Search Results (153)

Cell-penetrating peptides offer a promising strategy for intracellular delivery; however, non-specific uptake and off-target cytotoxicity limit their clinical utility. To address these limitations, a cold atmospheric plasma-responsive delivery platform was developed in which the membrane activity of a peptide was transiently suppressed upon complexation with a DNA-based nanostructure. Upon localized plasma exposure, DNA masking was disrupted, restoring the biological functions of the peptides. Transmission electron microscopy revealed that the synthesized DNA nanoflower structures were approximately 150–250 nm in size. Structural and functional analyses confirmed that the system remained inert under physiological conditions and was rapidly activated by plasma treatment. Fluorescence recovery, cellular uptake assays, and cytotoxicity measurements demonstrated that the peptide activity could be precisely controlled in both monolayer and three-dimensional spheroid models. This externally activatable nanomaterial-based system enables the spatial and temporal regulation of peptide function without requiring biochemical triggers or permanent chemical modifications. This platform provides a modular strategy for the development of potential peptide therapeutics that require precise control of activation in complex biological environments. Full article

Candida fungal species are the most common fungal opportunistic pathogens. Their ability to form antifungal resistant biofilms contributes to their increasing clinical frequency. These fungi express surface-anchored adhesins including members of the Als family. These adhesins mediate epithelial adhesion, aggregation, and biofilm formation. Many of the adhesins contain cross-β core sequences that form amyloid-like protein aggregates on the fungal surface. The aggregates mediate high-avidity bonding that contributes to biofilm establishment and persistence. Accordingly, autopsy sections from individuals with candidiasis and other mycoses have amyloids within abscesses. An amyloid-forming peptide containing a sequence from Candida albicans Als5 bound to C. albicans, C. tropicalis, and C. parapsilosis. C. albicans and C. tropicalis aggregated with beads coated with serum albumin, and the aggregates stained with the amyloid-binding dye thioflavin T. Additionally, an Als5-derived amyloid-inhibiting peptide blocked cell aggregation. The amyloid-inhibiting peptide also blocked C. albicans, C. tropicalis, and C. parapsilosis adhesion to monolayers of FaDu epithelial cells. These results show the involvement of amyloid-like interactions in pathogenesis in several Candida species. Full article

Seliciclib, a cyclin-dependent kinase 5 (CDK5) inhibitor, has demonstrated neuroprotective potential. However, its therapeutic application is limited by poor permeability across the blood–brain barrier (BBB). In this study, polymeric nanoparticles (NPs) modified with a BBB-targeting peptide ligand (His-Ala-Ile-Tyr-Pro-Arg-His) were employed to encapsulate seliciclib. In vitro transport studies showed that the peptide-modified NPs exhibited significantly greater translocation across a bEnd.3 cell monolayer compared to unmodified NPs. Furthermore, in vivo biodistribution analysis revealed that the brain accumulation of peptide-modified NPs was 3.38-fold higher than that of unmodified NPs. Notably, the peptide-conjugated, seliciclib-loaded NPs demonstrated a significant neuroprotective effect against the neurotoxin 1-methyl-4-phenylpyridinium (MPP⁺) in differentiated SH-SY5Y cells. Full article

Polymer coatings as thin films stand out as a commonly used strategy to modify biosensor surfaces for improving detection performance; however, nonspecific biomolecule interactions and the limited degree of ligand conjugation on the surface have necessitated the development of innovative methods for surface modification. To this end, methacrylated tethered telechelic polyethylene glycol (PEG-diMA) chains of three different molecular weights (2, 6, and 10 kDa) were synthesized herein and used for obtaining thiolated nanoparticles (NPs) upon adding excess amounts of a tetra-thiol crosslinker. Characterized according to their size, surface charge, morphology, and thiol amounts, these nanoparticles were immobilized on gold surfaces that mimicked gold-coated mass sensor platforms. The PEG-based nanoparticles, prepared especially by PEG6K-diMA polymers, were shown to result in the preparation of a monolayer and smooth coating of 80–120 nm thickness. Cysteine-modified NTS(8–13) peptide (RRPYIL) was conjugated to thiolated NP with reversible disulfide bonds and it was demonstrated that its cleavage with a reducing agent such as dithiothreitol (DTT) restores the NP-immobilized gold surface for at least two cycles. Together with its binding studies to NTSR2 antibodies, it was revealed that the peptide-conjugated NP-modified gold surface could be employed as a model for a reusable sensor surface for the detection of biomarkers of same or different types. Full article

PD-L1 (programmed cell death ligand-1) is a protein located on the surface of regulatory cells. It has an immunosuppressive role as it binds specifically to the protein programmed cell death-1 (PD-1), a checkpoint glycoprotein, present on the surface of immune cells such as T and B lymphocytes. Many tumor cells block the immune response by overexpressing PD-L1 on their surface; therefore, targeting PD-L1 represents a powerful strategy that allows tumor localization. To determine the presence of PD-L1 in cells, the use of ad hoc functionalized peptides that bind to PD-L1 can be exploited. One of them is the peptide CLP002 (Trp-His-Arg-Ser-Tyr-Tyr-Thr-Trp-Asn-Leu-Asn-Thr), which, bound to surface-enhanced Raman scattering (SERS) gold nanostructures via a suitable linker, was shown to be highly effective in recognizing MDA-MB-231 breast cancer cells and, importantly, this recognition can be measured by SERS experiments. To characterize, on a molecular scale, the interaction between PD-L1 and peptide functionalized nanostructures, we performed molecular dynamics (MDs) simulations, studying the features of peptide monolayers bound on gold surfaces in the absence and presence of PD-L1. The results obtained allow us to explain why the nature of the linker plays a fundamental role in the binding and why a peptide carrying the same amino acids as CPL002 but with a different sequence (scrambled) is much less active than CLP002. These results open the way to an in silico evaluation of the key parameters that regulate the binding of PD-L1 useful for cancer recognition. Full article

To develop a highly bioavailable calcium supplement, this study utilized Peruvian squid (Dosidicus gigas) skin as a raw material. Through alkaline protease hydrolysis and enzymatic membrane reactor separation, three molecular weight fractions of squid skin peptides were obtained, followed by calcium ion chelation to synthesize calcium-chelating peptides (CCPs-SS). Systematic characterization revealed that the less than 1 kDa fraction of CCPs-SS exhibited superior antioxidant capacity (82.18%) and calcium chelation efficiency (77.14%) in cellular models compared to higher molecular weight counterparts. Optimal synthesis conditions were identified as 60 °C, pH 9, and 12 mg/mL calcium chloride concentration. Post-chelation analyses demonstrated significant physicochemical alterations for CCPs-SS: ζ-potential shifted from −18.4 mV to −10.47 mV, while particle size increased from 476.75 nm to 664.4 nm. Notably, membrane separation enhanced phenylalanine and leucine molar concentrations by 25.5% and 57.6%, respectively, suggesting structural modifications that potentiate bioactivity. These findings demonstrate an innovative strategy for converting squid processing byproducts into functional nutraceuticals, which not only addresses calcium deficiency challenges but also promotes resource sustainability by utilizing waste materials. Full article

Acne vulgaris is one of the most common skin diseases, and its development is closely linked to the overgrowth of the bacterium Cutibacterium acnes. More than half of the strains of this bacterium are resistant to antibiotics, which has prompted scientists to look for alternatives, such as antibacterial peptides, that can replace traditional drugs. Due to its antioxidant properties, ascorbic acid may be a promising ally in the treatment of acne. The aim of our study was to evaluate the effect of peptide (KWK)₂-KWWW-NH₂(P5) in the presence of ascorbic acid (AA) and its derivative (3-O-ethyl-L-ascorbic acid, EAA) on the stability and organization of phosphatidylinositol monolayers (PI) at temperatures of 25–35 °C. This study showed that the monolayers were in the expanded liquid state (35.28–49.95 mN/m) or in the transition between the expanded liquid and condensed phases (51.50–57.49 mN/m). Compression and decompression isotherms indicated the highest flexibility of the PI + P5 system, where the compression reversibility coefficient of isotherm values ranged from 80.59% to 97.77% and increased for each loop with increasing temperature. At 35 °C, the surface pressure of the monolayer in the PI + P5, PI + P5 + AA and PI + P5 + EAA systems changed less with time. Full article

In this study, we explore the interactions between melittin, a cationic antimicrobial peptide, and model lipid membranes composed of the negatively charged phospholipids 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) and 1,2-dimyristoyl-sn-glycero-3-phosphoserine (DMPS). Using the Langmuir monolayer technique and atomic force microscopy (AFM), we reveal novel insights into these interactions. Our key finding is the observation of the ripple phase in the DMPS bilayer on mica, a phenomenon not previously reported for negatively charged single bilayers. This discovery is significant given the critical role of phosphatidylserine (PS) in cancer biology and the potential of melittin as an anticancer agent. We also highlight the importance of subphase composition, as melittin interacts preferentially with lipids in the liquid-condensed phase; thus, selecting the appropriate subphase composition is crucial because it affects lipid behavior and consequently melittin interactions. Our results show that melittin incorporates into lipid monolayers in both liquid-expanded and liquid-condensed phases, enhancing membrane fluidity and disorder, but is expelled from DMPS in the solid phase. AFM imaging further reveals that melittin induces substantial structural changes in the DMPG membrane and forms the ripple phase in the DMPS bilayers. Despite these alterations, melittin does not cause pore formation or membrane rupture, suggesting strong electrostatic adsorption on the membrane surface that prevents penetration. These findings highlight the differential impacts of melittin on lipid monolayers and bilayers and underscore its potential for interacting with membranes without causing disruption. Full article

Gramicidin A is a natural antimicrobial peptide produced by Bacillus brevis. Its transmembrane dimer is a cation-selective ion channel. The channel is characterized by the average lifetime of the conducting state and the monomer–dimer equilibrium constant. Dimer formation is accompanied by deformations of the membrane. We theoretically studied how the asymmetry in lipid membrane monolayers influences the formation of the gramicidin A channel. We calculated how the asymmetry in the spontaneous curvature and/or lateral tension of lipid monolayers changes the channel lifetime and shifts the equilibrium constant of the dimerization/dissociation process. For the asymmetry expected to arise in plasma membranes of mammalian cells upon the addition of gramicidin A or its derivatives to the cell exterior, our model predicts a manifold increase in the average lifetime and equilibrium constant. Full article

Nicotinamide mononucleotide (NMN) possesses a variety of physiological functions and has therapeutic effects on cardio-cerebral diseases, senile degenerative diseases, neurodegenerative diseases, delayed aging, etc. However, its ability to cross the blood–brain barrier (BBB) and the mechanism of its transport have not been reported. In this study, we used the immortalized hCMEC/D3 cell line to construct an in vitro monolayer cell BBB model, evaluated its ability to cross the blood–brain barrier, and explored the mechanism by carrying out transport and efflux experiments on NMN. The ability of NMN to cross the BBB was investigated by preparing NMN-loaded liposomes conjugated with ANG peptide and RVG peptide. The results showed that the transmembrane transport ability of NMN was moderate, and the transport mechanism was passive transport relying on the concentration difference. The trans-BBB ability of ANG peptide coupled with NMN could be highly significantly improved. Full article

Today, Candida albicans is still the most common cause of both local and life-threatening systemic candidiasis. The spread of resistant fungal strains has resulted in an urgent need to search for new promising antimycotics. Here, we investigated the antifungal action of the tobacco defensin NaD1 against susceptible and resistant to azoles and echinocandins strains of C. albicans. We demonstrated that NaD1 was equally effective and fungicidal against all tested strains. The MIC and MFC values were 6.25 and 12.5 µM, respectively. We showed for the first time that NaD1 could act synergistically not only with caspofungin but also with human host defense antimicrobial peptides cathelicidin LL-37 and β-defensin-2 (HBD2) against susceptible and resistant fungal strains. Using flow cytometry, we demonstrated that NaD1 in combinations with LL-37 or HBD2 can reinforce each other by enhancing membrane disruption. Using the Caco-2 cell monolayer model, we demonstrated that NaD1 impaired the adhesion of C. albicans cells to the human epithelium. Moreover, NaD1 inhibited the formation of fungal biofilms in Sabouraud broth and less markedly in nutrient-rich RPMI-1640 medium, and enhanced the antibiofilm activity of caspofungin. Thus, we hypothesized that NaD1 might affect the development of candidiasis in vivo, including that caused by resistant fungal strains. Full article

Acne vulgaris is one of the most common dermatological diseases and is strongly connected with the pathological growth of the Cutibacterium acnes. More than half of the cultures of this bacterium are resistant to antibiotics, resulting in the proposal of the use of antibacterial peptides as an alternative to traditional antibiotics. Ascorbic acid (AA) and its antioxidant properties may ally in acne therapy. The aim of this study was to determine the influence of the selected antibacterial peptides in the presence of ascorbic acid and 3-O-ethyl-ascorbic acid (EAA) on the properties of the monolayer formed by phosphatidylinositol. Studies of the properties of the phosphatidylinositol monolayer were carried out using the Langmuir–Wilhelmy balance. The recorded compression isotherms, hysteresis loops, and surface pressure values recorded at specific time intervals were evaluated to assess the influence of ascorbic acid and its derivatives in the presence of antimicrobial peptides on the stability and organization of phosphatidylinositol monolayers. The addition of AA to the subphase caused a faster phase transition at over 60 Ų/molecule and significantly reduced the plateau surface pressure by about 20% in most of the systems tested. The studied monolayers were found to be in the expanded liquid state (40.23–49.95 [mN/m]) or in the transition between the expanded and condensed liquid phase (51.47–60.98 [mN/m]). Compression and decompression isotherms indicated the highest flexibility of the systems at 20 °C and 25 °C. The surface pressure versus time dependence indicated the stability of the phosphatidylinositol monolayer with 3-O-ethyl–ascorbic acid and antimicrobial peptides up to 35 °C. Full article

Background/Objectives: Defensins are important components of the innate plant immune system, exhibiting antimicrobial activity against phytopathogens, as well as against fungi pathogenic to humans. Along with antifungal activity, plant defensins are also capable of influencing various immune processes, but not much is known about these effects. In this study, we investigated the immunomodulatory effects of the tobacco defensin NaD1, which possesses a pronounced antifungal activity. Methods and Results: We showed that NaD1 could penetrate the Caco-2 polarized monolayer. Using a multiplex assay with a panel of 48 cytokines, chemokines and growth factors, we demonstrated that NaD1 at a concentration of 2 μM had immunomodulatory effects on human dendritic cells and blood monocytes, mainly inhibiting the production of various immune factors. Using the sandwich ELISA method, we demonstrated that NaD1 at the same concentration had a pronounced immunomodulatory effect on unstimulated THP-1-derived macrophages and those stimulated by bacterial LPS or fungal zymosan. NaD1 had a dual effect and induced the production of both pro-inflammatory cytokine IL-1β as well as anti-inflammatory IL-10 on resting and pro-inflammatory THP-1-derived macrophages. We also found that the immunomodulatory effects of the tobacco defensin NaD1 and the pea defensin Psd1 differed from each other, indicating nonuniformity in the modes of action of plant defensins. Conclusions: Thus, our data demonstrated that the tobacco defensin NaD1 exhibits different immunomodulatory effects on various immune cells. We hypothesized that influence on human immune system along with antifungal activity, could determine the effectiveness of this peptide under infection in vivo. Full article

The use of antimicrobial peptides (AMPs) covalently grafted on surfaces has been recognized in recent years as a promising strategy to fight against biofilm formation. However, after grafting, the understanding of AMP–bacteria interactions is still debated in the literature. In this study, Nisin, a cyclic AMP, was grafted onto gold surfaces via an indirect grafting on acidic thiol self-assembled monolayers using succinimide linkers. The physical and chemical properties of these SAMs were then finely characterized by XPS and FT-IR to confirm the covalent grafting of Nisin. The antiadhesion and bactericidal effects were then studied for Escherichia coli ATCC25922, Staphylococcus aureus ATCC 25923, and Listeria ivanovii Li4(pVS2) by a posteriori analysis of the culture supernatants (i.e., indirect technique) and ex situ by optical microscopy following crystal violet staining (i.e., direct technique). Statistical analysis reveals that the Nisin coating has bactericidal and antiadhesive properties towards Gram-positive bacteria, while no significant results were obtained for Gram-negative bacteria. Full article

Background/Objectives: Atherosclerosis is a chronic inflammatory disease of the arterial wall, which involves multiple cell types. Peptide OG-5 is identified from collagen hydrolysates derived from Salmo salar and exhibits an inhibitory effect on early atherosclerosis. The primary objective of this study was to investigate the impact of OG-5 on advanced atherosclerotic lesions as well as its stability during absorption. Methods: In this study, the ApoE-/- mice were employed to establish advanced atherosclerosis model to investigate the treatment effect of peptide OG-5. Results: The results showed that oral administration of OG-5 at a dosage of 150 mg/kg bw resulted in a 30% reduction in the aortic plaque formation area in ApoE^−/− mice with few bleeding risks. Specifically, intervention with a low dose of OG-5 (50 mg/kg bw), initiated in the early stage of atherosclerosis, continues to provide benefits into the middle and late stages without bleeding risks. Furthermore, treatment of OG-5 increased expression levels of contractile phenotype markers and reduced the accumulation of lipoprotein in VSMCs induced by ox-LDL. Peptide OG-5 could ensure transport across Caco-2 cell monolayers, exhibiting a P_app value of 1.80 × 10⁻⁵ cm/s, and exhibited a robust stability in plasma with remaining content >70% after 8 h incubation. In vivo studies revealed that OG-5 reached maximum concentration in blood after 120 min. Conclusion: The present results demonstrate the potential efficacy of peptide OG-5 as a promising agent for intervention in anti-atherogenesis strategies. Full article