A Peptide-Conjugated Probe with Cleavage-Induced Morphological Change for Treatment on Tumor Cell Membrane

Spatiotemporally Controllable Covalent Bonding of RNA for Multi-Protein Interference

Many diseases are associated with genetic mutation and expression of mutated proteins, such as cancers. Therapeutic approaches that selectively target the synthesis process of multiple proteins show greater potential compared to single-protein approaches in oncological diseases. However, conventional agents to regulate the synthesis of multiple protein still suffer from poor spatiotemporal selectivity and stability. Here, a new method using a dye-peptide conjugate, PRFK, for multi-protein interference with spatiotemporal selectivity and reliable stability, is reported. By using the peptide sequence that targets tumor cells, PRFK can be efficiently taken up, followed by specific binding to the KDELR (KDEL receptor) protein located in the endoplasmic reticulum (ER). The dye generates 1O2 under light irradiation, enabling photodynamic therapy. This process converts the furan group into a cytidine-reactive intermediate, which covalently binds to mRNA, thereby blocking protein synthesis. Upon treating 4T1 cells, the proteomics data show alterations in apoptosis, ferroptosis, proliferation, migration, invasion, and immune infiltration, suggesting that multi-protein interference leads to the disruption of cellular physiological activities, ultimately achieving tumor treatment. This study presents a multi-protein interference probe with the potential for protein interference within various subcellular organelles in the future.

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.

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.

Cell Membrane as A Promising Therapeutic Target: From Materials Design to Biomedical Applications

The cell membrane is a crucial component of cells, protecting their integrity and stability while facilitating signal transduction and information exchange. Therefore, disrupting its structure or impairing its functions can potentially cause irreversible cell damage. Presently, the tumor cell membrane is recognized as a promising therapeutic target for various treatment methods. Given the extensive research focused on cell membranes, it is both necessary and timely to discuss these developments, from materials design to specific biomedical applications. This review covers treatments based on functional materials targeting the cell membrane, ranging from well-known membrane-anchoring photodynamic therapy to recent lysosome-targeting chimaeras for protein degradation. The diverse therapeutic mechanisms are introduced in the following sections: membrane-anchoring phototherapy, self-assembly on the membrane, in situ biosynthesis on the membrane, and degradation of cell membrane proteins by chimeras. In each section, we outline the conceptual design or general structure derived from numerous studies, emphasizing representative examples to understand advancements and draw inspiration. Finally, we discuss some challenges and future directions in membrane-targeted therapy from our perspective. This review aims to engage multidisciplinary readers and encourage researchers in related fields to advance the fundamental theories and practical applications of membrane-targeting therapeutic agents.

A Universal and Programmable Platform based on Fluorescent Peptide-Conjugated Probes for Detection of Proteins in Organelles of Living Cells

Realizing protein analysis in organelles of living cells is of great significance for developing diagnostic and therapeutic methods of diseases. Fluorescent-labeled antibodies with well imaging performance and high affinity are classical biochemical tools for protein analysis, while due to the inability to effectively enter into cells, not to mention organelles and the uncontrollable reaction sites that might cause antibodies inactivation when chemically modification, they are hard to apply to living cells. Inspired by the structure of fluorescent-labeled antibodies, we designed as a universal detection platform that was based on the peptide-conjugated probes (PCPs) and consisted of three parts: a) a rotor type fluorescent molecular scaffold for conjugation and signal output; b) the cell penetration protein recognition unit; c) the subcellular organelle targeting unit. In living cells, PCPs could firstly localize at organelles and then proceed protein specific recognition, thus jointly leading to the restriction of twisted intramolecular charge transfer and activation of fluorescence signal. As a proof-of-concept, six different proteins in three typical intracellular organelles could be detected by our platform through simply replacing the recognition sequence of proteins and matching organelle targeting units. The position and intensity of fluorescence signals demonstrated specificity of PCPs and universality of the platform.

Photo-Controlled Calcium Overload from Endogenous Sources for Tumor Therapy

Designing reactive calcium-based nanogenerators to produce excess calcium ions (Ca2+ ) in tumor cells is an attractive tumor treatment method. However, nanogenerators that introduce exogenous Ca2+ are either overactive incapable of on-demand release, or excessively inert incapable of an overload of calcium rapidly. Herein, inspired by inherently diverse Ca2+ -regulating channels, a photo-controlled Ca2+ nanomodulator that fully utilizes endogenous Ca2+ from dual sources was designed to achieve Ca2+ overload in tumor cells. Specifically, mesoporous silica nanoparticles were used to co-load bifunctional indocyanine green as a photodynamic/photothermal agent and a thermal-sensitive nitric oxide (NO) donor (BNN-6). Thereafter, they were coated with hyaluronic acid, which served as a tumor cell-targeting unit and a gatekeeper. Under near-infrared light irradiation, the Ca2+ nanomodulator can generate reactive oxygen species that stimulate the transient receptor potential ankyrin subtype 1 channel to realize Ca2+ influx from extracellular environments. Simultaneously, the converted heat can induce BNN-6 decomposition to generate NO, which would open the ryanodine receptor channel in the endoplasmic reticulum and allow stored Ca2+ to leak. Both in vitro and in vivo experiments demonstrated that the combination of photo-controlled Ca2+ influx and release could enable Ca2+ overload in the cytoplasm and efficiently inhibit tumor growth.

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.

MMP-responsive nanomaterials

Matrix metalloproteinases (MMP) are enzymes that degrade the extracellular matrix and regulate essential normal cell behaviors. Inhibition of these enzymes has been a strategy for anti-cancer therapy since the 1990s, but with limited success. A new type of MMP-targeting strategy exploits the innate selective hydrolytic activity and consequent catalytic signal amplification of the proteinases, rather than inhibiting it. Using nanomaterials, the enzymatic chemical reaction can trigger the temporal and spatial activation of the anti-cancer effects, amplify the associated response, and cause mechanical damage or report on cancer cells. We analyzed nearly 60 literature studies that incorporate chemical design strategies that lead to spatial, temporal, and mechanical control of the anti-cancer effect through four modes of action: nanomaterial shrinkage, induced aggregation, formation of cytotoxic nanofibers, and activation by de-PEGylation. From the literature analysis, we derived chemical design guidelines to control and enhance MMP activation of nanomaterials of various chemical compositions (peptide, lipid, polymer, inorganic). Finally, the review includes a guide on how multiple characteristics of the nanomaterial, such as substrate modification, supramolecular structure, and electrostatic charge should be collectively considered for the targeted MMP to result in optimal kinetics of enzyme action on the nanomaterial, which allow access to amplification and additional levels of spatial, temporal, and mechanical control of the response. Although this review focuses on the design strategies of MMP-responsive nanomaterials in cancer applications, these guidelines are expected to be generalizable to systems that target MMP for treatment or detection of cancer and other diseases, as well as other enzyme-responsive nanomaterials.

Peptide-Conjugated Probe Inducing Mitochondrial Dysfunction and Self-Reporting Cell Apoptosis by Aggregated Proteins

Inducing and monitoring cell apoptosis in a real-time manner are crucial for evaluating the therapeutic effect of drugs and avoiding excessive treatment. Although promising advancements have been made to monitor cell apoptosis by assessing cell membrane integrity, the chronic compromise of cellular fitness caused by imbalance proteostasis is not visible and hard to be detected. As an indicator for cell apoptosis, imaging of aggregated proteins provides a new direction. Herein, we design a peptide-conjugated probe (QRKN) that can induce mitochondrial dysfunction for self-reporting cell apoptosis by imaging aggregated proteins. Specifically, QRKN can be cleaved into the α-helix-forming part (QRK) and azide-modified small-molecule part (N) by overexpressed cathepsin B (CB) in tumor cells. The QRK part can destroy the mitochondrial membrane and promote cytochrome c (Cyt c) efflux and caspase 3 expression. The other N part can inhibit the activity of mitochondrial complex IV (Mito-IV) and decrease the expression level of adenosine triphosphate (ATP). Two signaling pathways cooperatively induce mitochondrial dysfunction, resulting in protein aggregation and cell apoptosis ultimately. Meanwhile, the cell apoptosis process can be monitored based on QRKN, which is highly sensitive to the aggregated protein-triggered viscosity change. The self-reporting probe can monitor therapeutic responses and provide valuable diagnosis information.