dehydrotripeptides afforded hydrogels at exceedingly low concentrations (0.1 and 0.04 wt%). The hydrogels revealed exceptional elasticity (G' = 5.44 × 104 and 3.43 × 106 Pa) and self-healing properties. STEM studies showed that the diastereomers of the Cbz-capped peptide undergo co-assembly, generating a fibrillar 3D network, while the diastereomers of the 2-Naph-capped dehydropeptide seem to undergo self-sorting, originating a fibril network with embedded spheroidal nanostructures. The 2-Naph-capped hydrogel displayed full fast recovery following breakup by a mechanical stimulus. Spheroidal nanostructures are absent in the recovered hydrogel, as seen by STEM, suggesting that the mechanical stimulus triggers rearrangement of the spheroidal nanostructures into fibers. Overall, this study demonstrates that diastereomeric mixtures of peptides can be efficacious gelators. Importantly, these results suggest that the structure (size, aromaticity) of the capping group can have a directing effect on the self-assembly (co-assembly vs. self-sorting) of diastereomers. The cytotoxicity of the newly synthesized gelators was evaluated using human keratinocytes (HaCaT cell line). The results indicated that the two gelators exhibited some cytotoxicity, having a small impact on cell viability. In sustained release experiments, the influence of the charge on model drug compounds was assessed in relation to their release rate from the hydrogel matrix. The hydrogels demonstrated sustained release for methyl orange (anionic), while methylene blue (cationic) was retained within the network.

Development and Performance Evaluation of a New Conformance Control Agent Gel

How to effectively plug the multi-scale fractured water channeling has always been the key to achieving efficient water flooding of fractured low-permeability oil reservoirs. In this paper, a new type of supramolecular-polymer composite gel is developed, which is suitable for plugging multi-scale fractured water channeling. The supramolecular-polymer composite gel is composed of a polymer (such as polyacrylamide), cross-linking agent (such as polyethyleneimine), supramolecular gel factor (such as cyclodextrin) and polarity regulator (such as ethyl alcohol). The mass fraction of polyacrylamide, polyethyleneimine, cyclodextrin and ethyl alcohol are 0.15%, 0.2%, 1% and 0.2%, respectively. At the initial state, the viscosity of the composite gelant system is less than 20 mPa·s. It has good injection performance in micro-scale fractures and can enter the deep part of a fractured reservoir. At 40 °C, the composite gelant system can form a gel with a double network structure after gelation. One of the networks is formed by the covalent interaction between polyacrylamide and polyethyleneimine, the other network is formed by the self-assembly of cyclodextrins under the action of the ethyl alcohol. The comprehensive performance of the composite gel is greatly improved. The strength of the composite gel is >5 × 104 mPa·s, and it has good plugging strength in large-scale fractures. The composite gel can be used as a conformance control agent for fractured low-permeability oilfields.

Hydrogel in the Treatment of Traumatic Brain Injury

The high prevalence of traumatic brain injury (TBI) poses an important global public health challenge. Current treatment modalities for TBI primarily involve pharmaceutical interventions and surgical procedures; however, the efficacy of these approaches remains limited. In the field of regenerative medicine, hydrogels have garnered significant attention and research efforts. This review provides an overview of the existing landscape and pathological manifestations of TBI, with a specific emphasis on delineating the therapeutic potential of hydrogels incorporated with various bioactive agents for TBI management. Particularly, the review delves into the utilization and efficacy of hydrogels based on extracellular matrix (ECM), stem cell-loaded, drug-loaded, self-assembled peptide structures or conductive in the context of TBI treatment. These applications are shown to yield favorable outcomes such as tissue damage mitigation, anti-inflammatory effects, attenuation of oxidative stress, anti-apoptotic properties, promotion of neurogenesis, and facilitation of angiogenesis. Lastly, a comprehensive analysis of the merits and constraints associated with hydrogel utilization in TBI treatment is presented, aiming to steer and advance future research endeavors in this domain.

Investigating the self-assembly of 2NapFF and ureido-pyrimidinone multicomponent systems for cell culture

Low molecular weight gels are formed via the self-assembly of small molecules into fibrous structures. In the case of hydrogels, these networks entrap large volumes of water, yielding soft materials. Such gels tend to have weak mechanical properties and a high permeability for cells, making them particularly appealing for regenerative medicine applications. Ureido-pyrimidinone (UPy) supramolecular gelators are self-assembling systems that have demonstrated excellent capabilities as biomaterials. Here, we combine UPy-gelators with another low molecular weight gelator, the functionalized dipeptide 2NapFF. We have successfully characterized these multicomponent systems on a molecular and bulk scale. The addition of 2NapFF to a crosslinked UPy hydrogel significantly increased hydrogel stiffness from 30 Pa to 1300 Pa. Small-angle X-ray scattering was used to probe the underlying structures of the systems and showed that the mixed UPy and 2NapFF systems resemble the scattering data produced by the pristine UPy systems. However, when a bifunctional UPy-crosslinker was added, the scattering was close to that of the 2NapFF only samples. The results suggest that the crosslinker significantly influences the assembly of the low molecular weight gelators. Finally, we analysed the biocompatibility of the systems using fibroblast cells and found that the cells tended to spread more effectively when the crosslinking species was incorporated. Our results emphasise the need for thorough characterisation at multiple length scales to finely control material properties, which is particularly important for developing novel biomaterials.

Peptide-based supramolecular hydrogels and their biotherapeutic applications

In recent years, supramolecular hydrogels have made groundbreaking research progress in biomedical fields such as drug delivery, biosensing, imaging analysis, and tissue engineering. Peptides, with their unique characteristics of facile preparation, low immunogenicity and easy biodegradability, are commonly used as building blocks of supramolecular hydrogels. Peptide-based supramolecular hydrogels loaded with drugs, prepared via physical means or covalent crosslinking, exhibit unique three-dimensional network structures and strong water retention capacities. These properties enhance drug bioavailability and reduce side effects, enabling drug accumulation and responsive release at disease sites, significantly improving the therapeutic efficacy. Here, we review recent advancements in peptide-based supramolecular hydrogels and their biotherapeutic applications, including chemotherapy, photothermal therapy, photodynamic therapy, immunotherapy, gene therapy, antibacterial and anti-inflammatory treatments, and other biological applications. This review aims to provide new inspiration for the development of biomaterials in the therapeutic field and provide more personalized options for disease treatment. Additionally, challenges and limitations in this field are briefly discussed.

Polyvinyl alcohol-chitosan-polyethylene glycol-glycerol incorporated with Peganum harmala loaded in lipid nanocapsules as an elastic nanocomposite surgical sealant to control bleeding

Uncontrolled hemorrhage remains a critical threat in trauma and surgery. This study developed a novel hemostatic composite by encapsulating Peganum harmala L. seed extract (PH) with known hemostatic properties into lipid nanocapsules (PH-LNCs) and then embedding them within a polyvinyl alcohol-chitosan-polyethylene glycol-glycerol (PVA-CS-PEG-G) matrix. The composite was physically crosslinked via the dual processes of freezing-thawing and thermal crosslinking and exhibited robust mechanical properties reaching 0.434 ± 0.014 MPa and elasticity of 40.685 % ± 4.04. It also demonstrated excellent biocompatibility, surface morphology, physical stability, and ex-vivo skin deposition/permeation were assessed. The characterization of PH-LNCs revealed optimal PH-LNC formation and successful integration into the composite with particle size, zeta potential, and PDI were approximately 45.45 ± 24 nm, -16.3 ± 1.4 mV, and 0.374 ± 0.1, respectively. In vitro studies highlighted enhanced blood clotting and platelet adhesion, while in vivo experiments confirmed superior hemostatic efficacy in a mouse tail amputation model. The composite's soft texture, conformability, and mechanical strength make it a promising candidate for effective traumatic wound management.

Thermal responsive sodium alginate/polyacrylamide/poly (N-isopropylacrylamide) ionic hydrogel composite via seeding calcium carbonate microparticles for the engineering of ultrasensitive wearable sensors

The design of polyelectrolyte hydrogel with unique tensile and adhesive properties which can be applied across disciplines has gradually become a popular trend. However, the phenomenon of global warming and the emergence of extreme weather, it still faces some urgent problems that should be solved, such as the optimal utilization of polyelectrolyte hydrogel across a wide range of temperatures. Herein, a wide temperature sensitivity and conductivity hydrogel based on sodium alginate, acrylamide and N-isopropylacrylamide was constructed, which exhibited excellent adhesion and temperature conductivity. It is worth noting that after the inclusion of CaCO3 and NaCl in the hydrogel, the hydrogel showed excellent tensile properties (fracture strain >2000 %). Within a wide temperature range (-15-50 °C), it exhibits exceptional electrical conductivity (2.75 S ∗ m-1) and sensitivity (GF = 8.76 under high strain). This innovative intelligent polyelectrolyte hydrogel provides suitable strategy for flexible sensors, smart wearable devices and medical monitoring equipment.

Oxidation-Responsive Supramolecular Hydrogels Based on Glucosamine Derivatives with an Aryl Sulfide Group

Supramolecular hydrogels can be obtained via self-assembly of small molecules in aqueous environments. In this study, we describe the development of oxidation-responsive supramolecular hydrogels comprising glucosamine derivatives with an aryl sulfide group. We demonstrate that hydrogen peroxide can induce a gel-sol transition through the oxidation of the sulfide group to the corresponding sulfoxide. Furthermore, we show that this oxidation responsiveness can be extended to photo-responsiveness with the aid of a photosensitizer.

Tough Supramolecular Hydrogels Crafted via Lignin-Induced Self-Assembly

Supramolecular hydrogels are typically assembled through weak non-covalent interactions, posing a significant challenge in achieving ultra strength. Developing a higher strength based on molecular/nanoscale engineering concepts is a potential improvement strategy. Herein, a super-tough supramolecular hydrogel is assembled by gradually diffusing lignosulfonate sodium (LS) into a polyvinyl alcohol (PVA) solution. Both simulations and analytical results indicate that the assembly and subsequent enhancement of the crosslinked network are primarily attributed to LS-induced formation and gradual densification of strong crystalline domains within the hydrogel. The optimized hydrogel exhibits impressive mechanical properties with tensile strength of ≈20 MPa, Young's modulus of ≈14 MPa, and toughness of ≈50 MJ m⁻3, making it the strongest lignin-PVA/polymer hydrogel known so far. Moreover, LS provides the supramolecular hydrogel with excellent low-temperature stability (<-60 °C), antibacterial, and UV-blocking capability (≈100%). Interestingly, the diffusion ability of LS is demonstrated for self-restructuring damaged supramolecular hydrogel, achieving 3D patterning on hydrogel surfaces, and enhancing the local strength of the freeze-thaw PVA hydrogel. The goal is to foster a versatile hydrogel platform by combining eco-friendly LS with biocompatible PVA, paving the way for innovation and interdisciplinarity in biomedicine, engineering materials, and forestry science.

Recent Advances in Smart Self-Assembled Bioinspired Hydrogels: A Bridging Weapon for Emerging Health Care Applications from Bench to Bedside

Stimuli-responsive low molecular weight hydrogel interventions for Biomedical challenges are a rapidly evolving paradigm in the bottom-up approach recently. Peptide-based self-assembled nano biomaterials present safer alternatives to their non-degradable counterparts as demanded for today's most urged clinical needs.Although a plethora of work has already been accomplished, programming hydrogelators with appropriate functionalities requires a better understanding as the impact of the macromolecular structure of the peptides and subsequently, their self-assembled nanostructures remain unidentified. Henceforth this review focuses on two aspects: Firstly, the underlying guidelines for building biomimetic strategies to tailor scaffolds leading to hydrogelation along with the role of non-covalent interactions that are the key components of various self-assembly processes. In the second section, it is aimed to bring together the recent achievements with designer assembly concerning their self-aggregation behaviour and applications mainly in the biomedical arena like drug delivery carrier design, antimicrobial, anti-inflammatory as well as wound healing materials. Furthermore, it is anticipated that this article will provide a conceptual demonstration of the different approaches taken towards the construction of these task-specific designer hydrogels. Finally, a collective effort among the material scientists is required to pave the path for the entrance of these intelligent materials into medicine from bench to bedside.

Designing intelligent bioorthogonal nanozymes: Recent advances of stimuli-responsive catalytic systems for biomedical applications

Bioorthogonal nanozymes have emerged as a potent tool in biomedicine due to their unique ability to perform enzymatic reactions that do not interfere with native biochemical processes. The integration of stimuli-responsive mechanisms into these nanozymes has further expanded their potential, allowing for controlled activation and targeted delivery. As such, intelligent bioorthogonal nanozymes have received more and more attention in developing therapeutic approaches. This review provides a comprehensive overview of the recent advances in the development and application of stimuli-responsive bioorthogonal nanozymes. By summarizing the design outlines for anchoring bioorthogonal nanozymes with stimuli-responsive capability, this review seeks to offer valuable insights and guidance for the rational design of these remarkable materials. This review highlights the significant progress made in this exciting field with different types of stimuli and the various applications. Additionally, it also examines the current challenges and limitations in the design, synthesis, and application of these systems, and proposes potential solutions and research directions. This review aims to stimulate further research toward the development of more efficient and versatile stimuli-responsive bioorthogonal nanozymes for biomedical applications.

Clustering of biphenyl oxamide ions by chiral recognition

Gels created by self-assembly of small organic molecules are dynamic soft materials that have unique properties and demanding characterization. Four chiral gelators, with two valinol- or leucinoloxamido arms attached to the 2,2'-positions of the proatropisomeric biphenyl group were chosen to show that the electrospray ionization mass spectrometry (ESI-MS) could be used to differentiate the gelation feature of the chiral compounds 1-4 and also to shed light on the gelation processes. By inspecting the gelation of several solvents, we showed that 1 (R, R) proved to be the most efficient gelator, forming the largest observable assemblies in the gas phase. The strong intermolecular H-bonds hold single-charged assemblies consisting of up to five monomer units detectable by ESI MS. Enantiomer 1 (R, R) is a good gelator due to favorable intramolecular interactions that remain preserved in the gas phase. Compound 3 (meso) does not have gelator properties and detected signals of larger assemblies in the gas phase. So, the detected signals correlate with the conformations of the studied compounds. MS could be used to elucidate the preferential type of noncovalent interaction due to the chiral recognition. The study paves a novel way to investigate the influence of chirality on the molecular assembly and consequently macroscopic properties and functions of materials.

Hydrogels: a promising therapeutic platform for inflammatory skin diseases treatment

Inflammatory skin diseases, such as psoriasis and atopic dermatitis, pose significant health challenges due to their long-lasting nature, potential for serious complications, and significant health risks, which requires treatments that are both effective and exhibit minimal side effects. Hydrogels offer an innovative solution due to their biocompatibility, tunability, controlled drug delivery capabilities, enhanced treatment adherence and minimized side effects risk. This review explores the mechanisms that guide the design of hydrogel therapeutic platforms from multiple perspectives, focusing on the components of hydrogels, their adjustable physical and chemical properties, and their interactions with cells and drugs to underscore their clinical potential. We also examine various therapeutic agents for psoriasis and atopic dermatitis that can be integrated into hydrogels, including traditional drugs, novel compounds targeting oxidative stress, small molecule drugs, biologics, and emerging therapies, offering insights into their mechanisms and advantages. Additionally, we review clinical trial data to evaluate the effectiveness and safety of hydrogel-based treatments in managing psoriasis and atopic dermatitis under complex disease conditions. Lastly, we discuss the current challenges and future opportunities for hydrogel therapeutics in treating psoriasis and atopic dermatitis, such as improving skin barrier penetration and developing multifunctional hydrogels, and highlight emerging opportunities to enhance long-term safety and stability.

D-Peptide cell culture scaffolds with enhanced antibacterial and controllable release properties

The development of peptide-based hydrogels characterized by both high biostability and potent antimicrobial activity, aimed at combating multidrug-resistant bacterial infections and providing scaffolds for cell cultures, continues to pose a significant challenge. The susceptibility of antimicrobial peptides (AMPs) to degradation by cations, serum, and proteases restricted their applications in clinical environments. In this study, we designed a peptide sequence (termed D-IK1) entirely consisting of D-amino acids, an enantiomer of a previously reported AMP IK1. Our results demonstrated remarkably improved antibacterial and anticancer activities of D-IK1 as compared to IK1. D-IK1 self-assembled into hydrogels that effectively inhibited bacterial and cancer cell growth by the controlled and sustained release of D-IK1. Importantly, D-IK1 was extremely stable in salt solutions and resisted serum and protease degradation. In addition, the D-IK1 hydrogel fostered cell adhesion and proliferation, proving its viability as a 3D scaffold for cell culture applications. Our research presents a versatile, highly stable antibacterial hydrogel scaffold with potential widespread applications in cell culture, wound healing, and the eradication of multidrug-resistant bacterial infections.

Ligand-Receptor Interaction-Induced Intracellular Phase Separation: A Global Disruption Strategy for Resistance-Free Lethality of Pathogenic Bacteria

Addressing the global challenge of bacterial resistance demands innovative approaches, among which multitargeting is a widely used strategy. Current strategies of multitargeting, typically achieved through drug combinations or single agents inherently aiming at multiple targets, face challenges such as stringent pharmacokinetic and pharmacodynamic requirements and cytotoxicity concerns. In this report, we propose a bacterial-specific global disruption approach as a vastly expanded multitargeting strategy that effectively disrupts bacterial subcellular organization. This effect is achieved through a pioneering chemical design of ligand-receptor interaction-induced aggregation of small molecules, i.e., DNA-induced aggregation of a diarginine peptidomimetic within bacterial cells. These intracellular aggregates display affinity toward various proteins and thus substantially interfere with essential bacterial functions and rupture bacterial cell membranes in an "inside-out" manner, leading to robust antibacterial activities and suppression of drug resistance. Additionally, biochemical analysis of macromolecule binding affinity, cytoplasmic localization patterns, and bacterial stress responses suggests that this bacterial-specific intracellular aggregation mechanism is fundamentally different from nonselective classic DNA or membrane binding mechanisms. These mechanistic distinctions, along with the peptidomimetic's selective permeation of bacterial membranes, contribute to its favorable biocompatibility and pharmacokinetic properties, enabling its in vivo antimicrobial efficacy in several animal models, including mice-based superficial wound models, subcutaneous abscess models, and septicemia infection models. These results highlight the great promise of ligand-receptor interaction-induced intracellular aggregation in achieving a globally disruptive multitargeting effect, thereby offering potential applications in the treatment of malignant cells, including pathogens, tumor cells, and infected tissues.

Supramolecular Hydrogels for 3D Biosensors and Bioassays

Supramolecular hydrogels play a pivotal role in many fields of biomedical research, including emerging applications in designing advanced tools for point-of-care testing, clinical diagnostics, and lab-on-chip analysis. This review outlines the growing relevance of supramolecular hydrogels in biosensing and bioassay devices, highlighting recent advancements that deliver increased sensitivity, real-time monitoring, and multiplexing capabilities through the distinctive properties of these nanomaterials. Furthermore, the exploration extends to additional applications, such as using hydrogels as three-dimensional matrices for cell-based assays.

Well-Defined Homopolymer Nanoparticles with Uniaxial Molecular Orientation by Synchronized Polymerization and Self-Assembly

Synthesizing anisotropic polymeric nanoparticles (NPs) with well-defined shapes, dimensions, and molecular orientations is a very challenging task. Herein, we report the synthesis of surprisingly highly uniform shape-anisotropic polymer NPs with uniaxial internal molecular orientation. Keys to our method are synchronized polymerization and self-assembly (SPSA), which can even be realized by regular dispersion polymerization. This is demonstrated using a monomer containing a rigid 4-nitroazobenzene (NAB) side group. The short nucleation period, the completion of microphase separation before molecular motion is frozen, and sufficient low particle/solvent interfacial tension are shown to be the origins of the highly uniform dimensions, single liquid crystal domains, and well-defined anisotropic shape of particles. The liquid crystallization ability of the polymers, control of molecular weight distribution, and the polymerization kinetics are identified as three key factors controlling the NP formation. The uniformity of these NPs facilitates their SA formation into colloidal crystals. The particles exhibit optically anisotropic properties depending on orientations and, in particular, show intriguing photoswitchable LC-glass (order-disorder) transition, which can be used for the detection of ultraviolet (UV) light and allows the fabrication of photoreversible colloidal films.

Selective sensing of cyanide ions: impact of molecular design and assembly on the response of π-conjugated acylhydrazone compounds

This study investigates the sensing properties of two distinct compounds, denoted as 1 and 2, featuring acylhydrazone units. Spectroscopic analyses reveal the disruption of the supramolecular assembly upon binding with cyanide ions, consequently due to the hydrogen bonding interaction with acylhydrazone units. This leads to a ratiometric, color-changing response of both the compounds specifically towards cyanide ions. The investigation sheds light on the reversible nature of the cyanide-probe interaction and highlights the potential for reusability in cyanide ion detection. Moreover, compound 1, distinguished by its long alkyl chains, displays a superior response to CN- ions (∼4-fold larger signal), in contrast to compound 2. However, interference was observed from other basic anions, such as F- and AcO-. The research suggests the dominating role of supramolecular assembly, intermolecular interaction, and local hydrophobic environment around the binding sites on the analytical performance of the probe molecules. The findings underscore the significance of structural design and molecular assembly in dictating the selectivity and sensitivity of compounds, offering valuable insights for the development of efficient sensor systems in diverse real-world applications.

In Situ Forming, Enzyme-Responsive Peptoid-Peptide Hydrogels: An Advanced Long-Acting Injectable Drug Delivery System

Long-acting drug delivery systems are promising platforms to improve patient adherence to medication by delivering drugs over sustained periods and removing the need for patients to comply with oral regimens. This research paper provides a proof-of-concept for the development of a new optimized in situ forming injectable depot based on a tetrabenzylamine-tetraglycine-d-lysine-O-phospho-d-tyrosine peptoid-D-peptide formulation ((NPhe)4GGGGk(AZT)y(p)-OH). The chemical versatility of the peptoid-peptide motif allows low-molecular-weight drugs to be precisely and covalently conjugated. After subcutaneous injection, a hydrogel depot forms from the solubilized peptoid-peptide-drug formulation in response to phosphatase enzymes present within the skin space. This system is able to deliver clinically relevant concentrations of a model drug, the antiretroviral zidovudine (AZT), for 35 days in Sprague-Dawley rats. Oscillatory rheology demonstrated that hydrogel formation began within ∼30 s, an important characteristic of in situ systems for reducing initial drug bursts. Gel formation continued for up to ∼90 min. Small-angle neutron scattering data reveal narrow-radius fibers (∼0.78-1.8 nm) that closely fit formation via a flexible cylinder elliptical model. The inclusion of non-native peptoid monomers and D-variant amino acids confers protease resistance, enabling enhanced biostability to be demonstrated in vitro. Drug release proceeds via hydrolysis of an ester linkage under physiological conditions, releasing the drug in an unmodified form and further reducing the initial drug burst. Subcutaneous administration of (NPhe)4GGGGk(AZT)y(p)-OH to Sprague-Dawley rats resulted in zidovudine blood plasma concentrations within the 90% maximal inhibitory concentration (IC90) range (30-130 ng mL-1) for 35 days.

A natural food-grade supramolecular self-assembly system for creation of hierarchically structured hydrogels

We develop a novel hierarchically structured hydrogel by the supramolecular self-assembly of all-natural food-grade building blocks, glycyrrhizic acid (GA) and carrageenan (CG). The co-assembled GA-CG hydrogel system displays an unusual structural transition with the appearance from opacity to translucence and then to opacity, as a function of the concentration of metal ions. The unique GA-CG supramolecular hydrogel system can serve as solid, edible, and responsive active cargo delivery platforms for food and biomedical applications.

Optimized Two-Photon Imaging by Stimuli-Responsive Peptide Self-Assembly Facilitates Self-Assisted Counteraction of Cisplatin-Resistance in Cancer Cells

Accurate diagnosis and effective treatment of tumors remain significant clinical challenges. While fluorescence imaging is essential for tumor detection, it has limitations in terms of specificity, penetration depth, and emission wavelength. Here, we report a novel glutathione (GSH)-responsive peptide self-assembly excimer probe (pSE) that optimizes two-photon tumor imaging and self-assisted counteraction of the cisplatin resistance in cancer cells. The GSH-responsive self-assembly of pSE induces a monomer-excimer transition of coumarin, promoting a near-infrared redshift of fluorescence emission under two-photon excitation. This process enhances penetration depth and minimizes interference from biological autofluorescence. Moreover, the intracellular self-assembly of pSE impacts GSH homeostasis, modulates relevant signaling pathways, and significantly reduces GSTP1 expression, resulting in decreased cisplatin efflux in cisplatin-resistant cancer cells. The proposed self-assembled excimer probe not only distinguishes cancer cells from normal cells but also enhances the efficacy of cisplatin chemotherapy, offering significant potential in tumor diagnosis and overcoming cisplatin-resistant tumors.

Bridge-rich and loop-less hydrogel networks through suppressed micellization of multiblock polyelectrolytes

Most triblock copolymer-based physical hydrogels form three-dimensional networks through micellar packing, and formation of polymer loops represents a topological defect that diminishes hydrogel elasticity. This effect can be mitigated by maximizing the fraction of elastically effective bridges in the hydrogel network. Herein, we report hydrogels constructed by complexing oppositely charged multiblock copolymers designed with a sequence pattern that maximizes the entropic and enthalpic penalty of micellization. These copolymers self-assemble into branched and bridge-rich network units (netmers), instead of forming sparsely interlinked micelles. We find that the storage modulus of the netmer-based hydrogel is 11.5 times higher than that of the micelle-based hydrogel. Complementary coarse grained molecular dynamics simulations reveal that in the netmer-based hydrogels, the numbers of charge-complexed nodes and mechanically reinforcing bridges increase substantially relative to micelle-based hydrogels.

Fabrication of Nanocatalytic Medicine from Self-Assembling Peptides Containing an ATCUN-Like Copper-Binding Motif for Anticancer Therapy

Development of nanomaterials with multiple enzymatic activities via a facile approach receives growing interests in recent years. Although peptide self-assembling provides an effective approach for the construction of biomimetic materials in recent years, fabrication of artificial enzymes from self-assembling peptides with multiple catalytic activities for anticancer therapy is still a challenge. Here, we report a simple method to prepare nanocatalysts with multienzyme-like activities from self-assembling peptides containing ATCUN copper-binding motifs. With the aid of the coordination interactions between the ATCUN motif and Cu(II) ions, these peptides could perform supramolecular self-assembly to form nanomaterials with biomimetic peroxidase, ascorbate oxidase and glutathione peroxidase activities. Moreover, these trienzyme-like effects can elevate oxidative stress levels and suppress the antioxidative capability of cancer cells, which synergistically induce the apoptosis of cancer cells. Because of the high biocompatibility, catalytic activities and drug encapsulation properties, this self-assembled peptide provides a biomimetic platform for the development of new nanocatalytic medicines for multimodal synergistic cancer therapies.

Peptide Sequence Variations Govern Hydrogel Stiffness: Insights from a Multi-Scale Structural Analysis of H-FQFQFK-NH2 Peptide Derivatives

Throughout the past decades, amphipathic peptide-based hydrogels have proven to be promising materials for biomedical applications. Amphipathic peptides are known to adopt β-sheet configurations that self-assemble into fibers that then interact to form a hydrogel network. A fundamental understanding of how the peptide sequence alters the structural properties of the hydrogels would allow for a more rational design of novel peptides for a variety of biomedical applications in the future. Therefore, the current work investigates how changing the type of amino acid, the amphipathic pattern, and the peptide length affects the secondary structure, fiber characteristics, and stiffness of peptide-based hydrogels. Hereto, seven amphipathic peptides of different sequence and length, four of which have not been previously reported, based on and including the hexapeptide H-Phe-Gln-Phe-Gln-Phe-Lys-NH2, are synthesized and thoroughly characterized by circular dichroism (CD), Fourier Transform Infrared (FTIR) spectroscopy, Wide Angle X-ray Scattering (WAXS), Small Angle X-ray Scattering (SAXS), Transmission Electron Microscopy (TEM), and Thioflavin T (ThT) fibrillization assays. The results show that a high amount of regularly spaced β-sheets, a high amount of fibers, and fiber bundling contribute to the stiffness of the hydrogel. Furthermore, a study of the time-dependent fibril formation process reveals complex transient dynamics. The peptide strands structure through an intermediate helical state prior to β-sheet formation, which is found to be concentration- and time-dependent.

Recent progress in quantitative analysis of self-assembled peptides

Self-assembled peptides have been among the important biomaterials due to its excellent biocompatibility and diverse functions. Over the past decades, substantial progress and breakthroughs have been made in designing self-assembled peptides with multifaceted biomedical applications. The techniques for quantitative analysis, including imaging-based quantitative techniques, chromatographic technique and computational approach (molecular dynamics simulation), are becoming powerful tools for exploring the structure, properties, biomedical applications, and even supramolecular assembly processes of self-assembled peptides. However, a comprehensive review concerning these quantitative techniques remains scarce. In this review, recent progress in techniques for quantitative investigation of biostability, cellular uptake, biodistribution, self-assembly behaviors of self-assembled peptide etc., are summarized. Specific applications and roles of these techniques are highlighted in detail. Finally, challenges and outlook in this field are concluded. It is believed that this review will provide technical guidance for researchers in the field of peptide-based materials and pharmaceuticals, and facilitate related research for newcomers in this field.

Design and synthesis of a nucleobase functionalized peptide hydrogel: in vitro assessment of anti-inflammatory and wound healing effects

Over the past several years, a significant increase in the expanding field of biomaterial sciences has been observed due to the development of biocompatible materials based on peptide derivatives that have intrinsic therapeutic potential. In this report, we synthesized nucleobase functionalized peptide derivatives (NPs). Hydrogelation in the synthesized NPs was induced by increasing their hydrophobicity with an aromatic moiety. The aggregation behavior of the NPs was analyzed by performing molecular dynamics simulations and DOSY NMR experiments. We performed circular dichroism (CD), thioflavin-T binding and PXRD to characterize the supramolecular aggregation in the NP1 hydrogel. The mechanical strength of the NP1 hydrogel was tested by performing rheological experiments. TEM and SEM experiments were performed to investigate the morphology of the NP1 hydrogel. The biocompatibility of the newly synthesized NP1 hydrogel was investigated using McCoy and A549 cell lines. The hemolytic activity of the NP1 hydrogel was examined in human blood cells. The stability of the newly formed NP1 hydrogel was examined using proteinase K and α-chymotrypsin. The NP1 hydrogel was used for in vitro wound healing. Western blotting, qRT-PCR and DCFDA assay were performed to determine the anti-inflammatory activity of the NP1 hydrogel. The synthesized NP1 hydrogel also exhibits antibacterial efficacy.

Bioinspired Flexible Hydrogelation with Programmable Properties for Tactile Sensing

Tactile sensing requires integrated detection platforms with distributed and highly sensitive haptic sensing capabilities along with biocompatibility, aiming to replicate the physiological functions of the human skin and empower industrial robotic and prosthetic wearers to detect tactile information. In this regard, short peptide-based self-assembled hydrogels show promising potential to act as bioinspired supramolecular substrates for developing tactile sensors showing biocompatibility and biodegradability. However, the intrinsic difficulty to modulate the mechanical properties severely restricts their extensive employment. Herein, by controlling the self-assembly of 9-fluorenylmethoxycarbonyl-modifid diphenylalanine (Fmoc-FF) through introduction of polyethylene glycol diacrylate (PEGDA), wider nanoribbons are achieved by untwisting from well-established thinner nanofibers, and the mechanical properties of the supramolecular hydrogels can be enhanced 10-fold, supplying bioinspired supramolecular encapsulating substrate for tactile sensing. Furthermore, by doping with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and 9-fluorenylmethoxycarbonyl-modifid 3,4-dihydroxy-l-phenylalanine (Fmoc-DOPA), the Fmoc-FF self-assembled hydrogels can be engineered to be conductive and adhesive, providing bioinspired sensing units and adhesive layer for tactile sensing applications. Therefore, the integration of these modules results in peptide hydrogelation-based tactile sensors, showing high sensitivity and sustainable responses with intrinsic biocompatibility and biodegradability. The findings establish the feasibility of developing programmable peptide self-assembly with adjustable features for tactile sensing applications.

Injectable Hydrogels: A Paradigm Tailored with Design, Characterization, and Multifaceted Approaches

Biomaterials denoting self-healing and versatile structural integrity are highly curious in the biomedicine segment. The injectable and/or printable 3D printing technology is explored in a few decades back, which can alter their dimensions temporarily under shear stress, showing potential healing/recovery tendency with patient-specific intervention toward the development of personalized medicine. Thus, self-healing injectable hydrogels (IHs) are stunning toward developing a paradigm for tissue regeneration. This review comprises the designing of IHs, rheological characterization and stability, several benchmark consequences for self-healing IHs, their translation into tissue regeneration of specific types, applications of IHs in biomedical such as anticancer and immunomodulation, wound healing and tissue/bone regeneration, antimicrobial potentials, drugs, gene and vaccine delivery, ocular delivery, 3D printing, cosmeceuticals, and photothermal therapy as well as in other allied avenues like agriculture, aerospace, electronic/electrical industries, coating approaches, patents associated with therapeutic/nontherapeutic avenues, and numerous futuristic challenges and solutions.

Intrahippocampal Supramolecular Assemblies Directed Bioorthogonal Liberation of Neurotransmitters to Suppress Seizures in Freely Moving Mice

The precise delivery of anti-seizure medications (ASM) to epileptic loci remains the major challenge to treat epilepsy without causing adverse drug reactions. The unprovoked nature of epileptic seizures raises the additional need to release ASMs in a spatiotemporal controlled manner. Targeting the oxidative stress in epileptic lesions, here the reactive oxygen species (ROS) induced in situ supramolecular assemblies that synergized bioorthogonal reactions to deliver inhibitory neurotransmitter (GABA) on-demand, are developed. Tetrazine-bearing assembly precursors undergo oxidation and selectively self-assemble under pathological conditions inside primary neurons and mice brains. Assemblies induce local accumulation of tetrazine in the hippocampus CA3 region, which allows the subsequent bioorthogonal release of inhibitory neurotransmitters. For induced acute seizures, the sustained release of GABA extends the suppression than the direct supply of GABA. In the model of permanent damage of CA3, bioorthogonal ligation on assemblies provides a reservoir of GABA that behaves prompt release upon 365 nm irradiation. Incorporated with the state-of-the-art microelectrode arrays, it is elucidated that the bioorthogonal release of GABA shifts the neuron spike waveforms to suppress seizures at the single-neuron precision. The strategy of in situ supramolecular assemblies-directed bioorthogonal prodrug activation shall be promising for the effective delivery of ASMs to treat epilepsy.

HydrogelFinder: A Foundation Model for Efficient Self-Assembling Peptide Discovery Guided by Non-Peptidal Small Molecules

Self-assembling peptides have numerous applications in medicine, food chemistry, and nanotechnology. However, their discovery has traditionally been serendipitous rather than driven by rational design. Here, HydrogelFinder, a foundation model is developed for the rational design of self-assembling peptides from scratch. This model explores the self-assembly properties by molecular structure, leveraging 1,377 self-assembling non-peptidal small molecules to navigate chemical space and improve structural diversity. Utilizing HydrogelFinder, 111 peptide candidates are generated and synthesized 17 peptides, subsequently experimentally validating the self-assembly and biophysical characteristics of nine peptides ranging from 1-10 amino acids-all achieved within a 19-day workflow. Notably, the two de novo-designed self-assembling peptides demonstrated low cytotoxicity and biocompatibility, as confirmed by live/dead assays. This work highlights the capacity of HydrogelFinder to diversify the design of self-assembling peptides through non-peptidal small molecules, offering a powerful toolkit and paradigm for future peptide discovery endeavors.

Applications of self-assembled peptide hydrogels in anti-tumor therapy

Peptides are a class of active substances composed of a variety of amino acids with special physiological functions. The rational design of peptide sequences at the molecular level enables their folding into diverse secondary structures. This property has garnered significant attention in the biomedical sphere owing to their favorable biocompatibility, adaptable mechanical traits, and exceptional loading capabilities. Concurrently with advancements in modern medicine, the diagnosis and treatment of tumors have increasingly embraced targeted and personalized approaches. This review explores recent applications of self-assembled peptides derived from natural amino acids in chemical therapy, immunotherapy, and other adjunctive treatments. We highlighted the utilization of peptide hydrogels as delivery systems for chemotherapeutic drugs and other bioactive molecules and then discussed the challenges and prospects for their future application.