Search Results (720)

Therapeutic peptides have rapidly evolved into multifunctional tools for precision oncology, offering molecular specificity and biocompatibility. Their roles in cancer therapy, however, are inherently overlapping. The same peptide can function as a targeting ligand, a cell-penetrating motif, a therapeutic effector, or a structural component of peptide–drug conjugates (PDCs), nanoparticle (NP) systems, and radionuclide constructs. This functional convergence makes rigid classification challenging. In this review, we therefore organize peptide modalities according to their dominant therapeutic function while acknowledging the fluid boundaries between categories. Firstly, we outline the main functional classes of therapeutic peptides, covering their use as targeting ligands and their roles as active agents (i.e., receptor agonists/antagonists, intracellular protein–protein interaction modulators, etc.). Additionally, we summarize their application in peptide–drug conjugates (PDCs), peptide-guided radionuclides, and cancer vaccines, integrating key mechanistic principles and clinical evidence. Finally, we discuss the major translational barriers to clinical use and how they might be overcome. The developments in peptide engineering position them as adaptable, multifunctional platforms capable of improving precision, reducing toxicity, and advancing personalized cancer care. Full article

Background/Objectives: Cervical cancer is a leading cause of cancer-related mortality among women, primarily driven by persistent infections with high-risk human papillomavirus (HPV), particularly HPV-16. Vaccines based on plasmid DNA encoding the viral oncogenes E6 and E7 represent a promising immunotherapeutic strategy, but their efficacy remains limited due to poor cellular uptake. Cell-penetrating peptides such as RALA improve intracellular delivery, and functionalization with octa-arginine peptide conjugated to mannose (R8M) further enhances targeting of antigen-presenting cells (APCs). This study aimed to obtain the minicircle DNA (mcDNA) encoding mutant HPV-16 E6 and/or E7 antigens, and optimize its complexation with mannosylated RALA-based nanoparticles to improve vector delivery and consequently antigen presentation. Methods: Nanoparticles were formulated at different concentrations of RALA, with and without R8M functionalization. Their characterization included hydrodynamic diameter, polydispersity index, zeta potential, complexation efficiency (CE), stability, morphology, and Fourier-Transform Infrared Spectroscopy. In vitro assays in JAWS II dendritic cells (DCs) assessed biocompatibility, transfection efficiency and target gene expression. Results: Optimal conditions were obtained at 72.5 µg/mL of RALA, producing nanoparticles smaller than 150 nm with high CE (>97%) and uniform size distribution. Functionalization with R8M at 58 µg/mL preserved these characteristics when complexed with all mcDNA vectors. The formulations were biocompatible and effectively transfected DCs. Mannosylated formulations enhanced antigenic expression compared to non-mannosylated counterparts, evidencing a mannose-receptor-mediated uptake, while increasing the production of pro-inflammatory cytokines. Conclusions: Nanoparticles based on the RALA peptide and functionalized with R8M significantly improved mcDNA transfection and gene expression in APCs. These findings support further investigation of this system as a targeted DNA vector delivery platform against HPV-16. Full article

Bacterial biofilms are critical contributors to chronic infections and antimicrobial resistance. Among the diverse extracellular matrix components, extracellular DNA (eDNA) and amyloid proteins have recently emerged as pivotal structural and functional molecules. Both individually contribute to biofilm stability and antibiotic tolerance, yet their cooperative roles remain underappreciated. This review aims to summarize current knowledge on the origins and functions of eDNA and amyloid proteins in biofilms, to highlight their molecular interactions, and to discuss how their synergistic effects promote biofilm-mediated resistance to antimicrobial agents. A comprehensive literature search was conducted using PubMed, Scopus, and Web of Science databases up to September 2025. Keywords included “biofilm”, “extracellular DNA”, “amyloid proteins”, “matrix”, and “antimicrobial resistance”. Relevant original research and review articles were systematically screened and critically analyzed to integrate emerging evidence on eDNA–amyloid interactions in bacterial biofilms. Current studies demonstrate that eDNA originates primarily from autolysis, active secretion, and host-derived DNA, while amyloid proteins are produced by multiple bacterial species, including Escherichia coli (curli), Pseudomonas aeruginosa (Fap), Bacillus subtilis (TasA), and Staphylococcus aureus (phenol-soluble modulins). Both molecules independently strengthen biofilm integrity and provide protective functions against antimicrobial agents. Importantly, recent evidence shows that eDNA can act as a nucleation template for amyloid fibrillation, while amyloid fibers stabilize and protect eDNA from degradation, creating a dense extracellular network. This synergistic eDNA–amyloid assembly enhances biofilm robustness, impedes antibiotic penetration, sequesters antimicrobial peptides, protects persister cells, and facilitates horizontal gene transfer of resistance determinants. The interplay between eDNA and amyloid proteins represents a central but underexplored mechanism driving biofilm-mediated antimicrobial resistance. Understanding this cooperative network not only deepens our mechanistic insights into bacterial pathogenesis but also highlights novel therapeutic targets. Strategies that disrupt eDNA–amyloid interactions may offer promising avenues for combating persistent biofilm-associated infections. Full article

Background: Intracellular delivery of high-molecular-weight proteins is limited by the cell membrane. Cell-penetrating peptides (CPPs) offer a potential solution, but effective cytosolic delivery remains hindered by endosomal sequestration. Pas2r12, a CPP-derived peptide, facilitates cytosolic delivery of proteins including immunoglobulin G. Because Pas2r12 internalization occurs via caveolae-dependent endocytosis, we hypothesized that cell-surface receptors contribute to uptake. Methods: HEK293 cells were treated with Pas2r12 alone or complexed with enhanced green fluorescent protein (EGFP). Phosphorylation of insulin receptor (INSR), insulin-like growth factor 1 receptor (IGF1R), and extracellular signal–regulated kinase 1/2 (ERK1/2) was analyzed by Western blot. Linsitinib was used to inhibit INSR/IGF1R kinase activity. Cytosolic delivery was assessed by confocal microscopy, and receptor involvement was evaluated using siRNA-mediated knockdown and receptor overexpression. Results: Pas2r12 alone transiently increased INSR/IGF1R phosphorylation at 2 min (6.6-fold), which was suppressed by linsitinib (1.3-fold), and strongly increased ERK1/2 phosphorylation (6.2-fold), which was not inhibited by linsitinib. Pas2r12–EGFP did not induce detectable INSR/IGF1R phosphorylation in parental cells but increased ERK1/2 phosphorylation (3.4-fold). Linsitinib markedly reduced cytosolic EGFP delivery to 16% of control. INSR knockdown decreased delivery to 13–16%, and IGF1R knockdown to 19–65%. In INSR-overexpressing lines, Pas2r12–EGFP induced INSR/IGF1R phosphorylation (6.0-fold) and enhanced delivery (230–270%). In IGF1R-overexpressing lines, Pas2r12–EGFP did not induce phosphorylation, and delivery decreased to 60–69%. Conclusions: Pas2r12-mediated cytosolic delivery involves both INSR and IGF1R, with INSR contributing more prominently. These findings, including the largely INSR/IGF1R-independent ERK1/2 activation, provide mechanistic insight into Pas2r12-mediated protein delivery. Full article

Background/Objectives: Cell-mediated and peptide-assisted delivery systems have emerged as powerful platforms at the intersection of chemistry, nanotechnology, and molecular medicine. By leveraging the intrinsic targeting, transport, and signaling capacities of living cells and bioinspired peptides, these systems facilitate the delivery of therapeutic agents across otherwise restrictive biological barriers such as the blood–brain barrier (BBB) and the tumor microenvironment. This review aims to summarize recent advances in engineered cell carriers, peptide vectors, and hybrid nanostructures designed for enhanced intracellular and tissue-specific delivery. Methods: We surveyed recent literature covering molecular design principles, mechanistic studies, and in vitro/in vivo evaluations of cell-mediated and peptide-enabled delivery platforms. Emphasis was placed on neuro-oncology, immunotherapy, and regenerative medicine, with particular focus on uptake pathways, endosomal escape mechanisms, and structure–function relationships. Results: Analysis of current strategies reveals significant progress in optimizing cell-based transport systems, peptide conjugates, and multifunctional nanostructures for the targeted delivery of drugs, nucleic acids, and immunomodulatory agents. Key innovations include improved BBB penetration, enhanced tumor homing, and more efficient cytosolic delivery enabled by advanced peptide designs and engineered cellular carriers. Several platforms have progressed toward clinical translation, underscoring their therapeutic potential. Conclusions: Cell-mediated and peptide-assisted delivery technologies represent a rapidly evolving frontier with broad relevance to next-generation therapeutics. Despite notable advances, challenges remain in scalability, manufacturing, safety, and regulatory approval. Continued integration of chemical design, molecular engineering, and translational research will be essential to fully realize the clinical impact of these delivery systems. Full article

The cell-penetrating peptide Pep-1 interacts with lipid membranes through combined electrostatic and hydrophobic forces, yet the structural details of its membrane remodeling activity remain unclear. Using atomic force microscopy (AFM), we examined how Pep-1 perturbs supported lipid bilayers of varying composition and geometry. In zwitterionic POPC bilayer patches, Pep-1 preferentially targeted patch boundaries, where lipid packing is less constrained, leading to edge erosion and detergent-like disintegration. Incorporation of anionic POPS enhanced peptide binding and localized disruption, giving rise to elevated annular rims, holes, and peptide–lipid aggregates. In cholesterol-containing POPC bilayer patches, Pep-1 induced extensive surface reorganization marked by protruded, ridge-like features, consistent with lipid redistribution and curvature generation. In continuous POPC/POPS bilayers lacking free edges, Pep-1 formed discrete, flower-like protrusions that coalesced into an interconnected network of thickened peptide-rich domains. These findings reveal composition-dependent remodeling pathways in which Pep-1 destabilizes, reorganizes, or curves membranes according to their mechanical and electrostatic properties, providing new insight into peptide–membrane interactions relevant to cell-penetrating peptide translocation. Full article

Skin aging is influenced by both internal and external factors, resulting in wrinkles, decreased elasticity and irregular pigmentation. Hyaluronic acid (HA), a key component of the extracellular matrix, is essential for skin hydration and structural support. Peptides, short amino acid chains, have gained attention in cosmetics due to their multifunctional biological activities. This study explored the moisturizing and metal-chelating properties of Chrono Control Penta (S-Cannabis Sativa-pentapeptide-1), a novel plant-derived peptide whose sequence is WVSPL. In vitro, it chelated iron ions up to 17.86 ± 2.50% and copper ions up to 47.08 ± 1.49% at 10 mM and 3 mM, respectively. Western blot and Enzyme-Linked Immunosorbent Assay (ELISA) analysis showed that, under H₂O₂-induced stress, Chrono Control Penta increased hyaluronan synthase 2 (HAS2) production by 81.72% in BJ-5ta fibroblasts and enhanced HA secretion by 20.11% compared to simulated aging conditions alone, respectively. Furthermore, experiments carried out with the Franz diffusion cell and human full thickness skin demonstrated the peptide’s ability to penetrate the skin layers and even diffuse laterally with a quantified peptide skin biodistribution accounting for 0.095/0.06 nM/mg in 6 h. Advanced AI-based modeling (AlphaFold2, RosettaFold) and docking analysis revealed stable peptide-peptide transporter 2 (PEPT2) interactions, supporting carrier-mediated skin permeation and linking computational predictions with experimental diffusion data. Hence, this study extends previous evidence on the cosmetic efficacy of Chrono Control Penta by (i) adding mechanistic insights into metal chelation and HAS2/HA modulation, (ii) rigorously quantifying local skin penetration and lateral diffusion with HPLC-MS/MS, and (iii) providing a plausible mechanistic link between skin biodistribution and PEPT2-mediated transport based on deep learning structural models. Full article

To identify novel peptides with potential antiviral activities, a database search was performed based on the primary sequence of the peptide I24 (CLAFYACFC), the effective part of the antiviral peptide TAT-I24 consisting of peptide I24 and the cell penetrating TAT-peptide (amino-acids 48–60; GRKKRRQRRRPPQ). A Protein BLAST search identified several sequences with high similarity to I24 in diverse proteins, some of which are known to be involved in the interaction with nucleic acids. Selected sequences and newly designed variants of I24 were synthesized as TAT fusion peptides and tested for antiviral activity in two well-established models: baculovirus transduction of HEK293 cells and mouse cytomegalovirus (MCMV) infection of NIH/3T3 cells. Several of the TAT-fusion peptides exhibited antiviral activities with a potency comparable to TAT-I24. The ability of these peptides to bind double-stranded DNA suggested the same mode of action. Several peptides caused swelling of red blood cells (RBC) but with only one peptide clearly inducing haemolysis. With two exceptions, RBC swelling was observed with antivirally active peptides but not with less active peptides, indicating that antiviral activities are linked to an effect on membrane integrity of target cells. Structural prediction of the TAT-fusion peptides indicated formation of two α-helical elements, with several of these peptides showing remarkable similarity when subjected to structural alignment. Full article

Legumain (LGMN), a lysosomal cysteine protease, is crucial for tumor progression, invasion, and metastasis, making it a promising target for cancer imaging and therapy. This study developed novel ⁶⁷Ga-labeled 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA)-conjugated LGMN-cleavable peptide probes ([⁶⁷Ga]Ga-NOTA-LCPs) composed of polyarginine and polyglutamic acid sequences linked by LGMN-cleavable sites for nuclear medicine imaging of LGMN activity. The probes were synthesized via fluorenylmethoxycarbonyl solid-phase peptide synthesis and radiolabeled in high radiochemical yields. In vitro assays with HCT116 cells showed significantly higher uptake of [⁶⁷Ga]Ga-NOTA-LCPs compared to non-cleavable controls, confirming efficient cleavage and cellular uptake. In vivo studies in tumor-bearing mice revealed rapid renal clearance, low non-specific binding, and favorable tumor-to-blood ratios, particularly for [⁶⁷Ga]Ga-NOTA-LCP-1. These results demonstrate the potential of [⁶⁷Ga]Ga-NOTA-LCPs as effective LGMN-responsive imaging agents, with further optimization needed to improve tumor specificity and reduce off-target accumulation. Full article

Blocking the protein–protein interaction (PPI) between programmed cell death protein 1 (PD-1) and its ligand PD-L1 is a crucial strategy in cancer immunotherapy. However, existing monoclonal antibody-based therapies have limitations such as high production costs and poor tumor penetration. In this study, we developed a novel cyclic peptide inhibitor, PD-1-0520, through structure-based design. Starting from key fragments of PD-L1 that interact with PD-1, we designed 5 mimetic peptides and further optimized them into 22 cyclic peptide candidates. Through molecular dynamics screening and in vitro and in vivo experimental validation, PD-1-0520 was proven to have potent antitumor activities. Results showed that PD-1-0520 effectively inhibited the PD-1/PD-L1 interaction, restored the immune activity of tumor-infiltrating T cells, and achieved a 68% tumor inhibition rate in B16-F10 tumor-bearing mice without systemic toxicity. It promoted CD8⁺ T cell infiltration into tumors and upregulated activation markers, remodeling the tumor immune microenvironment. These findings demonstrate that PD-1-0520 is a promising immune checkpoint inhibitor, and our design strategy provides a new approach for developing PPI-targeting bioactive inhibitors. Full article

Background: The golden era of antibiotics has long passed, and the clinical failures caused by emerging drug-resistant bacteria have intensified the demand for novel antimicrobial agents. Antimicrobial peptides have attracted significant attention as promising candidates for next-generation antibiotics. Methods: In this study, we identified a novel antimicrobial peptide, Caerin 1.1-LC, from the skin secretion of the Australian green tree frog, Litoria caerulea. Subsequent structure–activity relationship studies led us to design a series of analogues and revealed the critical role of the peptide’s intrinsic hinge structure in shaping its biological activity. Results: Incorporation of D-isomers at the valine residues within the hinge preserved overall helical content but altered the hinge conformation, resulting in an 8-fold increase in antibacterial activity against Gram-negative bacteria. Simultaneously, haemolytic activity was markedly reduced, leading to a 56-fold improvement in therapeutic index (from 0.47 to 26.6). Structural modulation of the hinge also switched the mechanism of action from classical membrane disruption with associated permeability changes to a non-membrane-permeabilising, ‘cell-penetrating-like’ behaviour, inducing membrane potential depolarisation and ATP disruption to trigger bacterial death. In vivo studies using infected larval models, along with in vitro LPS neutralisation assays, further demonstrated the therapeutic potential of the D-analogue as a novel antibacterial agent. Conclusions: This work highlights the pivotal role of hinge structures in Caerin-family/hinge-containing AMPs, offering a strategic avenue for optimising antibacterial efficacy. Full article

Peptides are emerging as versatile platforms in medicine, serving as therapeutic agents, diagnostic probes, and drug delivery vehicles. Their physical state—in a form of monomeric cell-penetrating peptides (CPPs), liquid-like coacervates, or solid amyloid fibrils—critically determines their interaction with cell surfaces and subsequent intracellular trafficking pathways. While the transport of CPPs has been extensively studied, the mechanisms governing the cellular uptake of peptide-based coacervates and fibrils are less understood. This review summarizes the current understanding of the intracellular transport mechanisms of all three distinct peptide states and their complexes or conjugates with cargo molecules. We examine a range of pathways, including direct membrane translocation, several endocytosis subtypes, and phagocytosis-like transport. Particular attention is given to unique aspects observed exclusively for CPPs, coacervates, or fibrils. Further verification and detailed characterization of internalization mechanisms are crucial for the rational design of next-generation peptide-based carriers that allow for precise cargo delivery and therapeutic efficacy. Full article

CRISPR-Cas systems have transformed genome engineering with their exceptional precision, programmability, and affordability. Although they originate from microbial defense mechanisms, expanding their use, especially in therapeutics, requires a chemically oriented framework that allows for tunable, reversible, and safe gene editing. This review offers a multidisciplinary look at recent progress in the structural, synthetic, and computational aspects of CRISPR-Cas technologies. Structural analyses examine the domain architectures of Cas enzymes, including the recognition (REC), nuclease (HNH and RuvC), and PAM-interacting domains, emphasizing the catalytic importance of divalent metal ions. Comparative insights into Cas9, Cas12, and Cas13 demonstrate functional diversity across DNA- and RNA-targeting systems, supported by high-resolution structural data on guide RNA pairing and conformational dynamics. The review highlights advances in chemical modulation, such as anti-CRISPR proteins, small-molecule inhibitors, and stimuli-responsive switches, focusing on structure–activity relationships. Additionally, bioorganic delivery systems like lipid nanoparticles, polymers, and cell-penetrating peptides are discussed for their role in improving in vivo delivery through formulation chemistry. Computational chemistry methods—molecular docking, molecular dynamics simulations, and virtual screening—are identified as critical tools for discovering and optimizing modulators. The use of AI-driven tools is proposed as a promising direction for rational CRISPR design. Overall, this chemistry-focused perspective emphasizes the importance of molecular control in developing the next generation of programmable and safe CRISPR-based therapies. Full article

Bovine viral diarrhea virus (BVDV) is a major pathogen responsible for significant economic losses in the global cattle industry. The diverse transmission routes and the characteristics of asymptomatic infections make it difficult to contain the spread; there is an urgent need to develop new effective antiviral strategies. Nanobodies (Nbs) have become a promising new type of antiviral agent due to their advantages, including small molecular size, stable structure, high specificity, and ease of production. This study successfully screened a specific nanobody, Nb7, targeting the key functional protein NS5A of BVDV using phage display technology. Furthermore, the nanobody was effectively delivered into Madin–Darby bovine kidney (MDBK) cells by fusing it with the cell-penetrating peptide TAT. The results demonstrate that TAT-Nb7, specifically targeting the non-structural protein NS5A of BVDV, significantly inhibits viral replication in MDBK cells. In conclusion, this study indicates that TAT-Nb7 holds promise as a therapeutic candidate for the prevention and control of BVDV infection. Full article

Liposomes modified with slightly acidic pH-sensitive peptides (SAPSp-lipo) are effectively delivered to tumor tissues, followed by cellular uptake in the tumor microenvironment. Although SAPSp-lipo can penetrate tumor tissues via the interspace route between cancer cells and the extracellular matrix (ECM), penetration needs to be enhanced to deliver liposomes into tumor cores comprising malignant cancer cells. To enhance the intratumoral penetration of SAPSp-lipo, we focused on the internalizing RGD peptide (iRGD), which can penetrate tumor tissue, differing from the penetration mechanism of SAPSp. In this study, we developed liposomes modified with iRGD-conjugated SAPSp (SAPSp-iRGD-lipo). Compared with SAPSp-lipo, SAPSp-iRGD-lipo was delivered to deeper regions within both spheroids and tumor tissues. The enhanced penetration was suppressed by a co-treatment with a Neuropilin-1 inhibitor, and the fluorescence signals from intratumorally injected SAPSp-iRGD-lipo were localized in Neuropilin-1-expressing regions, indicating a Neuropilin-1-mediated tumor penetration. Moreover, SAPSp-iRGD-lipo reduced F-actin formation in monolayered cells and was not localized in F-actin-rich regions in tumors, suggesting that SAPSp-iRGD-lipo facilitates tumor penetration through actin depolymerization. In addition, anticancer siRNA delivered by SAPSp-iRGD-lipid nanoparticles effectively induced apoptosis in cells under slightly acidic conditions. Taken together, SAPSp-iRGD-modified nanoparticles represent a novel class of tumor-penetrable and microenvironment-responsive drug carriers capable of efficient intratumoral delivery and therapeutic activity. Full article