Light-Triggered Self-Assembly of Peptide Nanoparticles into Nanofibers in Living Cells through Molecular Conformation Changes and H-Bond Interactions

Light/Ultrasound Dual Responsive Carbon Dots-Based Nanovaccines for Multimodal Activation Tumor Immunotherapy of Melanoma

Melanoma is a highly aggressive and metastatic tumor, and immunotherapy has become the current solution. However, conventional nanovaccines do not strongly activate T cell immune responses. Therefore, development of effective therapeutic nanovaccines to activate systemic antitumor immunity is urgently required. Herein, light/ultrasound (US) dual-responsive carbon dot-based nanovaccines (Cu-N-CDs@OVA) are designed using copper-nitrogen-coordinated carbon dots composited with ovalbumin. Under 650-nm laser irradiation, Cu-N-CDs@OVA exhibited superior photothermal ablation of primary tumors, induced immunogenic cell death and released antigens by phototherapy, facilitating the maturation of dendritic cells (DCs). More importantly, Cu-N-CDs@OVA stably penetrated and diffused upon US treatment, eradicating metastatic tumors and generating low-dose reactive oxygen species to activate DCs. By integrating with the model antigen OVA, the combined multimodal treatment promotes DC maturation to activate systematic antitumor immunity. This is the first example of a light/US dual-responsive therapeutic nanovaccine that provides a paradigm for the production of personalized nanovaccines against malignant tumors.

Provoking Lysosome Disruption via In Situ Engineered Double-Network Assemblies for Targeted Cancer Cell Death

Increasing evidence has demonstrated the critical role of lysosomes in tumor progression, as well as their involvement in drug resistance during cancer treatment. However, the exploitation of lysosome-targeting agents to inhibit malignant cell growth is still in high demand. Herein, we report an alkaline phosphatase (ALP)-responsive peptide-based precursor (C1) that selectively induced lysosome dysfunction in uveal melanoma cells via noncontact light manipulation. We demonstrated that C1 was dephosphorylated upon close contact with ALP-upregulated tumor cells, endocytosed, and accumulated in lysosomes. Further light irradiation facilitated the generation of two self-sorting components that self-assembled to form nanofibrils and nanorods, respectively. Mesoscale interactions between these two nanostructures triggered the formation of robust double-network assemblies within lysosomes, resulting in lysosomal membrane permeabilization and tumor cell death. By strategically utilizing ALP activity, light responsiveness, and lysosomal acidity in the design of a self-assembling precursor, we have developed double-network assemblies capable of selectively disrupting lysosomal membrane integrity and effectively inhibiting tumor cells. These findings provide valuable insights for the advancement of lysosome-targeting therapeutic agents.

Oleanolic acid-based nanoparticles for the treatment of ulcerative colitis

AIM

This study aims to develop and assess the therapeutic potential of oleanolic acid nanoparticles (OA NPs) in treating ulcerative colitis (UC).

MATERIALS & METHODS

OA NPs were synthesized using an emulsion solvent evaporation method, forming spherical nanoparticles with an average diameter of 138.1 nm. The nanoparticles were designed to target the colon through the enhanced permeability and retention (EPR) effect. Network pharmacology and molecular docking identified key inflammatory pathways, and in vitro (RAW264.7 cells) and in vivo (DSS-induced UC mouse model) experiments evaluated their anti-inflammatory effects and therapeutic efficacy.

RESULTS

OA NPs successfully targeted the colon and demonstrated improved bioavailability. In vitro experiments showed that OA NPs reduced oxidative stress and inflammation by downregulating pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) and promoting macrophage polarization from M1 to M2. In the DSS-induced UC mouse model, oral administration of OA NPs significantly alleviated colitis symptoms, improved colon length, reduced inflammation, and mitigated tissue damage.

CONCLUSION

OA NPs mitigate UC pathology through targeted delivery, enhanced stability, and modulation of inflammatory pathways, providing a promising approach for UC treatment. Further studies are needed to evaluate their long-term safety and clinical applicability.

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

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

Control the Gene Delivery and Anticancer Efficacy of Peptides through Chiral Modulation

Incorporating d-amino acids into peptides can influence the intermolecular interactions of peptides, thus determining the morphology and functionality of self-assembled supramolecular structures. Based on this, we propose a modular chirality regulation strategy and designed four chiral peptides by adjusting the chirality of different functional modules. The chirality can control the coassembly of peptides and nucleic acids into virus-like vesicles with controlled diameters and enzyme-responsiveness. Compared with homochiral peptides, the heterochiral peptides with chirality inversion in their hydrophobic domain transformed into more hydrophobic assemblies in response to the highly expressed enzyme matrix metalloproteinase 7 (MMP-7) in cancer cells and showed higher endosomal membrane disruption activity. Moreover, the heterochiral peptides exhibit high efficiency and selectivity in delivering siRNA gene drugs and inhibiting cancer cell growth, achieving a mortality rate of 95% in cancer cells. These results provide a promising strategy for designing peptide-based nucleic acid delivery systems through chiral modulation.

Recent Advances in Self-Assembling Peptide-Based Nanomaterials for Enhanced Photodynamic Therapy

Self-assembling peptide-based materials with ordered nanostructures possess advantages such as good biocompatibility and biodegradability, superior controllability, and ease of chemical modification. Through covalent conjugation or non-covalent encapsulation, photosensitizers (PSs) can be carried by self-assembling peptide-based nanomaterials for targeted delivery towards tumor tissues. This improves the stability, solubility, and tumor accumulation of PSs, as well as reduces their dark toxicity. More importantly, these nanomaterials can be tailored with responsiveness to tumor microenvironment, which enables smart release of PSs for precise and enhanced photodynamic therapy (PDT). In this review, the self-assembly of peptide from the perspective of driving forces is first described, and various self-assembling peptide materials with zero to 3D nanostructures are subsequently highlighted for PDT of cancers in recent years. Finally, an outlook in this field is provided to motivate fabrication of advanced PDT nanomaterials.

Peptide Designs for Cell-Interfacing Assemblies

Constructing synthetic materials to interact with cells offers significant promise for understanding natural cellular processes and manipulating cell behaviors beyond nature's capabilities. Peptide assemblies are particular promising in this regard, as they have demonstrated efficacy in promoting cell differentiation, repair, and regeneration as supportive scaffolds. However, distinct gaps persist between natural and synthetic assembly systems in various aspects. This Concept review explores representative studies focusing on developing chemical strategies to design peptide assemblies with precise control over displayed molecules, adjustable molecular dynamics to modulate cell behaviors, and responsiveness to biological stimuli. This paper would inspire more fundamental studies on molecular assemblies and foster inter-disciplinary interests in material applications, advancing the interplay between natural cells and synthetic materials.

Precise Regulations at the Subcellular Level through Intracellular Polymerization, Assembly, and Transformation

A living cell is an intricate machine that creates subregions to operate cell functions effectively. Subcellular dysfunction has been identified as a potential druggable target for successful drug design and therapy. The treatments based on intracellular polymerization, self-assembly, or transformation offer various advantages, including enhanced blood circulation of monomers, long-term drug delivery pharmacokinetics, low drug resistance, and the ability to target deep tissues and organelles. In this review, we discuss the latest developments of intracellular synthesis applied to precisely control cellular functions. First, we discuss the design and applications of endogenous and exogenous stimuli-triggered intracellular polymerization, self-assembly, and dynamic morphology transformation of biomolecules at the subcellular level. Second, we highlight the benefits of these strategies applied in cancer diagnosis and treatment and modulating cellular states or cell metabolism of living systems. Finally, we conclude the recent progress in this field, discuss future perspectives, analyze the challenges of the intracellular functional reactions for regulation, and find future opportunities.

Divergent self-assembly propensity of enantiomeric phenylalanine amphiphiles that undergo pH-induced nanofiber-to-nanoglobule conversion

This study presents the pathway diversity in the self-assembly of enantiomeric single phenylalanine derived amphiphiles (single F-PDAs), viz.L-NapF-EDA and D-NapF-EDA, that form supramolecular hydrogels at varied concentrations (≥1 mg mL-1 and ≥3 mg mL-1, respectively). By fitting the variable temperature circular dichroism (VT-CD) data to the isodesmic model, various thermodynamic parameters associated with their self-assembly, such as association constant (K), changes in enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG), were extracted. The self-assembly of these single F-PDAs was found to be enthalpy-driven but entropically-disfavored. Although self-assembly of the D-isomer was slow, it also exhibited greater free energy of association than the L-isomer. Consequently, thermally and mechanically more robust self-assemblies were formed by the D-isomer than the L-isomer. We term these results as the "butterfly effect in self-assembly" wherein the difference in the stereochemical orientation of the residues at a single chiral center present in these molecules resulted in strong differences in the self-assembly propensity as well as in their thermal and mechanical stability. These single F-PDAs form helical nanofibers of opposite chirality upon self-assembly at basic pH (≥8) that produce intense CD signals. However, upon decreasing the pH, a gradual nanofiber-to-nanoglobular transformation was noticed due to protonation-induced structural changes in the PDAs.

Compact Micropatterned Chip Empowers Undisturbed and Programmable Drug Addition in High-Throughput Cell Screening

Simultaneously adding multiple drugs and other chemical reagents to individual droplets at specific time points presents a significant challenge, particularly when dealing with tiny droplets in high-throughput screening applications. In this study, a micropatterned polymer chip is developed as a miniaturized platform for light-induced programmable drug addition in cell-based screening. This chip incorporates a porous superhydrophobic polymer film with atom transfer radical polymerization reactivity, facilitating the efficient grafting of azobenzene methacrylate, a photoconformationally changeable group, onto the hydrophilic regions of polymer matrix at targeted locations and with precise densities. By employing light irradiation, the cyclodextrin-azobenzene host-guest complexes formed on the polymer chip can switch from an "associated" to a "dissociated" state, granting precise photochemical control over the supramolecular coding system and its surface patterning ability. Significantly, the exceptional spatial and temporal control offered by these chemical transitions empowers to utilize digital light processing systems for simultaneous regulation and release of cyclodextrin-bearing drugs across numerous droplets containing suspended or adhered cells. This approach minimizes mechanical disruption while achieving precise control over the timing of addition, dosage, and integration varieties of released drugs in high-throughput screening, all programmable to meet specific requirements.

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.

Versatile Peptide-Based Nanosystems for Photodynamic Therapy

Photodynamic therapy (PDT) has become an important therapeutic strategy because it is highly controllable, effective, and does not cause drug resistance. Moreover, precise delivery of photosensitizers to tumor lesions can greatly reduce the amount of drug administered and optimize therapeutic outcomes. As alternatives to protein antibodies, peptides have been applied as useful targeting ligands for targeted biomedical imaging, drug delivery and PDT. In addition, other functionalities of peptides such as stimuli responsiveness, self-assembly, and therapeutic activity can be integrated with photosensitizers to yield versatile peptide-based nanosystems for PDT. In this article, we start with a brief introduction to PDT and peptide-based nanosystems, followed by more detailed descriptions about the structure, property, and architecture of peptides as background information. Finally, the most recent advances in peptide-based nanosystems for PDT are emphasized and summarized according to the functionalities of peptide in the system to reveal the design and development principle in different therapeutic circumstances. We hope this review could provide useful insights and valuable reference for the development of peptide-based nanosystems for PDT.

Chemical Reactions in Living Systems

The term "in vivo ("in the living") chemistry" refers to chemical reactions that take place in a complex living system such as cells, tissue, body liquids, or even in an entire organism. In contrast, reactions that occur generally outside living organisms in an artificial environment (e.g., in a test tube) are referred to as in vitro. Over the past decades, significant contributions have been made in this rapidly growing field of in vivo chemistry, but it is still not fully understood, which transformations proceed efficiently without the formation of by-products or how product formation in such complex environments can be characterized. Potential applications can be imagined that synthesize drug molecules directly within the cell or confer new cellular functions through controlled chemical transformations that will improve the understanding of living systems and develop new therapeutic strategies. The guiding principles of this contribution are twofold: 1) Which chemical reactions can be translated from the laboratory to the living system? 2) Which characterization methods are suitable for studying reactions and structure formation in complex living environments?

Photoresponsive peptide materials: Spatiotemporal control of self-assembly and biological functions

Peptides work as both functional molecules to modulate various biological phenomena and self-assembling artificial materials. The introduction of photoresponsive units to peptides allows the spatiotemporal remote control of their structure and function upon light irradiation. This article overviews the photoresponsive peptide design, interaction with biomolecules, and applications in self-assembling materials over the last 30 years. Peptides modified with photochromic (photoisomerizable) molecules, such as azobenzene and spiropyran, reversibly photo-controlled the binding to biomolecules and nanostructure formation through self-assembly. Photocleavable molecular units irreversibly control the functions of peptides through cleavage of the main chain and deprotection by light. Photocrosslinking between peptides or between peptides and other biomolecules enhances the structural stability of peptide assemblies and complexes. These photoresponsive peptides spatiotemporally controlled the formation and dissociation of peptide assemblies, gene expressions, protein-drug interactions, protein-protein interactions, liposome deformation and motility, cytoskeleton structure and stability, and cell functions by appropriate light irradiation. These molecular systems can be applied to photo-control biological functions, molecular robots, artificial cells, and next-generation smart drug delivery materials.

Intracellular Hyperbranched Polymerization for Circumventing Cancer Drug Resistance

Polymerization inside living cells provides chemists with a multitude of possibilities to modulate cell activities. Considering the advantages of hyperbranched polymers, such as a large surface area for target sites and multilevel branched structures for resistance to the efflux effect, we reported a hyperbranched polymerization in living cells based on the oxidative polymerization of organotellurides and intracellular redox environment. The intracellular hyperbranched polymerization was triggered by reactive oxygen species (ROS) in the intracellular redox microenvironment, effectively disrupting antioxidant systems in cells by an interaction between Te (+4) and selenoproteins, thus inducing selective apoptosis of cancer cells. Importantly, the obtained hyperbranched polymer aggregated into branched nanostructures in cells, which could effectively evade drug pumps and decrease drug efflux, ensuring the polymerization for persistent treatment. Finally, in vitro and in vivo studies confirmed that our strategy presented selective anticancer efficacy and well biosafety. This approach provides a way for intracellular polymerization with desirable biological applications to regulate cell activities.

Molecularly Stimuli-Responsive Self-Assembled Peptide Nanoparticles for Targeted Imaging and Therapy

Self-assembly has emerged as an extensively used method for constructing biomaterials with sizes ranging from nanometers to micrometers. Peptides have been extensively investigated for self-assembly. They are widely applied owing to their desirable biocompatibility, biodegradability, and tunable architecture. The development of peptide-based nanoparticles often requires complex synthetic processes involving chemical modification and supramolecular self-assembly. Stimuli-responsive peptide nanoparticles, also termed "smart" nanoparticles, capable of conformational and chemical changes in response to stimuli, have emerged as a class of promising materials. These smart nanoparticles find a diverse range of biomedical applications, including drug delivery, diagnostics, and biosensors. Stimuli-responsive systems include external stimuli (such as light, temperature, ultrasound, and magnetic fields) and internal stimuli (such as pH, redox environment, salt concentration, and biomarkers), facilitating the generation of a library of self-assembled biomaterials for biomedical imaging and therapy. Thus, in this review, we mainly focus on peptide-based nanoparticles built by self-assembly strategy and systematically discuss their mechanisms in response to various stimuli. Furthermore, we summarize the diverse range of biomedical applications of peptide-based nanomaterials, including diagnosis and therapy, to demonstrate their potential for medical translation.