Mitochondria localization induced self-assembly of peptide amphiphiles for cellular dysfunction

Nanoparticle-based therapeutic strategies for mitochondrial dysfunction in cardiovascular disease

Although cardiovascular diseases (CVD) are the leading cause of global mortality, there is a lack of therapies that target and revert underlying pathological processes. Mitochondrial dysfunction is involved in the pathophysiology of CVD, and thus is a potential target for therapeutic development. To target the mitochondria and improve therapeutic efficacy, nanoparticle-based delivery systems have been proposed as promising strategies for the delivery of therapeutic agents to the mitochondria. This review will first discuss how mitochondrial dysfunction is related to the progression of several CVD and then delineate recent progress in mitochondrial targeting using nanoparticle-based delivery systems including peptide-based nanosystems, polymeric nanoparticles, liposomes, and lipid nanoparticles. In addition, we summarize the advantages of these nanocarriers and remaining challenges in targeting the mitochondria as a therapeutic strategy for CVD treatment.

From cells to subcellular organelles: Next-generation cancer therapy based on peptide self-assembly

Due to the editability, functionality, and excellent biocompatibility of peptides, in situ self-assembly of peptides in cells is a powerful strategy for biomedical applications. Subcellular organelle targeting of peptides assemblies enables more precise drug delivery, enhances selectivity to disease cells, and mitigates drug resistance, providing an effective strategy for disease diagnosis and therapy. This reviewer first introduces the triggering conditions, morphological changes, and intracellular locations of self-assembling peptides. Then, the functions of peptide assemblies are summarized, followed by a comprehensive understanding of the interactions between peptide assemblies and subcellular organelles. Finally, we provide a brief outlook and the remaining challenges in this field.

Acid-assisted self-assembly of pyrene-capped tyrosine ruptures lysosomes to induce cancer cell apoptosis

Induced lysosomal membrane permeabilization (LMP) by peptide self-assembly has emerged as an effective platform for lysosome-targeted cancer therapy. In this study, we shift this strategical paradigm and present an innovative approach to LMP induction through amino acid-based self-assembly. Pyrene-capped tyrosine (Py-Tyr), as a proof-of-concept molecule, is designed with acidity-responsive self-assembly. Under acidic conditions (pH 4), Py-Tyr is protonated with reduced charge repulsion, and self-assembles into micrometer-scaled aggregates, which exceed the biological size of lysosomes. Cell experiments showed that Py-Tyr specifically accumulates in lysosomes and induces lysosome rupture, leading to the release of cathepsin B into the cytoplasm for subsequent apoptosis activation in cancer cells. This study capitalizes on the concept of amino acid assembly for efficient LMP induction, providing a simple and versatile platform for precise and effective therapeutic interventions in cancer therapy.

Self-assembly of peptides in living cells for disease theranostics

The past few decades have witnessed substantial progress in biomedical materials for addressing health concerns and improving disease therapeutic and diagnostic efficacy. Conventional biomedical materials are typically created through an ex vivo approach and are usually utilized under physiological environments via transfer from preparative media. This transfer potentially gives rise to challenges for the efficient preservation of the bioactivity and implementation of theranostic goals on site. To overcome these issues, the in situ synthesis of biomedical materials on site has attracted great attention in the past few years. Peptides, which exhibit remarkable biocompability and reliable noncovalent interactions, can be tailored via tunable assembly to precisely create biomedical materials. In this review, we summarize the progress in the self-assembly of peptides in living cells for disease diagnosis and therapy. After a brief introduction to the basic design principles of peptide assembly systems in living cells, the applications of peptide assemblies for bioimaging and disease treatment are highlighted. The challenges in the field of peptide self-assembly in living cells and the prospects for novel peptide assembly systems towards next-generation biomaterials are also discussed, which will hopefully help elucidate the great potential of peptide assembly in living cells for future healthcare applications.

Sulfatase-Induced In Situ Formulation of Antineoplastic Supra-PROTACs

Proteolysis targeting chimera (PROTAC) technology is an innovative strategy for cancer therapy, which, however, suffers from poor targeting delivery and limited capability for protein of interest (POI) degradation. Here, we report a strategy for the in situ formulation of antineoplastic Supra-PROTACs via intracellular sulfatase-responsive assembly of peptides. Coassembling a sulfated peptide with two ligands binding to ubiquitin VHL and Bcl-xL leads to the formation of a pro-Supra-PROTAC, in which the ratio of the two ligands is rationally optimized based on their protein binding affinity. The resulting pro-Supra-PROTAC precisely undergoes enzyme-responsive assembly into nanofibrous Supra-PROTACs in cancer cells overexpressing sulfatase. Mechanistic studies reveal that the pro-Supra-PROTACs selectively cause apparent cytotoxicity to cancer cells through the degradation of Bcl-xL and the activation of caspase-dependent apoptosis, during which the rationally optimized ligand ratio improves the bioactivity for POI degradation and cell death. In vivo studies show that in situ formulation enhanced the tumor accumulation and retention of the pro-Supra-PROTACs, as well as the capability for inhibiting tumor growth with excellent biosafety when coadministrating with chemodrugs. Our findings provide a new approach for enzyme-regulated assembly of peptides in living cells and the development of PROTACs with high targeting delivering and POI degradation efficiency.

Mitochondrial Localized In Situ Self-Assembly Reprogramming Tumor Immune and Metabolic Microenvironment for Enhanced Cancer Therapy

The inherent immune and metabolic tumor microenvironment (TME) of most solid tumors adversely affect the antitumor efficacy of various treatments, which is an urgent issue to be solved in clinical cancer therapy. In this study, a mitochondrial localized in situ self-assembly system is constructed to remodel the TME by improving immunogenicity and disrupting the metabolic plasticity of cancer cells. The peptide-based drug delivery system can be pre-assembled into nanomicelles in vitro and form functional nanofibers on mitochondria through a cascade-responsive process involving reductive release, targeted enrichment, and in situ self-assembly. The organelle-specific in situ self-assemblyeffectively switches the role of mitophagy from pro-survival to pro-death, which finally induces intense endoplasmic reticulum stress and atypical type II immunogenic cell death. Disintegration of the mitochondrial ultrastructure also impedes the metabolic plasticity of tumor cells, which greatly promotes the immunosuppresive TME remodeling into an immunostimulatory TME. Ultimately, the mitochondrial localized in situ self-assembly system effectively suppresses tumor metastases, and converts cold tumors into hot tumors with enhanced sensitivity to radiotherapy and immune checkpoint blockade therapy. This study offers a universal strategy for spatiotemporally controlling supramolecular self-assembly on sub-organelles to determine cancer cell fate and enhance cancer therapy.

Drug-Loaded Nanogel for Efficient Orchestration of Cell Death Pathways by Intramitochondrial Disulfide Polymerization

Chemotherapy using a nanoscaled drug delivery system is an effective cancer therapy, but its high drug concentration often causes drug resistance in cancer cells and normal cell damage. Combination therapy involving two or more different cell signaling pathways can be a powerful tool to overcome the limitations of chemotherapy. Herein, this article presents nanogel (NG)-mediated co-delivery of a chemodrug camptothecin (CPT) and mitochondria-targeting monomer (MT monomer) for efficient activation of two modes of the programmed cell death pathway (apoptosis and necroptosis) and synergistic enhancement of cancer therapy. CPT and the monomer are incorporated together into the redox-degradable polymeric NGs for release in response to the intracellular glutathione. The MT monomer is shown to undergo reactive oxygen species (ROS)-triggered disulfide polymerization inside the cancerous mitochondria in cooperation with the chemotherapeutic CPT elevating the intracellular ROS level. The CPT/monomer interconnection in cell death mechanisms for mitochondrial dysfunction and enhanced cell death is evidenced by a series of cell analyses showing ROS generation, mitochondria damage, impacts on (non)cancerous or drug-resistant cells, and cell death modes. The presented work provides beneficial insights for utilizing combination therapy to facilitate a desired cell death mechanism and developing a novel nanosystem for more efficacious cancer treatment.

Activation-Induced Senescent Cell Death based on Chiral CoHAu Nanoassemblies with Enantioselective Cascade-Catalytic Ability

Chirality is common in nature, which determines the high enantioselectivity of living systems. Selecting suitable chiral configurations is of great meaning for nanostructures to function better in biological systems. In this study, chiral Co3O4-H2TPPS-Au (CoHAu) nanoassemblies are constructed to accelerate the production ∙OH by consuming D-glucose (D-Glu, widely spread in nature) based on their outstanding enantioselective cascade-catalytic abilities. In particular, D-CoHAu nanoassemblies are more effective in the catalytic conversion of D-Glu than L-CoHAu nanoassemblies. This phenomenon is due to the stronger binding affinity of D-CoHAu nanoassemblies indicated by the lower Km value. Moreover, D-CoHAu nanoassemblies display excellent consumption-ability of D-Glu and production of ∙OH in living cells, which can eliminate senescent cells effectively based on their intracellular enantioselective cascade-catalysis. This research establishes the foundation for bio-mimicking nanostructures with unique functionalities to regulate abnormal biological activities better.

Nanomaterials in Medicine: Understanding Cellular Uptake, Localization, and Retention for Enhanced Disease Diagnosis and Therapy

Nanomaterials (NMs) have emerged as promising tools for disease diagnosis and therapy due to their unique physicochemical properties. To maximize the effectiveness and design of NMs-based medical applications, it is essential to comprehend the complex mechanisms of cellular uptake, subcellular localization, and cellular retention. This review illuminates the various pathways that NMs take to get from the extracellular environment to certain intracellular compartments by investigating the various mechanisms that underlie their interaction with cells. The cellular uptake of NMs involves complex interactions with cell membranes, encompassing endocytosis, phagocytosis, and other active transport mechanisms. Unique uptake patterns across cell types highlight the necessity for customized NMs designs. After internalization, NMs move through a variety of intracellular routes that affect where they are located subcellularly. Understanding these pathways is pivotal for enhancing the targeted delivery of therapeutic agents and imaging probes. Furthermore, the cellular retention of NMs plays a critical role in sustained therapeutic efficacy and long-term imaging capabilities. Factors influencing cellular retention include nanoparticle size, surface chemistry, and the cellular microenvironment. Strategies for prolonging cellular retention are discussed, including surface modifications and encapsulation techniques. In conclusion, a comprehensive understanding of the mechanisms governing cellular uptake, subcellular localization, and cellular retention of NMs is essential for advancing their application in disease diagnosis and therapy. This review provides insights into the intricate interplay between NMs and biological systems, offering a foundation for the rational design of next-generation nanomedicines.

Self-assembled porphyrin-peptide cages for photodynamic therapy

The development of photodynamic therapy requires access to smart photosensitizers which combine appropriate photophysical and biological properties. Interestingly, supramolecular and dynamic covalent chemistries have recently shown their ability to produce novel architectures and responsive systems through simple self-assembly approaches. Herein, we report the straightforward formation of porphyrin-peptide conjugates and cage compounds which feature on their surface chemical groups promoting cell uptake and specific organelle targeting. We show that they self-assemble, in aqueous media, into positively-charged nanoparticles which generate singlet oxygen upon green light irradiation, while also undergoing a chemically-controlled disassembly due to the presence of reversible covalent linkages. Finally, the biological evaluation in cells revealed that they act as effective photosensitizers and promote synergistic effects in combination with Doxorubicin.

Peptide-Mediated Nanocarriers for Targeted Drug Delivery: Developments and Strategies

Effective drug delivery is essential for cancer treatment. Drug delivery systems, which can be tailored to targeted transport and integrated tumor therapy, are vital in improving the efficiency of cancer treatment. Peptides play a significant role in various biological and physiological functions and offer high design flexibility, excellent biocompatibility, adjustable morphology, and biodegradability, making them promising candidates for drug delivery. This paper reviews peptide-mediated drug delivery systems, focusing on self-assembled peptides and peptide-drug conjugates. It discusses the mechanisms and structural control of self-assembled peptides, the varieties and roles of peptide-drug conjugates, and strategies to augment peptide stability. The review concludes by addressing challenges and future directions.

Nanofibers in Organelles: From Structure Design to Biomedical Applications

Nanofibers are one of the most important morphologies of molecular self-assemblies, the formation of which relies on the diverse intermolecular interactions of fibrous-forming units. In the past decade, rapid advances have been made in the biomedical application of nanofibers, such as bioimaging and tumor treatment. An important topic to be focused on is not only the nanofiber formation mechanism but also where it forms, because different destinations could have different influences on cells and its formation could be triggered by unique stimuli in organelles. It is therefore necessary and timely to summarize the nanofibers assembled in organelles. This minireview discusses the formation mechanism, triggering strategies, and biomedical applications of nanofibers, which may facilitate the rational design of nanofibers, improve our understanding of the relationship between nanofiber properties and organelle characteristics, allow a comprehensive recognition of organelles affected by materials, and enhance the therapeutic efficiency of nanofibers.

Role of Functionalized Peptides in Nanomedicine for Effective Cancer Therapy

Peptide-functionalized nanomedicine, which addresses the challenges of specificity and efficacy in drug delivery, is emerging as a pivotal approach for cancer therapy. Globally, cancer remains a leading cause of mortality, and conventional treatments, such as chemotherapy, often lack precision and cause adverse effects. The integration of peptides into nanomedicine offers a promising solution for enhancing the targeting and delivery of therapeutic agents. This review focuses on the three primary applications of peptides: cancer cell-targeting ligands, building blocks for self-assembling nanostructures, and elements of stimuli-responsive systems. Nanoparticles modified with peptides improved targeting of cancer cells, minimized damage to healthy tissues, and optimized drug delivery. The versatility of self-assembled peptide structures makes them an innovative vehicle for drug delivery by leveraging their biocompatibility and diverse nanoarchitectures. In particular, the mechanism of cell death induced by self-assembled structures offers a novel approach to cancer therapy. In addition, peptides in stimuli-responsive systems enable precise drug release in response to specific conditions in the tumor microenvironment. The use of peptides in nanomedicine not only augments the efficacy and safety of cancer treatments but also suggests new research directions. In this review, we introduce systems and functionalization methods using peptides or peptide-modified nanoparticles to overcome challenges in the treatment of specific cancers, including breast cancer, lung cancer, colon cancer, prostate cancer, pancreatic cancer, liver cancer, skin cancer, glioma, osteosarcoma, and cervical cancer.

Organelle-Mediated Dissipative Self-Assembly of Peptides in Living Cells

Implementing dissipative assembly in living systems is meaningful for creation of living materials or even artificial life. However, intracellular dissipative assembly remains scarce and is significantly impeded by the challenges lying in precisely operating chemical reaction cycles under complex physiological conditions. Here, we develop organelle-mediated dissipative self-assembly of peptides in living cells fueled by GSH, via the design of a mitochondrion-targeting and redox-responsive hexapeptide. While the hexapeptide undergoes efficient redox-responsive self-assembly, the addition of GSH into the peptide solution in the presence of mitochondrion-biomimetic liposomes containing hydrogen peroxide allows for transient assembly of peptides. Internalization of the peptide by LPS-stimulated macrophages leads to the self-assembly of the peptide driven by GSH reduction and the association of the peptide assemblies with mitochondria. The association facilitates reversible oxidation of the reduced peptide by mitochondrion-residing ROS and thereby dissociates the peptide from mitochondria to re-enter the cytoplasm for GSH reduction. The metastable peptide-mitochondrion complexes prevent the thermodynamically equilibrated self-assembly, thus establishing dissipative assembly of peptides in stimulated macrophages. The entire dissipative self-assembling process allows for elimination of elevated ROS and decrease of pro-inflammatory cytokine expression. Creating dissipative self-assembling systems assisted by internal structures provides new avenues for the development of living materials or medical agents in the future.

A D-Y Shaped Neuropeptide Y Mimetic Peptide-Dye Self-Assembly with Maximal Emission Beyond 1300 nm and Glioma Mitochondrial Activity Modulation

Neuropeptide Y (NPY), as one of the most abundant neuropeptides known, is widely distributed in the central and peripheral nervous system. However, most of the reported NPY-mimetic peptides are hard to cross the blood-brain barrier, target glioma mitochondria, and achieve self-assembly nanostructure in situ. Here, based on the α-helix structure of the novel chiral NPY-mimetic peptides D/L NPY(14), a Y-shaped peptide is designed with the sequences that can be recognized by enterokinase and achieved nanofibers conversion in glioma cell mitochondria. Coupling the Y-shaped NPY-mimetic peptide with the NIR-II fluorophore IR1048, a red-shifting of the fluorescence spectrum beyond 1300 nm is achieved through self-assembly. After the self-assembly in glioma mitochondria, the formed nanofibers can promote intracellular mitochondrial ROS production and extend the NIR-II fluorescence imaging time to at least 7 days in vivo. This work for the first time endows the self-assembly of α-helical-based chiral NPY-mimetic peptides, providing a novel strategy for glioma subcellular regulation enhanced antitumor treatment guided by NIR-II fluorescence imaging.

Artificial Peptide-Protein Necrosomes Promote Cell Death

The presence of disordered region or large interacting surface within proteins significantly challenges the development of targeted drugs, commonly known as the "undruggable" issue. Here, we report a heterogeneous peptide-protein assembling strategy to selectively phosphorylate proteins, thereby activating the necroptotic signaling pathway and promoting cell necroptosis. Inspired by the structures of natural necrosomes formed by receptor interacting protein kinases (RIPK) 1 and 3, the kinase-biomimetic peptides are rationally designed by incorporating natural or D -amino acids, or connecting D -amino acids in a retro-inverso (DRI) manner, leading to one RIPK3-biomimetic peptide PR3 and three RIPK1-biomimetic peptides. Individual peptides undergo self-assembly into nanofibrils, whereas mixing RIPK1-biomimetic peptides with PR3 accelerates and enhances assembly of PR3. In particular, RIPK1-biomimetic peptide DRI-PR1 exhibits reliable binding affinity with protein RIPK3, resulting in specific cytotoxicity to colon cancer cells that overexpress RIPK3. Mechanistic studies reveal the increased phosphorylation of RIPK3 induced by RIPK1-biomimetic peptides, elucidating the activation of the necroptotic signaling pathway responsible for cell death without an obvious increase in secretion of inflammatory cytokines. Our findings highlight the potential of peptide-protein hybrid aggregation as a promising approach to address the "undruggable" issue and provide alternative strategies for overcoming cancer resistance in the future.

Arginine Methylation Regulates Self-Assembly of Peptides

Bio-inspired design of peptides represents one facile strategy for development of supramolecular monomers for self-assembly into well-defined nanostructures. Inspired by methylation of arginine during post-translational modification for manipulating protein functions, herein, the controllable self-assembly of peptides via rational incorporation of methylated arginine residues into bola-amphiphilic peptides is reported. A series of bola-amphiphilic peptides are designed and synthesized either containing natural arginine or methylated arginine and investigate the influence of arginine methylation on peptide assembly. This study finds that incorporation of symmetrically di-methylated arginine into oppositely charged hexapeptide hex-SDMAE leads to distinct assembling performance compare to natural peptide hex-RE. The findings demonstrate that the methylation of rationally designed peptide sequences allows for regulation of self-assembly of peptides, thus implying the great potential of arginine methylation in establishing controllable peptide assembling systems and creating in situ formulation of biomedical materials in the future.

Advances in Peptide-Decorated Targeted Drug Delivery: Exploring Therapeutic Potential and Nanocarrier Strategies

Peptides are ideal biologicals for targeted drug delivery and have also been increasingly employed as theranostic tools in treating various diseases, including cancer, with minimal or no side effects. Owing to their receptor-specificity, peptide-mediated drug delivery aids in targeted drug delivery with better pharmacological biodistribution. Nanostructured self-assembled peptides and peptide-drug conjugates demonstrate enhanced stability and performance and captivating biological effects in comparison with conventional peptides. Moreover, they serve as valuable tools for establishing interfaces between drug carriers and biological systems, enabling the traversal of multiple biological barriers encountered by peptide-drug conjugates on their journeys to their intended targets. Peptide-based drugs play a pivotal role in the field of medicine and hold great promise for addressing a wide range of complex diseases such as cancer and autoimmune disorders. Nanotechnology has revolutionized the fields of medicine, biomedical engineering, biotechnology, and engineering sciences over the past two decades. With the help of nanotechnology, better delivery of peptides to the target site could be achieved by exploiting the small size, increased surface area, and passive targeting ability of the nanocarrier. Furthermore, nanocarriers also ensure safe delivery of the peptide moieties to the target site, protecting them from degradation. Nanobased peptide delivery systems would be of significant importance in the near future for the successful targeted and efficient delivery of peptides. This review focuses on peptide-drug conjugates and nanoparticle-mediated self-assembled peptide delivery systems in cancer therapeutics.

Telomerase-Mediated Self-Assembly of DNA Network in Cancer Cells Enabling Mitochondrial Interference

The precise control of the artificially induced reactions inside living cells is emerging as an effective strategy for the regulation of cell functions. Nevertheless, the manipulation of the assembly of exogenous molecules into artificial architectures in response to intracellular-specific signals remains a grand challenge. Herein, we achieve the precise self-assembly of deoxyribonucleic acid (DNA) network inside cancer cells, specifically responding to telomerase, and realize effective mitochondrial interference and the consequent regulation of cellular behaviors. Two functional DNA modules were designed: a mitochondria-targeting branched DNA and a telomerase-responsive linear DNA. Upon uptake by cancer cells, the telomerase primer in linear DNA responded to telomerase, and a strand displacement reaction was triggered by the reverse transcription of telomerase, thus releasing a linker DNA from the linear DNA. The linker DNA afterward hybridized with the branched DNA to form a DNA network on mitochondria. The DNA network interfered with the function of mitochondria, realizing the apoptosis of cancer cells. This system was further administered in a nude mouse tumor model, showing remarkable suppression of tumor growth. We envision that the telomerase-mediated intracellular self-assembly of the DNA network provides a promising route for cancer therapy.

Tools to enable the study and translation of supramolecular amphiphiles

This tutorial review focuses on providing a summary of the key techniques used for the characterisation of supramolecular amphiphiles and their self-assembled aggregates; from the understanding of low-level molecular interactions, to materials analysis, use of data to support computer-aided molecular design and finally, the translation of this class of compounds for real world application, specifically within the clinical setting. We highlight the common methodologies used for the study of traditional amphiphiles and build to provide specific examples that enable the study of specialist supramolecular systems. This includes the use of nuclear magnetic resonance spectroscopy, mass spectrometry, X-ray scattering techniques (small- and wide-angle X-ray scattering and single crystal X-ray diffraction), critical aggregation (or micelle) concentration determination methodologies, machine learning, and various microscopy techniques. Furthermore, this review provides guidance for working with supramolecular amphiphiles in in vitro and in vivo settings, as well as the use of accessible software programs, to facilitate screening and selection of druggable molecules. Each section provides: a methodology overview - information that may be derived from the use of the methodology described; a case study - examples for the application of these methodologies; and a summary section - providing methodology specific benefits, limitations and future applications.

Endogenous miRNA and K+ Co-Activated Dynamic Assembly of DNA Coacervates for Intracellular miRNA Imaging and Mitochondrial Intervention

Intracellular dynamic assembly of DNA structures may be beneficial for the development of multifunctional nanoplatforms for the regulation of cell behaviors, providing new strategies for disease diagnosis and intervention. Herein, we propose the dynamic assembly of DNA coacervates in living cells triggered by miRNA-21 and K+, which can be used for both miRNA imaging and mitochondrial intervention. The rationale is that miRNA-21 can trigger the hybridization chain reaction to generate G-quadruplex precursors, and K+ can mediate the assembly of G-quadruplex-based coacervates, allowing the colorimetric detection of miRNA-21 ranging from 10 pM to 10 μM. Moreover, the as-formed DNA coacervates can specifically target mitochondria in MCF-7 breast cancer cells using the MCF-7 cell membrane as delivery carriers, which further act as an anionic shielding to inhibit communication between mitochondria and environments, with a significant inhibitory effect on ATP production and cellular migration behaviors. This work provides an ideal multifunctional nanoplatform for rationally interfering with cellular metabolism and migration behaviors through the dynamic assembly of DNA coacervates mediated by endogenous molecules, which has a large number of potential applications in the biomedical field, especially theranostics for cancer metastasis.

Hierarchical Assembly of Intrinsically Disordered Short Peptides

The understanding on how short peptide assemblies transit from disorder to order remains limited due to the lack of atomistic structures. Here we report cryo-EM structure of the nanofibers short intrinsically disordered peptides (IDPs). Upon lowering pH or adding calcium ions, the IDP transitions from individual nanoparticles to nanofibers containing an aromatic core and a disordered periphery comprised of 2 to 5 amino acids. Protonating the phosphate or adding more metal ions further assembles the nanofibers into filament bundles. The assemblies of the IDP analogs with controlled chemistry, such as phosphorylation site, hydrophobic interactions, and sequences indicate that metal ions interact with the flexible periphery of the nanoparticles of the IDPs to form fibrils and enhance the interfibrillar interactions to form filament bundles. Illustrating that an IDP self-assembles from disorder to order, this work offers atomistic molecular insights to understand assemblies of short peptides driven by noncovalent interactions.

Supramolecular immunotherapy on diversiform immune cells

Supramolecular immunotherapy employs supramolecular materials to stimulate the immune system for inhibiting tumor cell growth and metastasis, reducing the cancer recurrence rate, and improving the quality of the patient's life. Additionally, it can lessen patient suffering and the deterioration of their illness, as well as increase their survival rate. This paper will outline the fundamentals of tumor immunotherapy based on supramolecular materials as well as its current state of development and potential applications. To be more specific, we will first introduce the basic principles of supramolecular immunotherapy, including the processes, advantages and limitations of immunotherapy, the construction of supramolecular material structures, and its benefits in treatment. Second, considering the targeting of supramolecular drugs to immune cells, we comprehensively discuss the unique advantages of applying supramolecular drugs with different types of immune cells in tumor immunotherapy. The current research advances in supramolecular immunotherapy, including laboratory research and clinical applications, are also described in detail. Finally, we reveal the tremendous promise of supramolecular materials in tumor immunotherapy, as well as discuss the opportunities and challenges that may be faced in future development.

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.

Transformable nano-antibiotics for mechanotherapy and immune activation against drug-resistant Gram-negative bacteria

The dearth of antibiotic candidates against Gram-negative bacteria and the rise of antibiotic resistance create a global health concern. The challenge lies in the unique Gram-negative bacterial outer membrane that provides the impermeable barrier for antibiotics and sequesters antigen presentation. We designed a transformable nano-antibiotics (TNA) that can transform from nontoxic nanoparticles to bactericidal nanofibrils with reasonable rigidity (Young's modulus, 21.6 ± 5.9 MPa) after targeting β-barrel assembly machine A (BamA) and lipid polysaccharides (LPSs) of Gram-negative bacteria. After morphological transformation, the TNA can penetrate and damage the bacterial envelope, disrupt electron transport and multiple conserved biosynthetic and metabolic pathways, burst bacterial antigen release from the outer membrane, and subsequently activate the innate and adaptive immunity. TNA kills Gram-negative bacteria in vitro and in vivo with undetectable resistance through multiple bactericidal modes of action. TNA treatment-induced vaccination results in rapid and long-lasting immune responses, protecting against lethal reinfections.

Intra-Lysosomal Peptide Assembly for the High Selectivity Index against Cancer

Lysosomes remain powerful organelles and important targets for cancer therapy because cancer cell proliferation is greatly dependent on effective lysosomal function. Recent studies have shown that lysosomal membrane permeabilization induces cell death and is an effective way to treat cancer by bypassing the classical caspase-dependent apoptotic pathway. However, most lysosome-targeted anticancer drugs have very low selectivity for cancer cells. Here, we show intra-lysosomal self-assembly of a peptide amphiphile as a powerful technique to overcome this problem. We designed a peptide amphiphile that localizes in the cancer lysosome and undergoes cathepsin B enzyme-instructed supramolecular assembly. This localized assembly induces lysosomal swelling, membrane permeabilization, and damage to the lysosome, which eventually causes caspase-independent apoptotic death of cancer cells without conventional chemotherapeutic drugs. It has specific anticancer effects and is effective against drug-resistant cancers. Moreover, this peptide amphiphile exhibits high tumor targeting when attached to a tumor-targeting ligand and causes significant inhibition of tumor growth both in cancer and drug-resistant cancer xenograft models.

Evolving strategies and application of proteins and peptide therapeutics in cancer treatment

Several proteins and peptides have therapeutic potential and can be used for cancer therapy. By binding to cell surface receptors and other indicators uniquely linked with or overexpressed on tumors compared to healthy tissue, protein biologics enhance the active targeting of cancer cells, as opposed to the passive targeting of cells by conventional small-molecule chemotherapeutics. This study focuses on peptide medications that exist to slow or stop tumor growth and the spread of cancer, demonstrating the therapeutic potential of peptides in cancer treatment. As an alternative to standard chemotherapy, peptides that selectively kill cancer cells while sparing healthy tissue are developing. A mountain of clinical evidence supports the efficacy of peptide-based cancer vaccines. Since a single treatment technique may not be sufficient to produce favourable results in the fight against cancer, combination therapy is emerging as an effective option to generate synergistic benefits. One example of this new area is the use of anticancer peptides in combination with nonpeptidic cytotoxic drugs or the combination of immunotherapy with conventional therapies like radiation and chemotherapy. This review focuses on the different natural and synthetic peptides obtained and researched. Discoveries, manufacture, and modifications of peptide drugs, as well as their contemporary applications, are summarized in this review. We also discuss the benefits and difficulties of potential advances in therapeutic peptides.

Stimuli-responsive drug delivery systems triggered by intracellular or subcellular microenvironments

Drug delivery systems (DDS) triggered by local microenvironment represents the state-of-art of nanomedicine design, where the triggering hallmarks at intracellular and subcellular levels could be employed to exquisitely recognize the diseased sites, reduce side effects, and expand the therapeutic window by precisely tailoring the drug-release kinetics. Though with impressive progress, the DDS design functioning at microcosmic levels is fully challenging and underexploited. Here, we provide an overview describing the recent advances on stimuli-responsive DDSs triggered by intracellular or subcellular microenvironments. Instead of focusing on the targeting strategies as listed in previous reviews, we herein mainly highlight the concept, design, preparation and applications of stimuli-responsive systems in intracellular models. Hopefully, this review could give useful hints in developing nanoplatforms proceeding at a cellular level.

An enzyme-instructed self-assembly system induces tumor acidosis via sequential-dual effect for cancer selective therapy

The acidosis anti-tumor therapy, based on the altered energy metabolism pathway of tumor cells, has been proposed as an attractive method for cancer selective treatment. However, the strategy of inducing tumor acidosis by using a single drug to simultaneously inhibit both lactate efflux and consumption has not been reported yet. Herein, an in situ enzyme-instructed self-assembly (EISA) system was rationally fabricated to induce tumor acidosis apoptosis for cancer selective therapy. Depending on the sequential effect of the in situ EISA system, the targeted drug was successively distributed on the membrane and intracellular, inhibiting MCT4 mediated lactate efflux and mitochondrial tricarboxylic acid (TCA) cycle mediated lactate consumption, respectively. Through the dual obstruction of lactate metabolism to trigger tumor acidosis, the in situ EISA nanomedicine showed selective growth and migration inhibition against cancer cells. In addition, the nanomedicine also displayed a radio-sensitization effect in vitro due to causing the mitochondrial dysfunction, and exhibited a prominent synergistic chemo-radiotherapy anti-tumor performance in vivo. Accordingly, this work demonstrated that the in situ EISA system could endow the LND with sequential-dual effects to induce tumor acidosis, which may provide an enlightening strategy for anticancer drug delivery and cancer selective therapy. STATEMENT OF SIGNIFICANCE: With the help of the sequential effect of in situ EISA, the serial attack of LND against different targets was effectively realized to induce tumor acidosis and combined chemo-radiotherapy, implying the importance of the relationship between structure and function, which could offer a distinctive inspiration for future drug delivery system design and anti-tumor application.

Peptide Supramolecular Assembly-Instructed In Situ Self-Aggregation for Stratified Targeting Sonodynamic Therapy Enhancement of AIE Luminogens

The emergence of aggregation-induced emission luminogens (AIEgens) has attracted substantial scientific attention. However, their antitumor efficacy in photodynamic therapy (PDT) is significantly restricted by the poor water solubility and limited treatment depth. Therefore, a novel AIEgens-involved therapeutic platform with good permeability and bioavailability is urgently required. Herein, supramolecular chemistry is combined with the AIEgen bis-pyrene (BP) to construct a peptide-AIEgen hybrid nanosystem (PAHN). After intravenous injection, the versatile nanoplatform not only improved the hydrophilicity of BP but also achieved stratified targeting from tumor to mitochondrial and induced mitochondrial dysfunction, thus activating caspase-3 upregulation. Then, sonodynamic therapy (SDT), an alternative modality with high tissue penetrability, is performed to evoke reactive oxygen species (ROS) generation for BP. More importantly, since the hydrophilic shell is separated from the nanosystem by the specific cleavage of caspase-3, the resulting decrease in hydrophilicity induced tight self-aggregation of PAHN residues in situ, further allowing more absorbed energy to be used for ROS generation under ultrasound irradiation and enhancing SDT efficacy. Moreover, severe oxidative stress resulting from ROS imbalance in the mitochondria initiates the immunogenic cell death process, thus evoking antitumor immunogenicity. This PAHN provides prospective ideas into AIE-involved antitumor therapy and design of peptide-AIEgens hybrids.

Persistent Endoplasmic Reticulum Stress Stimulated by Peptide Assemblies for Sensitizing Cancer Chemotherapy

Pharmacological targeting of endoplasmic reticulum (ER) stress represents one of important methods for disease therapy, which, however, is significantly suppressed by the ER homeostatic processe. Herein, a proof-of-concept strategy is reported for persistent stimulation of ER stress via preventing ER stress adaptation by utilizing multifunctional peptide assemblies. The strategy is established via creation of peptide assemblies with ER-targeting and chaperone glucose-regulated protein 78 (GRP78)-inhibiting functions. The peptides assemblies form well-defined nanofibers that are retrieved by ER organelles in human cervical cancer cell. The underlying mechanism studies unravel that the ER-accumulated peptide assemblies simultaneously stimulate ER stress and inhibit GRP78 refolding activity and thereby promoting endogenous protein aggregation. Combining the internalized peptide assemblies with the induced protein aggregates leads to the persistent stimulation of ER stress. The persistent ER stress induced by the peptide assemblies bestows their application in sensitizing cancer chemotherapy. Both in vitro and in vivo results confirm the enhanced cytotoxicity of drug toyocamycin against HeLa cells by peptide assemblies, thus efficiently inhibiting in vivo tumor growth. The strategy reported here discloses the fundamental keys for efficient promotion of ER stress, thus providing the guidance for development of ER-targeting-assisted cancer chemotherapy in the future.

Mitochondrial dysfunction-targeted nanosystems for precise tumor therapeutics

Mitochondria play critical roles in the regulation of the proliferation and apoptosis of cancerous cells. Targeted induction of mitochondrial dysfunction in cancer cells by multifunctional nanosystems for cancer treatment has attracted increasing attention in the past few years. Numerous therapeutic nanosystems have been designed for precise tumor therapy by inducing mitochondrial dysfunction, including reducing adenosine triphosphate, breaking redox homeostasis, inhibiting glycolysis, regulating proteins, membrane potential depolarization, mtDNA damage, mitophagy dysregulation and so on. Understanding the mechanisms of mitochondrial dysfunction would be helpful for efficient treatment of diseases and accelerating the translation of these therapeutic strategies into the clinic. Then, various strategies to construct mitochondria-targeted nanosystems and induce mitochondrial dysfunction are summarized, and the recent research progress regarding precise tumor therapeutics is highlighted. Finally, the major challenges and an outlook in this rapidly developing field are discussed. This review is expected to inspire further development of novel mitochondrial dysfunction-based strategies for precise treatments of cancer and other human diseases.

Enhancing Photothermal Therapy Efficacy by In Situ Self-Assembly in Glioma

The residence time of some small molecular imaging and therapeutic agents in tumor tissue is short and the molecules can be easily dispersed, which decreases treatment efficacy. Therefore, methods that enhance oncotherapy performance are of significant importance. Here, we report an in situ self-assembly strategy aimed at enhancing the photothermal therapy of glioblastomas. The probe, ICG-PEP-c(RGD)fk, consisted of a glutathione-reactive self-assembling polypeptide as the skeleton, indocyanine green (ICG) as a theranostic agent, and cyclic Arg-Gly-Asp [c(RGD)fk] peptides as the targeting group. ICG-PEP-c(RGD)fk was synthesized and found to be assembled in the glutathione environment at 9.446 μM in vitro. Human glioblastoma cell line U87MG-luc with high integrin αvβ3 expression was applied to invivo experiments. ICG-PEP-c(RGD)fk provided clearer tumor imaging and had a tumor retention time of 6.12 times longer than that of ICG-c(RGD)fk. In therapeutic experiments, ICG-PEP-c(RGD)fk significantly suppressed glioblastoma growth and the tumor volume was 2.61 times smaller than in the ICG-c(RGD)fk group at the end of the observation period. Moreover, the median survival time of ICG-PEP-c(RGD)fk group was significantly improved by 2.78 times compared with that of the control group. In conclusion, glutathione-reactive self-assembling peptides are capable of increasing the tumor retention time and improving the photothermal therapeutic effect. The in situ self-assembly strategy is a potential and feasible method to enhance oncotherapy.

Nanomedicine for renal cell carcinoma: imaging, treatment and beyond

The kidney is a vital organ responsible for maintaining homeostasis in the human body. However, renal cell carcinoma (RCC) is a common malignancy of the urinary system and represents a serious threat to human health. Although the overall survival of RCC has improved substantially with the development of cancer diagnosis and management, there are various reasons for treatment failure. Firstly, without any readily available biomarkers, timely diagnosis has been greatly hampered. Secondly, the imaging appearance also varies greatly, and its early detection often remains difficult. Thirdly, chemotherapy has been validated as unavailable for treating renal cancer in the clinic due to its intrinsic drug resistance. Concomitant with the progress of nanotechnological methods in pharmaceuticals, the management of kidney cancer has undergone a transformation in the recent decade. Nanotechnology has shown many advantages over widely used traditional methods, leading to broad biomedical applications ranging from drug delivery, prevention, diagnosis to treatment. This review focuses on nanotechnologies in RCC management and further discusses their biomedical translation with the aim of identifying the most promising nanomedicines for clinical needs. As our understanding of nanotechnologies continues to grow, more opportunities to improve the management of renal cancer are expected to emerge.

A Totipotent "All-In-One" Peptide Sequentially Blocks Immune Checkpoint and Reverses the Immunosuppressive Tumor Microenvironment

Immune checkpoint blockade combined with reversal of the immunosuppressive tumor microenvironment (TME) can dramatically enhance anti-tumor immunity, which can be achieved by using multiple-agent therapy. However, the optimal dose and order of administration of different agents remain elusive. To address this dilemma, multiple agents are often grafted together to construct "all-in-one" totipotent drugs, but this usually comes at the cost of a lack of synergy between the agents. Herein, by comprehensively analyzing the conserved sites of the immune checkpoint and TME drug targets, peptide secondary structures, assembly properties, and other physicochemical properties, a high-content peptide library is designed. By using the "3D-molecular-evolution" screening strategy, an efficient and totipotent "all-in-one" peptide (TAP) is obtained, which possesses the abilities of self-assembling, blocking the PD-1/PD-L1 axis, inhibiting Rbm38-eIF4E complex formation, and activating p53. It is shown that in mice treated with TAP, with either subcutaneous tumors or patient-derived xenografts, PD-L1 is blocked, with increased activation of both T and NK cells whilst reversing the immunosuppressive TME. Moreover, TAP can mitigate tumor activity and suppress tumor growth, showing superior therapeutic effect over antibody-based drugs.

Approaches and Perspective of Coarse-Grained Modeling and Simulation for Polymer-Nanoparticle Hybrid Systems

Molecular modeling and simulations have emerged as effective and indispensable tools to characterize polymeric systems. They provide fundamental and essential insights to design a product of the required properties and to improve the understanding of a phenomenon at the molecular level for a particular system. The polymer-nanoparticle hybrids are materials with outstanding properties and correspondingly large applications whose study has benefited from this new paradigm. However, despite the significant expansion of modern day computational powers, investigation of the long time and large length scale phenomenon in polymeric and polymer-nanoparticle systems is still a challenging task to complete through all-atom molecular dynamics (AA-MD) simulations. To circumvent this problem, a variety of coarse-grained (CG) models have been proposed, ranging from the generic CG models for qualitative properties predictions to more realistic chemically specific CG models for quantitative properties predictions. These CG models have already delivered some success stories in the study of several spatial and temporal evolutions of many processes. Some of these studies were beyond the feasibility of traditional atomistic resolution models due to either the size or the time constraints. This review captures the different types of popular CG approaches that are utilized in the investigation of the microscopic behavior of polymer-nanoparticle hybrid systems. The rationale of this article is to furnish an overview of the popular CG approaches and their applications, to review several important and most recent developments, and to delineate the perspectives on future directions in the field.

Nanomolar LL-37 induces permeability of a biomimetic mitochondrial membrane

LL-37, the only human host cathelicidin peptide, is proposed to be able to induce host cell apoptosis through mitochondrial membrane permeabilization (MMP). Detailed pathways of the LL-37-triggered MMP are however still disputed. It is generally believed that cationic peptides permeate a membrane mostly in conditions of micromolar peptide concentrations and negatively charged membranes, which are not usually satisfied in the mitochondrial circumstance. Herein, using a variety of single-molecule techniques, we show that nanomolar LL-37 specifically induces permeability of a phosphoethanolamine (PE)-rich biomimetic mitochondrial membrane in a protein-independent manner. The insertion dynamics of single LL-37 molecules exhibit different metastable states in bilayers composed of different lipids. Moreover, the PE lipids significantly facilitate adsorption and accumulation of LL-37 on the PE-rich bilayer, and produce deeper insertion of peptide oligomers, especially tetramers, into the bilayer. This work offers an alternative pathway of the LL-37-triggered MMP and apoptosis.

SIAH proteins regulate the degradation and intra-mitochondrial aggregation of PINK1: Implications for mitochondrial pathology in Parkinson's disease

Parkinson's disease (PD) is characterized by degeneration of neurons, particularly dopaminergic neurons in the substantia nigra. PD brains show accumulation of α-synuclein in Lewy bodies and accumulation of dysfunctional mitochondria. However, the mechanisms leading to mitochondrial pathology in sporadic PD are poorly understood. PINK1 is a key for mitophagy activation and recycling of unfit mitochondria. The activation of mitophagy depends on the accumulation of uncleaved PINK1 at the outer mitochondrial membrane and activation of a cascade of protein ubiquitination at the surface of the organelle. We have now found that SIAH3, a member of the SIAH proteins but lacking ubiquitin-ligase activity, is increased in PD brains and cerebrospinal fluid and in neurons treated with α-synuclein preformed fibrils (α-SynPFF). We also observed that SIAH3 is aggregated together with PINK1 in the mitochondria of PD brains. SIAH3 directly interacts with PINK1, leading to their intra-mitochondrial aggregation in cells and neurons and triggering a cascade of toxicity with PINK1 inactivation along with mitochondrial depolarization and neuronal death. We also found that SIAH1 interacts with PINK1 and promotes ubiquitination and proteasomal degradation of PINK1. Similar to the dimerization of SIAH1/SIAH2, SIAH3 interacts with SIAH1, promoting its translocation to mitochondria and preventing its ubiquitin-ligase activity toward PINK1. Our results support the notion that the increase in SIAH3 and intra-mitochondrial aggregation of SIAH3-PINK1 may mediate α-synuclein pathology by promoting proteotoxicity and preventing the elimination of dysfunctional mitochondria. We consider it possible that PINK1 activity is decreased in sporadic PD, which impedes proper mitochondrial renewal in the disease.

Enzyme-instructed morphology transformation of mitochondria-targeting peptide for the selective eradication of osteosarcoma

The treatment of osteosarcoma involves an adjuvant therapy that combines surgery and chemotherapy. However, considering that children are the main victims of osteosarcoma, replacing such a harsh treatment with a soft but powerful method that ensures a complete cure while having no adverse effects is highly desirable. To achieve this aim, we have developed a supramolecular therapeutic strategy based on morphology-transformable mitochondria-targeting peptides for the eradication of osteosarcoma with enhanced selectivity and reduced side effects. A newly designed micelle-forming amphiphilic peptide, l-Mito-FFYp, consisting of a phosphate substrate for the biomarker enzyme of osteosarcoma alkaline phosphatase (ALP), disassembles in response to the ALP enzyme in the cell membrane to generate positively charged l-Mito-FFY molecules, which diffuse inside the targeted cell and self-assemble to form nanostructures specifically inside the mitochondria to induce cell apoptosis.

Spatiotemporal Self-Assembly of Peptide Amphiphiles by Carbonic Anhydrase IX-Targeting Induces Cancer-Lysosomal Membrane Disruption

To achieve spatiotemporal control, an enzyme-instructed self-assembly system is widely used, but this approach typically has a small effect on cellular fate. In this study, we show that the intralysosomal assembly by a carbonic anhydrase IX (CAIX)-targeting peptide amphiphile (Pep-AT) can control cellular fate with a low therapeutic dose by tuning the surface charge based on pH change. Pep-AT self-assembles into a fibrous aggregate with a negative surface charge in an extracellular environment near CAIX. During endocytosis, it changes into a nanofiber with a positive surface charge at the lysosome. Then, it can disrupt the lysosomal membrane and induce cellular apoptosis. This study demonstrates that a spatiotemporal assembly induced by a cancer enzyme and specific organelle can control the cellular fate of cancer.

Improved Coarse-Grained Model for Nanoparticles Based on the Martini Force Field and Its Application in Molecular Dynamics Simulation on Gel Ink

Research on the dispersion and stability of nanoparticles in liquid media is one of the key subjects for nanomaterial utilization. In consideration of the preponderance of coarse-grained (CG) molecular dynamics (MD) simulation in following and understanding the structure and dynamics on the nanoscale, an improved CG model for nanoparticles based on the Martini force field is established to facilitate the more extensive applications of this simulation method and further studies on complex nanoparticle liquid systems. Gel ink is selected as the liquid system for nanoparticles to validate the improved CG model on the one hand and introduce the CGMD simulation method into the studies of this system on the other. The calculation shows that the improved model can provide relatively precise results and has good computational stability. The effect mechanisms of the thickener and disperser on the carbon black nanoparticle are similar, namely the result of a delicate balance between the interaction of the thickener/disperser with the carbon black nanoparticle and the interaction of the thickener and disperser with each other. Furthermore, the phase assimilating effect of disperser molecules is key for separating the agglomerated carbon black nanoparticles; thereafter, the space steric hindrance effect and the electrostatic hindrance effect play main roles in maintaining the dispersion of carbon black nanoparticles.

Recent advances of bioresponsive polymeric nanomedicine for cancer therapy

A bioresponsive polymeric nanocarrier for drug delivery is able to alter its physical and physicochemical properties in response to a variety of biological signals and pathological changes, and can exert its therapeutic efficacy within a confined space. These nanosystems can optimize the biodistribution and subcellular location of therapeutics by exploiting the differences in biochemical properties between tumors and normal tissues. Moreover, bioresponsive polymer-based nanosystems could be rationally designed as precision therapeutic platforms by optimizing the combination of responsive elements and therapeutic components according to the patient-specific disease type and stage. In this review, recent advances in smart bioresponsive polymeric nanosystems for cancer chemotherapy and immunotherapy will be summarized. We mainly discuss three categories, including acidity-sensitive, redox-responsive, and enzyme-triggered polymeric nanosystems. The important issues regarding clinical translation such as reproducibility, manufacture, and probable toxicity, are also commented.

Metal-Ion-Induced Evolution of Phenylalanine Self-Assembly: Structural Polymorphism of Novel Metastable Intermediates

The self-assembly of aromatic amino acids has been widely studied due to their ability to form well-defined amyloid-like fibrillar structures. Herein, for the first time, we report the existence of different metastable intermediate states of diverse morphologies, for example, droplets, spheres, vesicles, flowers, and toroids, that are sequentially formed in aqueous medium during the self-assembly process of phenylalanine in the presence of different divalent (Zn²⁺, Cd²⁺, and Hg²⁺) and trivalent (Al³⁺, Ga³⁺, and In³⁺) metal ions having low pK_a values. Due to metal ion-amino acid coordination and strong hydrophobic interaction induced by these metal ions, spherical aggregates are obtained at the initial stage of the structural evolution and further transformed into other intermediate states. Our work may facilitate understanding of the role of metal ions in the amino acid self-assembly process and broaden future applications of the obtained nanostructures in drug delivery, tissue engineering, bioimaging, biocatalysis, and other fields.

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.

Controlling Intracellular Enzymatic Self-Assembly of Peptide by Host-Guest Complexation for Programming Cancer Cell Death

Controlling the enzymatic reaction of macromolecules in living systems plays an essential role in determining the biological functions, which remains challenging in the synthetic system. This work shows that host-guest complexation could be an efficient strategy to tune the enzymatic self-assembly of the peptide. The formed host-guest complexation prevents the enzymatic kinetics of peptide assemblies on the cell surface and promotes cellular uptake of assemblies. For uptake inside cells, the host-guest complex undergoes dissociation in the acidic lysosome, and the released peptide further self-assembles inside the mitochondria. Accumulating assemblies at mitochondria induce the ferroptosis of cancer cells, resulting in cancer cell death in vitro and the tumor-bearing mice model. As the first example of using host-guest complexation to modulate the kinetics of enzymatic self-assembly, this work provides a general method to control enzymatic self-assembly in living cells for selective programming cancer cell death.

A Supramolecular Self-Assembling Nanoagent by Inducing Intracellular Aggregation of PSMA for Prostate Cancer Molecularly Targeted Theranostics

Prostate cancer (PCa) with prostate-specific membrane antigen (PSMA)-specific high expression is well suited for molecularly targeted theranostics. PSMA expression correlates with the malignancy of PCa, and its dimeric form can promote tumor progression by exerting enzymatic activity to activate downstream signal transduction. However, almost no studies have shown that arresting the procancer signaling of the PSMA receptors themselves can cause tumor cell death. Meanwhile, supramolecular self-assembling peptides are widely used to design anticancer agents due to their unique and excellent properties. Here, a PSMA-targeting supramolecular self-assembling nanotheranostic agent, DBT-2FFGACUPA, which actively targets PSMA receptors on PCa cell membranes and induces them to enter the cell and form large aggregates, is developed. This process not only selectively images PSMA-positive tumor cells but also suppresses the downstream procancer signals of PSMA, causing tumor cell death. This work provides an alternative approach and an advanced agent for molecularly targeted theranostics options in PCa that can induce tumor cell death without relying on any reported anticancer drugs.