A Neutrophil-Inspired Supramolecular Nanogel for Magnetocaloric-Enzymatic Tandem Therapy

A Light-Triggered J-Aggregation-Regulated Therapy Conversion: from Photodynamic/Photothermal Therapy to Long-Lasting Chemodynamic Therapy for Effective Tumor Ablation

Reactive oxygen species (ROS) have become an effective tool for tumor treatment. The combination of photodynamic therapy (PDT) and chemodynamic therapy (CDT) takes advantage of various ROS and enhances therapeutic effects. However, the activation of CDT usually occurs before PDT, which hinders the sustained maintenance of hydroxyl radicals (⋅OH) and reduces the treatment efficiency. Herein, we present a light-triggered nano-system based on molecular aggregation regulation for converting cancer therapy from PDT/photothermal therapy (PTT) to a long-lasting CDT. The ordered J-aggregation enhances the photodynamic properties of the cyanine moiety while simultaneously suppressing the chemodynamic capabilities of the copper-porphyrin moiety. Upon light irradiation, Cu-PCy JNPs demonstrate strong photodynamic and photothermal effects. Meanwhile, light triggers a rapid degradation of the cyanine backbone, leading to the destruction of the J-aggregation. As a result, a long-lasting CDT is sequentially activated, and the sustained generation of ⋅OH is observed for up to 48 hours, causing potent cellular oxidative stress and apoptosis. Due to their excellent tumor accumulation, Cu-PCy JNPs exhibit effective in vivo tumor ablation through the converting therapy. This work provides a new approach for effectively prolonging the chemodynamic activity in ROS-based cancer therapy.

Nanomedicine-Enabled Chemical Regulation of Reactive X Species for Versatile Disease Treatments

Reactive X species (RXS), encompassing elements such as O, N, C, S, Se, Cl, Br, I, and H, play vital roles in cell biology and physiological function, impacting cellular signal transduction, metabolic regulation, and disease processes. The redox unbalance of RXS is firmly implicated in an assortment of physiological and pathological disorders, including cancer, diabetes, cardiovascular disease, and neurodegenerative diseases. However, the intricate nature and multifactorial dependence of RXS pose challenges in comprehending and precisely modulating their biological behavior. Nanomaterials with distinct characteristics and biofunctions offer promising avenues for generating or scavenging RXS to maintain redox homeostasis and advance disease therapy. This minireview provides a tutorial summary of the relevant chemistry and specific mechanisms governing different RXS, focusing on cellular metabolic regulation, stress responses, and the role of nanomedicine in RXS generation and elimination. The challenges associated with chemically regulating RXS for diverse disease treatments are further discussed along with the future prospects, aiming to facilitate the clinical translation of RXS-based nanomedicine and open new avenues for improved therapeutic interventions.

Inflammatory Cell-Inspired Cascade Nanozyme Induces Intracellular Radical Storm for Enhanced Anticancer Therapy

Manipulating intracellular levels of reactive oxygen and nitrogen species (RONS) is of great potential for cancer treatment. Inspired by the natural mechanism of a radical storm in inflammatory cells via activated and regulatable biocatalysis, the authors herein report a self-powered nanozyme that can enable RONS production in tumor cells via cascade reactions. The nanozymes are constructed via glucose oxidase (GOx)-templated inverse microemulsion polymerization from acrylamide, arginine-acrylamide, ferrocene-acrylate, and N,N'-bis(acryloyl)cystamine, followed by surface coating with hyaluronic acid. After targeted delivery into cancer cells, the nanozymes are dissociated by intracellular glutathione to release GOx, which decomposed glucose to generate gluconic acid and H₂ O₂ . Under such acidified conditions, H₂ O₂ efficiently oxidized pendant arginine residues to produce nitric oxide , transformed into a highly toxic hydroxyl radical and superoxide anion via ferrocene-mediated Fenton reaction and Haber-Weiss cycle, and simultaneously generated peroxynitrite anion via reaction between NO and ·O₂ ^- , thus provoking the RONS radical storm to effectively eradicate A549 tumor cells both in vitro and in vivo. This nature-inspired enzyme-chemical dynamic therapy may provide a promising modality for anti-cancer treatment.

Chemical, physical, and biological stimuli-responsive nanogels for biomedical applications (mechanisms, concepts, and advancements): A review

The development of nanotechnology has influenced the advancements in biomedical and pharmaceutical fields. The design and formulation of stimuli-responsive nano-drug delivery systems, also called smart drug delivery systems, have attracted significant research worldwide and have been seen as a breakthrough in nanomedicines. The ability of these nanocarriers to respond to external and internal stimuli, such as pH, temperature, redox, electric and magnetic fields, enzymes, etc., has allowed them to deliver the cargo at targeted sites in a controlled fashion. The targeted drug delivery systems limit the harmful side effects on healthy tissue by toxic drugs and furnish spatial and temporal control drug delivery, improved patient compliance, and treatment efficiency. The polymeric nanogels (hydrogel nanoparticles) with stimuli-responsive characteristics have shown great potential in various biomedical, tissue engineering, and pharmaceutical fields. It is primarily because of their small size, biocompatibility, biodegradability, stimuli-triggered drug deliverability, high payload capacity, and tailored functionality. This comprehensive review deals distinctively with polymeric nanogels, their chemical, physical, and biological stimuli, the concepts of nanogels response to different stimuli, and recent advancements. This document will further improve the current understanding of stimuli-responsive materials and drug delivery systems and assist in exploring advanced potential applications of these intelligent materials.

Spatiotemporally Controlled Formation and Rotation of Magnetic Nanochains In Vivo for Precise Mechanotherapy of Tumors

Systemic cancer therapy is always accompanied with toxicity to normal tissue, which has prompted concerted efforts to develop precise treatment strategies. Herein, we firstly develop an approach that enables spatiotemporally controlled formation and rotation of magnetic nanochains in vivo, allowing for precise mechanotherapy of tumor. The nanochain comprised nanocomposites of pheophorbide-A (PP) modified iron oxide nanoparticle (IONP) and lanthanide-doped down-conversion NP (DCNP). In a permanent magnetic field, the nanocomposites would be aligned to form nanochain. Next, MnO₂ NPs were subsequently administered to accumulate in tumor as suppliers of Mn²⁺ , which coordinates with PP to immobilize the nanochain. In a rotating magnetic field, the nanochain would rapidly rotate, leading to apoptosis/necrosis of tumor cell. The nanochain showed high T₂ -MR and NIR-II fluorescence imaging signals, which facilitated guided therapy. The strategy has great potential in practical applications.

Gold-Nanoparticle Hybrid Nanostructures for Multimodal Cancer Therapy

With the urgent need for bio-nanomaterials to improve the currently available cancer treatments, gold nanoparticle (GNP) hybrid nanostructures are rapidly rising as promising multimodal candidates for cancer therapy. Gold nanoparticles (GNPs) have been hybridized with several nanocarriers, including liposomes and polymers, to achieve chemotherapy, photothermal therapy, radiotherapy, and imaging using a single composite. The GNP nanohybrids used for targeted chemotherapy can be designed to respond to external stimuli such as heat or internal stimuli such as intratumoral pH. Despite their promise for multimodal cancer therapy, there are currently no reviews summarizing the current status of GNP nanohybrid use for cancer theragnostics. Therefore, this review fulfills this gap in the literature by providing a critical analysis of the data available on the use of GNP nanohybrids for cancer treatment with a specific focus on synergistic approaches (i.e., triggered drug release, photothermal therapy, and radiotherapy). It also highlights some of the challenges that hinder the clinical translation of GNP hybrid nanostructures from bench to bedside. Future studies that could expedite the clinical progress of GNPs, as well as the future possibility of improving GNP nanohybrids for cancer theragnostics, are also summarized.

Multifunctional stimuli-responsive hybrid nanogels for cancer therapy: Current status and challenges

With cancer research shifting focus to achieving multifunctionality in cancer treatment strategies, hybrid nanogels are making a rapid rise to the spotlight as novel, multifunctional, stimuli-responsive, and biocompatible cancer therapeutic strategies. They can possess cancer cell-specific cytotoxic effects themselves, carry drugs or enzymes that can produce cytotoxic effects, improve imaging modalities, and target tumor cells over normal cells. Hybrid nanogels bring together a wide range of desirable properties for cancer treatment such as stimuli-responsiveness, efficient loading and protection of molecules such as drugs or enzymes, and effective crossing of cellular barriers among other properties. Despite their promising abilities, hybrid nanogels are still far from being used in the clinic, and their available data remains relatively limited. However, many studies can be done to facilitate this clinical transition. This review is critically summarizing and analyzing the recent information and progress on the use of hybrid nanogels particularly inorganic nanoparticle-based and organic nanoparticle-based hybrid nanogels in the field of oncology and future directions to aid in transferring those results to the clinic. This work concludes that the future of hybrid nanogels is greatly impacted by therapeutic and non-therapeutic factors. Therapeutic factors include the lack of hemocompatibility studies, acute and chronic toxicological studies, and information on agglomeration capability and extent, tumor heterogeneity, interaction with proteins in physiological fluids, endocytosis-exocytosis, and toxicity of the nanogels' breakdown products. Non-therapeutic factors include the lack of clear regulatory guidelines and standardized assays, limitations of animal models, and difficulties associated with good manufacture practices (GMP).

Oncocyte Membrane-Camouflaged Multi-Stimuli-Responsive Nanohybrids for Synergistic Amplification of Tumor Oxidative Stresses and Photothermal Enhanced Cancer Therapy

The combination of various therapeutic modalities has received considerable attention for improving antitumor performance. Herein, an innovative nanohybrid, namely CaO₂@FePt-DOX@PDA@CM (CFDPM), was developed for synergistic chemotherapy/chemodynamic therapy/Ca²⁺ overloading-mediated amplification of tumor oxidative stress and photothermal enhanced cancer therapy. Camouflage of the 4T1 cell membrane enabled CFDPM to escape the immune surveillance and accumulate in the tumor tissue. Ca²⁺, released from CaO₂, could lead to mitochondrial dysfunction and facilitate the production of reactive oxygen species to amplify intracellular oxidative stress. Meanwhile, the increase of H₂O₂ concentration could enhance the efficiency of the chemodynamic therapy (CDT). Moreover, the hypoxic condition could be alleviated remarkably, which is attributed to the sufficient O₂ supply by CaO₂, resulting in the suppression of drug resistance and promotion of the chemotherapeutic effect. The nanohybrids involving Ca²⁺ overloading/CDT/chemotherapy could synergistically amplify the tumor oxidative stresses and remarkably aggravate the death of cancer cells. Significantly, the excellent photothermal conversion performance of CFDPM could further promote the tumoricidal effect. The in vitro and in vivo studies revealed that CFDPM could effectively advance the therapeutic efficiency via the cooperation of various therapeutic modalities to optimize their individual virtue, which would open a valuable avenue for effective cancer treatment.

Design and Development of Gold-Loaded and Boron-Attached Multicore Manganese Ferrite Nanoparticles as a Potential Agent in Biomedical Applications

Early diagnosis and effective treatment of cancer are significant issues that should be focused on since it is one of the most deadly diseases. Multifunctional nanomaterials can offer new cancer diagnoses and treatment possibilities. These nanomaterials with diverse functions, including targeting, imaging, and therapy, are being studied extensively in a way that minimize overcoming the limitations associated with traditional cancer diagnosis and treatment. Therefore, the goal of this study is to prepare multifunctional nanocomposites possessing the potential to be used simultaneously in imaging such as magnetic resonance imaging (MRI) and dual cancer therapy such as photothermal therapy (PTT) and boron neutron capture therapy (BNCT). In this context, multi-core MnFe₂O₄ nanoparticles, which can be used as a potential MRI contrast agent and target the desired region in the body via a magnetic field, were successfully synthesized via the solvothermal method. Then, multi-core nanoparticles were coated with polydopamine (PDA) to reduce gold nanoparticles, bind boron on the surface, and ensure the biocompatibility of all materials. Finally, gold nanoparticles were reduced on the surface of PDA-coated MnFe₂O₄, and boric acid was attached to the hybrid materials for also possessing the ability to be used as a potential agent in PTT and BNCT applications in addition to being an MRI agent. According to the cell viability assay, treatment of the glioblastoma cell line (T98G) with MnFe₂O₄@PDA-Au-BA for 24 and 48 h did not cause any significant cell death, indicating good biocompatibility. All analysis results showed that the developed MnFe₂O₄@PDA-Au-BA multifunctional material could be a helpful candidate for biomedical applications such as MRI, PTT, and BNCT.

Biomimetic and Materials-Potentiated Cell Engineering for Cancer Immunotherapy

In cancer immunotherapy, immune cells are the main force for tumor eradication. However, they appear to be dysfunctional due to the taming of the tumor immunosuppressive microenvironment. Recently, many materials-engineered strategies are proposed to enhance the anti-tumor effect of immune cells. These strategies either utilize biomimetic materials, as building blocks to construct inanimate entities whose functions are similar to natural living cells, or engineer immune cells with functional materials, to potentiate their anti-tumor effects. In this review, we will summarize these advanced strategies in different cell types, as well as discussing the prospects of this field.

Magnetically Boosted Generation of Intracellular Reactive Oxygen Species toward Magneto-Photodynamic Therapy

The generation of reactive oxygen species (ROS) in photodynamic therapy (PDT) involves excited-state intermediates with both singlet and triplet spin configurations, which provides possibilities to modulate the ROS production in PDT under an external magnetic field. Here, we present that magnetically modulated ROS production can promote PDT efficacy and develop a magnetic-field-assisted PDT (magneto-PDT) method for effectively and selectively killing cancer cells. The photosensitization reaction between excited-state riboflavin and oxygen molecules is influenced by the applied field, and the overall magnetic field effect (MFE) shows a moderate increase at a low field (<1000 G) and then a boost up to the saturation ∼100% at a high field (>1000 G). It is found that the spin precession occurring in radical ion pairs (electron transfer from riboflavin to oxygen) facilitates the O₂^•- generation at the low field. In comparison, the spin splitting in an encounter complex (energy transfer from riboflavin to oxygen) benefits the production of ¹O₂ species at the high field. The field modulation on the two types of ROS in PDT, i.e., O₂^•- and ¹O₂, is also demonstrated in living cells. The magneto-PDT strategy shows the capability to inhibit the proliferation of cancer cells (e.g., HeLa, RBL-2H3, and MCF-7) effectively and selectively, which reveals the potential of using the MFE on chemical reactions in biological applications.

Enzyme-Instructed Self-Assembly of Peptides: From Concept to Representative Applications

Enzyme-instructed self-assembly, integrating enzymatic reaction and molecular self-assembly, has drawn noticeable attention over the last decade with the intension of being used in valuable applications. Recent advances in the field allow it possible to spatiotemporally control peptide self-assembly in cellular milieu, broadening the potential applications of peptide assemblies to cancer therapy and subcellular delivery. In this minireview, the concept of enzyme-instructed self-assembly of peptide, containing enzymatic trigger and spatiotemporal control, is described. Representative applications in cells are also discussed, followed by outlook on the field of enzyme-instructed self-assembly.

Near-Infrared Light Triggered H2 Generation for Enhanced Photothermal/Photodynamic Therapy against Hypoxic Tumor

The principle of photochemical transformation has shown significant inspiration on phototherapy of solid tumors. However, both photodynamic therapy (PDT) and photothermal therapy (PTT) can induce stress response of tumor cells, which draw the attention in recent. Herein, an asymmetric and lollipop like nanostructure consisting of gold nanorod/titanium dioxide (l-TiO₂ -GNR) is developed by controlling single head growth of titanium dioxide (TiO₂ ) on gold nanorods (GNR). Through the reasonable utilization of hot electrons of GNR by 808 nm light irradiation, l-TiO₂ -GNR perform type I-PDT, mild PTT (48 °C), and H₂ therapy which is efficient for hypoxic tumors. In particular, H₂ can downregulate both triphosadenine and heat shock protein which are found to be main source of tumor stress response. l-TiO₂ -GNR opens a new window for treatment of hypoxic tumor by the perfect synergy of type I-PDT, mild PTT, and H₂ therapy.

One-Step Integration of Tumor Microenvironment-Responsive Calcium and Copper Peroxides Nanocomposite for Enhanced Chemodynamic/Ion-Interference Therapy

Recently, various metal peroxide nanomaterials have drawn increasing attention as an efficient hydrogen peroxide (H₂O₂) self-supplying agent for enhanced tumor therapy. However, a single kind of metal peroxide is insufficient to achieve more effective antitumor performance. Here, a hyaluronic acid modified calcium and copper peroxides nanocomposite has been synthesized by a simple one-step strategy. After effective accumulation at the tumor site due to the enhanced permeability and retention (EPR) effect and specific recognition of hyaluronate acid with CD44 protein on the surface of tumor cells, plenty of Ca²⁺, Cu²⁺, and H₂O₂ can be simultaneously released in acid and hyaluronidase overexpressed tumor microenvironment (TME), generating abundant hydroxyl radical through enhanced Fenton-type reaction between Cu²⁺ and self-supplying H₂O₂ with the assistance of glutathione depletion. Overloaded Ca²⁺ can lead to mitochondria injury and thus enhance the oxidative stress in tumor cells. Moreover, an unbalanced calcium transport channel caused by oxidative stress can further promote tumor calcification and necrosis, which is generally defined as ion-interference therapy. As a result, the synergistic effect of Fenton-like reaction by Cu²⁺ and mitochondria dysfunction by Ca²⁺ in ROS generation is performed. Therefore, a TME-responsive calcium and copper peroxides nanocomposite based on one-step integration has been successfully established and exhibits a more satisfactory antitumor efficiency than any single kind of metal peroxide.

A MXene-Based Bionic Cascaded-Enzyme Nanoreactor for Tumor Phototherapy/Enzyme Dynamic Therapy and Hypoxia-Activated Chemotherapy

The enzyme-mediated elevation of reactive oxygen species (ROS) at the tumor sites has become an emerging strategy for regulating intracellular redox status for anticancer treatment. Herein, we proposed a camouflaged bionic cascaded-enzyme nanoreactor based on Ti₃C₂ nanosheets for combined tumor enzyme dynamic therapy (EDT), phototherapy and deoxygenation-activated chemotherapy. Briefly, glucose oxidase (GOX) and chloroperoxidase (CPO) were chemically conjugated onto Ti₃C₂ nanosheets, where the deoxygenation-activated drug tirapazamine (TPZ) was also loaded, and the Ti₃C₂-GOX-CPO/TPZ (TGCT) was embedded into nanosized cancer cell-derived membrane vesicles with high-expressed CD47 (m_eTGCT). Due to biomimetic membrane camouflage and CD47 overexpression, m_eTGCT exhibited superior immune escape and homologous targeting capacities, which could effectively enhance the tumor preferential targeting and internalization. Once internalized into tumor cells, the cascade reaction of GOX and CPO could generate HClO for efficient EDT. Simultaneously, additional laser irradiation could accelerate the enzymic-catalytic reaction rate and increase the generation of singlet oxygen (¹O₂). Furthermore, local hypoxia environment with the oxygen depletion by EDT would activate deoxygenation-sensitive prodrug for additional chemotherapy. Consequently, m_eTGCT exhibits amplified synergistic therapeutic effects of tumor phototherapy, EDT and chemotherapy for efficient tumor inhibition. This intelligent cascaded-enzyme nanoreactor provides a promising approach to achieve concurrent and significant antitumor therapy.

Peroxisome inspired hybrid enzyme nanogels for chemodynamic and photodynamic therapy

Peroxisome, a special cytoplasmic organelle, possesses one or more kinds of oxidases for hydrogen peroxide (H₂O₂) production and catalase for H₂O₂ degradation, which serves as an intracellular H₂O₂ regulator to degrade toxic peroxides to water. Inspired by this biochemical pathway, we demonstrate the reactive oxygen species (ROS) induced tumor therapy by integrating lactate oxidase (LOx) and catalase (CAT) into Fe₃O₄ nanoparticle/indocyanine green (ICG) co-loaded hybrid nanogels (designated as FIGs-LC). Based on the O₂ redistribution and H₂O₂ activation by cascading LOx and CAT catalytic metabolic regulation, hydroxyl radical (·OH) and singlet oxygen (¹O₂) production can be modulated for glutathione (GSH)-activated chemodynamic therapy (CDT) and NIR-triggered photodynamic therapy (PDT), by manipulating the ratio of LOx and CAT to catalyze endogenous lactate to produce H₂O₂ and further cascade decomposing H₂O₂ into O₂. The regulation reactions of FIGs-LC significantly elevate the intracellular ROS level and cause fatal damage to cancer cells inducing the effective inhibition of tumor growth. Such enzyme complex loaded hybrid nanogel present potential for biomedical ROS regulation, especially for the tumors with different redox state, size, and subcutaneous depth.

The control of reactive oxygen species in cancer cells is an attractive approach for anticancer applications. Here, the authors create a peroxisome inspired lactate oxidase and catalase loaded hydrogel with iron nanoparticles and NIR photosensitizer for glutathione activated chemodynamic and photodynamic therapy.

A Tumor-Microenvironment-Responsive Nanocomposite for Hydrogen Sulfide Gas and Trimodal-Enhanced Enzyme Dynamic Therapy

Recently, enzyme dynamic therapy (EDT) has drawn much attention as a new type of dynamic therapy. However, the selection of suitable nanocarriers to deliver chloroperoxidase (CPO) and enhancement of the level of hydrogen peroxide (H2 O2 ) in the tumor microenvironment (TME) are critical factors for improving the efficiency of EDT. In this study, a rapidly decomposing nanocomposite is designed using tetra-sulfide-bond-incorporating dendritic mesoporous organosilica (DMOS) as a nanocarrier, followed by loading CPO and sodium-hyaluronate-modified calcium peroxide nanoparticles (CaO2 -HA NPs). The nanocomposite can effectively generate singlet oxygen (1 O2 ) for tumor therapy without any exogenous stimulus via trimodal-enhanced EDT, including DMOS-induced depletion of glutathione (GSH), H2 O2 compensation from CaO2 -HA NPs in mildly acidic TME, and oxidative stress caused by overloading of Ca2+ . As tetra-sulfide bonds are sensitive to GSH, DMOS can generate hydrogen sulfide (H2 S) gas as a new kind of H2 S gas nanoreactor. Additionally, the overloading of Ca2+ can cause tumor calcification to accelerate in vivo tumor necrosis and promote computed tomography imaging efficacy. Therefore, a novel H2 S gas, EDT, and Ca2+ -interference combined therapy strategy is developed.

Magnetic-responsive hydrogels: From strategic design to biomedical applications

Smart hydrogels which can respond to external stimuli have been widely focused with increasing interest. Thereinto, magnetic-responsive hydrogels that are prepared by embedding magnetic nanomaterials into hydrogel networks are more advantageous in biomedical applications due to their rapid magnetic response, precisely temporal and spatial control and non-invasively remote actuation. Upon the application of an external magnetic field, magnetic hydrogels can be actuated to perform multiple response modes such as locomotion, deformation and thermogenesis for therapeutic purposes without the limit of tissue penetration depth. This review summarizes the latest advances of magnetic-responsive hydrogels with focus on biomedical applications. The synthetic methods of magnetic hydrogels are firstly introduced. Then, the roles of different response modes of magnetic hydrogels played in different biomedical applications are emphatically discussed in detail. In the end, the current limitations and future perspectives for magnetic hydrogels are given.

Photoresponsive metallopolymer nanoparticles for cancer theranostics

Over the past decades, transition metal complexes have been successfully used in anticancer phototherapies. They have shown promising properties in many different areas including photo-induced ligand exchange or release, rich excited state behavior, and versatile biochemical properties. When encorporated into polymeric frameworks and become part of nanostructures, photoresponsive metallopolymer nanoparticles (MPNs) show enhanced water solubility, extended blood circulation and increased tumor-specific accumulation, which greatly improves the tumor therapeutic effects compared to low-molecule-weight metal complexes. In this review, we aim to present the recent development of photoresponsive MPNs as therapeutic nanomedicines. This review will summarize four major areas separately, namely platinum-containing polymers, zinc-containing polymers, iridium-containing polymers and ruthenium-containing polymers. Representative MPNs of each type are discussed in terms of their design strategies, fabrication methods, and working mechanisms. Current challenges and future perspectives in this field are also highlighted.

Enzyme-Laden Bioactive Hydrogel for Biocatalytic Monitoring and Regulation

Enzymes, a class of highly efficient and specific catalysts in Nature, dictate a myriad of reactions that constitute various cascades in biological systems. There is growing evidence that many cellular reactions within metabolic pathways are catalyzed by matrix-associated multienzyme complexes, not via the free enzymes, verifying the vital effects of microenvironmental organization, which would reveal implications for the high efficiency, specificity, and regulation of metabolic pathways. The extracellular matrix (ECM), as the noncellular component, is composed of various proteins such as collagens, laminins, proteoglycans, and remodeling enzymes, playing the key role in tissue architecture and homeostasis. Hydrogels are defined as highly hydrated polymer materials and maintain structural integrity by physical and chemical force, which are thought of as the most suitable materials for matching the chemical, physical, and mechanical properties with natural ECM. As one specific type of soft and wet materials, hydrogels are suitable three-dimensional carriers to locally confine bioactive guests, such as enzymes, for molecular-level biological interactions. The efficient cascade catalysis can be realized by enzyme-laden hydrogels, which can potentially interact with cells and tissues by material-to-biology communication. In this Account, we present recent progress on the preparation of enzymatic bioactive hydrogels, including in situ coassembly, in situ cross-linking strategy, and in situ enzymatic radical polymerization technology, further promoting their applications on biomedical tissue engineering, biocatalytic health monitoring, and therapeutic research. First, we provide a brief introduction of the basic concept related to an enzymatic strategy in living systems and the importance of bioinspired enzyme-laden bioactive hydrogel systems. We discuss the difficulties of the fabrication of a bioactive hydrogel with a high catalytic efficiency, thereby providing the novel molecular design and regulation based on a noncovalent coassembly and in situ self-immobilization strategy to obtain the compartmentalized enzyme-laden structure. Then the applications of an enzyme-laden bioactive hydrogel for biocatalytic applications are discussed in detail. The enzyme-laden bioactive hydrogel can maintain the favorable perception and regulation behavior of enzymes with optimal enzymatic efficacy between this confined hydrogel network and a surrounding environment. A highlight to the advances in the responsively biocatalytic monitoring and regulation of bioactive hydrogel, including the enzymatic biomedical tissue engineering and health monitoring, enzymatic regulation of tumor reactive oxygen species and therapeutic research are given. Finally, the outlook of open challenges and future developments of this rapidly evolving field is provided. This Account with highlights of diverse enzyme-laden bioactive hydrogel systems not only provides interesting insights to understand the cascade enzymatic strategy of life but also inspires to broaden and enhance the molecular-level material design and bioapplications of existing enzymatic materials in chemistry, materials science, and biology.

Recent Progress in the Design and Application of Supramolecular Peptide Hydrogels in Cancer Therapy

Supramolecular peptide hydrogel (SPH) is a class of biomaterials self-assembled from peptide-based gelators through non-covalent interactions. Among many of its biomedical applications, the potential of SPH in cancer therapy has been vastly explored in the past decade, taking advantage of its good biocompatibility, multifunctionality, and injectability. SPHs can exert localized cancer therapy and induce systemic anticancer immunity to prevent tumor recurrence, depending on the design of SPH. This review first gives a brief introduction to SPH and then outlines the major types of peptide-based gelators that have been developed so far. The methodologies to tune the physicochemical properties and biological activities are summarized. The recent advances of SPH in cancer therapy as carriers, prodrugs, or drugs are highlighted. Finally, the clinical translation potential and main challenges in this field are also discussed.

Magnetic microgels and nanogels: Physical mechanisms and biomedical applications

Soft micro- and nanostructures have been extensively developed for biomedical applications. The main focus has been on multifunctional composite materials that combine the advantages of hydrogels and colloidal particles. Magnetic microgels and nanogels can be realized by hybridizing stimuli-sensitive gels and magnetic nanoparticles. They are of particular interest since they can be controlled in a wide range of biological environments by using magnetic fields. In this review, we elucidate physical principles underlying the design of magnetic microgels and nanogels for biomedical applications. Particularly, this article provides a comprehensive and conceptual overview on the correlative structural design and physical functionality of the magnetic gel systems under the concept of colloidal biodevices. To this end, we begin with an overview of physicochemical mechanisms related to stimuli-responsive hydrogels and transport phenomena and summarize the magnetic properties of inorganic nanoparticles. On the basis of the engineering principles, we categorize and summarize recent advances in magnetic hybrid microgels and nanogels, with emphasis on the biomedical applications of these materials. Potential applications of these hybrid microgels and nanogels in anticancer treatment, protein therapeutics, gene therapy, bioseparation, biocatalysis, and regenerative medicine are highlighted. Finally, current challenges and future opportunities in the design of smart colloidal biodevices are discussed.

Enzymatic Noncovalent Synthesis

Enzymatic reactions and noncovalent (i.e., supramolecular) interactions are two fundamental nongenetic attributes of life. Enzymatic noncovalent synthesis (ENS) refers to a process where enzymatic reactions control intermolecular noncovalent interactions for spatial organization of higher-order molecular assemblies that exhibit emergent properties and functions. Like enzymatic covalent synthesis (ECS), in which an enzyme catalyzes the formation of covalent bonds to generate individual molecules, ENS is a unifying theme for understanding the functions, morphologies, and locations of molecular ensembles in cellular environments. This review intends to provide a summary of the works of ENS within the past decade and emphasize ENS for functions. After comparing ECS and ENS, we describe a few representative examples where nature uses ENS, as a rule of life, to create the ensembles of biomacromolecules for emergent properties/functions in a myriad of cellular processes. Then, we focus on ENS of man-made (synthetic) molecules in cell-free conditions, classified by the types of enzymes. After that, we introduce the exploration of ENS of man-made molecules in the context of cells by discussing intercellular, peri/intracellular, and subcellular ENS for cell morphogenesis, molecular imaging, cancer therapy, and other applications. Finally, we provide a perspective on the promises of ENS for developing molecular assemblies/processes for functions. This review aims to be an updated introduction for researchers who are interested in exploring noncovalent synthesis for developing molecular science and technologies to address societal needs.

Recent Advances in Crosslinked Nanogel for Multimodal Imaging and Cancer Therapy

Nanomaterials have been widely applied in the field of cancer imaging and therapy. However, conventional nanoparticles including micelles and liposomes may suffer the issue of dissociation in the circulation. In contrast, crosslinked nanogels the structures of which are covalently crosslinked have better physiological stability than micelles and liposomes, making them more suitable for cancer theranostics. In this review, we summarize recent advances in crosslinked nanogels for cancer imaging and therapy. The applications of nanogels in drug and gene delivery as well as development of novel cancer therapeutic methods are first introduced, followed by the introduction of applications in optical and multimodal imaging, and imaging-guided cancer therapy. The conclusion and future direction in this field are discussed at the end of this review.