Enzyme-responsive progelator cyclic peptides for minimally invasive delivery to the heart post-myocardial infarction

Liquid Metal-Ionogel Core-Shell Fibers for Reflection-Suppressed Electromagnetic Interference Shielding and Strain Sensing

Electromagnetic interference (EMI) shielding fibers are crucial in practical uses for their flexibility and one-dimensional form. However, their application is limited by poor compatibility between EMI shielding components and fiber substrates, and high electromagnetic wave reflectivity. Herein, a core/shell-structured EMI shielding fiber is introduced, featuring a core of Ga-In-Sn-Zn alloy, Carbopol, and air bubbles, and a shell of ionogel formed from copolymerized acrylamide and acrylic acid. A single fiber achieves a total shielding effectiveness of ∼35 dB within the 2-18 GHz range, which increases to ∼70 dB when three fibers are stacked. Remarkably, the fiber demonstrates enhanced EMI shielding performance following stretching and recovery. Additionally, it exhibits excellent impedance matching, with a reflection power coefficient as low as 0.14 at 10 GHz. The fiber's EMI shielding mechanism encompasses reflection shielding, absorption shielding─attributable to conduction loss and polarization loss─and multiple reflection shielding. Furthermore, the fiber shows potential as a strain sensor. This research offers an effective strategy for creating flexible fibers with high EMI shielding capabilities and low EM wave reflection.

Protein-Like Polymers Targeting Keap1/Nrf2 as Therapeutics for Myocardial Infarction

Myocardial infarction (MI) results in oxidative stress to the myocardium and frequently leads to heart failure (HF). There is an unmet clinical need to develop therapeutics that address the inflammatory stress response and prevent negative left ventricular remodeling. Here, the Keap1/Nrf2 protein-protein interaction is specifically targeted, as Nrf2 activation is known to mitigate the inflammatory response following MI. This is achieved using a Nrf2-mimetic protein-like polymer (PLP) to inhibit the Keap1-Nrf2 interaction. The PLP platform technology provides stability in vivo, potent intracellular bioactivity, and multivalency leading to high avidity Keap1 binding. In vitro and in vivo assays to probe cellular activity and MI therapeutic utility are employed. These Keap1-inhibiting PLPs (Keap1i-PLPs) impart cytoprotection from oxidative stress via Nrf2 activation at sub-nanomolar concentrations in primary cardiomyocytes. Single-digit mg kg-1, single-dose, intravenous PLP administration significantly improves cardiac function in rats post-MI through immunomodulatory, anti-apoptotic, and angiogenic mechanisms. Thus Keap1i-PLPs disrupt key intracellular protein-protein interactions following intravenous, systemic administration in vivo. These results have broad implications not only for MI but also for other oxidative stress-driven diseases and conditions.

Towards precision medicine using biochemically triggered cleavable conjugation

Personalised and precision medicines are emerging as the future of therapeutic strategies. Biochemically triggered cleavable conjugation is thus crucial and timely due to its potential to response as per the loco-regional environment. It enables targeted release of therapeutic agents in response to specific biochemical signals and thus minimizing off-target effects and improving treatment precision. It holds promise in a range of biomedical applications, including cancer therapy, senolytic therapy, gene therapy, and regenerative medicine. The focus of this review is to offer comprehensive insight into the significance of biochemically cleavable conjugations within intrinsically stimuli-responsive architectures. Pathological conditions and alteration in tissues microenvironment in the body exhibit distinct biochemical settings characterized by change in redox potential, pH level, hypoxia, reactive oxygen species (ROS), and various catalytic protein/enzyme overexpression. Understanding these intrinsic features is crucial for researchers aiming to develop intelligent cleavable bio-engineered systems for biomedicines. By strategically designing cleavable linkage, researchers can leverage the variations in the tumor, infection, inflammation, and senescence microenvironments. Through an extensive examination of relevant literature, we present a comprehensive classification of the intrinsic physicochemical differences found in pathological areas and their applications in drug delivery, prodrug activation, imaging, and theranostics for future personalised medicines. This review will provide comprehensive guidance and critical insights to researchers in both industry and academia who are involved in the design of advanced, functional biochemically cleavable conjugations.

Easily Injectable, Organic Solvent-Free Self-Assembled Hydrogel Platform for Endoscope Mediated Gastrointestinal Polypectomy

Endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (ESR) are used to eliminate tiny, flat lesions in the gastrointestinal tract (GIT). A substantial submucosal cushion is required for effective dissection. Commonly used saline and hypertonic dextrose injections disperse quickly and do not offer significant elevation, whereas polymers such as gelatin and alginate are challenging to inject. In this study, a novel amphiphilic polyglycerol stearate-based hydrogel (PGSH) platform is demonstrated which could be administered via an endoscopic catheter to help create a stable submucosal elevation. PGSH is easy to inject across different needle gauges, shear-thinning, and forms a long-lasting submucosal cushion during ESD. This hydrogel can encapsulate hydrophilic drugs such as streptomycin, allowing controlled enzymatic and nonenzymatic release. Ex-vivo experiments on goat's GIT demonstrate that PGSH is smoothly injectable without clogging the catheter's needle, achieving the necessary submucosal elevation. Furthermore, ex-vivo blood studies demonstrate immediate clotting behavior while maintaining hemocompatibility. In-vivo, investigations in mice show that the hydrogel forms a biocompatible cushion of suitable height with a nontoxic organ profile that does not overexpress inflammatory cytokines. ESD studies in the porcine model suggest that PGSH has the potential to significantly improve treatment outcomes in the early endoscopic removal of gastrointestinal polyps.

Shear-Thinning Hydrogel for Delayed Delivery of a Small Molecule Metalloproteinase Inhibitor Attenuates Myocardial Infarction Remodeling

Strategic delivery of hydrogels to the newly formed myocardial infarction (MI) is an area of active investigation and offers high target specificity for releasing a small molecule therapeutic payload. This study examined the effects of delayed post-MI delivery (pigs, 3 days post-MI) of a shear-thinning hydrogel which encapsulated and released a small molecule matrix metalloproteinase inhibitor. The results demonstrated the feasibility and efficacy of targeted delivery of a shear-thinning injectable hydrogel containing a small molecule matrix metalloproteinase inhibitor to attenuate post-MI remodeling.

4D printing biological stimuli-responsive hydrogels for tissue engineering and localized drug delivery applications - part 1

INTRODUCTION

The advent of 3D printing has revolutionized biomedical engineering, yet limitations in creating dynamic human tissues remain. The emergence of 4D printing, which introduces time as a fourth dimension, offers new possibilities by enabling the production of adaptable, stimuli-responsive structures. A thorough literature search was performed across various databases, including Google Scholar, PubMed, Scopus, and Web of Science, to identify pertinent studies published up to 2025. The search parameters were confined to articles published in English that concentrated on peer-reviewed clinical studies.

AREAS COVERED

This review explores the transition from 3D to 4D printing and focuses on stimuli-responsive materials, particularly hydrogels, which react to environmental changes. The literature search examined recent studies on the interaction of these materials with biological stimuli, emphasizing their application in tissue engineering and drug delivery applications.

EXPERT OPINION

4D printing, combined with smart materials, holds immense promise for advancing biomedical treatments, including customized therapies and regenerative medicine. However, technological challenges must be addressed to realize its full potential.

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.

Current status and future developments of biopolymer microspheres in the field of pharmaceutical preparation

Polymer composite microspheres offer several advantages including highly designable structural properties, adjustable micro-nano particle size distribution, easy surface modification, large specific surface area, and high stability. These features make them valuable in various fields such as medicine, sensing, optics, and display technologies, with significant applications in clinical diagnostics, pathological imaging, and drug delivery in the medical field. Currently, microspheres are primarily used in biomedical research as long-acting controlled-release agents and targeted delivery systems, and are widely applied in bone tissue repair, cancer treatment, and wound healing. Different types of polymer microspheres offer distinct advantages and application prospects. Efforts are ongoing to transition successful experimental research to industrial production by expanding various fabrication technologies. This article provides an overview of materials used in microsphere manufacturing, different fabrication methods, modification techniques to enhance their properties and applications, and discusses the role of microspheres in drug delivery engineering.

Advancements in Hydrogels for Corneal Healing and Tissue Engineering

Hydrogels have garnered significant attention for their versatile applications across various fields, including biomedical engineering. This review delves into the fundamentals of hydrogels, exploring their definition, properties, and classification. Hydrogels, as three-dimensional networks of crosslinked polymers, possess tunable properties such as biocompatibility, mechanical strength, and hydrophilicity, making them ideal for medical applications. Uniquely, this article offers original insights into the application of hydrogels specifically for corneal tissue engineering, bridging a gap in current research. The review further examines the anatomical and functional complexities of the cornea, highlighting the challenges associated with corneal pathologies and the current reliance on donor corneas for transplantation. Considering the global shortage of donor corneas, this review discusses the potential of hydrogel-based materials in corneal tissue engineering. Emphasis is placed on the synthesis processes, including physical and chemical crosslinking, and the integration of bioactive molecules. Stimuli-responsive hydrogels, which react to environmental triggers, are identified as promising tools for drug delivery and tissue repair. Additionally, clinical applications of hydrogels in corneal pathologies are explored, showcasing their efficacy in various trials. Finally, the review addresses the challenges of regulatory approval and the need for further research to fully realize the potential of hydrogels in corneal tissue engineering, offering a promising outlook for future developments in this field.

Enzymatically Activatable Polymers for Disease Diagnosis and Treatment

The irregular expression or activity of enzymes in the human body leads to various pathological disorders and can therefore be used as an intrinsic trigger for more precise identification of disease foci and controlled release of diagnostics and therapeutics, leading to improved diagnostic accuracy, sensitivity, and therapeutic efficacy while reducing systemic toxicity. Advanced synthesis strategies enable the preparation of polymers with enzymatically activatable skeletons or side chains, while understanding enzymatically responsive mechanisms promotes rational incorporation of activatable units and predictions of the release profile of diagnostics and therapeutics, ultimately leading to promising applications in disease diagnosis and treatment with superior biocompatibility and efficiency. By overcoming the challenges, new opportunities will emerge to inspire researchers to develop more efficient, safer, and clinically reliable enzymatically activatable polymeric carriers as well as prodrugs.

Protease-Driven Phase Separation of Elastin-Like Polypeptides

Elastin-like polypeptides (ELPs) are a promising material platform for engineering stimuli-responsive biomaterials, as ELPs undergo phase separation above a tunable transition temperature. ELPs with phase behavior that is isothermally regulated by biological stimuli remain attractive for applications in biological systems. Herein, we report protease-driven phase separation of ELPs. Protease-responsive "cleavable" ELPs comprise a hydrophobic ELP block connected to a hydrophilic ELP block by a protease cleavage site linker. The hydrophilic ELP block acts as a solubility tag for the hydrophobic ELP block, creating a temperature window in which the cleavable ELP reactant is soluble and the proteolytically generated hydrophobic ELP block is insoluble. Within this temperature window, isothermal, protease-driven phase separation occurs when a critical concentration of hydrophobic cleavage product accumulates. Furthermore, protease-driven phase separation is generalizable to four compatible protease-cleavable ELP pairings. This work presents exciting opportunities to regulate ELP phase behavior in biological systems using proteases.

Chemically Programmed Hydrogels for Spatiotemporal Modulation of the Cardiac Pathological Microenvironment

After myocardial infarction (MI), sustained ischemic events induce pathological microenvironments characterized by ischemia-hypoxia, oxidative stress, inflammatory responses, matrix remodeling, and fibrous scarring. Conventional clinical therapies lack spatially targeted and temporally responsive modulation of the infarct microenvironment, leading to limited myocardial repair. Engineered hydrogels have a chemically programmed toolbox for minimally invasive localization of the pathological microenvironment and personalized responsive modulation over different pathological periods. Chemically programmed strategies for crosslinking interactions, interfacial binding, and topological microstructures in hydrogels enable minimally invasive implantation and in situ integration tailored to the myocardium. This enhances substance exchange and signal interactions within the infarcted microenvironment. Programmed responsive polymer networks, intelligent micro/nanoplatforms, and biological therapeutic cues contribute to the formation of microenvironment-modulated hydrogels with precise targeting, spatiotemporal control, and on-demand feedback. Therefore, this review summarizes the features of the MI microenvironment and chemically programmed schemes for hydrogels to conform, integrate, and modulate the cardiac pathological microenvironment. Chemically programmed strategies for oxygen-generating, antioxidant, anti-inflammatory, provascular, and electrointegrated hydrogels to stimulate iterative and translational cardiac tissue engineering are discussed.

Tips and Tricks in the Modeling of Supramolecular Peptide Assemblies

Supramolecular peptide assemblies (SPAs) hold promise as materials for nanotechnology and biomedicine. Although their investigation often entails adapting experimental techniques from their protein counterparts, SPAs are fundamentally distinct from proteins, posing unique challenges for their study. Computational methods have emerged as indispensable tools for gaining deeper insights into SPA structures at the molecular level, surpassing the limitations of experimental techniques, and as screening tools to reduce the experimental search space. However, computational studies have grappled with issues stemming from the absence of standardized procedures and relevant crystal structures. Fundamental disparities between SPAs and protein simulations, such as the absence of experimentally validated initial structures and the importance of the simulation size, number of molecules, and concentration, have compounded these challenges. Understanding the roles of various parameters and the capabilities of different models and simulation setups remains an ongoing endeavor. In this review, we aim to provide readers with guidance on the parameters to consider when conducting SPA simulations, elucidating their potential impact on outcomes and validity.

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.

Advances in injectable hydrogels for radiation-induced heart disease

Radiological heart damage (RIHD) is damage caused by unavoidable irradiation of the heart during chest radiotherapy, with a long latency period and a progressively increasing proportion of delayed cardiac damage due to conventional doses of chest radiotherapy. There is a risk of inducing diseases such as acute/chronic pericarditis, myocarditis, delayed myocardial fibrosis and damage to the cardiac conduction system in humans, which can lead to myocardial infarction or even death in severe cases. This paper details the pathogenesis of RIHD and gives potential targets for treatment at the molecular and cellular level, avoiding the drawbacks of high invasiveness and immune rejection due to drug therapy, medical device implantation and heart transplantation. Injectable hydrogel therapy has emerged as a minimally invasive tissue engineering therapy to provide necessary mechanical support to the infarcted myocardium and to act as a carrier for various bioactive factors and cells to improve the cellular microenvironment in the infarcted area and induce myocardial tissue regeneration. Therefore, this paper combines bioactive factors and cellular therapeutic mechanisms with injectable hydrogels, presents recent advances in the treatment of cardiac injury after RIHD with different injectable gels, and summarizes the therapeutic potential of various types of injectable hydrogels as a potential solution.

Widely distributable and retainable in-situ gelling material for treating myocardial infarction

Intramyocardial hydrogel injection is a promising therapy to prevent negative remodeling following myocardial infarction (MI). In this study, we report a mechanism for in-situ gel formation without external stimulation, resulting in an injectable and tissue-retainable hydrogel for MI treatment, and investigate its therapeutic outcomes. A liquid-like polymeric solution comprising poly(3-acrylamidophenylboronic acid-co-acrylamide) (BAAm), polyvinyl alcohol (PVA), and sorbitol (S) increases the viscous modulus by reducing the pre-added sorbitol concentration is developed. This solution achieves a sol-gel transition in-vitro in heart tissue by spontaneously diffusing the sorbitol. After intramyocardial injection, the BAAm/PVA/S with lower initial viscous modulus widely spreads in the myocardium and gelate compared to a viscoelastic alginate (ALG) hydrogel and is retained longer than the BAAm/S solution. Serial echocardiogram analyses prove that injecting the BAAm/PVA/S into the hearts of subacute MI rats significantly increases the fraction shortening and ejection shortening and attenuates the expansion of systolic LV diameter for up to 21 d after injection compared to the saline injection as a control, but the ALG injection does not. In addition, histological evaluation shows that only the BAAm/PVA/S decreases the infarct size and increases the wall thickness 21 d after injection. The BAAm/PVA/S intramyocardial injection is better at restraining systolic ventricular dilatation and cardiac failure in the rat MI model than in the control groups. Our findings highlight an effective injectable hydrogel therapy for MI by optimizing injectability-dependent distribution and retention of injected material. STATEMENT OF SIGNIFICANCE: In-situ gelling material is a promising strategy for intramyocardial hydrogel injection therapy for myocardial infarction (MI). Since the sol-gel transition of reported materials is driven by external stimulation such as temperature, pH, or ultraviolet, their application in vivo remains challenging. In this study, we first reported a synthetic in-situ gelling material (BAAm/PVA/S) whose gelation is stimulated by spontaneously reducing pre-added sorbitol after contacting the heart tissue. The BAAm/PVA/S solution spreads evenly, and is retained for at least 21 d in the heart tissue. Our study demonstrated that intramyocardial injection of the BAAm/PVA/S with more extensive distribution and longer retention had better effects on preventing LV dilation and improving cardiac function after MI than that of viscoelastic ALG and saline solution. We expect that these findings provide fundamental information for the optimum design of injectable biomaterials for treating MI.

Assessment of the MARTINI 3 Performance for Short Peptide Self-Assembly

The coarse-grained MARTINI force field, initially developed for membranes, has proven to be an exceptional tool for investigating supramolecular peptide assemblies. Over the years, the force field underwent refinements to enhance accuracy, enabling, for example, the reproduction of protein-ligand interactions and constant pH behavior. However, these protein-focused improvements seem to have compromised its ability to model short peptide self-assembly. In this study, we assess the performance of MARTINI 3 in reproducing peptide self-assembly using the well-established diphenylalanine (FF) as our test case. Unlike its success in version 2.1, FF does not even exhibit aggregation in version 3. By systematically exploring parameters for the aromatic side chains and charged backbone beads, we established a parameter set that effectively reproduces tube formation. Remarkably, these parameter adjustments also replicate the self-assembly of other di- and tripeptides and coassemblies. Furthermore, our analysis uncovers pivotal insights for enhancing the performance of MARTINI in modeling short peptide self-assembly. Specifically, we identify issues stemming from overestimated hydrophilicity arising from charged termini and disruptions in π-stacking interactions due to insufficient planarity in aromatic groups and a discrepancy in intermolecular distances between this and backbone-backbone interactions. This investigation demonstrates that strategic modifications can harness the advancements offered by MARTINI 3 for the realm of short peptide self-assembly.

A multifunctional and self-adaptive double-layer hydrogel dressing based on chitosan for deep wound repair

Hydrogel wound dressing for irregular shape and deep wound repair is a research hotspot. Herein, a multifunctional and self-adaptive double-layer hydrogel was constructed, which was comprised of chitosan-based inner layer hydrogel and gellan gum-based outer layer hydrogel. Various properties of inner layer hydrogel were systematically investigated, including injectability, shape-adaptability, solid-liquid phase transition, biocompatibility, hemostasis, antibacterial performance and anti-inflammatory. Thanks to the phase-transition from solid to liquid at body temperature, inner layer hydrogel exhibited stronger adaptability to fill irregular and deep wounds, in which chitosan was liquefied and its therapeutic effect was maximized. Outer layer hydrogel was fabricated by calcium ions and gellan gum, whose certain mechanical strength could provide protection and a moister environment for wounds. Because of these characteristics, double-layer hydrogel markedly promoted skin tissue regeneration and wound closure and thereby possessed potential clinical application prospect as wound dressing for deep wounds.

Pathogenesis-adaptive polydopamine nanosystem for sequential therapy of ischemic stroke

Ischemic stroke is lethal cerebrovascular disease, and reperfusion as the main strategy of blood supply restoration can cause severe ischemic brain damage. Considered as the major obstacle in medication for stroke, neuroinflammation after reperfusion undergoes dynamic progression, making precision treatment for stroke a Herculean task. In this work, we report a pathogenesis-adaptive polydopamine nanosystem for sequential therapy of ischemic stroke. Intrinsic free radical scavenging and tailored mesostructure of the nanosystem can attenuate oxidative stress at the initial stage. Upon microglial overactivation at the later stage, minocycline-loaded nanosystem can timely reverse the pro-inflammatory transition in response to activated matrix metalloproteinase-2, providing on-demand regulation. Further in vivo stroke study demonstrates a higher survival rate and improved brain recovery of the sequential strategy, compared with mono-therapy and combined therapy. Complemented with satisfactory biosafety results, this adaptive nanosystem for sequential and on-demand regulation of post-stroke neuroinflammation is a promising approach to ischemic stroke therapy.

A Core-Shell Nanoreinforced Ion-Conductive Implantable Hydrogel Bioelectronic Patch with High Sensitivity and Bioactivity for Real-Time Synchronous Heart Monitoring and Repairing

To achieve synchronous repair and real-time monitoring the infarcted myocardium based on an integrated ion-conductive hydrogel patch is challenging yet intriguing. Herein, a novel synthetic strategy is reported based on core-shell-structured curcumin-nanocomposite-reinforced ion-conductive hydrogel for synchronous heart electrophysiological signal monitoring and infarcted heart repair. The nanoreinforcement and multisite cross-linking of bioactive curcumin nanoparticles enable well elasticity with negligible hysteresis, implantability, ultrahigh mechanoelectrical sensitivity (37 ms), and reliable sensing capacity (over 3000 cycles) for the nanoreinforced hydrogel. Results of in vitro and in vivo experiments demonstrate that such solely physical microenvironment of electrophysiological and biomechanical characteristics combining with the role of bioactive curcumin exert the synchronous benefit of regulating inflammatory microenvironment, promoting angiogenesis, and reducing myocardial fibrosis for effective myocardial infarction (MI) repair. Especially, the hydrogel sensors offer the access for achieving accurate acquisition of cardiac signals, thus monitoring the whole MI healing process. This novel bioactive and electrophysiological-sensing ion-conductive hydrogel cardiac patch highlights a versatile strategy promising for synchronous integration of in vivo real-time monitoring the MI status and excellent MI repair performance.

Current Advances in Stimuli-Responsive Hydrogels as Smart Drug Delivery Carriers

In recent years, significant advancements in the field of advanced materials and hydrogel engineering have enabled the design and fabrication of smart hydrogels and nanogels that exhibit sensitivity to specific signals or pathological conditions, leading to a wide range of applications in drug delivery and disease treatment. This comprehensive review aims to provide an in-depth analysis of the stimuli-responsive principles exhibited by smart hydrogels in response to various triggers, such as pH levels, temperature fluctuations, light exposure, redox conditions, or the presence of specific biomolecules. The functionality and performance characteristics of these hydrogels are highly influenced by both their constituent components and fabrication processes. Key design principles, their applications in disease treatments, challenges, and future prospects were also discussed. Overall, this review aims to contribute to the current understanding of gel-based drug delivery systems and stimulate further research in this rapidly evolving field.

Peptide-drug co-assembling: A potent armament against cancer

Cancer is still one of the major problems threatening human health and the therapeutical efficacies of available treatment choices are often rather low. Due to their favorable biocompatibility, simplicity of modification, and improved therapeutic efficacy, peptide-based self-assembled delivery systems have undergone significant evolution. Physical encapsulation and covalent conjugation are two common approaches to load drugs for peptide assembly-based delivery, which are always associated with drug leaks in the blood circulation system or changed pharmacological activities, respectively. To overcome these difficulties, a more elegant peptide-based assembly strategy is desired. Notably, peptide-mediated co-assembly with drug molecules provides a new method for constructing nanomaterials with improved versatility and structural stability. The co-assembly strategy can be used to design various nanostructures for cancer therapy, such as nanotubes, nanofibrils, hydrogels, and nanovesicles. Recently, these co-assembled nanostructures have gained tremendous attention for their unique superiorities in tumor therapy. This article describes the classification of assembled peptides, driving forces for co-assembly, and specifically, the design methodologies for various drug molecules in co-assembly. It also highlights recent research on peptide-mediated co-assembled delivery systems for cancer therapy. Finally, it summarizes the pros and cons of co-assembly in cancer therapy and offers some suggestions for conquering the challenges in this field.

Dynamic Control of Cyclic Peptide Assembly to Form Higher-Order Assemblies

Chirality correction, asymmetry, ring-chain tautomerism and hierarchical assemblies are fundamental phenomena in nature. They are geometrically related and may impact the biological roles of a protein or other supermolecules. It is challenging to study those behaviors within an artificial system due to the complexity of displaying these features. Herein, we design an alternating D,L peptide to recreate and validate the naturally occurring chirality inversion prior to cyclization in water. The resulting asymmetrical cyclic peptide containing a 4-imidazolidinone ring provides an excellent platform to study the ring-chain tautomerism, thermostability and dynamic assembly of the nanostructures. Different from traditional cyclic D,L peptides, the formation of 4-imidazolidinone promotes the formation of intertwined nanostructures. Analysis of the nanostructures confirmed the left-handedness, representing chirality induced self-assembly. This proves that a rationally designed peptide can mimic multiple natural phenomena and could promote the development of functional biomaterials, catalysts, antibiotics, and supermolecules.

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.

Stimuli-responsive hydrogels: smart state of-the-art platforms for cardiac tissue engineering

Biomedicine and tissue regeneration have made significant advancements recently, positively affecting the whole healthcare spectrum. This opened the way for them to develop their applications for revitalizing damaged tissues. Thus, their functionality will be restored. Cardiac tissue engineering (CTE) using curative procedures that combine biomolecules, biomimetic scaffolds, and cells plays a critical part in this path. Stimuli-responsive hydrogels (SRHs) are excellent three-dimensional (3D) biomaterials for tissue engineering (TE) and various biomedical applications. They can mimic the intrinsic tissues' physicochemical, mechanical, and biological characteristics in a variety of ways. They also provide for 3D setup, adequate aqueous conditions, and the mechanical consistency required for cell development. Furthermore, they function as competent delivery platforms for various biomolecules. Many natural and synthetic polymers were used to fabricate these intelligent platforms with innovative enhanced features and specialized capabilities that are appropriate for CTE applications. In the present review, different strategies employed for CTE were outlined. The light was shed on the limitations of the use of conventional hydrogels in CTE. Moreover, diverse types of SRHs, their characteristics, assembly and exploitation for CTE were discussed. To summarize, recent development in the construction of SRHs increases their potential to operate as intelligent, sophisticated systems in the reconstruction of degenerated cardiac tissues.

A Matrix-Metalloproteinase-Responsive Hydrogel System for Modulating the Immune Microenvironment in Myocardial Infarction

Injectable hydrogels carrying therapeutic factors to modulate the infarct immune microenvironment show great potential in the treatment of myocardial infarction (MI). However, conventional injectable hydrogels release therapeutic factors in an uncontrolled manner, which leads to poor treatment efficacy and acute side effects on normal tissues. In this work, a matrix metalloproteinase (MMP)2/9-responsive hydrogel system (MPGC4) is developed, considering the characteristics of the post-MI microenvironment. MPGC4 consists of tetra-poly(ethylene glycol) (PEG) hydrogels and a composite gene nanocarrier (CTL4) that is composed of carbon dots (CDots) coupled with interleukin-4 plasmid DNA via electrostatic interactions. MPGC4 can be automatically triggered to release CTL4 on demand after MI to regulate the infarct immune microenvironment. In addition, due to the photoluminescence properties of CDots, a large amount of viscoelastic MPGC4 is found to be retained in situ after injection into the infarct region without leakage. The in vitro results demonstrate that CTL4 promotes proinflammatory M1 macrophage polarization to the anti-inflammatory M2 subtype and contributes to cardiomyocyte survival through macrophage transition. In a rat model of MI, MPGC4 clears MMPs and precisely targets CTL4 to the infarcted region. In particular, MPGC4 improves cardiac function by modulating macrophage transition to reduce early inflammatory responses and proangiogenic activity.

Injectable MMP1-sensitive microspheres with spatiotemporally controlled exosome release promote neovascularized bone healing

Bone marrow mesenchymal stromal cell-derived exosomes (BMSC-Exos) can recruit stem cells for bone repair, with neovessels serving as the main migratory channel for stem cells to the injury site. However, existing exosome (Exo) delivery strategies cannot reach the angiogenesis phase following bone injury. To that end, an enzyme-sensitive Exo delivery material that responds to neovessel formation during the angiogenesis phase was designed in the present study to achieve spatiotemporally controlled Exo release. Herein, matrix metalloproteinase-1 (MMP1) was found to be highly expressed in neovascularized bone; as a result, we proposed an injectable MMP1-sensitive hydrogel microspheres (KGE) made using a microfluidic chip prepared by mixing self-assembling peptide (KLDL-MMP1), GelMA, and BMSC-Exos. The results revealed that KGE microspheres had a uniform diameter of 50-70 µm, ideal for minimally invasive injection and could release exosomes in response to MMP1 expression. In vitro experiments demonstrated that KGE had less cytotoxicity and could promote the migration and osteodifferentiation of BMSCs. Furthermore, in vivo experiments confirmed that KGE could promote bone repair during angiogenesis by recruiting CD90⁺ stem cells via neovessels. Collectively, our results suggest that injectable enzyme-responsive KGE microspheres could be a promising Exo-secreting material for accelerating neovascularized bone healing. STATEMENT OF SIGNIFICANCE: Exosomes can spread through blood vessels and activate stem cells to participate in bone repair, but under normal circumstances, exosomes lacking sustained-release delivery materials cannot be maintained until the angiogenesis phase. In this study, we found that MMP1 was highly expressed in neovascularized bone, then we proposed an MMP1-sensitive injectable microsphere that carries exosomes and responds temporally and spatially to neovascularization, which maximizes the ability of exosomes to recruit stem cells. Different from previous strategies that focus on promoting angiogenesis to accelerate bone healing, this is a brand new delivery strategy that is stimuli-responsive to neovessel formation. In addition, the preparation of self-assembled peptide microspheres by a microfluidic chip is also proposed for the first time.

Recent advances in responsive antibacterial materials: design and application scenarios

Bacterial infection is one of the leading causes of death globally, although modern medicine has made considerable strides in the past century. As traditional antibiotics are suffering from the emergence of drug resistance, new antibacterial strategies are of great interest. Responsive materials are appealing alternatives that have shown great potential in combating resistant bacteria and avoiding the side effects of traditional antibiotics. In this review, the responsive antibacterial materials are introduced in terms of stimulus signals including intrinsic (pH, enzyme, ROS, etc.) and extrinsic (light, temperature, magnetic fields, etc.) stimuli. Their biomedical applications in therapeutics and medical devices are then discussed. Finally, the author's perspective of the challenge and the future of such a system is provided.

Hierarchical Materials from High Information Content Macromolecular Building Blocks: Construction, Dynamic Interventions, and Prediction

Hierarchical materials that exhibit order over multiple length scales are ubiquitous in nature. Because hierarchy gives rise to unique properties and functions, many have sought inspiration from nature when designing and fabricating hierarchical matter. More and more, however, nature's own high-information content building blocks, proteins, peptides, and peptidomimetics, are being coopted to build hierarchy because the information that determines structure, function, and interfacial interactions can be readily encoded in these versatile macromolecules. Here, we take stock of recent progress in the rational design and characterization of hierarchical materials produced from high-information content blocks with a focus on stimuli-responsive and "smart" architectures. We also review advances in the use of computational simulations and data-driven predictions to shed light on how the side chain chemistry and conformational flexibility of macromolecular blocks drive the emergence of order and the acquisition of hierarchy and also on how ionic, solvent, and surface effects influence the outcomes of assembly. Continued progress in the above areas will ultimately usher in an era where an understanding of designed interactions, surface effects, and solution conditions can be harnessed to achieve predictive materials synthesis across scale and drive emergent phenomena in the self-assembly and reconfiguration of high-information content building blocks.

Multifunctional biomaterial platforms for blocking the fibrosis process and promoting cellular restoring effects in myocardial fibrosis therapy

Myocardial fibrosis is the result of abnormal healing after acute and chronic myocardial damage and is a direct cause of heart failure and cardiac insufficiency. The clinical approach is to preserve cardiac function and inhibit fibrosis through surgery aimed at dredging blood vessels. However, this strategy does not adequately address the deterioration of fibrosis and cardiac function recovery. Therefore, numerous biomaterial platforms have been developed to address the above issues. In this review, we summarize the existing biomaterial delivery and restoring platforms, In addition, we also clarify the therapeutic strategies based on biomaterial platforms, including general strategies to block the fibrosis process and new strategies to promote cellular restoring effects. The development of structures with the ability to block further fibrosis progression as well as to promote cardiomyocytes viability should be the main research interests in myocardial fibrosis, and the reestablishment of structures necessary for normal cardiac function is central to the treatment of myocardial fibrosis. Finally, the future application of biomaterials for myocardial fibrosis is also highlighted.

Advanced Drug Delivery Micro- and Nanosystems for Cardiovascular Diseases

Advanced drug delivery micro- and nanosystems have been widely explored due to their appealing specificity/selectivity, biodegradability, biocompatibility, and low toxicity. They can be applied for the targeted delivery of pharmaceuticals, with the benefits of good biocompatibility/stability, non-immunogenicity, large surface area, high drug loading capacity, and low leakage of drugs. Cardiovascular diseases, as one of the primary mortalities cause worldwide with significant impacts on the quality of patients’ life, comprise a variety of heart and circulatory system pathologies, such as peripheral vascular diseases, myocardial infarction, heart failure, and coronary artery diseases. Designing novel micro- and nanosystems with suitable targeting properties and smart release behaviors can help circumvent crucial challenges of the tolerability, low stability, high toxicity, and possible side- and off-target effects of conventional drug delivery routes. To overcome different challenging issues, namely physiological barriers, low efficiency of drugs, and possible adverse side effects, various biomaterials-mediated drug delivery systems have been formulated with reduced toxicity, improved pharmacokinetics, high bioavailability, sustained release behavior, and enhanced therapeutic efficacy for targeted therapy of cardiovascular diseases. Despite the existing drug delivery systems encompassing a variety of biomaterials for treating cardiovascular diseases, the number of formulations currently approved for clinical use is limited due to the regulatory and experimental obstacles. Herein, the most recent advancements in drug delivery micro- and nanosystems designed from different biomaterials for the treatment of cardiovascular diseases are deliberated, with a focus on the important challenges and future perspectives.

Progress in Stimuli-Responsive Biomaterials for Treating Cardiovascular and Cerebrovascular Diseases

Cardiovascular and cerebrovascular diseases (CCVDs) describe abnormal vascular system conditions affecting the brain and heart. Among these, ischemic heart disease and ischemic stroke are the leading causes of death worldwide, resulting in 16% and 11% of deaths globally. Although several therapeutic approaches are presented over the years, the continuously increasing mortality rates suggest the need for more advanced strategies for their treatment. One of these strategies lies in the use of stimuli-responsive biomaterials. These "smart" biomaterials can specifically target the diseased tissue, and after "reading" the altered environmental cues, they can respond by altering their physicochemical properties and/or their morphology. In this review, the progress in the field of stimuli-responsive biomaterials for CCVDs in the last five years, aiming at highlighting their potential as early-stage therapeutics in the preclinical scenery, is described.

Enzyme-manipulated hydrogelation of small molecules for biomedical applications

Enzyme-manipulated hydrogelation based on self-assembly of small molecules is an attractive methodology for development of functional biomaterials. Upon the catalysis of enzymes, small-molecular precursors are converted into assemblable building blocks, which arrange into high-ordered nanofibers via non-covalent interactions at the molecular level, and further trap water to form hydrogels at the macroscopic level. Such approach has numerous advantages of region- and enantioselectivity, and mild reaction conditions for encapsulation of biomedications or cells that are fragile to environmental change. In addition to the common applications as drug reservoirs or cell scaffolds, the utilization of endogenous enzymes as stimuli to initiate self-assembly in the living cells and tissue is considered as an intelligent spatiotemporally controllable hydrogelation strategy for biomedical applications. The enzyme-instructed in situ self-assembly and hydrogelation can modulate the cell behavior, and even present therapeutic bioactivities, which provides a new perspective in the field of disease treatment. In this review, we categorize distinct enzymatic stimuli and elaborate substrate design, catalytic characteristics, and mechanisms of self-assembly and hydrogelation. The biomedical applications in drug delivery, tissue engineering, bioimaging, and in situ gelation-produced bioactivity are outlined. Advantages and limitations regarding the state-of-the-art enzyme-driven hydrogelation technologies and future perspectives are also discussed. STATEMENT OF SIGNIFICANCE: Hydrogel is a semi-solid soft material containing a large amount of water. Due to the features of adjustable flexibility, extremely porous architecture, and the high similarity of structure to natural extracellular matrices, the hydrogel has broad application prospects in biomedicine. In recent 20 years, enzyme-manipulated hydrogelation based on self-assembly of small molecules has developed rapidly as an attractive methodology for the construction of functional biomaterials. Upon the catalysis of enzymes, small-molecular precursors are converted into assemblable building blocks, which arrange into high-ordered nanofibers via non-covalent interactions at the molecular level, and further trap water to form hydrogels at the macroscopic level. This review summarized the characteristics of enzymatic hydrogel, as well as the traditional application and emerging prospect of enzyme-instructed self-assembly and hydrogelation.

Engineering stem cell therapeutics for cardiac repair

Cardiovascular disease is the leading cause of death in the world. Stem cell-based therapies have been widely investigated for cardiac regeneration in patients with heart failure or myocardial infarction (MI) and surged ahead on multiple fronts over the past two decades. To enhance cellular therapy for cardiac regeneration, numerous engineering techniques have been explored to engineer cells, develop novel scaffolds, make constructs, and deliver cells or their derivatives. This review summarizes the state-of-art stem cell-based therapeutics for cardiac regeneration and discusses the emerged bioengineering approaches toward the enhancement of therapeutic efficacy of stem cell therapies in cardiac repair. We cover the topics in stem cell source and engineering, followed by stem cell-based therapies such as cell aggregates and cell sheets, and biomaterial-mediated stem cell therapies such as stem cell delivery with injectable hydrogel, three-dimensional scaffolds, and microneedle patches. Finally, we discuss future directions and challenges of engineering stem cell therapies for clinical translation.

Recent Advances in Peptides-Based Stimuli-Responsive Materials for Biomedical and Therapeutic Applications: A Review

Smart materials are engineered materials that have one or more properties that are introduced in a controlled fashion by surrounding stimuli. Engineering of biomacromolecules like proteins into a smart material call for meticulous artistry. Peptides have grabbed notable attention as a preferred source for smart materials in the medicinal field, promoted by their versatile chemical and biophysical attributes of biocompatibility, and biodegradability. Recent advances in the synthesis of multifunctional peptides have proliferated their application in diverse domains: agriculture, nanotechnology, medicines, biosensors, therapeutics, and soft robotics. Stimuli such as pH, temperature, light, metal ions, and enzymes have vitalized physicochemical properties of peptides by augmented sensitivity, stability, and selectivity. This review elucidates recent (2018-2021) advances in the design and synthesis of smart materials, from stimuli-responsive peptides followed by their biomedical and therapeutic applications.

Injectable Self-Healing First-Aid Tissue Adhesives with Outstanding Hemostatic and Antibacterial Performances for Trauma Emergency Care

Soft-tissue trauma emergency caused by natural disasters and traffic accidents is highly prevalent, which can result in massive bleeding, pathogen infection, and even death. Although numerous tissue adhesives can bind to tissue surfaces and cover wounds, most of them still have several deficiencies, including long gelation time, poor adhesive strength, and anti-infection, making them inappropriate for use as first-aid bandages. Herein, injectable and self-healing four-arm-PEG-CHO/polyethyleneimine (PEI) tissue adhesives as liquid first-aid supplies are developed via the dynamic Schiff base reaction for trauma emergency. It is found that the prepared hydrogel adhesives exhibit short and controlled gelation time (9∼88 s), strong adhesive strength, and excellent antibacterial ability. Their hemostatic and antimicrobial performances can be tailored by the mass ratio of four-arm-PEG-CHO/PEI. Moreover, in vitro biological assays display that the developed tissue adhesives possess satisfactory cyto/hemocompatibility. Importantly, in vivo the designed adhesives show fast hemostatic capacity and excellent anti-infection as compared to commercial Prontosan gel. Thus, this work indicates that the four-arm-PEG-CHO/PEI first-aid tissue adhesives display great potential for wound emergency management.

A GSH/CB Dual-Controlled Self-Assembled Nanomedicine for High-Efficacy Doxorubicin-Resistant Breast Cancer Therapy

Chemoresistance is a major therapeutic obstacle in the treatment of breast cancer. Therefore, how to overcome chemoresistance is a problem to be solved. Here, a glutathione (GSH)/cathepsin B (CB) dual-controlled nanomedicine formed by cyclic disulfide-bridged peptide (cyclic-1a) as a potent anticancer agent is reported. Under the sequential treatment of GSH and CB, cyclic-1a can efficiently self-assemble into nanofibers. In vitro studies show that cyclic-1a promotes the apoptosis of MCF-7/DOX cells by inducing the cleavages of caspase-3 and PARP. In vivo studies confirm that cyclic-1a significantly inhibits the progression of MCF-7/DOX cells-derived xenograft in nude mice, with no obvious adverse reactions. This study provides a paradigm of GSH/CB dual-controlled nanomedicine for high-efficacy and low-toxic DOX-resistant breast cancer therapy.

Enzyme-responsive strategy as a prospective cue to construct intelligent biomaterials for disease diagnosis and therapy

Stimuli-responsive materials have been widely studied and applied in biomedical field. Under the stimulation of enzymes, the enzyme-responsive materials (ERMs) can be triggered to change their structures, properties and functions....

Hydrogel Formation with Enzyme-Responsive Cyclic Peptides

Self-assembling peptides (SAPs), which form hydrogels through physical cross-linking of soluble structures, are an intriguing class of materials that have been applied as tissue engineering scaffolds and drug delivery vehicles. For feasible application of these tissue mimetics via minimally invasive delivery, their bulk mechanical properties must be compatible with current delivery strategies. However, injectable SAPs which possess shear-thinning capacity, as well as the ability to reassemble after cessation of shearing can be technically challenging to generate. Many SAPs either clog the high-gauge needle/catheter at high concentration during delivery or are incapable of reassembly following delivery. In this chapter, we provide a detailed protocol for topological control of enzyme-responsive peptide-based hydrogels that enable the user to access both advantages. These materials are formulated as sterically constrained cyclic peptide progelators to temporarily disrupt self-assembly during injection-based delivery, which avoids issues with clogging of needles and catheters as well as nearby vasculature. Proteolytic cleavage by enzymes produced at the target tissue induces progelator linearization and hydrogelation. The scope of this approach is demonstrated by their ability to flow through a catheter without clogging and activated gelation upon exposure to target enzymes.

Therapeutic Acellular Scaffolds for Limiting Left Ventricular Remodelling-Current Status and Future Directions

Myocardial infarction (MI) is one of the leading causes of heart-related deaths worldwide. Following MI, the hypoxic microenvironment triggers apoptosis, disrupts the extracellular matrix and forms a non-functional scar that leads towards adverse left ventricular (LV) remodelling. If left untreated this eventually leads to heart failure. Besides extensive advancement in medical therapy, complete functional recovery is never accomplished, as the heart possesses limited regenerative ability. In recent decades, the focus has shifted towards tissue engineering and regenerative strategies that provide an attractive option to improve cardiac regeneration, limit adverse LV remodelling and restore function in an infarcted heart. Acellular scaffolds possess attractive features that have made them a promising therapeutic candidate. Their application in infarcted areas has been shown to improve LV remodelling and enhance functional recovery in post-MI hearts. This review will summarise the updates on acellular scaffolds developed and tested in pre-clinical and clinical scenarios in the past five years with a focus on their ability to overcome damage caused by MI. It will also describe how acellular scaffolds alone or in combination with biomolecules have been employed for MI treatment. A better understanding of acellular scaffolds potentialities may guide the development of customised and optimised therapeutic strategies for MI treatment.

Peptide-Based Drug Delivery Systems

Peptide-based drug delivery systems have many advantages when compared to synthetic systems in that they have better biocompatibility, biochemical and biophysical properties, lack of toxicity, controlled molecular weight via solid phase synthesis and purification. Lysosomes, solid lipid nanoparticles, dendrimers, polymeric micelles can be applied by intravenous administration, however they are of artificial nature and thus may induce side effects and possess lack of ability to penetrate the blood-brain barrier. An analysis of nontoxic drug delivery systems and an establishment of prospective trends in the development of drug delivery systems was needed. This review paper summarizes data, mainly from the past 5 years, devoted to the use of peptide-based carriers for delivery of various toxic drugs, mostly anticancer or drugs with limiting bioavailability. Peptide-based drug delivery platforms are utilized as peptide–drug conjugates, injectable biodegradable particles and depots for delivering small molecule pharmaceutical substances (500 Da) and therapeutic proteins. Controlled drug delivery systems that can effectively deliver anticancer and peptide-based drugs leading to accelerated recovery without significant side effects are discussed. Moreover, cell penetrating peptides and their molecular mechanisms as targeting peptides, as well as stimuli responsive (enzyme-responsive and pH-responsive) peptides and peptide-based self-assembly scaffolds are also reviewed.

Expanding the Biocatalytic Scope of Enzyme-Loaded Polymeric Hydrogels

In recent years, polymeric hydrogels have appeared promising matrices for enzyme immobilization to design, signify and expand bio-catalysis engineering. Therefore, the development and deployment of polymeric supports in the form of hydrogels and other robust geometries are continuously growing to green the twenty-first-century bio-catalysis. Furthermore, adequately fabricated polymeric hydrogel materials offer numerous advantages that shield pristine enzymes from denaturation under harsh reaction environments. For instance, cross-linking modulation of hydrogels, distinct rheological behavior, tunable surface entities along with elasticity and mesh size, larger surface-volume area, and hydrogels' mechanical cushioning attributes are of supreme interest makes them the ideal candidate for enzyme immobilization. Furthermore, suitable coordination of polymeric hydrogels with requisite enzyme fraction enables pronounced loading, elevated biocatalytic activity, and exceptional stability. Additionally, the unique catalytic harmony of enzyme-loaded polymeric hydrogels offers numerous applications, such as hydrogels as immobilization matrix, bio-catalysis, sensing, detection and monitoring, tissue engineering, wound healing, and drug delivery applications. In this review, we spotlight the applied perspective of enzyme-loaded polymeric hydrogels with recent and relevant examples. The work also signifies the combined use of multienzyme systems and the future directions that should be attempted in this field.

Innovations in Disease State Responsive Soft Materials for Targeting Extracellular Stimuli Associated with Cancer, Cardiovascular Disease, Diabetes, and Beyond

Recent advances in polymer chemistry, materials sciences, and biotechnology have allowed the preclinical development of sophisticated programmable nanomedicines and materials that are able to precisely respond to specific disease-associated triggers and microenvironments. These stimuli, endogenous to the targeted diseases, include pH, redox-state, small molecules, and protein upregulation. Herein, recent advances and innovative approaches in programmable soft materials capable of sensing the aforementioned disease-associated stimuli and responding via a range of dynamic processes including morphological and size transitions, changes in mobility and retention, as well as disassembly are described. In this field generally, the majority of ongoing and past research effort has focused on oncology. Given this interest, examples of the latest innovative approaches to chemo- and immunotherapy treatment strategies for cancer are presented. Moreover, as the field broadens its attention, applications of programmable materials in other diseases are highlighted, with a special focus on cardiovascular disease and diabetes mellitus, where limited attention is paid by the field, but where many promising avenues exist with high potential impact.

Bioresponsive nanomedicines based on dynamic covalent bonds

Trends in the development of modern medicine necessitate the efficient delivery of therapeutics to achieve the desired treatment outcomes through precise spatiotemporal accumulation of therapeutics at the disease site. Bioresponsive nanomedicine is a promising platform for this purpose. Dynamic covalent bonds (DCBs) have attracted much attention in studies of the fabrication of bioresponsive nanomedicines with an abundance of combinations of therapeutic modules and carrier function units. DCB-based nanomedicines could be designed to maintain biological friendly synthesis and site-specific release for optimal therapeutic effects, allowing the complex to retain an integrated structure before accumulating at the disease site, but disassembling into individual active components without compromising function in the targeted organs or tissues. In this review, we focus on responsive nanomedicines containing dynamic chemical bonds that can be cleaved by various specific stimuli, enabling achievement of targeted drug release for optimal therapy in various diseases.

Intracellular artificial supramolecules based on de novo designed Y15 peptides

De novo designed self-assembling peptides (SAPs) are promising building blocks of supramolecular biomaterials, which can fulfill a wide range of applications, such as scaffolds for tissue culture, three-dimensional cell culture, and vaccine adjuvants. Nevertheless, the use of SAPs in intracellular spaces has mostly been unexplored. Here, we report a self-assembling peptide, Y15 (YEYKYEYKYEYKYEY), which readily forms β-sheet structures to facilitate bottom-up synthesis of functional protein assemblies in living cells. Superfolder green fluorescent protein (sfGFP) fused to Y15 assembles into fibrils and is observed as fluorescent puncta in mammalian cells. Y15 self-assembly is validated by fluorescence anisotropy and pull-down assays. By using the Y15 platform, we demonstrate intracellular reconstitution of Nck assembly, a Src-homology 2 and 3 domain-containing adaptor protein. The artificial clusters of Nck induce N-WASP (neural Wiskott-Aldrich syndrome protein)-mediated actin polymerization, and the functional importance of Nck domain valency and density is evaluated.