(Macro)molecular self-assembly for hydrogel drug delivery

Tailoring curcumin ternary complex nanocrystals via microfluidic mediated assembly: Stability, solubility, bioaccessibility and formation mechanism

Microfluidic technique was employed to precisely modulate both the microenvironment and composition, enabling the dynamic assembly of curcumin, soy protein isolates, and rhamnolipid into ternary nanocrystals through hydrogen bonding and hydrophobic interactions. As the concentration of rhamnolipid increased, the loading capacity of curcumin in ternary complex nanocrystals rose from 4.23 % to 10.82 %, while its water dispersibility and bioaccessibility enhanced by 141.94- to 664.67-fold and 5.11- to 6.49-fold, respectively. Moreover, the stability of curcumin in ternary complex nanocrystals was significantly enhanced during both storage and exposure to UV light. The longest half-life of curcumin in the nanocrystals increased from 65.39 days to 385.08 days during storage at 25 °C, and from 87.74 min to 198.04 min under UV light. These findings provide important insights for the development of bio-assemblies, and the resulting complex nanocrystals can be used as pigment or bioactivity in foods, cosmetics and pharmaceuticals.

Anti-neuroinflammatory agent rhein lysinate-based self-assembled injectable hydrogel loaded with ZL006 for promoting post-stroke functional recovery

The therapeutic agent-based self-assembled hydrogel is gaining interest for biomedical applications, because it overcomes the poor biodegradability and low therapeutic agent loading of conventional polymer gelator-based hydrogel. Here, we present rhein lysinate (RHL), a therapeutic agent that self-assembles to form a stable hydrogel through the π-π stacking and hydrogen bonding interactions, while also exerting anti-neuroinflammatory effect. As a small molecular hydrogelator, RHL has significantly improved water solubility and enhanced self-assembly and gelation capabilities compared to the natural anthraquinone rhein. The relaxed gel-forming conditions enhance the practical application potential of self-assembled hydrogel of RHL (RHL gel). The RHL gel can be loaded with the bioactive agents such as 5-Fluorouracil, temozolomide, edaravone, and ZL006, mainly based on efficient stacking between aromatic rings in the bioactive agents and anthraquinone rings in the hydrogel network structure. The pre-gelled RHL gel and ZL006-loaded RHL gel (ZL006-RHL gel) exhibit shear-thinning behavior, flowing like a liquid under high shear stress during injection. Once this shear stress is removal within the body, they rapidly recover to the initial solid-like state. When a single dose of ZL006-RHL gel is administrated to stroke cavity in the subacute phase of stroke, RHL gel matrix effectively reduces post-stroke neuroinflammation, creates a favorable environment for ZL006 to enhance neuroplasticity, and confers a sustained and stable action to ZL006, leading to a long-lasting improvement of motor performance. This study may provide a valuable strategy for therapeutic intervention to promote post-stroke functional recovery, for which there are no clinically available drugs.

Electrostatic Regulation of Bola-Amphiphilic Peptide Self-Assembly and Nanotube Formation Induced by Salt Ions

Peptide self-assembly into nanostructures offers substantial potential for applications in catalysis, drug delivery, and nanodevice fabrication. However, controlling the morphology of these assemblies remains a challenge. In this study, we investigate the role of salt ions in regulating the self-assembly of the bola-amphiphilic peptide KFFFFK, facilitating a transition from twisted fibrils to nanotubes. Using transmission electron microscopy, we show that the addition of NaCl induces the formation of nanotubes, and we detail the time-dependent assembly process. Increased salt concentrations reduce electrostatic repulsion, promoting the lateral merging of fibrils and supporting the formation of closed nanotubes. This phenomenon is also observed with several other salts. These findings underscore the critical role of electrostatic interactions in peptide self-assembly and highlight the importance of salt concentration in directing assembly pathways. Our results provide valuable insights into the mechanisms of peptide self-assembly and offer a versatile approach for designing advanced biomaterials and nanodevices based on well-defined peptide nanostructures.

Smart self-assembled peptide-based hydrogels: Mechanism, design and biomedical applications

Peptide hydrogels have gained widespread attention in biomedical engineering due to their unique ability to mimic the cellular microenvironment in vivo. Stimulus-responsive self-assembled (SAP) hydrogels can undergo conformational changes in response to changes in the external environment, prompting a sol-gel transition. Their inherent biodegradability, excellent surface activity and biocompatibility make them ideal candidates for a wide range of biomedical applications, and these SAP hydrogels can be widely used in the fields of tissue engineering, cell and drug delivery, wound healing and medical diagnostic imaging. In this paper, the basic properties, design principles, preparation methods and self-assembly mechanisms of different types of stimuli-responsive SAP hydrogels are reviewed. By designing and constructing stimulus-responsive SAP hydrogels, we can create materials that mimic natural physiological environments, thereby better simulating cell behavior and tissue repair. In addition, it highlights specific applications of these hydrogels in biomedical engineering, supported by examples from recent literature. The report summarizes the current state of research, highlights key challenges, and provides insights into future prospects to encourage continued innovation and exploration in this rapidly evolving field.

Tissue-Informed Biomaterial Innovations Advance Pulmonary Regenerative Engineering

Irreversible progressive pulmonary diseases drastically reduce the patient quality of life, while transplantation remains the only definitive cure. Research into lung regeneration pathways holds significant potential to expand and promote the discovery of new treatment options. Polymeric biomaterials designed to replicate key tissue characteristics (i.e., biochemical composition and mechanical cues) show promise for creating environments in which to study chronic lung diseases and initiate lung tissue regeneration. In this Viewpoint, we explore how naturally derived materials can be employed alone or combined with engineered polymer systems to create advanced tissue culture platforms. Pulmonary tissue models have historically leveraged natural materials, including basement membrane extracts and a decellularized extracellular matrix, as platforms for lung regeneration studies. Here, we provide an overview of the progression of pulmonary regenerative engineering, exploring how innovations in the growing field of tissue-informed biomaterials have the potential to advance lung regeneration research by bridging the gap between biological relevance and mechanical precision.

High-performance silk fibroin/hyaluronic acid interpenetrating network hydrogel microneedles for diabetes management

Hydrogel microneedles (MNs) gained more attentions for diabetes treatments owing to their biocompatibility and versatility. However, the inherent fragility and instability of hydrogels pose limitations on their efficacy in biomedical applications. To overcome this limitation, we developed interpenetrating network hydrogels (IPNs) by incorporating silk fibroin (SF) and methacrylated hyaluronic acid (HAMA). These hydrogels exhibit rapid formation, structural stability, mechanical robustness, and sustainability through photo-crosslinking without the need for crosslinking agents. The hydrogels demonstrated an average formation time of 86 ± 8 s and exhibited favorable elasticity, along with a high compressive stress at break of 70.9 ± 8.2 kPa. Additionally, the extensive proliferation and well-distributed network of human umbilical vein endothelial cells (hUVECs) on the microneedles' (MNs) surface underscored the high cytocompatibility and cell viability of the MNs. In a diabetic mouse model, the MNs were able to maintain normal blood glucose levels for approximately 6 h. The administration of insulin-loaded microneedles to diabetic mice resulted in glucose tolerance levels comparable to those of non-diabetic mice, indicating the efficacy of microneedle therapy in improving the glycemic condition of diabetic subjects. These hydrogel MNs possess a stable structure, can be rapidly fabricated, are sustainable, and hold significant potential for the clinical management of patients with diabetes mellitus.

Understanding the combinatorial impact of amino acids as bio-linker on rheological behavior of gellan hydrogel blends

Amino acids (AAs) can serve as essential bio-linkers due to their different functional groups, which may facilitate physical cross-linking in hydrogels. The mechanical properties of such hydrogels can be fine-tuned by varying the type and concentration of cross-linking agents. In this study, we developed novel gellan gum (GG) hydrogels by incorporating combinations of native AAs, including ʟ-Arginine, ʟ-Lysine, ʟ-Glutamic acid, and ʟ-Aspartic acid. These hydrogels exhibit thermo-reversible properties attributed to non-covalent interactions, enabling a gel-to-sol transition at temperatures above 37 °C owing to their upper critical solution temperature (UCST). Interestingly, these hydrogels were transparent, suggesting a uniform network structure. Moreover, they display a relatively low swelling capacity (10-25 %), indicating strong electrostatic interactions between AAs and GG. Rheological analyses highlight the significant role of AA combinations in modulating hydrogel behavior, showing improvements in shear-thinning, elasticity, self-healing, creep resistance, and overall mechanical performance. Mathematical modeling further supported these findings. Notably, mixtures containing ʟ-Aspartic acid and ʟ-Glutamic acid exhibited enhanced mechanical strength and stability, highlighting the importance of strategic cross-linker selection. These results demonstrate that tailoring cross-linkers can transform hydrogel properties, enabling the development of innovative materials for industrial applications.

Dual Drug Loaded Topical Cubosomal Gel Against Candida Albicans: An In Vitro and In Vivo Proof of Concept

Dual drug approaches are gaining research interest owing to the reduction of drug resistance and additive or synergistic effects in treating fungal infections caused by Candida albicans. The present study includes the combination of ketoconazole (KTC) and eugenol (EGN) co-embedded cubosomes (KTC-EGN-CBs) for the effective treatment of candidiasis.The bio-membrane-typical framework of the cubic phase in CBs can help retain both drugs leading to enhancement of antifungal activity. KTC-EGN-CBs were developed by high-speed homogenization, followed by the probe sonication. The optimized KTC-EGN-CBs depicted lower particle size (138.8 ± 1.03 nm) and PdI (0.260 ± 0.006) with a high entrapment efficiency of KTC (79.73 ± 1.21%) and EGN (90.92 ± 2.53%). Further, KTC-EGN-CBs were loaded into the hydrogel system for ease of topical application. The ex vivo diffusion study depicted the CBs helping the KTC and EGN to exhibit significantly higher permeation and retention owing to the resemblance in cubic structure with the skin. Additionally, the in vitro antifungal study of KTC-EGN-CBs resulted in a higher zone of inhibition when compared to the plain drugs against Candida albicans. Furthermore, the effectiveness of cubosomal formulation was observed in the inhibition of planktonic growth, yeast to hyphal formation, biofilm formation, and ROS production. The antifungal activity of KTC-EGN-CBs was found to be more prominent in the infected silkworm model than the plain KTC-EGN. The cell cytotoxicity study on human keratinocyte cells and the irritation study on the hen's egg test-chorioallantoic membrane assay revealed the non-cytotoxic and non-irritant nature of the prepared cubosomes. In a nutshell, these findings demonstrated CBs as a promising carrier for KTC and EGN to effectively treat candidiasis.

Recent advances in poly(amino acids), polypeptides, and their derivatives in drug delivery

Poly(amino acids), polypeptides, and their derivatives have demonstrated significant potential as biodegradable biomaterials in the field of drug delivery. As degradable drug carriers, they can effectively load or conjugate drug molecules including small molecule drugs, nucleic acids, peptides, and protein-based drugs, enhancing the stability and targeting of the drugs in vivo. This strategy ultimately facilitates precise drug delivery and controlled release, thereby improving therapeutic efficacy and reducing side effects within the body. This review systematically describes the structural characteristics and preparation methods of poly(amino acids) and polypeptides, summarizes the advantages of poly(amino acids), polypeptides, and their derivatives in drug delivery, and detailedly introduces the latest advancements in this area. The review also discusses current challenges and opportunities associated with poly(amino acids), peptides, and their derivatives, and offers insights into the future directions for these biodegradable materials. This review aims to provide valuable references for scientific research and clinical translation of biodegradable biomaterials based on poly(amino acids) and peptides.

Hydrogels and Nanogels: Pioneering the Future of Advanced Drug Delivery Systems

Conventional drug delivery approaches, including tablets and capsules, often suffer from reduced therapeutic effectiveness, largely attributed to inadequate bioavailability and difficulties in ensuring patient adherence. These challenges have driven the development of advanced drug delivery systems (DDS), with hydrogels and especially nanogels emerging as promising materials to overcome these limitations. Hydrogels, with their biocompatibility, high water content, and stimuli-responsive properties, provide controlled and targeted drug release. This review explores the evolution, properties, and classifications of hydrogels versus nanogels and their applications in drug delivery, detailing synthesis methods, including chemical crosslinking, physical self-assembly, and advanced techniques such as microfluidics and 3D printing. It also examines drug-loading mechanisms (e.g., physical encapsulation and electrostatic interactions) and release strategies (e.g., diffusion, stimuli-responsive, and enzyme-triggered). These gels demonstrate significant advantages in addressing the limitations of traditional DDS, offering improved drug stability, sustained release, and high specificity. Their adaptability extends to various routes of administration, including topical, oral, and injectable forms, while emerging nanogels further enhance therapeutic targeting through nanoscale precision and stimuli responsiveness. Although hydrogels and nanogels have transformative potential in personalized medicine, challenges remain in scalable manufacturing, regulatory approval, and targeted delivery. Future strategies include integrating biosensors for real-time monitoring, developing dual-stimuli-responsive systems, and optimizing surface functionalization for specificity. These advancements aim to establish hydrogels and nanogels as cornerstones of next-generation therapeutic solutions, revolutionizing drug delivery, and paving the way for innovative, patient-centered treatments.

Amphiphilic Gelator-Based Shear-Thinning Hydrogel for Minimally Invasive Delivery via Endoscopy Catheter to Remove Gastrointestinal Polyps

Injectable polymeric hydrogels delivered via endoscopic catheter have emerged as promising submucosal agents, offering durable, long-lasting cushions to enhance the efficacy of endoscopic submucosal dissection (ESD) for the removal of small, flat polyps from the gastrointestinal tract (GIT). However, polymer-based injections do not meet the easy-injectability criteria via catheter because their high viscosity tends to clog the catheter needle. To the best of knowledge, for the first time, report the fabrication of an amphiphile-based small molecule hydrogel of diglycerol monostearate (DGMS) that self-assembles to form hydrogel (DGMSH) for delivery via an endoscopic catheter. Physicochemical characterization of the hydrogel reveals its fibrous morphology, shear-thinning behaviour, and easy injectability, along with its scalability and long shelf-life (6 months). Ex vivo studies on the goat's stomach and intestine demonstrate the ease of injectability through the catheters and the development of visible submucosal cushion depots with the desired height. Moreover, the hydrogel can encapsulate both hydrophobic and hydrophilic drugs/dyes. In vivo studies in small animals have found that the hydrogel depot is durable, biocompatible, non-immunogenic, and has a hemostatic effect. Endoscopic studies in the porcine model demonstrate a safe injection and endoscopic excision of GI polyps acting as a suitable agent for ESD.

The versatility of peptide hydrogels: From self-assembly to drug delivery applications

Pharmaceuticals often suffer from limitations such as low solubility, low stability, and  short half-life. To address these challenges and reduce the need for frequent drug administrations, a more efficient delivery is required. In this context, the development of controlled drug delivery systems, acting as a protective depot for the drug, has expanded significantly over the last decades. Among these, injectable hydrogels have emerged as a promising platform, especially in view of the rise of biologicals as therapeutics. Hydrogels are functional, solid-like biomaterials, composed of cross-linked hydrophilic polymers and high water content. Their physical properties, which closely mimic the extracellular matrix, make them suitable for various biomedical applications. This review discusses the different types of hydrogel systems and their self-assembly process, with an emphasis on peptide-based hydrogels. Due to their structural and functional diversity, biocompatibility, synthetic accessibility, and tunability, peptides are regarded as promising and versatile building blocks. A comprehensive overview of the variety of peptide hydrogels is outlined, with β-sheet forming sequences being highlighted. Key factors to consider when using peptide hydrogels as a controlled drug delivery system are reviewed, along with a discussion of the main drug release mechanisms and the emerging trend towards affinity-based systems to further refine drug release profiles.

Supramolecular Peptide Depots for Glucose-Responsive Glucagon Delivery

Precise blood glucose control continues to be a critical challenge in the treatment and management of type 1 diabetes in order to mitigate both acute and chronic complications. This study investigates the development of a supramolecular peptide amphiphile (PA) material functionalized with phenylboronic acid (PBA) for glucose-responsive glucagon delivery. The PA-PBA system self-assembles into nanofibrillar hydrogels in the presence of physiological glucose levels, resulting in stable hydrogels capable of releasing glucagon under hypoglycemic conditions. Glucose responsiveness is driven by reversible binding between PBA and glucose, which modulates the electrostatic interactions necessary for hydrogel formation and dissolution. Through comprehensive in vitro characterization, including circular dichroism, zeta potential measurements, and rheological assessments, the PA-PBA system is found to exhibit glucose-dependent assembly, enabling controlled glucagon release that is inversely related to glucose concentration. Glucagon release is accelerated under low glucose conditions, simulating a hypoglycemic state, with a reduced rate seen at higher glucose levels. Evaluation of the platform in vivo using a type 1 diabetic mouse model demonstrates the efficacy in protecting against insulin-induced hypoglycemia by restoring blood glucose levels following an insulin overdose. The ability to tailor glucagon release in response to fluctuating glucose concentrations underscores the potential of this platform for improving glycemic control. These findings suggest that glucose-stabilized supramolecular peptide hydrogels hold significant promise for responsive drug delivery applications, offering an approach to manage glucose levels in diabetes and other metabolic disorders.

Design and Characterization of Novel Polymeric Hydrogels with Protein Carriers for Biomedical Use

Hydrogels are three-dimensional polymeric matrices capable of absorbing significant amounts of water or biological fluids, making them promising candidates for biomedical applications such as drug delivery and wound healing. In this study, novel hydrogels were synthesized using a photopolymerization method and modified with cisplatin-loaded protein carriers, as well as natural extracts of nettle (Urtica dioica) and chamomile (Matricaria chamomilla L.). The basic components of the hydrogel were polyvinylpyrrolidone and polyvinyl alcohol, while polyethylene glycol diacrylate was used as a crosslinking agent and 2-methyl-2-hydroxypropiophenone as a photoinitiator. The hydrogels demonstrated high swelling capacities, with values up to 4.5 g/g in distilled water, and lower absorption in Ringer's solution and simulated body fluid (SBF), influenced by ionic interactions. Wettability measurements indicated water contact angles between 51° and 59°, suggesting balanced hydrophilic properties conducive to biomedical applications. Surface roughness analyses revealed that roughness values decreased after incubation, with Ra values ranging from 6.73 µm before incubation to 5.94 µm after incubation for samples with the highest protein content. Incubation studies confirmed the stability of the hydrogel matrix, with no significant structural degradation observed over 20 days. However, hydrogels containing 2.0 mL of protein suspension exhibited structural damage and were excluded from further testing. The synthesized hydrogels show potential for application as carriers in localized drug delivery systems, offering a platform for future development in areas such as targeted therapy for skin cancer or other localized treatments.

Recent advances in carrier-free natural small molecule self-assembly for drug delivery

Natural small-molecule drugs have been used for thousands of years for the prevention and treatment of human diseases. Most of the natural products available on the market have been modified into various polymer materials for improving the solubility, stability, and targeted delivery of drugs. However, these nanomedicines formed based on polymer carriers would produce severe problems such as systemic toxicity and kidney metabolic stress. In contrast, the carrier-free nanomedicines formed by their self-assembly in water have inherent advantages such as low toxicity, good biocompatibility, and biodegradability. This review summarizes the assembly process and application of natural small-molecule products, which are mainly driven by multiple non-covalent interactions, and includes single-molecule assembly, bimolecular assembly, drug-modified assembly, and organogels. Meanwhile, the molecular mechanism involved in different self-assembly processes is also discussed. Self-assembly simulation and structural modification of natural small-molecule products or traditional Chinese medicine molecules using molecular dynamics simulation and computer-assisted methods are proposed, which will lead to the discovery of more carrier-free nanomedicine drug delivery systems. Overall, this review provides an important understanding and strategy to study single-molecule and multi-molecule carrier-free nanomedicines.

Nanogel-Carbon Dot Conjugates: A Synergistic Approach for Enhanced Cancer Treatment through Combination Therapy

The present study reports the development of a novel nanoconjugate, NG-FACD, comprising a positively charged self-assembled nanogel (NG) derived from a peptide amphiphilic hydrogelator and a negatively charged folic acid-functionalized blue-emitting carbon dot (FACD), bound via electrostatic interactions. NG-FACD was developed to combine the advantages of the individual nanocarriers and overcome their drawbacks. The presence of folic acid enables NG-FACD to be successfully used in selective bioimaging and targeted combination therapy against folate receptor-positive (FR+) B16F10 over FR- cells. NG-FACD demonstrated improved riboflavin (RbF) and paclitaxel (PTX) loading compared to individual nanocarriers that made it ∼1.8- and 1.5-fold more cytotoxic toward FR+ B16F10 cells over RbF- and PTX-loaded individual nanocarriers. The concurrent presence of RbF and PTX on NG-FACD displayed ∼1.9-2.8-fold higher cytotoxicity than single drug-loaded individual nanocarriers and ∼3-4.5-fold higher cytotoxicity through RbF-mediated photodynamic therapy and PTX-induced chemotherapy in synergy compared to free drugs against FR+ B16F10 cells.

Self-healing and injectable chitosan/konjac glucomannan hydrogel with pH response for controlled protein release

Dynamic hydrogels with the features of injection, self-healing, and remodeling at the target site have been developed as smart multifunctional biomaterials for drug delivery. However, most self-healing injectable hydrogels are difficult to control protein release after implantation, owing to the deficiency of pH responsiveness, which reduces the bioavailability of proteins. Herein, we propose a facile strategy to endow pH responsiveness into a dynamic hydrogel with both self-healing and injectable capabilities, by crosslinking biomacromolecular backbones via dual pH sensitive dynamic covalent bond. Particularly, oxidized konjac glucomannan (OKGM) can be crosslinked with poly (aspartic hydrazide) (PAHy) and N-carboxyethyl chitosan (CEC) to form dynamic acylhydrazone bonds and imide bonds, respectively, endowing the hydrogel with pH responsiveness and dynamic behaviors. Specifically, PAHy facilitates the formation of acylhydrazone bonds, improving the mechanical properties and pH sensitivity while reducing the degradation behavior of the hydrogels under physiological conditions. Kinetics indicate that the release of bovine serum albumin follows Fick diffusion under different pH conditions. The pH responsive hydrogel with self-healing injectable capabilities has the potential to be used as a controllable and sustain release carrier for protein drugs.

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.

Injectable polyamide-amine dendrimer-crosslinked meloxicam-containing poly-γ-glutamic acid hydrogel for prevention of postoperative tissue adhesion through inhibiting inflammatory responses and balancing the fibrinolytic system

Establishing a physical barrier between the peritoneum and the cecum is an effective method to reduce the risk of postoperative abdominal adhesions. Meloxicam (MX), a nonsteroidal anti-inflammatory drug has also been applied to prevent postoperative adhesions. However, its poor water solubility has led to low bioavailability. Herein, we developed an injectable hydrogel as a barrier and drug carrier for simultaneous postoperative adhesion prevention and treatment. A third-generation polyamide-amine dendrimer (G3) was exploited to dynamically combine with MX to increase the solubility and the bioavailability. The formed G3@MX was further used to crosslink with poly-γ-glutamic acid (γ-PGA) to prepare a hydrogel (GP@MX hydrogel) through the amide bonding. In vitro and in vivo experiments evidenced that the hydrogel had good biosafety and biodegradability. More importantly, the prepared hydrogel could control the release of MX, and the released MX is able to inhibit inflammatory responses and balance the fibrinolytic system in the injury tissues in vivo. The tunable rheological and mechanical properties (compressive moduli: from ∼ 57.31 kPa to ∼ 98.68 kPa;) and high anti-oxidant capacity (total free radical scavenging rate of ∼ 94.56 %), in conjunction with their syringeability and biocompatibility, indicate possible opportunities for the development of advanced hydrogels for postoperative tissue adhesions management.

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.

Propelling Minimally Invasive Tissue Regeneration With Next-Era Injectable Pre-Formed Scaffolds

The growing aging population, with its associated chronic diseases, underscores the urgency for effective tissue regeneration strategies. Biomaterials play a pivotal role in the realm of tissue reconstruction and regeneration, with a distinct shift toward minimally invasive (MI) treatments. This transition, fueled by engineered biomaterials, steers away from invasive surgical procedures to embrace approaches offering reduced trauma, accelerated recovery, and cost-effectiveness. In the realm of MI tissue repair and cargo delivery, various techniques are explored. While in situ polymerization is prominent, it is not without its challenges. This narrative review explores diverse biomaterials, fabrication methods, and biofunctionalization for injectable pre-formed scaffolds, focusing on their unique advantages. The injectable pre-formed scaffolds, exhibiting compressibility, controlled injection, and maintained mechanical integrity, emerge as promising alternative solutions to in situ polymerization challenges. The conclusion of this review emphasizes the importance of interdisciplinary design facilitated by synergizing fields of materials science, advanced 3D biomanufacturing, mechanobiological studies, and innovative approaches for effective MI tissue regeneration.

Iterative Design Reveals Molecular Domain Relationships in Supramolecular Peptide-Drug Conjugates

Supramolecular peptide-drug conjugates (sPDCs) are prepared by covalent attachment of a drug moiety to a peptide motif programmed for one-dimensional self-assembly, with subsequent physical entanglement of these fibrillar structures enabling formation of nanofibrous hydrogels. This class of prodrug materials presents an attractive platform for mass-efficient and site-specific delivery of therapeutic agents using a discrete, single-component molecular design. However, a continued challenge in sPDC development is elucidating relationships between supramolecular interactions in their drug and peptide domains and the resultant impacts of these domains on assembly outcomes and material properties. Inclusion of a saturated alkyl segment alongside the prodrug in the hydrophobic domain of sPDCs could relieve some of the necessity for ordered, prodrug-produg interactions. Accordingly, nine sPDCs are prepared here to iterate the design variables of amino acid sequence and hydrophobic prodrug-alkyl block design. All molecules spontaneously formed hydrogels under physiological conditions, indicating a less hindered thermodynamic path to self-assembly relative to previous prodrug-only designs. However, material studies on the supramolecular arrangement, formation, and mechanical properties of the resultant sPDC hydrogels as well as their drug release profiles showed complex relationships between the hydrophobic and peptide domains in the formation and function of the resulting assemblies. Together, these results indicate that sPDC material properties are intrinsically linked to holistic molecular design with coupled contributions from their prodrug and peptide domains in directing properties of the emergent materials.

Unveiling the Impact of Gelation Temperature on the Rheological and Microstructural Properties of Type A Gelatin Hydrogels

Gelatin-based hydrogels have garnered significant attention in the fields of drug delivery systems and tissue engineering owing to their biodegradability, biocompatibility, elasticity, flexibility and nontoxic nature. However, there is a lack of information regarding type-A-gelatin-based hydrogels. In this sense, the main aim of this work was the evaluation of the properties of type-A-gelatin-based hydrogel achieved using two different gelation temperatures (4 °C and 20 °C). Thus, the main novelty of this study lies in the analysis of the impact of gelation time on the rheological and microstructural properties of type-A-gelatin-based hydrogels. Moreover, the addition of a drug was also analyzed in order to evaluate the hydrogels' behavior as a drug delivery system. For this purpose, rheological (strain, frequency sweep tests and flow curves) and microstructural (SEM) characterizations were carried out. The results demonstrated that lowering the gelation temperature improved the rheological properties of the systems, obtaining hydrogels with an elastic modulus of 20 kPa when processing at 4 °C. On the other hand, the increase in the gelation temperature improved the critical strain of the systems at low temperatures. In conclusion, this work showed the feasibility of producing hydrogels with potential application in drug delivery with different properties, varying the testing temperature and incorporating tetracycline into their formulation.

Continuous and Controllable Preparation of Sodium Alginate Hydrogel Tubes Guided by the Soft Cap Inspired by the Apical Growth of the Plant

Hydrogel tubes made of sodium alginate (SA) have potential applications in drug delivery, soft robots, biomimetic blood vessels, tissue stents, and other fields. However, the continuous preparation of hollow SA hydrogel tubes with good stability and size control remains a huge challenge for chemists, material scientists, and medical practitioners. Inspired by the plant apical growth strategy, a new method named soft cap-guided growth was proposed to produce SA hydrogel tubes. Due to the introduction of inert low gravity substances, such as air and heptane, into the extrusion needle in front of calcium chloride solution to form a soft cap, the SA hydrogel tubes with controllable sizes were fabricated rapidly and continuously without using a template through a negative gravitropism mechanism. The SA hydrogel tubes had good tensile strength, high burst pressure, and good cell compatibility. In addition, hydrogel tubes with complex patterns were conveniently created by controlling the motion path of a soft cap, such as a rotating SA bath or magnetic force. Our research provided a simple innovative technique to steer the growth of hydrogel tubes, which made it possible to mass produce hydrogel tubes with controllable sizes and programmable patterns.

ROS-responsive thermosensitive polypeptide hydrogels for localized drug delivery and improved tumor chemoimmunotherapy

In this study, we developed a ROS-responsive thermosensitive poly(ethylene glycol)-polypeptide hydrogel loaded with a chemotherapeutic drug, doxorubicin (Dox), an antiviral imidazoquinoline, resiquimod (R848), and antibody targeting programmed cell death protein 1 (aPD-1) for local chemoimmunotherapy. The hydrogel demonstrated controllable degradation and sustained drug release behavior according to the concentration of ROS in vitro. Following intratumoral injection into mice bearing B16F10 melanoma, the Dox/R848/aPD-1 co-loaded hydrogel effectively inhibited tumor growth, prolonged animal survival time and promoted anti-tumor immune responses with low systemic toxicity. In the postoperative model, the Dox/R848/aPD-1 co-loaded hydrogel exhibited enhanced tumor recurrence prevention and long-term immune memory effects. Thus, the hydrogel-based local chemoimmunotherapy system demonstrates potential for effective anti-tumor treatment and suppression of tumor recurrence.

Understanding the Role of Filamentous Actin in Food Quality: From Structure to Application

Actin, a multifunctional protein highly expressed in eukaryotes, is widely distributed throughout cells and serves as a crucial component of the cytoskeleton. Its presence is integral to maintaining cell morphology and participating in various biological processes. As an irreplaceable component of myofibrillar proteins, actin, including G-actin and F-actin, is highly related to food quality. Up to now, purification of actin at a moderate level remains to be overcome. In this paper, we have reviewed the structures and functions of actin, the methods to obtain actin, and the relationships between actin and food texture, color, and flavor. Moreover, actin finds applications in diverse fields such as food safety, bioengineering, and nanomaterials. Developing an actin preparation method at the industrial level will help promote its further applications in food science, nutrition, and safety.

Application of pulsed electric field technology to skin engineering

Tissue engineering encompasses a range of techniques that direct the growth of cells into a living tissue construct for regenerative medicine applications, disease models, drug discovery, and safety testing. These techniques have been implemented to alleviate the clinical burdens of impaired healing of skin, bone, and other tissues. Construct development requires the integration of tissue-specific cells and/or an extracellular matrix-mimicking biomaterial for structural support. Production of such constructs is generally expensive and environmentally costly, thus eco-sustainable approaches should be explored. Pulsed electric field (PEF) technology is a nonthermal physical processing method commonly used in food production and biomedical applications. In this review, the key principles of PEF and the application of PEF technology for skin engineering will be discussed, with an emphasis on how PEF can be applied to skin cells to modify their behaviour, and to biomaterials to assist in their isolation or sterilisation, or to modify their physical properties. The findings indicate that the success of PEF in tissue engineering will be reliant on systematic evaluation of key parameters, such as electric field strength, and their impact on different skin cell and biomaterial types. Linking tangible input parameters to biological responses critical to healing will assist with the development of PEF as a sustainable tool for skin repair and other tissue engineering applications.

Polyethylene glycol hydrogel coatings for protection of electroactive bacteria against chemical shocks

Loss of bioelectrochemical activity in low resource environments or from chemical toxin exposure is a significant limitation in microbial electrochemical cells (MxCs), necessitating the development of materials that can stabilize and protect electroactive biofilms. Here, polyethylene glycol (PEG) hydrogels were designed as protective coatings over anodic biofilms, and the effect of the hydrogel coatings on biofilm viability under oligotrophic conditions and ammonia-N (NH4+-N) shocks was investigated. Hydrogel deposition occurred through polymerization of PEG divinyl sulfone and PEG tetrathiol precursor molecules, generating crosslinked PEG coatings with long-term hydrolytic stability between pH values of 3 and 10. Simultaneous monitoring of coated and uncoated electrodes co-located within the same MxC anode chamber confirmed that the hydrogel did not compromise biofilm viability, while the coated anode sustained nearly a 4 × higher current density (0.44 A/m2) compared to the uncoated anode (0.12 A/m2) under oligotrophic conditions. Chemical interactions between NH4+-N and PEG hydrogels revealed that the hydrogels provided a diffusive barrier to NH4+-N transport. This enabled PEG-coated biofilms to generate higher current densities during NH4+-N shocks and faster recovery afterwards. These results indicate that PEG-based coatings can expand the non-ideal chemical environments that electroactive biofilms can reliably operate in.

Injectable and Self-Curing Single-Component Hydrogel for Stem Cell Encapsulation and In Vivo Bone Regeneration

An ideal hydrogel for stem cell therapy would be injectable and efficiently promote stem cell proliferation and differentiation in body. Herein, an injectable, single-component hydrogel with hyaluronic acid (HA) modified with phenylboronic acid (PBA) and spermidine (SM) is introduced. The resulting HAps (HA-PBA-SM) hydrogel is based on the reversible crosslinking between the diol and the ionized PBA, which is stabilized by the SM. It has a shear-thinning property, enabling its injection through a syringe to form a stable hydrogel inside the body. In addition, HAps hydrogel undergoes a post-injection "self-curing," which stiffens the hydrogel over time. This property allows the HAps hydrogel to meet the physical requirements for stem cell therapy in rigid tissues, such as bone, while maintaining injectability. The hydrogel enabled favorable proliferation of human mesenchymal stem cells (hMSCs) and promoted their differentiation and mineralization. After the injection of hMSCs-containing HAps into a rat femoral defect model, efficient osteogenic differentiation of hMSCs and bone regeneration is observed. The study demonstrates that simple cationic modification of PBA-based hydrogel enabled efficient gelation with shear-thinning and self-curing properties, and it would be highly useful for stem cell therapy and in vivo bone regeneration.

Thermosensitive hydrogel with programmed dual-octenidine release combating biofilm for the treatment of apical periodontitis

The utilization of intracanal medicaments is an indispensable procedure in root-canal treatment. However, the conventional intracanal medicaments still need improvement regarding antimicrobial efficacy and ease of clinical operation. To address the above issues, OCT/PECT@OCT + ALK composite hydrogel characterized by programming sequential release of dual antimicrobial agents has been proposed. Thanks to the self-assemble ability of amphiphilic copolymer poly(ε-caprolactone-co-1,4,8-trioxa [4.6]spiro-9-undecanone)-poly(ethylene glycol)-poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone) (PECT), dual hydrophilic and hydrophobic antimicrobial agents could be easily encapsulated in the hydrogel system and tailored for sequential drug release for a better antibiofilm effect. The hydrophilic octenidine (Octenidine dihydrochloride, OCT-HCl) is encapsulated in the hydrophilic part of hydrogel for instantaneous elevating the drug concentration through bursting release, and the hydrophobic octenidine (Octenidine, OCT) is further loaded into the PECT nanoparticles to achieve a slower and sustained-release profile. Additionally, calcium hydroxide (Ca(OH)2) was incorporated into the system and evenly dispersed among PECT nanoparticles to create an alkaline (ALK) environment, synergistically enhancing the antibiofilm effect with higher efficiency and prolonged duration. The antibiofilm effect has been demonstrated in root-canal models and apical periodontitis rats, exhibiting superior performance compared to clinically used Ca(OH)2 paste. This study demonstrates that OCT/PECT@OCT + ALK composite thermosensitive hydrogel is a potential intracanal medicament with excellent antibiofilm effect and clinical operability.

Glucose-Driven Droplet Formation in Complexes of a Supramolecular Peptide and Therapeutic Protein

Biology achieves remarkable function through processes arising from spontaneous or transient liquid-liquid phase separation (LLPS) of proteins and other biomolecules. While polymeric systems can achieve similar phenomena through simple or complex coacervation, LLPS with supramolecular materials has been less commonly shown. Functional applications for synthetic LLPS systems are an expanding area of emphasis, with particular focus on capturing the transient and dynamic state of these structures for use in biomedicine. Here, a net-cationic supramolecular peptide amphiphile building block with a glucose-binding motif is shown that forms LLPS structures when combined with a net-negatively charged therapeutic protein, dasiglucagon, in the presence of glucose. The droplets that arise are dynamic and coalesce quickly. However, the interface can be stabilized by addition of a 4-arm star PEG. When the stabilized droplets formed in glucose are transferred to a bulk phase containing different glucose concentrations, their stability and lifetime decrease according to bulk glucose concentration. This glucose-dependent formation translates into an accelerated release of dasiglucagon in the absence of glucose; this hormone analogue itself functions therapeutically to correct low blood glucose (hypoglycemia). These droplets also offer function in mitigating the most severe effects of hypoglycemia arising from an insulin overdose through delivery of dasiglucagon in a mouse model of hypoglycemic rescue. Accordingly, this approach to use complexation between a supramolecular peptide amphiphile and a therapeutic protein in the presence of glucose leads to droplets with functional potential to dissipate for the release of the therapeutic material in low blood glucose environments.

Emerging trends in the application of hydrogel-based biomaterials for enhanced wound healing: A literature review

Currently, there is a rising global incidence of diverse acute and chronic wounds, underscoring the immediate necessity for research and treatment advancements in wound repair. Hydrogels have emerged as promising materials for wound healing due to their unique physical and chemical properties. This review explores the classification and characteristics of hydrogel dressings, innovative preparation strategies, and advancements in delivering and releasing bioactive substances. Furthermore, it delves into the functional applications of hydrogels in wound healing, encompassing areas such as infection prevention, rapid hemostasis and adhesion adaptation, inflammation control and immune regulation, granulation tissue formation, re-epithelialization, and scar prevention and treatment. The mechanisms of action of various functional hydrogels are also discussed. Finally, this article also addresses the current limitations of hydrogels and provides insights into their potential future applications and upcoming innovative designs.

Stimuli-responsive peptide hydrogels for biomedical applications

Stimuli-responsive hydrogels can respond to external stimuli with a change in the network structure and thus have potential application in drug release, intelligent sensing, and scaffold construction. Peptides possess robust supramolecular self-assembly ability, enabling spontaneous formation of nanostructures through supramolecular interactions and subsequently hydrogels. Therefore, peptide-based stimuli-responsive hydrogels have been widely explored as smart soft materials for biomedical applications in the last decade. Herein, we present a review article on design strategies and research progress of peptide hydrogels as stimuli-responsive materials in the field of biomedicine. The latest design and development of peptide hydrogels with responsive behaviors to stimuli are first presented. The following part provides a systematic overview of the functions and applications of stimuli-responsive peptide hydrogels in tissue engineering, drug delivery, wound healing, antimicrobial treatment, 3D cell culture, biosensors, etc. Finally, the remaining challenges and future prospects of stimuli-responsive peptide hydrogels are proposed. It is believed that this review will contribute to the rational design and development of stimuli-responsive peptide hydrogels toward biomedical applications.

Self-Assembly of a Novel Pentapeptide into Hydrogelated Dendritic Architecture: Synthesis, Properties, Molecular Docking and Prospective Applications

Currently, ultrashort oligopeptides consisting of fewer than eight amino acids represent a cutting-edge frontier in materials science, particularly in the realm of hydrogel formation. By employing solid-phase synthesis with the Fmoc/tBu approach, a novel pentapeptide, FEYNF-NH2, was designed, inspired by a previously studied sequence chosen from hen egg-white lysozyme (FESNF-NH2). Qualitative peptide analysis was based on reverse-phase high performance liquid chromatography (RP-HPLC), while further purification was accomplished using solid-phase extraction (SPE). Exact molecular ion confirmation was achieved by matrix-assisted laser desorption-ionization mass spectrometry (MALDI-ToF MS) using two different matrices (HCCA and DHB). Additionally, the molecular ion of interest was subjected to tandem mass spectrometry (MS/MS) employing collision-induced dissociation (CID) to confirm the synthesized peptide structure. A combination of research techniques, including Fourier-transform infrared spectroscopy (FTIR), fluorescence analysis, transmission electron microscopy, polarized light microscopy, and Congo red staining assay, were carefully employed to glean valuable insights into the self-assembly phenomena and gelation process of the modified FEYNF-NH2 peptide. Furthermore, molecular docking simulations were conducted to deepen our understanding of the mechanisms underlying the pentapeptide's supramolecular assembly formation and intermolecular interactions. Our study provides potential insights into amyloid research and proposes a novel peptide for advancements in materials science. In this regard, in silico studies were performed to explore the FEYNF peptide's ability to form polyplexes.

Stimuli-responsive polysaccharide-based smart hydrogels for diabetic wound healing: Design aspects, preparation methods and regulatory perspectives

Diabetes adversely affects wound-healing responses, leading to the development of chronic infected wounds. Such wound microenvironment is characterized by hyperglycaemia, hyperinflammation, hypoxia, variable pH, upregulation of matrix metalloproteinases, oxidative stress, and bacterial colonization. These pathological conditions pose challenges for the effective wound healing. Therefore, there is a paradigm shift in diabetic wound care management wherein abnormal pathological conditions of the wound microenvironment is used as a trigger for controlling the drug release or to improve properties of wound dressings. Hydrogels composed of natural polysaccharides showed tremendous potential as wound dressings as well as stimuli-responsive materials due to their unique properties such as biocompatibility, biodegradability, hydrophilicity, porosity, stimuli-responsiveness etc. Hence, polysaccharide-based hydrogels have emerged as advanced healthcare materials for diabetic wounds. In this review, we presented important aspects for the design of hydrogel-based wound dressings with an emphasis on biocompatibility, biodegradability, entrapment of therapeutic agents, moisturizing ability, swelling, and mechanical properties. Further, various crosslinking methods that enable desirable properties and stimuli responsiveness to the hydrogels have been mentioned. Subsequently, state-of-the-art developments in mono- and multi- stimuli-responsive hydrogels have been presented along with the case studies. Finally regulatory perspectives, challenges for the clinical translation and future prospects have been discussed.

Supramolecular hydrogels for wound repair and hemostasis

The unique network characteristics and stimuli responsiveness of supramolecular hydrogels have rendered them highly advantageous in the field of wound dressings, showcasing unprecedented potential. However, there are few reports on a comprehensive review of supramolecular hydrogel dressings for wound repair and hemostasis. This review first introduces the major cross-linking methods for supramolecular hydrogels, which includes hydrogen bonding, electrostatic interactions, hydrophobic interactions, host-guest interactions, metal ligand coordination and some other interactions. Then, we review the advanced materials reported in recent years and then summarize the basic principles of each cross-linking method. Next, we classify the network structures of supramolecular hydrogels before outlining their forming process and propose their potential future directions. Furthermore, we also discuss the raw materials, structural design principles, and material characteristics used to achieve the advanced functions of supramolecular hydrogels, such as antibacterial function, tissue adhesion, substance delivery, anti-inflammatory and antioxidant functions, cell behavior regulation, angiogenesis promotion, hemostasis and other innovative functions in recent years. Finally, the existing problems as well as future development directions of the cross-linking strategy, network design, and functions in wound repair and hemostasis of supramolecular hydrogels are discussed. This review is proposed to stimulate further exploration of supramolecular hydrogels on wound repair and hemostasis by researchers in the future.

Fundamental properties of smart hydrogels for tissue engineering applications: A review

Tissue engineering is an advanced and potential biomedical approach to treat patients suffering from lost or failed an organ or tissue to repair and regenerate damaged tissues that increase life expectancy. The biopolymers have been used to fabricate smart hydrogels to repair damaged tissue as they imitate the extracellular matrix (ECM) with intricate structural and functional characteristics. These hydrogels offer desired and controllable qualities, such as tunable mechanical stiffness and strength, inherent adaptability and biocompatibility, swellability, and biodegradability, all crucial for tissue engineering. Smart hydrogels provide a superior cellular environment for tissue engineering, enabling the generation of cutting-edge synthetic tissues due to their special qualities, such as stimuli sensitivity and reactivity. Numerous review articles have presented the exceptional potential of hydrogels for various biomedical applications, including drug delivery, regenerative medicine, and tissue engineering. Still, it is essential to write a comprehensive review article on smart hydrogels that successfully addresses the essential challenging issues in tissue engineering. Hence, the recent development on smart hydrogel for state-of-the-art tissue engineering conferred progress, highlighting significant challenges and future perspectives. This review discusses recent advances in smart hydrogels fabricated from biological macromolecules and their use for advanced tissue engineering. It also provides critical insight, emphasizing future research directions and progress in tissue engineering.

Cypate-loaded hollow mesoporous Prussian blue nanoparticle/hydrogel system for efficient photodynamic therapy/photothermal therapy dual-modal antibacterial therapy

Infectious diseases caused by pathogenic microorganisms are a significant burden on public health and the economic stability of societies all over the world. The appearance of drug-resistant bacteria has severely blocked the effectiveness of conventional antibiotics. Therefore, developing novel antibiotic-free strategies to combat bacteria holds huge potential for maximizing validity and minimizing the risk of enhancing bacterial resistance. Herein, a cypate-loaded hollow mesoporous Prussian blue nanoparticles (Cy-HMPBs) was built to achieve the PDT/PTT synergistic antimicrobial therapy. The carbomer hydrogel (CH) was combined with the Cy-HMPBs to form a nanoparticle/hydrogel therapeutic system (Cy-HMPBs/CH) to reach the goal of local delivery of antimicrobial cargo. The low concentration of Cy-HMPBs/CH receives over 99% of antimicrobial ability against Escherichia coli and Staphylococcus aureus upon near-infrared (NIR) irradiation. More importantly, Cy-HMPBs/CH has favorable biocompatibility and can play therapeutic effects only after laser irradiation, indicating the on-demand therapy at the targeted region to avert side effects on healthy tissue. This study provides ideas for the design of an antibiotic-free antimicrobial strategy against infectious diseases.

Preparation and optimization of agarose or polyacrylamide/amino acid-based double network hydrogels for photocontrolled drug release

The high water content and biocompatibility of amino-acid-based supramolecular hydrogels have generated growing interest in drug delivery research. Nevertheless, the existing dominant approach of constructing such hydrogels, the exploitation of a single amino acid type, typically comes with several drawbacks such as weak mechanical properties and long gelation times, hindering their applications. Here, we design a near-infrared (NIR) light-responsive double network (DN) structure, containing amino acids and different synthetic or natural polymers, i.e., polyacrylamide, poly(N-isopropylacrylamide), agarose, or low-gelling agarose. The hydrogels displayed high mechanical strength and high drug-loading capacity. Adjusting the ratio of Fmoc-Tyr-OH/Fmoc-Tyr(Bzl)-OH or Fmoc-Phe-OH/Fmoc-Tyr(Bzl)-OH, we could drastically shorten the gelation time of the DN hydrogels at room and body temperatures. Moreover, introducing photothermal agents (graphene oxide, carbon nanotubes, molybdenum disulfide nanosheets, or indocyanine green), we equipped the hydrogels with NIR responsivity. We demonstrated the light-triggered release of the drug baclofen, which is used in severe spasticity treatment. Rheology and stability tests confirmed the positive impact of the polymers on the mechanical strength of the hydrogels, while maintaining good stability under physiological conditions. Overall, our study contributed a novel hydrogel formulation with high mechanical resistance, rapid gel formation, and efficient NIR-controlled drug release, offering new opportunities for biomedical applications.

Growth factors: Bioactive macromolecular drugs for peripheral nerve injury treatment - Molecular mechanisms and delivery platforms

Bioactive macromolecular drugs known as Growth Factors (GFs), approved by the Food and Drug Administration (FDA), have found successful application in clinical practice. They hold significant promise for addressing peripheral nerve injuries (PNIs). Peripheral nerve guidance conduits (NGCs) loaded with GFs, in the context of tissue engineering, can ensure sustained and efficient release of these bioactive compounds. This, in turn, maintains a stable, long-term, and effective GF concentration essential for treating damaged peripheral nerves. Peripheral nerve regeneration is a complex process that entails the secretion of various GFs. Following PNI, GFs play a pivotal role in promoting nerve cell growth and survival, axon and myelin sheath regeneration, cell differentiation, and angiogenesis. They also regulate the regenerative microenvironment, stimulate plasticity changes post-nerve injury, and, consequently, expedite nerve structure and function repair. Both exogenous and endogenous GFs, including NGF, BDNF, NT-3, GDNF, IGF-1, bFGF, and VEGF, have been successfully loaded onto NGCs using techniques like physical adsorption, blend doping, chemical covalent binding, and engineered transfection. These approaches have effectively promoted the repair of peripheral nerves. Numerous studies have demonstrated similar tissue functional therapeutic outcomes compared to autologous nerve transplantation. This evidence underscores the substantial clinical application potential of GFs in the domain of peripheral nerve repair. In this article, we provide an overview of GFs in the context of peripheral nerve regeneration and drug delivery systems utilizing NGCs. Looking ahead, commercial materials for peripheral nerve repair hold the potential to facilitate the effective regeneration of damaged peripheral nerves and maintain the functionality of distant target organs through the sustained release of GFs.

Therapeutic Supramolecular Polymers: Designs and Applications

The self-assembly of low-molecular-weight building motifs into supramolecular polymers has unlocked a new realm of materials with distinct properties and tremendous potential for advancing medical practices. Leveraging the reversible and dynamic nature of non-covalent interactions, these supramolecular polymers exhibit inherent responsiveness to their microenvironment, physiological cues, and biomolecular signals, making them uniquely suited for diverse biomedical applications. In this review, we intend to explore the principles of design, synthesis methodologies, and strategic developments that underlie the creation of supramolecular polymers as carriers for therapeutics, contributing to the treatment and prevention of a spectrum of human diseases. We delve into the principles underlying monomer design, emphasizing the pivotal role of non-covalent interactions, directionality, and reversibility. Moreover, we explore the intricate balance between thermodynamics and kinetics in supramolecular polymerization, illuminating strategies for achieving controlled sizes and distributions. Categorically, we examine their exciting biomedical applications: individual polymers as discrete carriers for therapeutics, delving into their interactions with cells, and in vivo dynamics; and supramolecular polymeric hydrogels as injectable depots, with a focus on their roles in cancer immunotherapy, sustained drug release, and regenerative medicine. As the field continues to burgeon, harnessing the unique attributes of therapeutic supramolecular polymers holds the promise of transformative impacts across the biomedical landscape.

Editorial on Special Issue "Design and Optimization of Pharmaceutical Gels"

The efficacy of many bioactive agents, including drugs, food supplements, and vaccines, is limited because of their poor chemical stability, low water solubility, and low oral bioavailability [...].

Controlling the Morphology in Electrostatic Self-Assembly via Light

Electrostatic self-assembly of macroions is an emerging area with great potential in the development of nanoscale functional objects, where photo-irradiation responsiveness can either elevate or suppress the self-assembly. The ability to control the size and shape of macroion assemblies would greatly facilitate the fabrication of desired nano-objects that can be harnessed in various applications such as catalysis, drug delivery, bio-sensors, and actuators. Here, we demonstrate that a polyelectrolyte with a size of 5 nm and multivalent counterions with a size of 1 nm can produce well-defined nanostructures ranging in size from 10-1000 nm in an aqueous environment by utilizing the concept of electrostatic self-assembly and other intermolecular non-covalent interactions including dipole-dipole interactions. The pH- and photoresponsiveness of polyelectrolytes and azo dyes provide diverse parameters to tune the nanostructures. Our findings demonstrate a facile approach to fabricating and manipulating self-assembled nanoparticles using light and neutron scattering techniques.

Water dynamics in eutectic solutions of sodium chloride and magnesium sulfate: implications for life in Europa's subsurface ocean and ice shell

Liquid water is essential for life as we know it and the coupling between water and biomolecular dynamics is crucial for life processes. Jupiter's moon Europa is a good candidate for searching for extraterrestrial life in our outer solar system, mainly because a liquid water salty ocean in contact with a rocky seafloor underlies its ice shell. Little, however, is known about the chemical composition of the subglacial ocean of Europa or the brine pockets within its ice shell and their impacts on water dynamics. Here, we employ 1H, 17O, 23Na and 35Cl NMR spectroscopy, especially NMR spin relaxation and diffusion methods, and investigate the mobility of water molecules and ions in eutectic solutions of magnesium sulfate and sodium chloride, two salts ubiquitously present on the surface of Europa, over a range of temperatures and pressures pertinent to Europa's subglacial ocean. The NMR data demonstrate the more pronounced effect of magnesium sulfate compared with sodium chloride on the mobility of water molecules. Even at its much lower eutectic temperature, the sodium chloride solution retains a relatively large level of water mobility. Our results highlight the higher potential of a sodium chloride-rich than magnesium sulfate-rich Europa's ocean to accommodate life and support life origination within the eutectic melts of Europa's ice shell.

Additive-Free Method for Enhancing the Volume Phase Transition Rate in Light-Responsive Hydrogels: A Study of Micro-Nano Bubble Water on PNIPAM-co-AAc Hydrogels

Light-responsive hydrogels containing light-thermal convertible pigments have received interest for their possible applications in light-responsive shutters, valves, drug delivery systems, etc. However, their utility is limited by the slow response time. In this study, we investigated the use of micro-nano bubble water as a preparation solvent to accelerate the volume phase transition kinetics of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-AAc) hydrogels. The hydrogels were characterized by dynamic light scattering (DLS) and dissolved oxygen (DO) measurements. The mechanical properties, surface morphology, and chemical composition of the hydrogels were analyzed by Young's modulus measurements, scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy, respectively. The results showed that hydrogels prepared with bubble water changed the volume transition rate by more than two orders of magnitude by simply changing the standing time of the bubble water for only a few hours. The cooperative diffusion coefficients obtained from the light-induced volume transition kinetics correlated linearly with Young's modulus and metastable state swelling ratio. Our results suggest that bubbles act as efficient water channels, thereby modulating the response rate and providing a simple, additive-free method for preparing hydrogels with a wide range of response rates.

Double network hydrogels: Design, fabrication, and application in biomedicines and foods

Research on the design, fabrication, and application of double network (DN) hydrogels, assembled from pairs of polymers, has grown recently due to their unique structural, physicochemical, and functional properties. DN hydrogels can be designed to exhibit a broader range of functional attributes than single network (SN) ones, which extends their applications in various fields. There has been strong interest in the development of biopolymer DN hydrogels because of their environmental, sustainability, and safety benefits. However, there is limited knowledge on the formation and application of these novel materials. This article reviews the principles underlying the design and fabrication of hydrogels using different crosslinking approaches, including covalent and/or non-covalent bonding, and the formation mechanisms, network structures, and functional attributes of different DN hydrogels. The impact of polymer composition, structural organization, and bonding on the mechanical and functional properties of DN hydrogels is reviewed. Potential applications of these hydrogels are highlighted, including in tissue engineering, biomedicines, and foods. The functional attributes of DN hydrogels can be tailored to each of these applications by careful selection of the biopolymers and crosslinking mechanisms used to assemble them. Finally, areas where further research are needed to overcome the current limitations of DN hydrogels are highlighted.

Peptide Amphiphilic Supramolecular Nanogels: Competent Host for Notably Efficient Lipase-Catalyzed Hydrolysis of Water-Insoluble Substrates

The present work depicts the development of stable nanogels in an aqueous medium that were exploited for efficient surface-active lipase-catalyzed hydrolysis of water-insoluble substrates. Surfactant-coated gel nanoparticles (neutral NG1, anionic NG2, and cationic NG3) were prepared from peptide amphiphilic hydrogelator (G1, G2, and G3, respectively) at different hydrophilic and lipophilic balance (HLB). Chromobacterium viscosum (CV) lipase activity towards hydrolysis of water-insoluble substrates (p-nitrophyenyl-n-alkanoates (C4-C10)) in the presence of nanogels got remarkably improved by ~1.7-8.0 fold in comparison to that in aqueous buffer and other self-aggregates. An increase in hydrophobicity of the substrate led to a notable improvement in lipase activity in the hydrophilic domain (HLB>8.0) of nanogels. The micro-heterogeneous interface of small-sized (10-65 nm) nanogel was found to be an appropriate scaffold for immobilizing surface-active lipase to exhibit superior catalytic efficiency. Concurrently, the flexible conformation of lipase immobilized in nanogels was reflected in its secondary structure having the highest α-helix content from the circular dichroism spectra.

Immune homeostasis modulation by hydrogel-guided delivery systems: a tool for accelerated bone regeneration

Immune homeostasis is delicately mediated by the dynamic balance between effector immune cells and regulatory immune cells. Local deviations from immune homeostasis in the microenvironment of bone fractures, caused by an increased ratio of effector to regulatory cues, can lead to excessive inflammatory conditions and hinder bone regeneration. Therefore, achieving effective and localized immunomodulation of bone fractures is crucial for successful bone regeneration. Recent research has focused on developing localized and specific immunomodulatory strategies using local hydrogel-based delivery systems. In this review, we aim to emphasize the significant role of immune homeostasis in bone regeneration, explore local hydrogel-based delivery systems, discuss emerging trends in immunomodulation for enhancing bone regeneration, and address the limitations of current delivery strategies along with the challenges of clinical translation.

Development of double crosslinked sodium alginate/chitosan based hydrogels for controlled release of metronidazole and its antibacterial activity

Double network sodium alginate/chitosan hydrogels were prepared using calcium chloride (CaCl2) and glutaraldehyde as the crosslinking agents by the ionotropic interaction method for controlled metronidazole release. The effect of polymer ratios and CaCl2 amount is investigated by the developing porosity, gel fraction, and extent of swelling in simulated physiological fluids. Interaction between the polymers with the formation of crosslinked structures, good stability, phase nature, and morphology of the hydrogels is revealed by Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. A sodium alginate/chitosan hydrogel (weight ratio of 75:25) crosslinked with two percent CaCl2 is chosen for the in-situ loading of 200 mg of metronidazole. The drug release kinetics using different models show that the best-fit Korsmeyer-Peppas model suggests metronidazole release from the matrix follows diffusion and swelling-controlled time-dependent non-Fickian transport related to hydrogel erosion. This composition displays enhanced antimicrobial activity against Staphylococcus aureus and Escherichia coli.

Short Peptide Nanofiber Biomaterials Ameliorate Local Hemostatic Capacity of Surgical Materials and Intraoperative Hemostatic Applications in Clinics

Short designer self-assembling peptide (dSAP) biomaterials are a new addition to the hemostat group. It may provide a diverse and robust toolbox for surgeons to integrate wound microenvironment with much safer and stronger hemostatic capacity than conventional materials and hemostatic agents. Especially in noncompressible torso hemorrhage (NCTH), diffuse mucosal surface bleeding, and internal medical bleeding (IMB), with respect to the optimal hemostatic formulation, dSAP biomaterials are the ingenious nanofiber alternatives to make bioactive neural scaffold, nasal packing, large mucosal surface coverage in gastrointestinal surgery (esophagus, gastric lesion, duodenum, and lower digestive tract), epicardiac cell-delivery carrier, transparent matrix barrier, and so on. Herein, in multiple surgical specialties, dSAP-biomaterial-based nano-hemostats achieve safe, effective, and immediate hemostasis, facile wound healing, and potentially reduce the risks in delayed bleeding, rebleeding, post-operative bleeding, or related complications. The biosafety in vivo, bleeding indications, tissue-sealing quality, surgical feasibility, and local usability are addressed comprehensively and sequentially and pursued to develop useful surgical techniques with better hemostatic performance. Here, the state of the art and all-round advancements of nano-hemostatic approaches in surgery are provided. Relevant critical insights will inspire exciting investigations on peptide nanotechnology, next-generation biomaterials, and better promising prospects in clinics.