Enzyme-Instructed Peptide Assembly Favored by Preorganization for Cancer Cell Membrane Engineering

Enhancing the Inhibition of Corneal Neovascularization Efficacy by Self-Assembled into Supramolecular Hydrogel of Anti-Angiogenic Peptide

Background

Corneal neovascularization (CNV) is a common eye disease that leads to blindness. New treatment strategies are urgently needed due to the limitations of current treatment methods.

Methods

We report the synthesis of peptide Nap-FFEEPCAIWF ( Comp.3 ) via chemical conjugation of Nap-FFEE ( Comp.2 ) to antiangiogenic peptide PCAIWF (Comp.1). Comp.3 self-assembled into a hydrogel ( gel of 3 ) composed of nanofibers, which enhanced the antiangiogenic function of the epitope.

Results

We developed a novel peptide with an amphiphilic framework, Comp.3 , which could self-assemble into a supramolecular hydrogel with a well-ordered nanofiber structure. The nanofibers exhibited good biocompatibility with corneal epithelial cells, presenting a promising strategy to enhance the efficacy of free peptide-based drugs in the treatment of ocular vascular diseases, such as CNV and other angiogenesis-related diseases.

Conclusion

Nap-FFEEPCAIWF nanofibers provide an alternative approach to enhancing the therapeutic efficiency of free peptide-based drugs against ocular vascular diseases.

An in-situ peptide-antibody self-assembly to block CD47 and CD24 signaling enhances macrophage-mediated phagocytosis and anti-tumor immune responses

Targeted immunomodulation for reactivating innate cells, especially macrophages, holds great promise to complement current adaptive immunotherapy. Nevertheless, there is still a lack of high-performance therapeutics for blocking macrophage phagocytosis checkpoint inhibitors in solid tumors. Herein, a peptide-antibody combo-supramolecular in situ assembled CD47 and CD24 bi-target inhibitor (PAC-SABI) is described, which undergoes biomimetic surface propagation on cancer cell membranes through ligand-receptor binding and enzyme-triggered reactions. By simultaneously blocking CD47 and CD24 signaling, PAC-SABI enhances the phagocytic ability of macrophages in vitro and in vivo, promoting anti-tumor responses in breast and pancreatic cancer mouse models. Moreover, building on the foundation of PAC-SABI-induced macrophage repolarization and increased CD8+ T cell tumor infiltration, sequential anti-PD-1 therapy further suppresses 4T1 tumor progression, prolonging survival rate. The in vivo construction of PAC-SABI-based nano-architectonics provides an efficient platform for bridging innate and adaptive immunity to maximize therapeutic potency.

Lysosomal Peptide Self-Assembly to Control Cell Behavior

Lysosomes are membrane-enclosed organelles that play key roles in degrading and recycling cellular debris, cellular signaling, and energy metabolism processes. Confinement of amphiphilic peptides in the lysosome to construct functional nanostructures through noncovalent interactions is an emerging approach to tune the homeostasis of lysosome. After briefly introducing the importance of lysosome and its functions, we discuss the advantages of lysosomal nanostructure formation for disease therapy. We next discuss the strategy for triggering the self-assembly of peptides in the lysosome, followed by a concise outlook of the future perspective about this emerging research direction.

Applications of self-assembled peptide hydrogels in anti-tumor therapy

Peptides are a class of active substances composed of a variety of amino acids with special physiological functions. The rational design of peptide sequences at the molecular level enables their folding into diverse secondary structures. This property has garnered significant attention in the biomedical sphere owing to their favorable biocompatibility, adaptable mechanical traits, and exceptional loading capabilities. Concurrently with advancements in modern medicine, the diagnosis and treatment of tumors have increasingly embraced targeted and personalized approaches. This review explores recent applications of self-assembled peptides derived from natural amino acids in chemical therapy, immunotherapy, and other adjunctive treatments. We highlighted the utilization of peptide hydrogels as delivery systems for chemotherapeutic drugs and other bioactive molecules and then discussed the challenges and prospects for their future application.

Copper-Induced Supramolecular Peptide Assemblies for Multi-Pathway Cell Death and Tumor Inhibition

Although self-assembly has emerged as an effective tool for fabricating biomaterials, achieving precise control over the morphologies and functionalities of the resultant assemblies remains an ongoing challenge. Inspired by the copper peptide naturally present in human plasma, in this study, we designed a synthetic precursor, FcGH. FcGH can self-assemble via two distinct pathways: spontaneous and Cu2+-induced. These two assembly pathways enabled the formation of assemblies with tunable morphologies by adjusting the amount of added Cu2+. We found that the nanoparticles formed by Cu2+-induced self-assembly exhibited a significantly higher cellular uptake efficiency than the wormlike fibers formed spontaneously. Moreover, this Cu2+-induced assembly process occurred spontaneously at a 1 : 1 molar ratio of Cu2+ to FcGH, avoiding the excessive use of Cu2+ and a tedious preparation procedure. By co-assembling with 10-hydroxycamptothecin (HCPT)-conjugated FcGH, Cu2+-induced supramolecular nanodrugs elicited multiple cell death modalities in cancer cells with elevated immunogenicity, enhancing the therapeutic effect compared to free HCPT. This study highlights Cu2+-induced self-assembly as an efficient tool for directing the assembly of nanodrugs and for synergistic tumor therapy.

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.

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.

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.

pH-responsive drug-loaded peptides enhance drug accumulation and promote apoptosis in tumor cells

The efficacy of chemotherapeutic drugs in tumor treatment is limited by their toxicity and side effects due to their inability to selectively accumulate in tumor tissue. In addition, chemotherapeutic agents are easily pumped out of tumor cells, resulting in their inadequate accumulation. To overcome these challenges, a drug delivery system utilizing the amphiphilic peptide Pep1 was designed. Pep1 can self-assemble into spherical nanoparticles (PL/Pep1) and encapsulate paclitaxel (PTX) and lapatinib (LAP). PL/Pep1 transformed into nanofibers in an acidic environment, resulting in longer drug retention and higher drug concentrations within tumor cells. Ultimately, PL/Pep1 inhibited tumor angiogenesis and enhanced tumor cell apoptosis. The use of shape-changing peptides as drug carriers to enhance cancer cell apoptosis is promising.

Intelligent Biomaterialomics: Molecular Design, Manufacturing, and Biomedical Applications

Materialomics integrates experiment, theory, and computation in a high-throughput manner, and has changed the paradigm for the research and development of new functional materials. Recently, with the rapid development of high-throughput characterization and machine-learning technologies, the establishment of biomaterialomics that tackles complex physiological behaviors has become accessible. Breakthroughs in the clinical translation of nanoparticle-based therapeutics and vaccines have been observed. Herein, recent advances in biomaterials, including polymers, lipid-like materials, and peptides/proteins, discovered through high-throughput screening or machine learning-assisted methods, are summarized. The molecular design of structure-diversified libraries; high-throughput characterization, screening, and preparation; and, their applications in drug delivery and clinical translation are discussed in detail. Furthermore, the prospects and main challenges in future biomaterialomics and high-throughput screening development are highlighted.

Transformable Supramolecular Self-Assembled Peptides for Cascade Self-Enhanced Ferroptosis Primed Cancer Immunotherapy

Immunotherapy has received widespread attention for its effective and long-term tumor-eliminating ability. However, for immunogenic "cold" tumors, such as prostate cancer (PCa), the low immunogenicity of the tumor itself is a serious obstacle to efficacy. Here, this work reports a strategy to enhance PCa immunogenicity by triggering cascade self-enhanced ferroptosis in tumor cells, turning the tumor from "cold" to "hot". This work develops a transformable self-assembled peptide TEP-FFG-CRApY with alkaline phosphatase (ALP) responsiveness and glutathione peroxidase 4 (GPX4) protein targeting. TEP-FFG-CRApY self-assembles into nanoparticles under aqueous conditions and transforms into nanofibers in response to ALP during endosome/lysosome uptake into tumor cells, promoting lysosomal membrane permeabilization (LMP). On the one hand, the released TEP-FFG-CRAY nanofibers target GPX4 and selectively degrade the GPX4 protein under the light irradiation, inducing ferroptosis; on the other hand, the large amount of leaked Fe2+ further cascade to amplify the ferroptosis through the Fenton reaction. TEP-FFG-CRApY-induced immunogenic ferroptosis improves tumor cell immunogenicity by promoting the maturation of dendritic cells (DCs) and increasing intratumor T-cell infiltration. More importantly, recovered T cells further enhance ferroptosis by secreting large amounts of interferon-gamma (IFN-γ). This work provides a novel strategy for the molecular design of synergistic molecularly targeted therapy for immunogenic "cold" tumors.

In Situ Nanofiber Formation Blocks AXL and GAS6 Binding to Suppress Ovarian Cancer Development

Anexelekto (AXL) is an attractive molecular target for ovarian cancer therapy because of its important role in ovarian cancer initiation and progression. To date, several AXL inhibitors have entered clinical trials for the treatment of ovarian cancer. However, the disadvantages of low AXL affinity and severe off-target toxicity of these inhibitors limit their further clinical applications. Herein, by rational design of a nonapeptide derivative Nap-Phe-Phe-Glu-Ile-Arg-Leu-Arg-Phe-Lys (Nap-IR), a strategy of in situ nanofiber formation is proposed to suppress ovarian cancer growth. After administration, Nap-IR specifically targets overexpressed AXL on ovarian cancer cell membranes and undergoes a receptor-instructed nanoparticle-to-nanofiber transition. In vivo and in vitro experiments demonstrate that in situ formed Nap-IR nanofibers efficiently induce apoptosis of ovarian cancer cells by blocking AXL activation and disrupting subsequent downstream signaling events. Remarkably, Nap-IR can synergistically enhance the anticancer effect of cisplatin against HO8910 ovarian tumors. It is anticipated that the Nap-IR can be applied in clinical ovarian cancer therapy in the near future.

Intranuclear assembly of leucine-rich peptides for selective death of osteosarcoma cells

Herein, we show a pair of leucine-rich L- and D-phosphopeptides which self-assemble into twisting nanofibers, whose secondary structures contain a strong β-sheet component after being dephosphorylated by alkaline phosphatase (ALP). While being incubated with ALP overexpressing osteosarcoma cells, both of the peptides self-assemble in the nuclei and induce cell death. The cell death involves multiple cell death modalities and occurs along with the disruption of cell membranes. Enzyme-instructed self-assembly (EISA) inhibits osteosarcoma cells and shows no side effect to other cells. In addition, the cancer cells hardly gain drug resistance after repeated treatment. This work reports a pair of EISA-based nanofibers to target cell nuclei, and also provides a novel chemotherapeutic agent to inhibit osteosarcoma cells without side effects and drug resistance.

Self-assembly of peptide nanomaterials at biointerfaces: molecular design and biomedical applications

Self-assembly is an important strategy for constructing ordered structures and complex functions in nature. Based on this, people can imitate nature and artificially construct functional materials with novel structures through the supermolecular self-assembly pathway of biological interfaces. Among the many assembly units, peptide molecular self-assembly has received widespread attention in recent years. In this review, we introduce the interactions (hydrophobic interaction, hydrogen bond, and electrostatic interaction) between peptide nanomaterials and biological interfaces, summarizing the latest advancements in multifunctional self-assembling peptide materials. We systematically demonstrate the assembly mechanisms of peptides at biological interfaces, such as proteins and cell membranes, while highlighting their application potential and challenges in fields like drug delivery, antibacterial strategies, and cancer therapy.

Assessment of the Enzymatic Dephosphorylation Kinetics in the Assemblies of a Phosphopentapeptide that Forms Intranuclear Nanoribbons

Although the formation of peptide assemblies catalyzed by alkaline phosphatase (ALP) has received increasing attention in inhibiting cancer cells, the detailed enzyme kinetics of the dephosphorylation of the corresponding phosphopeptide assemblies have yet to be determined. We recently discovered that assemblies from a phosphopentapeptide can form intracellular nanoribbons that kill induced pluripotent stem cells or osteosarcoma cells, but the kinetics of enzymatic dephosphorylation remain unknown. Thus, we chose to examine the enzyme kinetics of the dephosphorylation of the phosphopentapeptide [NBD-LLLLpY (1)] from concentrations below to above its critical micelle concentration (CMC). Our results show that the phosphopeptide exhibits a CMC of 75 μM in phosphate saline buffer, and the apparent Vmax and Km values of alkaline phosphatase catalyzed dephosphorylation are approximately 0.24 μM/s and 5.67 mM, respectively. Despite dephosphorylation remaining incomplete at 60 min in all the concentrations tested, dephosphorylation of the phosphopeptide at concentrations of 200 μM or above mainly results in nanoribbons, dephosphorylation at concentrations of CMC largely produces nanofibers, and dephosphorylation below the CMC largely generates nanoparticles. Moreover, the formation of nanoribbons correlates with the intranuclear accumulation of the pentapeptide. By providing the first examination of the enzymatic kinetics of phosphopeptide assemblies, this work further supports the notion that the assemblies of phosphopentapeptides can act as a new functional entity for controlling cell fates.

Cationic and amphiphilic peptide-based hydrogels with dual activities as anticancer and antibacterial agents

The emergence of peptide-based functional biomaterials is on the rise. To fulfil this purpose, a series of amphiphilic peptides, such as H2N-X-Met-Phe-C12H25, where X = L-lysine (CP1), X = L-histidine (CP2), and X = L-leucine (CP3), have been designed, synthesised, purified and fully characterised. Herein, we reported peptide-based supramolecular hydrogels with antibacterial and anticancer activities. An attempt has been made to investigate the antibacterial properties of these peptide-based hydrogels against Gram-positive (S. aureus and B. subtilis) and Gram-negative (E. coli and P. aeruginosa) bacteria. Investigations show that the L-lysine containing gelator, CP1, is active against both Gram-positive and Gram-negative bacteria and the L-histidine containing gelator, CP2, selectively inhibits the growth of Gram-negative bacteria. Interestingly, the L-leucine containing gelator, CP3, does not show any antibacterial properties. Moreover, the L-lysine containing gelator exhibits the best potency. Generation of reactive oxygen species (ROS) is a probable way to damage the bacterial membrane. To explore the cytotoxic properties and to determine the efficacy of the synthesized compounds in inhibiting cell viability, a comprehensive investigation was performed using three distinct cell lines: MDA-MB-231 (human triple-negative breast cancer), MDA-MB-468 (human triple-negative breast cancer) and HEK 293 (human embryonic kidney). Remarkably, the results of our study revealed a substantial cytotoxic impact of these peptide gelators on the MDA-MB-231 and MDA-MB-468 cell lines in comparison to the HEK 293 cells. Caspase 3/7 activity is the possible mechanistic path to determine the apoptotic rates of the cell lines. This finding emphasizes the promising potential of these peptide-based gelators in targeting and suppressing the growth of human triple negative breast cancer cells, while showing non-cytotoxicity towards non-cancerous HEK 293 cells. In a nutshell, these peptide-based materials are coming to light as next generation biomaterials.

Phosphates as Assisting Groups in Glycan Synthesis

In nature, phosphates are added to and cleaved from molecules to direct biological pathways. The concept was adapted to overcome limitations in the chemical synthesis of complex oligosaccharides. Phosphates were chemically placed on synthetic glycans to ensure site-specific enzymatic elongation by sialylation. In addition, the deliberate placement of phosphates helped to solubilize and isolate aggregating glycans. Upon traceless removal of the phosphates by enzymatic treatment with alkaline phosphatase, the native glycan structure was revealed, and the assembly of glycan nanostructures was triggered.

Enzyme-Induced Shape-Shifting Peptide Nanocarrier Coloaded with Paclitaxel and Dipyridamole Inhibits Platelet Function and Tumor Metastasis

Tumor-associated platelets can bind to tumor cells and protect circulating tumor cells from NK-mediated immune surveillance. Tumor-associated platelets secrete cytokines to induce the epithelial-mesenchymal transition (EMT) in tumor cells, which promotes tumor metastasis. Combining chemotherapeutic agents with antiplatelet drugs can reduce the occurrence of metastasis, but the systemic application of chemotherapeutic agents and antiplatelet drugs is prone to causing serious side effects. Therefore, delivering drugs to the tumor microthrombus site for long-lasting inhibition is a problem that needs to be addressed. Here, we show that small molecule peptide nanoparticles containing the Cys-Arg-Glu-Lys-Ala (CREKA) peptide can deliver the platelet inhibitor dipyridamole (DIP) and the chemotherapeutic drug paclitaxel (PTX) to tumor tissues, thereby inhibiting tumor-associated platelet function while killing tumor cells. The drug-loaded nanoparticles PD/Pep1 inhibited platelet-tumor cell interactions, were effectively taken up by tumor cells, and underwent morphological transformation induced by alkaline phosphatase (ALP) to prolong the retention time of the drugs. After intravenous injection, PD/Pep1 can target tumors and inhibit tumor metastasis. Thus, this small molecule peptide nanoformulation provides a simple strategy for efficient drug delivery and shows promise as a novel cancer therapy platform.

Chemo-immunotherapy by dual-enzyme responsive peptide self-assembling abolish melanoma

Herein, we designed Comp. 1 to simultaneously respond to two enzymes: alkaline phosphatase and matrix metalloproteinase 2, which is commonly found in highly malignant cancer cell lines containing B16-F10 murine melanoma cells and CT26 murine colon carcinoma cells. We used the regional differences in the expression levels of dual-markers to accurately release immune molecule IND into tumor microenvironment for the activation of anti-tumor related immune effects, while in-situ self-assembly occurs. The dual-enzyme response process can further regulate the peptide precursors' self-assembly in the form of short rod-shaped nanofibers, enabling the delivery of the loaded chemotherapeutic drug HCPT into the cancer cells and further allowing the peptide assemblies to escape from lysosomes and return to cytoplasm in the form of tiny nanoparticles to induce apoptosis of cancer cells. This process does not occur in the single-positive breast cancer cell line MCF-7 or the normal hepatocytes cell line LO2, indicating the selectivity of the cancer cells exhibited using our strategy. In vivo studies revealed that Comp. 1 can effectively cooperate with chemotherapy to enhance the immunotherapy effect and induce immune responses associated with elevated pro-inflammatory cytokines in vivo to inhibit malignant tumors growth. Our dual-enzyme responsive chemo-immunotherapy strategy feasible in anti-tumor treatment, provides a new avenue for regulating peptide self-assembly to adapt to diverse tumor properties and may eventually be used for the development of novel multifunctional anti-tumor nanomedicines.

Aflibercept Loaded Eye-Drop Hydrogel Mediated with Cell-Penetrating Peptide for Corneal Neovascularization Treatment

Corneal neovascularization (CoNV) is a major cause of visual impairment worldwide. Currently, available treatment options have limited efficacy and are associated with adverse effects due to biological barriers and clearance mechanisms. To address this challenge, a novel topical delivery system is developed-Gel 2_1&Eylea-an aflibercept-loaded eye-drop hydrogel mediated with cell-penetrating peptide 1. Gel 2_1&Eylea demonstrates superior membrane permeability, increased stability, and prolonged drug retention time on the ocular surface, and thus may improve drug efficacy. In a rabbit CoNV model, Gel 2_1&Eylea significantly reduces the density of neovascularization with no adverse effects on normal corneoscleral limbal vessels, demonstrating high efficacy and biocompatibility. This work identifies a promising treatment for CoNV which has the potential to benefit other ocular neovascular diseases.

Therapeutic Supramolecular Polymers: Designs and Applications

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

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.

Multistage Self-Assembled Nanomaterials for Cancer Immunotherapy

Advances in nanotechnology have brought innovations to cancer therapy. Nanoparticle-based anticancer drugs have achieved great success from bench to bedside. However, insufficient therapy efficacy due to various physiological barriers in the body remains a key challenge. To overcome these biological barriers and improve the therapeutic efficacy of cancers, multistage self-assembled nanomaterials with advantages of stimuli-responsiveness, programmable delivery, and immune modulations provide great opportunities. In this review, we describe the typical biological barriers for nanomedicines, discuss the recent achievements of multistage self-assembled nanomaterials for stimuli-responsive drug delivery, highlighting the programmable delivery nanomaterials, in situ transformable self-assembled nanomaterials, and immune-reprogramming nanomaterials. Ultimately, we perspective the future opportunities and challenges of multistage self-assembled nanomaterials for cancer immunotherapy.

Modular co-assembly of peptides and polyoxometalates into underwater adhesives with photoluminescence and adjustable adhesion

Supramolecular polymerization between cationic peptides and anionic polyoxometalates has emerged as a promising strategy for the creation of peptide-based biomimetic underwater adhesives. However, the extremely rigorous requirements for peptide design are an important obstacle to the fabrication of available peptide adhesives with controlled adhesion and versatile functionality. Inspired by marine sessile organisms in nature, here we reported a modular co-assembly method to easily produce peptide/polyoxometalate underwater adhesive materials through mixing two complementary cationic peptides (Pep1 and Pep2) with a single anionic polyoxometalate K6H[SiW9V3O40] in aqueous solution, which are not possible to be obtained from an individual peptide module. We demonstrated that the relatively hydrophobic Pep1 contributes to the bulk cohesion of the resulting adhesive, while the relatively hydrophilic Pep2 not only enables the interfacial adhesion but also regulates the bulk cohesion of the Pep1/Pep2/SiW9V3 adhesive. Rheological and shear adhesion tests showed that the macroscopic adhesion performance of the resulting adhesive materials could be conveniently adjusted by simply changing the molar ratio of the complementary peptide modules without any complicated peptide design. Interestingly, the luminescence properties of K11[Eu(PW11O39)2] (labelled as EuPW11) could be maintained within the Pep1/Pep2/EuPW11 adhesive even in a water environment. The lifetime of the Pep1/Pep2/EuPW11 adhesive was 2.19 ms. The fluorescence quantum yield of the Pep1/Pep2/EuPW11 adhesive was measured to be 27.46%. This study unveils that the modular co-assembly method can effectively simplify the material design of peptide/polyoxometalate underwater adhesives, which will significantly broaden the horizon of material pools and extend their availability space.

Phosphorescence Enzyme-Mimics for Time-Resolved Sensitive Diagnostics and Environment-Adaptive Specific Catalytic Therapeutics

Enzyme mimics (EMs) with intrinsic catalysis activity have attracted enormous interest in biomedicine. However, there is a lack of environmentally adaptive EMs for sensitive diagnosis and specific catalytic therapeutics in simultaneous manners. Herein, the coordination modulation strategy is designed to synthesize silicon-based phosphorescence enzyme-mimics (SiPEMs). Specifically, the atomic-level engineered Co-N4 structure in SiPEMs enables the environment-adaptive peroxidase, oxidase, and catalase-like activities. More intriguingly, the internal Si-O networks are able to stabilize the triplet state, exhibiting long-lived phosphorescence with lifetime of 124.5 ms, suitable for millisecond-range time-resolved imaging of tumor cells and tissue in mice (with high signal-to-background ratio values of ∼60.2 for in vitro and ∼611 for in vivo). Meanwhile, the SiPEMs act as an oxidative stress amplifier, allowing the production of ·OH via cascade reactions triggered by the tumor microenvironment (∼136-fold enhancement in peroxidase catalytic efficiency); while the enzyme-mimics can scavenge the accumulation of reactive oxygen species to alleviate the oxidative damage in normal cells, they are therefore suitable for environment-adaptive catalytic treatment of cancer in specific manners. We innovate a systematic strategy to develop high-performance enzymemics, constructing a promising breakthrough for replacing traditional enzymes in cancer treatment applications.

Co-assembled Supramolecular Hydrogel of Salvianolic Acid B and a Phosphopeptide for Enhanced Wound Healing

Supramolecular natural product gels (NPGs) have emerged as promising biomaterials for scalable and adjustable drug delivery systems. These gels possess biocompatibility, biodegradability, and the ability to mimic the extracellular matrix. Salvianolic acid B (SAB), derived from Salvia miltiorrhiza, a Chinese medicinal plant, exhibits various beneficial properties such as antioxidant, antifibrotic, and angiogenic effects. In our research, we serendipitously discovered that the co-assembly of SAB and a soluble phosphopeptide results in the formation of a robust and adhesive hydrogel termed 1&SAB hydrogel. This hydrogel effectively prolongs the retention time of the therapeutic agents on the skin's wound surface, thereby promoting wound healing. The hydrogel demonstrates antioxidant effects, enhances cell migration, accelerates angiogenesis, and inhibits scar hyperplasia. This innovative gel material offers a simple and efficient approach to managing skin wounds and holds promise for application in complex wound-healing treatments.

Constructing Antiretroviral Supramolecular Polymers as Long-Acting Injectables through Rational Design of Drug Amphiphiles with Alternating Antiretroviral-Based and Hydrophobic Residues

One of the main challenges in the development of long-acting injectables for HIV treatment is the limited duration of drug release, which results in the need for frequent dosing and reduced patient adherence. In this context, we leverage the intrinsic reversible features of supramolecular polymers and their unique ability to form a three-dimensional network under physiological conditions to design a class of self-assembling drug amphiphiles (DAs) based upon lamivudine, a water-soluble antiretroviral (ARV) agent and nucleoside reverse transcriptase inhibitor. The designed ARV DAs contain three pairs of alternating hydrophobic valine (V) and hydrophilic lamivudine-modified lysine (K3TC) residues with a varying number of glutamic acids (E) placed on the C-terminus. Upon dissolution in deionized water, all three ARV DAs were found to spontaneously associate into supramolecular filaments of several micrometers in length, with varying levels of lateral stacking. Addition of 1× PBS triggered immediate gelation of the two ARV DAs with 2 or 3 E residues, and upon dilution in an in vitro setting, the dissociation from the supramolecular state to the monomeric state enabled a long-acting linear release of the ARV DAs. In vivo studies further confirmed their injectability, rapid in situ hydrogel formation, enhanced local retention, and long-acting therapeutic release over a month. Importantly, our pharmacokinetic studies suggest that the injected ARV supramolecular polymeric hydrogel was able to maintain a plasma concentration of lamivudine above its IC50 value for more than 40 days in mice and showed minimal systemic immunogenicity. We believe that these results shed important light on the rational design of long-acting injectables using the drug-based molecular assembly strategy, and the reported ARV supramolecular hydrogels hold great promise for improving HIV treatment outcomes.

EISA in Tandem with ICD to Form In Situ Nanofiber Vaccine for Enhanced Tumor Radioimmunotherapy

Radiotherapy (RT) can produce a vaccine effect and remodel a tumor microenvironment (TME) by inducing immunogenic cell death (ICD) and inflammation in tumors. However, RT alone is insufficient to elicit a systemic antitumor immune response owing to limited antigen presentation, immunosuppressive microenvironment, and chronic inflammation within the tumor. Here, a novel strategy is reported for the generation of in situ peptide-based nanovaccines via enzyme-induced self-assembly (EISA) in tandem with ICD. As ICD progresses, the peptide Fbp-GD FD FD pY (Fbp-pY), dephosphorylated by alkaline phosphatase (ALP) forms a fibrous nanostructure around the tumor cells, resulting in the capture and encapsulation of the autologous antigens produced by radiation. Utilizing the adjuvant and controlled-release advantages of self-assembling peptides, this nanofiber vaccine effectively increases antigen accumulation in the lymph nodes and cross-presentation by antigen-presenting cells (APCs). In addition, the inhibition of cyclooxygenase 2 (COX-2) expression by the nanofibers promotes the repolarization of M2-macrophages into M1 and reduces the number of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) required for TME remodeling. As a result, the combination of nanovaccines and RT significantly enhances the therapeutic effect on 4T1 tumors compared with RT alone, suggesting a promising treatment strategy for tumor radioimmunotherapy.

Autohydrolysis of Diglycine-Activated Succinic Esters Boosts Cellular Uptake

Rapid cellular uptake of synthetic molecules remains a challenge, and the motif frequently employed to generate prodrugs, succinic ester, unfortunately lowers the efficacy of the desired drugs due to their slow ester hydrolysis and low cell entry. Here we show that succinic ester-containing diglycine drastically boosts the cellular uptake of supramolecular assemblies or prodrugs. Specifically, autohydrolysis of the diglycine-activated succinic esters turns the nanofibers of the conjugates of succinic ester and self-assembling motif into nanoparticles for fast cellular uptake. The autohydrolysis of diglycine-activated succinic esters and drug conjugates also restores the efficacy of the drugs. 2D nuclear magnetic resonance (NMR) suggests that a "U-turn" of diglycine favors intramolecular hydrolysis of diglycine-activated succinic esters to promote autohydrolysis. As an example of rapid autohydrolysis of diglycine-activated succinic esters for instant cellular uptake, this work illustrates a nonenzymatic bond cleavage approach to develop effective therapeutics for intracellular targeting.

Peptide Assemblies for Cancer Therapy

Supramolecular assemblies made by the self-assembly of peptides are finding an increasing number of applications in various fields. While the early exploration of peptide assemblies centered on tissue engineering or regenerative medicine, the recent development has shown that peptide assemblies can act as supramolecular medicine for cancer therapy. This review covers the progress of applying peptide assemblies for cancer therapy, with the emphasis on the works appeared over the last five years. We start with the introduction of a few seminal works on peptide assemblies, then discuss the combination of peptide assemblies with anticancer drugs. Next, we highlight the use of enzyme-controlled transformation or shapeshifting of peptide assemblies for inhibiting cancer cells and tumors. After that, we provide the outlook for this exciting field that promises new kind of therapeutics for cancer therapy.

In Situ Construction of Ferrocene-Containing Membrane-Bound Nanofibers for the Redox Control of Cancer Cell Death and Cancer Therapy

Precise manipulation of cancer cell death by harnessing reactive oxygen species (ROS) is a promising strategy to defeat malignant tumors. However, it is quite difficult to produce active ROS with spatial precision and regulate their biological outcomes. We succeed here in selectively generating short-lived and lipid-reactive hydroxyl radicals (•OH) adjacent to cancer cell membranes, successively eliciting lipid peroxidation and ferroptosis. DiFc-K-pY, a phosphorylated self-assembling precursor that consists of two branched Fc moieties and interacts specifically with epidermal growth factor receptor, can in situ produce membrane-bound nanofibers and enrich ferrocene moieties on cancer cell membranes in response to alkaline phosphatase. Within the acidic tumor microenvironment, DiFc-K-pY nanofibers efficiently convert tumoral H2O2 to active •OH around the target cell membranes via Fenton-like reactions, leading to lipid peroxidation and ferroptosis with good cellular selectivity. Our strategy successfully prevents tumor progression with acceptable biocompatibility through intratumoral administration.

Evaluating Alkaline Phosphatase-Instructed Self-Assembly of d-Peptides for Selectively Inhibiting Ovarian Cancer Cells

Cancer is a major public health concern requiring novel treatment approaches. Enzyme-instructed self-assembly (EISA) provides a unique approach for selectively inhibiting cancer cells. However, the structure and activity correlation of EISA remains to be explored. This study investigates new EISA substrates of alkaline phosphatase (ALP) to hinder ovarian cancer cells. Analogues 2-8 were synthesized by modifying the amino acid residues of a potent EISA substrate 1 that effectively inhibits the growth of OVSAHO, a high-grade serous ovarian cancer (HGSOC) cell line. The efficacy of 2-8 against OVSAHO was assessed, along with the combination of substrate 1 with clinically used drugs. The results reveal that substrate 1 displays the highest cytotoxicity against OVSAHO cells, with an IC50 of around 8 μM. However, there was limited synergism observed between substrate 1 and the tested clinically used drugs. These findings indicate that EISA likely operates through a distinct mechanism that necessitates further elucidation.

Reassembly of Peptide Nanofibrils on Live Cell Surfaces Promotes Cell-Cell Interactions

Nature regulates cellular interactions through the cell-surface molecules and plasma membranes. Despite advances in cell-surface engineering with diverse ligands and reactive groups, modulating cell-cell interactions through scaffolds of the cell-binding cues remains a challenging endeavor. Here, we assembled peptide nanofibrils on live cell surfaces to present the ligands that bind to the target cells. Surprisingly, with the same ligands, reducing the thermal stability of the nanofibrils promoted cellular interactions. Characterizations of the system revealed a thermally induced fibril disassembly and reassembly pathway that facilitated the complexation of the fibrils with the cells. Using the nanofibrils of varied stabilities, the cell-cell interaction was promoted to different extents with free-to-bound cell conversion ratios achieved at low (31%), medium (54%), and high (93%) levels. This study expands the toolbox to generate desired cell behaviors for applications in many areas and highlights the merits of thermally less stable nanoassemblies in designing functional materials.

MC1R Peptide Agonist Self-Assembles into a Hydrogel That Promotes Skin Pigmentation for Treating Vitiligo

Vitiligo, a common skin disease that seriously affects 0.5-2.0% of the worldwide population, lacks approved therapeutics due to a wide range of adverse side effects. As a key regulator of skin pigmentation, MC1R may be an effective therapeutic target for vitiligo. Herein, we report an MC1R peptide agonist that directly self-assembles into nanofibrils that form a hydrogel matrix under normal physiological conditions. This hydrogel exhibits higher stability than free peptides, sustained release, rapid recovery from shear-thinning, and resistance to enzymatic proteolysis. Furthermore, this peptidal MC1R agonist upregulates tyrosinase, tyrosinase-related protein-1 (TYRP-1), and tyrosinase-related protein-2 (TYRP-2) to stimulate melanin synthesis. More importantly, MC1R agonist hydrogel promotes skin pigmentation in mice more potently than free MC1R agonist. This study supports the development of this MC1R agonist hydrogel as a promising pharmacological intervention for vitiligo.