Intracellular construction of topology-controlled polypeptide nanostructures with diverse biological functions

Polymerization in Living Organisms for Biomedical Applications

Intra-tissue polymerization as a kind of polymerization reaction in biological tissues has the advantages of good biocompatibility, accurate localization, and dynamic response. In this review, the progress and applications of intra-tissue polymerization technologies in biomedicine are summarized. The biomedical applications of polymerization in different tissues are discussed, including living neural tissues to improve neural device performance, preparation of electronic devices in plants and animals, polymerization in tumor tissues for therapeutic and monitoring purposes, and polymerization in skin tissues for wound monitoring and therapy. Various polymerization strategies, including electrochemical polymerization, enzymatic polymerization, photopolymerization, and free radical polymerization, are used and described in the different intra-tissue polymerization methods. Moreover, the challenges in this field are discussed, such as the precise control of polymerization reactions and the development of biocompatible materials, and the future development direction of this field is also prospected.

Synthesis of Abiotic Supramolecular Polymers Inside Living Cells via Organocatalysis-Mediated Self-Assembly

Cells execute mesmerizing functions using supramolecular polymers (SPs) formed through the self-assembly of biological precursors. Integration of the vast array of synthetic SPs with living cells would offer a powerful way to remold cellular functions and bridge the gap between synthetic materials and the biological realm, yet remains a challenge because of the lack of robust abiotic SP systems that can be triggered to self-assemble inside cells. Here, we report how fully abiotic SPs can be synthesized inside living cells via an organocatalysis-responsive self-assembly strategy, and how the in situ-generated SPs are capable of interfering and can interfere with cellular functions. The incorporation of a nucleophilic organocatalyst (CAT) into living cells accelerates the intracellular conversion of hydrazide (H) and aldehyde-derived precursors (A) to hydrazone-based monomers (HA3) that locally self-assemble into SPs. Interestingly, the in situ-generated SPs possess ignorable effects on cell viability and proliferation but remarkably hinder cell migration. Furthermore, the presence of SPs is found to retard intracellular diffusion and alter the organization of the actin cytoskeleton, both of which are suggested to be responsible for the hindered cellular migration. In considering the vastly wide range of synthetic SPs, tremendous non-natural cellular functionalities can be obtained by in situ-synthesizing SPs.

Glutathione and transglutaminase responsive janus gold nanorods for photoacoustic imaging-guided radiotherapy and chemodynamic therapy of tumors

Gold nanorods (AuNRs) have become promising as radiosensitizers and photoacoustic (PA) imaging agents due to their strong X-ray attenuation ability and adjustable near-infrared (NIR) absorption. However, there remains room to further improve AuNRs for the imaging and treatment of tumors. We developed a biomarker responsive AuNR-based Janus nanoprobe by integrating MnO2 on one end of the AuNRs and specific ligands on the other end. In the tumor microenvironment, highly expressed transglutaminase (TGase), which facilitates the formation of isopeptide linkages between glutamine (Gln) and lysine (Lys), induces the aggregation of AuNRs. This in-situ aggregation amplifies the PA signal, extends the time window for PA imaging and enhances the radiosensitization effect. Meanwhile, the highly expressed glutathione (GSH) in tumors degrades MnO2 which triggers a chemodynamic treatment.

Harnessing Amino Acid Modularity for Programmable Function in Covalent Peptide Assemblies

Covalent peptide assembly leverages robust covalent bonds and dynamic non-covalent interactions to provide enhanced stability and introduce diverse functionalities. Nevertheless, it remains significantly challenging to achieve modular control over the structural diversity and functional complexity while elucidating how specific amino acid sequences contribute to these processes. Here, the systematic encoding of peptide derivative characteristics is demonstrated through amino acid modularity to enable precise control over both the structural diversity and functional complexity in covalent peptide assemblies. By systematically screening single amino acid substitutions in pentapeptides using tyrosine crosslinking, a diverse library of peptide constructs is developed. Each construct is tailored to exhibit distinct properties, including charge repulsion, aggregation-induced quenching, disassembly behavior, and redox responsiveness. The strategic manipulation of sequence composition, both in individual assemblies and combinatorial systems, enables programmable control over the structural diversity and functional complexity. This approach yields various module-specific functions, including frustrated growth, hierarchical hollow architecture formation, affinity enrichment, stimuli-responsive behavior, and fluorescence signal amplification. This work establishes a framework for the design of modular peptide materials with programmable functionalities, advancing the development of next-generation multicomponent peptide assembly technologies characterized by unprecedented complexity and adaptability.

Hypoxia-Initiated Supramolecular Free Radicals Induce Intracellular Polymerization for Precision Tumor Therapy

Despite the development of various controlled release systems for antitumor therapies, off-target side effects remain a persistent challenge. In situ therapeutic synthesis from biocompatible substances offers a safer and more precise alternative. This study presents a hypoxia-initiated supramolecular free radical system capable of inducing intracellular polymerization, thereby disrupting the cytoskeleton and organelles within 4T1 cells. The system utilizes a 2:1 supramolecular host-guest complex of cucurbit[7]uril (CB[7]) and perylene diimide derivative (PDI), termed PDI+2CB[7], which is selectively reduced by the tumor's hypoxic and reducing environment to generate delocalized free radical anions. CB[7] effectively stabilizes these anions, enabling the PDI+2CB[7] complex to initiate free radical polymerization with 2-hydroxyethyl methacrylate (HEMA) inside the 4T1 cells. The resulting in situ polymerization significantly disrupts tumor metabolism, leading to a strong antitumor response without systemic toxicity. This study demonstrates that stable, endogenous stimulus-induced supramolecular free radicals can trigger intracellular polymerization reactions, achieving a selective and effective antitumor therapy without conventional chemotherapeutic agents.

Light-Controlled Intracellular Synthesis of Poly(luciferin) Polymers Induces Cell Paraptosis

Accumulation of misfolded proteins challenges cellular proteostasis and is implicated in aging and chronic disorders. Cancer cells, moreover, face an elevated level of basal proteotoxic stress; hence, exacerbating endoplasmic reticulum (ER) stress has been shown to induce programmed cell death while enhancing anticancer immunogenicity. We hypothesize that hydrophobic abiotic macromolecules can trigger a similar stress response. Most polymers and nanoparticles, however, are sequestered in endo/lysosomes after endocytosis, which prevents their interaction with the proteostasis machinery. We adopted an in situ polymerization approach to synthesize polymers in cells with cell-permeable monomers. Specifically, we developed a biocompatible polycondensation between l-cysteine and 2-cyanobenzothiazole (CBT) with photochemical control to form insoluble poly(luciferin) aggregates. We identified that in situ polymerization activates the BiP-PERK-CHOP pathway of the unfolded protein response and that the unresolved ER stress initiates a form of regulated cell death consistent with paraptosis. In addition, the dying cells emit damage-associated molecular patterns (DAMPs), indicating an immunogenic cell death that could potentiate antitumor immunity. Our results show that in situ polymerization mimics misfolded protein aggregates to induce proteotoxic stress and cancer cell death, offering a novel therapeutic strategy to exploit cancer vulnerability.

Engineering Cyborg Pathogens through Intracellular Hydrogelation

Synthetic biology primarily focuses on two kinds of cell chassis: living cells and nonliving systems. Living cells are autoreplicating systems that have active metabolism. Nonliving systems, including artificial cells and nanoparticles, are nonreplicating systems typically lacking active metabolism. In recent work, Cyborg bacteria that are nonreplicating-but-metabolically active have been engineered through intracellular hydrogelation. Intracellular hydrogelation is conducted by infusing gel monomers and photoactivators into cells, followed by the activation of polymerization of the gel monomers inside the cells. However, the previous work investigated only Escherichia coli cells. Extending the Cyborg-Cell method to pathogenic bacteria could enable the exploitation of their pathogenic properties in biomedical applications. Here, we focus on different strains of Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae. To synthesize the Cyborg pathogens, we first reveal the impact of different hydrogel concentrations on the metabolism, replication, and intracellular gelation of Cyborg pathogens. Next, we demonstrate that the Cyborg pathogens are taken up by macrophages in a similar magnitude as wild-type pathogens through confocal microscopy and real-time PCR. Finally, we show that the macrophage that takes up the Cyborg pathogen exhibits a similar phenotypic response to the wild-type pathogen. Our work generalizes the intracellular hydrogelation approach from lab strains of E. coli to bacterial pathogens. The new Cyborg pathogens could be applied in biomedical applications ranging from drug delivery to immunotherapy.

Noncanonical Amino Acid Incorporation Modulates Condensate States of Intrinsically Disordered Proteins in Escherichia coli Cells

Biomolecular condensates are distinct subcellular structures with on-demand material states and dynamics in living cells. However, strategies for modulating their material states and physicochemical properties are lacking. Here, we report a chemical strategy for modulating the condensate states of intrinsically disordered proteins in bacterial Escherichia coli cells. This is achieved by noncanonical amino acid (DOPA) incorporation into model resilin-like proteins (RLPs) to endow autonomous oxidative and coordinative cross-linking mechanisms. Biogenesis of spherical gel-like condensates is achieved upon heterologous expression of the DOPA-incorporated RLP in the cells at 30 °C. We reveal that liquid-liquid phase separation underlies the formation of liquid condensates, and this liquid-like state is metastable and its dynamics is compromised by the oxidative and coordinative cross-linkings that ultimately drive the liquid-to-gel transition. Therefore, this study has deepened our understanding of biomolecular condensation and offers a new chemical strategy to expand the landscape of condensation phenotypes of living cells.

Synthetic Nanoassemblies for Regulating Organelles: From Molecular Design to Precision Therapeutics

Each organelle referring to a complex multiorder architecture executes respective biological processes via its distinct spatial organization and internal microenvironment. As the assembly of biomolecules is the structural basis of living cells, creating synthetic nanoassemblies with specific physicochemical and morphological properties in living cells to interfere or couple with the natural organelle architectures has attracted great attention in precision therapeutics of cancers. In this review, we give an overview of the latest advances in the synthetic nanoassemblies for precise organelle regulation, including the formation mechanisms, triggering strategies, and biomedical applications in precision therapeutics. We summarize the emerging material systems, including polymers, peptides, and deoxyribonucleic acids (DNAs), and their respective intermolecular interactions for intercellular synthetic nanoassemblies, and highlight their design principles in constructing precursors that assemble into synthetic nanoassemblies targeting specific organelles in the complex cellular environment. We further showcase the developed intracellular synthetic nanoassemblies targeting specific organelles including mitochondria, the endoplasmic reticulum, lysosome, Golgi apparatus, and nucleus and describe their underlying mechanisms for organelle regulation and precision therapeutics for cancer. Last, the essential challenges in this field and prospects for future precision therapeutics of synthetic nanoassemblies are discussed. This review should facilitate the rational design of organelle-targeting synthetic nanoassemblies and the comprehensive recognition of organelles by materials and contribute to the deep understanding and application of the synthetic nanoassemblies for precision therapeutics.

Artificial Polymerizations in Living Organisms for Biomedical Applications

Within living organisms, numerous nanomachines are constantly involved in complex polymerization processes, generating a diverse array of biomacromolecules for maintaining biological activities. Transporting artificial polymerizations from lab settings into biological contexts has expanded opportunities for understanding and managing biological events, creating novel cellular compartments, and introducing new functionalities. This review summarizes the recent advancements in artificial polymerizations, including those responding to external stimuli, internal environmental factors, and those that polymerize spontaneously. More importantly, the cutting-edge biomedical application scenarios of artificial polymerization, notably in safeguarding cells, modulating biological events, improving diagnostic performance, and facilitating therapeutic efficacy are highlighted. Finally, this review outlines the key challenges and technological obstacles that remain for polymerizations in biological organisms, as well as offers insights into potential directions for advancing their practical applications and clinical trials.

Self-Assembled Peptide with Morphological Structure for Bioapplication

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

Deformable nanocarriers for enhanced drug delivery and cancer therapy

Recently, the field of nanomedicine has witnessed substantial advancements in the development of nanocarriers for targeted drug delivery, emerges as promising platforms to enhance therapeutic efficacy and minimize adverse effects associated with conventional chemotherapy. Notably, deformable nanocarriers have garnered considerable attention due to their unique capabilities of size changeable, tumor-specific aggregation, stimuli-triggered disintegration, and morphological transformations. These deformable nanocarriers present significant opportunities for revolutionizing drug delivery strategies, by responding to specific stimuli or environmental cues, enabling achieved various functions at the tumor site, including size-shrinkage nanocarriers enhance drug penetration, aggregative nanocarriers enhance retention effect, disintegrating nanocarriers enable controlled drug release, and shape-changing nanocarriers improve cellular uptake, allowing for personalized treatment approaches and combination therapies. This review provides an overview of recent developments and applications of deformable nanocarriers for enhancing tumor therapy, underscores the diverse design strategies employed to create deformable nanocarriers and elucidates their remarkable potential in targeted tumor therapy.

Encoding signal propagation on topology-programmed DNA origami

Biological systems often rely on topological transformation to reconfigure connectivity between nodes to guide the flux of molecular information. Here we develop a topology-programmed DNA origami system that encodes signal propagation at the nanoscale, analogous to topologically efficient information processing in cellular systems. We present a systematic molecular implementation of topological operations involving 'glue-cut' processes that can prompt global conformational change of DNA origami structures, with demonstrated major topological properties including genus, number of boundary components and orientability. By spatially arranging reactive DNA hairpins, we demonstrate signal propagation across transmission paths of varying lengths and orientations, and curvatures on the curved surfaces of three-dimensional origamis. These DNA origamis can also form dynamic scaffolds for regulating the spatial and temporal signal propagations whereby topological transformations spontaneously alter the location of nodes and boundary of signal propagation network. We anticipate that our strategy for topological operations will provide a general route to manufacture dynamic DNA origami nanostructures capable of performing global structural transformations under programmable control.

Depleting profibrotic macrophages using bioactivated in vivo assembly peptides ameliorates kidney fibrosis

Managing renal fibrosis is challenging owing to the complex cell signaling redundancy in diseased kidneys. Renal fibrosis involves an immune response dominated by macrophages, which activates myofibroblasts in fibrotic niches. However, macrophages exhibit high heterogeneity, hindering their potential as therapeutic cell targets. Herein, we aimed to eliminate specific macrophage subsets that drive the profibrotic immune response in the kidney both temporally and spatially. We identified the major profibrotic macrophage subset (Fn1+Spp1+Arg1+) in the kidney and then constructed a 12-mer glycopeptide that was designated as bioactivated in vivo assembly PK (BIVA-PK) to deplete these cells. BIVA-PK specifically binds to and is internalized by profibrotic macrophages. By inducing macrophage cell death, BIVA-PK reshaped the renal microenvironment and suppressed profibrotic immune responses. The robust efficacy of BIVA-PK in ameliorating renal fibrosis and preserving kidney function highlights the value of targeting macrophage subsets as a potential therapy for patients with CKD.

Light-mediated intracellular polymerization

The synthesis of synthetic intracellular polymers offers groundbreaking possibilities in cellular biology and medical research, allowing for novel experiments in drug delivery, bioimaging and targeted cancer therapies. These macromolecules, composed of biocompatible monomers, are pivotal in manipulating cellular functions and pathways due to their bioavailability, cytocompatibility and distinct chemical properties. This protocol details two innovative methods for intracellular polymerization. The first one uses 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) as a photoinitiator for free radical polymerization under UV light (365 nm, 5 mW/cm2). The second method employs photoinduced electron transfer-reversible addition-fragmentation chain-transfer polymerization with visible light (470 nm, 100 mW/cm2). We further elaborate on isolating these intracellular polymers by streptavidin/biotin interaction or immobilized metal ion affinity chromatography for polymers tagged with biotin or histidine. The entire process, from polymerization to isolation, takes ~48 h. Moreover, the intracellular polymers thus generated demonstrate significant potential in enhancing actin polymerization, in bioimaging applications and as a novel avenue in cancer treatment strategies. The protocol extends to animal models, providing a comprehensive approach from cellular to systemic applications. Users are advised to have a basic understanding of organic synthesis and cell biology techniques.

Enzyme-Instructed Photoactivatable Supramolecular Antigens on Cancer Cell Membranes for Precision-Controlled T-Cell-Based Cancer Immunotherapy

Cancer immunotherapies based on cytotoxic CD8+ T lymphocytes (CTLs) are highly promising for cancer treatment. The specific interaction between T-cell receptors and peptide-MHC-I complexes (pMHC-I) on cancer cell membranes critically determines their therapeutic outcomes. However, the lack of appropriate endogenous antigens for MHC-I presentation disables tumor recognition by CTLs. By devising three antigen-loaded self-assembling peptides of pY-K(Ag)-ERGD, pY-K(Ag)-E, and Y-K(Ag)-ERGD to noncovalently generate light-activatable supramolecular antigens at tumor sites in different manners, we report pY-K(Ag)-ERGD as a promising candidate to endow tumor cells with pMHC-I targets on demand. Specifically, pY-K(Ag)-ERGD first generates low-antigenic supramolecular antigens on cancer cell membranes, and a successive light pulse allows antigen payloads to efficiently release from the supramolecular scaffold, directly producing antigenic pMHC-I. Intravenous administration of pY-K(Ag)-ERGD enables light-controlled tumor inhibition when combined with adoptively transferred antigen-specific CTLs. Our strategy is feasible for broadening tumor antigen repertoires for T-cell immunotherapies and advancing precision-controlled T-cell immunotherapies.

Bioorthogonal In Situ Polymerization of Dendritic Agents for Hijacking Lysosomes and Enhancing Antigen Presentation in Cancer Cells

A low-generation lysine dendrimer, SPr-G2, responds to intracellular glutathione to initiate bioorthogonal in situ polymerization, resulting in the formation of large assemblies in mouse breast cancer cells. The intracellular large assemblies of SPr-G2 can interact with lysosomes to induce lysosome expansion and enhance lysosomal membrane permeabilization, leading to major histocompatibility complex class I upregulation on tumor cell surfaces and ultimately tumor cell death. Moreover, the use of the SPr-G2 dendrimer to conjugate the chemotherapeutic drug, camptothecin (CPT), can boost the therapeutic potency of CPT. Excellent antitumor effects in vitro and in vivo are obtained from the combinational treatment of the SPr-G2 dendrimer and CPT. This combinational effect also enhances antitumor immunity through promoting activation of cytotoxic T cells in tumor tissues and maturation of dendritic cells. This study can shed new light on the development of peptide dendritic agents for cancer therapy.

Synthetic control of living cells by intracellular polymerization

An emerging cellular engineering method creates synthetic polymer matrices inside cells. By contrast with classical genetic, enzymatic, or radioactive techniques, this materials-based approach introduces non-natural polymers inside cells, thus modifying cellular states and functionalities. Here, we cover various materials and chemistries that have been exploited to create intracellular polymer matrices. In addition, we discuss emergent cellular properties due to the intracellular polymerization, including nonreplicating but active metabolism, maintenance of membrane integrity, and resistance to environmental stressors. We also discuss past work and future opportunities for developing and applying synthetic cells that contain intracellular polymers. The materials-based approach will usher in new applications of synthetic cells for broad biotechnological applications.

Intranasal Morphology Transformation Nanomedicines for Long-Term Intervention of Allergic Rhinitis

Intranasal administration has been widely explored as a potential treatment for allergic rhinitis, and improving intranasal penetration and retention of drugs is a challenging requirement to further improve efficacy. Delivery strategies of nanocarriers that enhance mucosal adhesion or mucus penetration have been proposed to improve nasal drug delivery; however, delivery efficiency remains limited by excessive pulmonary deposition and nonspecific cell phagocytosis. In this work, a "nasal in situ assembly" strategy was presented to construct intranasal morphology transformation nanomedicines with enhanced effective drug concentration for long-term intervention of allergic rhinitis. The polymer-polypeptide nanomedicine (PHCK) with a CCR3 antagonistic peptide (C) and a pH-responsive polyethylene glycol (H) was developed, encapsulating ketotifen (KT). PHCK nanoparticles displayed nasal mucosa permeability and transformed to nanofibers in the acidic environment of the nasal cavity, realizing responsive burst release of KT simultaneously. The fibrotic reassembly reduced the cellular internalization of nanomedicine and increased the CCR3 blockade on the eosinophil (EOS) membranes. Both in vitro and in vivo data indicated that PHCK achieved improved drug accumulation and retention in the nasal cavity and decreased pulmonary deposition, then effectively inhibited mast cell degranulation and EOS chemotaxis. This study demonstrates that the "nasal in situ assembly" strategy can improve drug delivery efficiency upon nasal responsive morphologic transformation, providing exploratory perspectives for nasal delivery platforms establishment and boosting therapeutic effect of allergic rhinitis.

Engineered Extracellular Vesicles to Enhance Antigen Presentation for Boosting Light-Driven Tumor Immunotherapy

Extracellular vesicles (EVs) have emerged as potential tools for tumor-target therapy accompanied with activating anticancer immune responses by serving as an integrated platform, but usually suffered from the limited cross presentation of tumor-associated antigen by dendritic cells (DCs). Here, a straightforward engineering strategy to construct heat shock proteins 70 (HSP70) highly expressed EVs incapsulated with Te nanoparticles (Te@EVsHSP70 ) for tumor photothermal therapy triggering improved immunotherapy is proposed. Tumor cells are firstly used as bioreactors for intracellular synthesis of Te nanoparticles, and NIR irradiation is subsequently introduced to upregulate the expression of HSP70 to give engineered Te@EVsHSP70 through exocytosis. Te@EVsHSP70 exhibits excellent photothermal performance and enhanced tumor antigen capture capability, which induces significant immunogenic death of tumor cells and improves DCs maturation both in vitro and in vivo. Thus, the engineered EVs demonstrate superior antitumor efficacy through photothermal effect and following provoked antitumor immune responses. This work provides a facile method to fabricate multifunctional EVs-based drug delivery system for improving photothermal-triggered tumor immunotherapy.

Synthesizing biomaterials in living organisms

Living organisms fabricate biomacromolecules such as DNA, RNA, and proteins by the self-assembly process. The research on the mechanism of biomacromolecule formation also inspires the exploration of in vivo synthesized biomaterials. By elaborate design, artificial building blocks or precursors can self-assemble or polymerize into functional biomaterials within living organisms. In recent decades, these so-called in vivo synthesized biomaterials have achieved extensive applications in cell-fate manipulation, disease theranostics, bioanalysis, cellular surface engineering, and tissue regeneration. In this review, we classify strategies for in vivo synthesis into non-covalent, covalent, and genetic types. The development of these approaches is based on the chemical principles of supramolecular chemistry and synthetic chemistry, biological cues such as enzymes and microenvironments, and the means of synthetic biology. By summarizing the design principles in detail, some insights into the challenges and opportunities in this field are provided to  enlighten further research.

In situ stimulus-responsive self-assembled nanomaterials for drug delivery and disease treatment

The individual motifs that respond to specific stimuli for the self-assembly of nanomaterials play important roles. In situ constructed nanomaterials are formed spontaneously without human intervention and have promising applications in bioscience. However, due to the complex physiological environment of the human body, designing stimulus-responsive self-assembled nanomaterials in vivo is a challenging problem for researchers. In this article, we discuss the self-assembly principles of various nanomaterials in response to the tissue microenvironment, cell membrane, and intracellular stimuli. We propose the applications and advantages of in situ self-assembly in drug delivery and disease diagnosis and treatment, with a focus on in situ self-assembly at the lesion site, especially in cancer. Additionally, we introduce the significance of introducing exogenous stimulation to construct self-assembly in vivo. Based on this foundation, we put forward the prospects and possible challenges in the field of in situ self-assembly. This review uncovers the relationship between the structure and properties of in situ self-assembled nanomaterials and provides new ideas for innovative drug molecular design and development to solve the problems in the targeted delivery and precision medicine.

Tumor-Specific Photothermal-Therapy-Assisted Immunomodulation via Multiresponsive Adjuvant Nanoparticles

Multiresponsive adjuvant nanoparticles (RMmAGL) are fabricated to perform tumor-specific photothermal therapy while regulating the behavior of tumor-associated immune cells for primary tumor eradication and metastasis inhibition. Core-satellite-like RMmAGL have a core of mannose-functionalized mesoporous silica nanoparticles loaded with the TLR7 agonist imiquimod (R837@MSN-mannose) connected via hydrazone bonds to satellites of glutamine (Glu)- and lysine (Lys)-comodified gold nanoparticles (AuNPs-Glu/Lys). During therapy, the acidic environment in tumor tissue cleaves the hydrazone bonds to release AuNPs-Glu/Lys, which further accumulate in tumor cells. After internalization, photothermal agents (aggregated AuNPs-Glu/Lys) are generated in situ through the intratumoral enzyme-catalyzed reaction between Glu and Lys, resulting in tumor-specific photothermal therapy. The detachment of AuNPs-Glu/Lys also triggers the release of R837, which matured dendritic cells (DCs) via a vaccine-like mechanism along with the tumor-associated antigens generated by photothermal therapy. These matured DCs further activates surrounding T cells for immunotherapy. Moreover, the resulting free MSN-mannose serves as an artificial glycocalyx to continuously induce the polarization of tumor-associated macrophages from an immunosuppressive phenotype to an inflammatory phenotype, thus further enhancing immunotherapy. Both in vivo and in vitro experiments demonstrate significant inhibition of malignant tumors after therapy.

Covalently triggered self-assembly of peptide-based nanodrugs for cancer theranostics

Covalently triggered peptide self-assembly is achieved through sequential integration of spontaneous covalent reaction and noncovalent interactions, thus both enhancing the physiological stability and extending unexpected functionality of the resulting peptide-based assemblies, different from popular supramolecular peptide self-assembly merely associated with noncovalent interactions. This review summarizes the recent progress on the development of covalently triggered peptide self-assembly for cancer theranostics. Especially, we propose the fundamental design principle of covalently triggered peptide self-assembly for constructing a variety of peptide-based assemblies including nanoparticles, nanofibers, hollow nanospheres, and other nanoarchitectures. Subsequently, the discussion is anchored in an overview of representative covalently assembled peptide-based nanodrugs for the cancer theranostics. Finally, the challenges and perspectives on the clinical potential of the covalently assembled peptide-based nanodrugs are highlighted. This review will provide new insights into construction of peptide-based nanodrugs through combination of covalent reaction and noncovalent self-assembly and prompt their clinical applications in cancer diagnosis and therapeutics.

Patient-derived xenografts or organoids in the discovery of traditional and self-assembled drug for tumor immunotherapy

In addition to the rapid development of immune checkpoint inhibitors, there has also been a surge in the development of self-assembly immunotherapy drugs. Based on the immune target, traditional tumor immunotherapy drugs are classified into five categories, namely immune checkpoint inhibitors, direct immune modulators, adoptive cell therapy, oncolytic viruses, and cancer vaccines. Additionally, the emergence of self-assembled drugs with improved precision and environmental sensitivity offers a promising innovation approach to tumor immunotherapy. Despite rapid advances in tumor immunotherapy drug development, all candidate drugs require preclinical evaluation for safety and efficacy, and conventional evaluations are primarily conducted using two-dimensional cell lines and animal models, an approach that may be unsuitable for immunotherapy drugs. The patient-derived xenograft and organoids models, however, maintain the heterogeneity and immunity of the pathological tumor heterogeneity.

Polymer Chemistry in Living Cells

The polymerization of biomolecules is a central operation in biology that connects molecular signals with proliferative and information-rich events in cells. As molecules arrange precisely across 3-D space, they create new functional capabilities such as catalysis and transport highways and exhibit new phase separation phenomena that fuel nonequilibrium dynamics in cells. Hence, the observed polymer chemistry manifests itself as a molecular basis leading to cellular phenotypes, expressed as a multitude of hierarchical structures found in cell biology. Although many milestone discoveries had accompanied the rise of the synthetic polymer era, fundamental studies were realized within a closed, pristine environment and that their behavior in a complex multicomponent system remains challenging and thus unexplored. From this perspective, there is a rich trove of undiscovered knowledge that awaits the polymer science community that can revolutionize understanding in the interactive nanoscale world of the living cell.In this Account, we discuss the strategies that have enabled synthetic polymer chemistry to be conducted within the cells (membrane inclusive) and to establish monomer design principles that offer spatiotemporal control of the polymerization. As reaction considerations such as monomer concentration, polymer growth dynamics, and reactivities are intertwined with the subcellular environment and transport processes, we first provide a chemical narrative of each major cellular compartment. The conditions within each compartment will therefore set the boundaries on the type of polymer chemistry that can be conducted. Both covalent and supramolecular polymerization concepts are explored separately in the context of scaffold design, polymerization mechanism, and activation. To facilitate transport into a localized subcellular space, we show that monomers can be reversibly modified by targeting groups or stimulus-responsive motifs that react within the specific compartment. Upon polymerization, we discuss the characterization of the resultant polymeric structures and how these phase-separated structures would impact biological processes such as cell cycle, metabolism, and apoptosis. As we begin to integrate cellular biochemistry with in situ polymer science, we identify landmark challenges and technological hurdles that, when overcome, would lead to invaluable discoveries in macromolecular therapeutics and biology.

Intracellular Enzyme-Instructed Self-Assembly of Peptides (IEISAP) for Biomedical Applications

Despite the remarkable significance and encouraging breakthroughs of intracellular enzyme-instructed self-assembly of peptides (IEISAP) in disease diagnosis and treatment, a comprehensive review that focuses on this topic is still desirable. In this article, we carefully review the advances in the applications of IEISAP, including the development of various bioimaging techniques, such as fluorescence imaging, photoacoustic imaging, magnetic resonance imaging, positron-emission tomography imaging, radiation imaging, and multimodal imaging, which are successfully leveraged in visualizing cancer tissues and cells, bacteria, and enzyme activity. We also summarize the utilization of IEISAP in disease treatments, including anticancer, antibacterial, and antiinflammation applications, among others. We present the design, action modes, structures, properties, functions, and performance of IEISAP materials, such as nanofibers, nanoparticles, nanoaggregates, and hydrogels. Finally, we conclude with an outlook towards future developments of IEISAP materials for biomedical applications. It is believed that this review may foster the future development of IEISAP with better performance in the biomedical field.

TfR Aptamer Enhanced Blood-Brain Barrier Penetration of Biomimetic Nanocomplexes for Intracellular Transglutaminase 2 Imaging and Silencing in Glioma

Engineering a versatile nanocomplex integrating effective penetration of the blood-brain barrier (BBB), accurate diagnosis, and boosting therapy has always been an intractable challenge in glioblastoma multiforme (GBM). Herein, biomimetic nanocomplexes (TMPsM) for single intracellular transglutaminase 2 (TG2)-triggered self-assembly imaging and RNAi therapy for GBM are subtly developed. To prove the concept, transferrin receptor (TfR) aptamer-modified brain metastatic tumor cell membrane is prepared as the shell for dual BBB targeting capability and prolonged blood retention time. Upon targeting entering into GBM, hollow MnO₂ is decomposed to release KKGKGQQ-tetraphenylethene (Pep-TPE) and siRNA. Owing to TG2 dependence, the non-emissive Pep-TPE would be self-aggregated to induce the emission turn-on in GBM that contain overexpressed TG2. The resulting aggregation-induced emission fluorescence imaging with a high signal-to-noise ratio can achieve the precise localization of the tumor and dynamic detection of TG2 activity, thereby allowing the GBM accurate diagnosis. Notably, the TG2 can be silenced by the released siRNA to cause cell apoptosis and increase chemotherapeutic sensitivity, ultimately realizing excellent antitumor efficacy. In vitro and in vivo results demonstrate that the as-prepared TMPsM indeed possess superior BBB penetration, precise diagnosis, and effective therapy of GBM. The proposed strategy may pioneer a new path for the theranostics of brain tumors.

A Lysosome-Targeting Self-Condensation Prodrug-Nanoplatform System for Addressing Drug Resistance of Cancer

Lysosome-targeting self-assembling prodrugs had emerged as an attractive approach to overcome the acquisition of resistance to chemotherapeutics by inhibiting lysosomal sequestration. Taking advantage of lysosomal acidification induced intracellular hydrolytic condensation, we developed a lysosomal-targeting self-condensation prodrug-nanoplatform (LTSPN) system for overcoming lysosome-mediated drug resistance. Briefly, the designed hydroxycamptothecine (HCPT)-silane conjugates self-assembled into silane-based nanoparticles, which were taken up into lysosomes by tumor cells. Subsequently, the integrity of the lysosomal membrane was destructed because of the acid-triggered release of alcohol, wherein the nanoparticles self-condensed into silicon particles outside the lysosome through intracellular hydrolytic condensation. Significantly, the LTSPN system reduced the half-maximal inhibitory concentration (IC₅₀) of HCPT by approximately 4 times. Furthermore, the LTSPN system realized improved control of large established tumors and reduced regrowth of residual tumors in several drug-resistant tumor models. Our findings suggested that target destructing the integrity of the lysosomal membrane may improve the therapeutic effects of chemotherapeutics, providing a potent treatment strategy for malignancies.

Harnessing Oxidative Microenvironment for In Vivo Synthesis of Subcellular Conductive Polymer Microesicles Enhances Nerve Reconstruction

Conductive polymers (CPs) are promising biomaterials to address signal connection at biointerfaces for tissue regeneration. However, regulating material microstructure at the subcellular scale to provide a more seamless interface between conductive substrates and cells remains a great challenge. Here, we demonstrate that chemical factors and enzyme-carried subcellular structures at lesion site provide a natural bioreactor to self-assemble conductive microvesicles (CMVs) for improving bioelectrical signal reconstruction. The synthesized CMVs contribute to the electrical conduction of the injured nerve in the early stage. Moreover, CMVs are eventually expelled via lymphatic capillary to minimize space-occupying and chronic inflammation. Therefore, we provide a prototype to integrate specific physiological microenvironments and polymer chemistry to manufacture subcellular functional materials with self-adaptive interface in vivo for biomedical applications.

Supramolecular Self-Assembly in Living Cells

Supramolecular interactions rely on non-covalent forces, such as hydrophobic effects, hydrogen-bonding, and electrostatic interactions, which govern many intracellular biological pathways. In cellulo supramolecular self-assembly is mainly based on host-guest interactions, changes in pH, enzymes, and polymerization-induced self-assembly to accurately induce various unnatural reactions without disturbing natural biological processes. This process can produce synthetic biocompatible macromolecules to control cell properties and regulate biological functions, such as cell proliferation and differentiation. This Minireview focuses on the latest reports in the field of in cellulo supramolecular self-assembly and anticipates future advances regarding its activation in response to internal and external stimuli, such as pH changes, reactive oxygen species, and enzymes, as well as external light illumination.

Bioorthogonal in situ assembly of nanomedicines as drug depots for extracellular drug delivery

Developing precise nanomedicines to improve the transport of anticancer drugs into tumor tissue and to the final action site remains a critical challenge. Here, we present a bioorthogonal in situ assembly strategy for prolonged retention of nanomedicines within tumor areas to act as drug depots. After extravasating into the tumor site, the slightly acidic microenvironment induces the exposure of cysteine on the nanoparticle surface, which subsequently undergoes a bioorthogonal reaction with the 2-cyanobenzothiazole group of another neighboring nanoparticle, enabling the formation of micro-sized drug depots to enhance drug retention and enrichment. This in situ nanoparticle assembly strategy remarkably improves the antimetastatic efficacy of extracellular-targeted drug batimastat, and also leads to the simultaneous enhanced retention and sustained release of multiple agents for combined cocktail chemoimmunotherapy to finally elicit a potent antitumor immune response. Such in situ assembly of nanomedicines represents a generalizable strategy towards extracellular drug delivery and cocktail chemoimmunotherapy.

Delivering the correct concentration of drugs to the correct location is a challenge in cancer therapy. Here, the authors generate a drug loaded nanoparticle that enlarges following contact with the internal tumour cell environment, resulting in the retention of the nanoparticle and loaded drugs in cancer cells.

Designing bioresponsive nanomaterials for intracellular self-assembly

Supramolecular assemblies are essential components of living organisms. Cellular scaffolds, such as the cytoskeleton or the cell membrane, are formed via secondary interactions between proteins or lipids and direct biological processes such as metabolism, proliferation and transport. Inspired by nature’s evolution of function through structure formation, a range of synthetic nanomaterials has been developed in the past decade, with the goal of creating non-natural supramolecular assemblies inside living mammalian cells. Given the intricacy of biological pathways and the compartmentalization of the cell, different strategies can be employed to control the assembly formation within the highly crowded, dynamic cellular environment. In this Review, we highlight emerging molecular design concepts aimed at creating precursors that respond to endogenous stimuli to build nanostructures within the cell. We describe the underlying reaction mechanisms that can provide spatial and temporal control over the subcellular formation of synthetic nanostructures. Showcasing recent advances in the development of bioresponsive nanomaterials for intracellular self-assembly, we also discuss their impact on cellular function and the challenges associated with establishing structure–bioactivity relationships, as well as their relevance for the discovery of novel drugs and imaging agents, to address the shortfall of current solutions to pressing health issues.

Creating artificial nanostructures inside living cells requires the careful design of molecules that can transform into active monomers within a complex cellular environment. This Review explores the recent development of bioresponsive precursors for the controlled formation of intracellular supramolecular assemblies.

Cell-based biocomposite engineering directed by polymers

Biological cells such as bacterial, fungal, and mammalian cells always exploit sophisticated chemistries and exquisite micro- and nano-structures to execute life activities, providing numerous templates for engineering bioactive and biomorphic materials, devices, and systems. To transform biological cells into functional biocomposites, polymer-directed cell surface engineering and intracellular functionalization have been developed over the past two decades. Polymeric materials can be easily adopted by various cells through polymer grafting or in situ hydrogelation and can successfully bridge cells with other functional materials as interfacial layers, thus achieving the manufacture of advanced biocomposites through bioaugmentation of living cells and transformation of cells into templated materials. This review article summarizes the recent progress in the design and construction of cell-based biocomposites by polymer-directed strategies. Furthermore, the applications of cell-based biocomposites in broad fields such as cell research, biomedicine, and bioenergy are discussed. Last, we provide personal perspectives on challenges and future trends in this interdisciplinary area.

MMP-responsive transformation nanomaterials with IAP antagonist to boost immune checkpoint therapy

The clinical effect of immune checkpoint therapy is limited by the poor blocking efficiency of immune checkpoints and the insufficient infiltration of tumor-specific T cells. Here, we constructed enzyme-responsive PVA-peptide conjugates (PPCs) to achieve re-assembly with enhanced accumulation in the tumor region, enable enhanced PD-L1 occupancy and improve the blocking efficiency. The self-assembled PPC-1 nanoparticles can enter tumor environment, whereas the enzyme-cleavable peptide was digested under overgenerated matrix metalloproteinases (MMP). The accumulated PPC-1 simultaneously transformed into β-sheet fibrous structures around the solid tumor and remained stable for over 96 h, which led to efficiently interrupting the PD-1/PD-L1 interaction. Upon introduction of the IAP antagonists, the non-classical NF-κB pathway of dendritic cells was activated and increased the infiltration of T cells in tumors. With the synergistic contribution of IAP antagonists from the substantial increase in expression of chemokines (CCL5 and CXCL9) and adequate T-cell infiltration in tumor sites, PPC-1 improved the biodistribution and accumulation of PD-L1 antagonists in tumor regions ultimately realizing higher-performance (P < 0.01) tumor growth inhibition efficiency (~80%) than PPC-2 group (~58%) in B16F10 tumor-bearing mice. The growth of the second tumor at the distal end was obviously inhibited (P < 0.01) after the resection of the primary tumor. The combined efficacy was similar to that observed in a Pan02 pancreatic cancer tumor model. This strategy aims to offer novel perspective for the development of locational assembly platforms in vivo and the optimal design of immune checkpoint combination therapy.

Photocontrollable thermosensitive chemical spatiotemporally destabilizes mitochondrial membranes for cell fate manipulation

Perturbations in mitochondrial membrane stability lead to cytochrome c release and induce caspase-dependent apoptosis. Using synthetic smart chemicals that with changeable physicochemical properties to interfere the mitochondrial membrane stability has...

Spatiotemporal Dynamic Assembly/Disassembly of Organelle-Mimics Based on Intrinsically Disordered Protein-Polymer Conjugates

Design of reversible organelle-like microcompartments formed by liquid-liquid phase separation in cell-mimicking entities has significantly advanced the bottom-up construction of artificial eukaryotic cells. However, organizing the formation of artificial organelle architectures in a spatiotemporal manner within complex primitive compartments remains scarcely explored. In this work, thermoresponsive hybrid polypeptide-polymer conjugates are rationally engineered and synthesized, resulting from the conjugation of an intrinsically disordered synthetic protein (IDP), namely elastin-like polypeptide, and synthetic polymers (poly(ethylene glycol) and dextran) that are widely used as macromolecular crowding agents. Cell-like constructs are built using droplet-based microfluidics that are filled with such bioconjugates and an artificial cytoplasm system that is composed of specific polymers conjugated to the IDP. The distinct spatial organizations of two polypeptide-polymer conjugates and the dynamic assembly and disassembly of polypeptide-polymer coacervate droplets in response to temperature are studied in the cytomimetic protocells. Furthermore, a monoblock IDP with longer length is concurrently included with bioconjugates individually inside cytomimetic compartments. Both bioconjugates exhibit an identical surfactant-like property, compartmentalizing the monoblock IDP coacervates via temperature control. These findings lay the foundation for developing hierarchically structured synthetic cells with interior organelle-like structures which could be designed to localize in desired phase-separated subcompartments.

Spatiotemporal Control over Chemical Assembly in Living Cells by Integration of Acid-Catalyzed Hydrolysis and Enzymatic Reactions

Spatiotemporal control of chemical assembly in living cells remains challenging. We have now developed an efficient and general platform to precisely control the formation of assemblies in living cells. We introduced an O-[bis(dimethylamino)phosphono]tyrosine protection strategy in the self-assembly motif as the Trojan horse, whereby the programmed precursors resist hydrolysis by phosphatases on and inside cells because the unmasking of the enzymatic cleavage site occurs selectively in the acidic environment of lysosomes. After demonstrating the multistage self-assembly processes in vitro by liquid chromatography/mass spectrometry (LC-MS), cryogenic electron microscopy (Cryo-EM), and circular dichroism (CD), we investigated the formation of site-specific self-assembly in living cells using confocal laser scanning microscopy (CLSM), LC-MS, and biological electron microscopy (Bio-EM). Controlling chemical assembly in living systems spatiotemporally may have applications in supramolecular chemistry, materials science, synthetic biology, and chemical biology.

Targeted Enrichment of Enzyme-Instructed Assemblies in Cancer Cell Lysosomes Turns Immunologically Cold Tumors Hot

Lysosome-relevant cell death induced by lysosomal membrane permeabilization (LMP) has recently attracted increasing attention. However, nearly no studies show that currently available LMP inducers can evoke immunogenic cell death (ICD) or convert immunologically cold tumors to hot. Herein, we report a LMP inducer named TPE-Py-pYK(TPP)pY, which can respond to alkaline phosphatase (ALP), leading to formation of nanoassembies along with fluorescence and singlet oxygen turn-on. TPE-Py-pYK(TPP)pY tends to accumulate in ALP-overexpressed cancer cell lysosomes as well as induce LMP and rupture of lysosomal membranes to massively evoke ICD. Such LMP-induced ICD effectively converts immunologically cold tumors to hot as evidenced by abundant CD8⁺ and CD4⁺ T cells infiltration into the cold tumors. Exposure of ALP-catalyzed nanoassemblies in cancer cell lysosomes to light further intensifies the processes of LMP, ICD and cold-to-hot tumor conversion. This work thus builds a new bridge between lysosome-relevant cell death and cancer immunotherapy.

Photoacoustic probe of targeting intracellular Staphylococcus aureus infection with signal-enhanced by self-assembly

In this chapter, we introduce the photoacoustic imaging probe in detecting the infection of bacterial in host cells. We give detailed protocols for the synthesis and confirmation of a PA probe which response to caspase-1 and then self-assembly to enhance the signal. With this PA contrast agent, we may provide a new approach for an intracellular bacterial infection with the selective and sensitive diagnosis.

Photoactivated In Situ Generation of Near Infrared Cyanines for Spatiotemporally Controlled Fluorescence Imaging in Living Cells

Photoactivated trimerization of 2,3,3-trimethyl-3H-indole derivatives created near infrared fluorophore Cy5. The synthetic method is air-tolerant, photosensitizer free, metal free, and condensation agent free. Living cells make Cy5 on a time scale of minutes under white light irradiation at a low power intensity, with the monomer as the only exogenous agent. The new method is promising to find applications in cell studies for in situ spatiotemporally controlled fluorescence imaging in living cells.