Search Results (279)

Cyanobacterial blooms are becoming increasingly frequent and intense worldwide, often dominated by Microcystis aeruginosa, a species capable of producing a wide array of bioactive metabolites beyond microcystins. This study evaluates the ecotoxicological potential of a non-microcystin-producing strain, M. aeruginosa CCIBt3106, using acute immobilization assays with three microcrustacean species: Daphnia similis, Artemia salina, and Parhyale hawaiensis. Biomass was extracted using solvents of varying polarity, and selected extracts (aqueous and 50% methanol) were further fractionated and analyzed via high-resolution liquid chromatography–tandem mass spectrometry (HR-LC-MS/MS). Significant toxicity was observed in D. similis and P. hawaiensis, with EC₅₀ values ranging from 660 to 940 µg mL⁻¹. Metabolomic profiling revealed the presence of chemically diverse metabolite classes, including peptides, polyketides, and fatty acyls, with putative annotations linked to known bioactivities. These findings demonstrate that cyanobacterial strains lacking microcystins can still produce complex metabolite mixtures capable of inducing species-specific toxic effects under environmentally relevant exposure levels. Overall, the results highlight the need to expand ecotoxicological assessments and monitoring frameworks to include non-microcystin cyanobacterial metabolites and strains in water quality management. Full article

Protein phosphorylation is one of the most common and important post-translational modifications (PTMs) and is highly involved in various biological processes. Ideal adsorbents with high sensitivity and specificity toward phosphopeptides with large coverage are therefore essential for enrichment and mass spectroscopy-based phosphoproteomics analysis. In this study, a newly designed IMAC adsorbent composite was constructed on the graphene matrix coated with mesoporous silica. The outer functional 3D-network layer was prepared by free radical polymerization of the phosphonate-functionalized vinyl imidazolium salt monomer and subsequent metal immobilization. Due to its unique structural feature and high content of Ti⁴⁺ ions, the resulting phosphonate-immobilized adsorbent composite G@mSiO₂@PPFIL-Ti⁴⁺ exhibits excellent performance in phosphopeptide enrichment with a low detection limit (0.1 fmol, tryptic β-casein digest) and superior selectivity (molar ratio of 1:15,000, digest mixture of β-casein and bovine serum albumin). G@mSiO₂@PPFIL-Ti⁴⁺ displays high tolerance to loading and elution conditions and thus can be reused without a marked decrease in enrichment efficacy. The captured phosphopeptides can be released globally, and mono-/multi-phosphopeptides can be isolated stepwise by gradient elution. When applying this material to enrich phosphopeptides from human lung cell lysates, a total of 3268 unique phosphopeptides were identified, corresponding to 1293 phosphoproteins. Furthermore, 2698 phosphorylated peptides were found to be differentially expressed (p < 0.05) between human lung adenocarcinoma cells (SPC-A1) and human normal epithelial cells (Beas-2B), of which 1592 were upregulated and 1106 were downregulated in the cancer group. These results demonstrate the material’s superior enrichment efficiency in complex biological samples. Full article

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by synaptic dysfunction and neuronal loss due to the accumulation of amyloid-β peptides and tau proteins. In the pursuit of novel neuroprotective strategies, organotin(IV) compounds have garnered attention due to their unique chemical and biological properties. This study evaluates the inhibitory potential of two triphenyltin(IV) derivatives—(3-propan-1-ol)triphenyltin(IV) (Ph₃SnL₁) and (4-butan-1-ol)triphenyltin(IV) (Ph₃SnL₂)—in both free form and immobilized into mesoporous silica SBA-15~Cl, targeting acetylcholinesterase (AChE), a key enzyme involved in AD pathophysiology. The SBA-15~Cl|Ph₃SnL₂ nanostructures exhibited the most potent inhibitory activity against AChE (IC₅₀ = 0.58 μM), significantly outperforming the standard drug galantamine. Molecular docking, molecular dynamics simulations, and MM/GBSA and MM/PBSA analyses confirmed the stability and selectivity of interactions with AChE, primarily driven by hydrophobic interactions. Compound transport was also simulated using a multi-scale 3D mouse brain model to evaluate brain tissue distribution and blood–brain barrier permeability. The results highlight the strong potential of SBA-15-loaded organotin(IV) compounds as biocompatible neuroprotective agents for novel treatments of neurodegenerative diseases. Full article

Short- and medium-sized peptides have long been used as effective and versatile organocatalysts. In the early 80s, Inoue used diketopiperazines in the Strecker reaction, while Juliá and Colonna reported the epoxidation of chalcone catalyzed by poly-L-Ala. Since then, a variety of peptide-catalyzed reactions have been described. However, peptide synthesis typically implicates the use of toxic reagents and generates wastes; therefore, peptide recycling is expected to significantly improve the overall sustainability of the process. Easy recovery and recycling of peptide catalysts can be expediently attained by covalent binding, inclusion, or adsorption. In addition, immobilization can significantly accelerate the screening of new peptide catalysts. For these reasons, diverse supports have been tested, including natural or synthetic polymers, porous polymeric networks, inorganic porous materials, organic-inorganic hybrid materials, and finally metal–organic frame-works. Full article

Nanoquenchers with a single quenching cofactor exhibit limited fluorescence quenching efficiency. In this work, a metal–organic hybrid with dual quenching cofactors (Cu²⁺ and pyrroloquinoline quinone or PQQ) was prepared by metal-coordinated assembly and used as a nanoquencher for a protease assay with enhanced quenching efficiency. The peptide substrate with an oligohistidine (His₆) tag was labeled with a fluorophore. Caspase-3 was determined as a protease example. The substrate was attached onto the surface of the Cu-PQQ nanoquencher by a metal coordination interaction between the unsaturated Cu²⁺ on the nanoparticle surface and the His₆ tag in the peptide. The cleavage of the peptide substrate by enzymatic hydrolysis led to the release of a fluorophore-conjugated segment from the nanoquencher surface, thus turning on the fluorescence. The nanoprobe was used to determine caspase-3 with a linear range of 0.01–5 ng/mL and a detection limit of 7 pg/mL. Furthermore, the method was used to evaluate inhibition efficiency and monitor drug-induced cell apoptosis. In contrast to other means of peptide immobilization, such as physical adsorption and covalent coupling, the strategy based on the metal coordination interaction is simple and powerful, thereby achieving assays of caspase-3 activity in lysates with a satisfactory result. The work should be valuable for the design of nanoquenchers with multiple quenching cofactors and the development of novel biosensors. 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

Surface display technology has revolutionized whole-cell biocatalysis by enabling efficient enzyme immobilization on microbial cell surfaces. Compared with traditional enzyme immobilization, this technology has the advantages of high enzyme activity, mild process, simple operation and low cost, which thus has been widely studied and applied in various fields. This review explores the principles, optimization strategies, applications in the food industry, and future prospects. We summarize the membrane and anchor protein structures of common host cells (Escherichia coli, Bacillus subtilis, and yeast) and discuss cutting-edge optimization approaches, including host strain genetic engineering, rational design of anchor proteins, innovative linker peptide engineering, and precise regulation of signal peptides and promoters, to maximize surface display efficiency. Additionally, we also explore its diverse applications in food processing and manufacturing, additive synthesis, food safety, and other food-related industries (such as animal feed and PET packaging degradation), demonstrating their potential to address key challenges in the food industry. This work bridges fundamental research and industrial applications, offering valuable insights for advancing agricultural and food chemistry. Full article

Myosin phosphatase (MP) holoenzyme consists of protein phosphatase-1 (PP1) catalytic subunit (PP1c) associated with myosin phosphatase target subunit-1 (MYPT1) and it plays an important role in mediating the phosphorylation of the 20 kDa light chain (MLC20) of myosin, thereby regulating cell contractility. The association of MYPT1 with PP1c increases the phosphatase activity toward myosin; therefore, disrupting/dissociating this interaction may result in inhibition of the dephosphorylation of myosin. In this study, we probed how MYPT1^32–58 peptide including major PP1c interactive regions coupled with biotin and cell-penetrating TAT sequence (biotin-TAT-MYPT1) may influence MP activity. Biotin-TAT-MYPT1 inhibited the activity of MP holoenzyme and affinity chromatography as well as surface plasmon resonance (SPR) binding studies established its stable association with PP1c. Biotin-TAT-MYPT1 competed for binding to PP1c with immobilized GST-MYPT1 in SPR assays and it partially relieved PP1c inhibition by thiophosphorylated (on Thr696 and Thr853) MYPT1. Moreover, biotin-TAT-MYPT1 dissociated PP1c from immunoprecipitated PP1c-MYPT1 complex implying its holoenzyme disrupting ability. Biotin-TAT-MYPT1 penetrated into A7r5 smooth muscle cells localized in the cytoplasm and nucleus and exerted inhibition on MP with a parallel increase in MLC20 phosphorylation. Our results imply that the biotin-TAT-MYPT1 peptide may serve as a specific MP regulatory cell-penetrating peptide as well as possibly being applicable to further development for pharmacological interventions. Full article

Prolactin-releasing peptide (PrRP) has a regulatory role in both acute and chronic stress, suggesting its potential contribution to stress-related disorders such as depression. However, not all individuals with depression respond equally to stressors. We aimed to determine whether the PrRP system could underlie stress coping, an important aspect of depression. The forced swim test was used both as a stressor and as a method to assess coping strategy. Based on immobility time, active coping and passive coping subgroups were identified, and 10 brain regions were studied using qPCR to measure the mRNA expression levels of PrRP and its receptors (specific: GPR10; non-specific: NPFFR2). Passive coping animals spent more time in an immobile posture and exhibited altered mRNA expression levels in the medullary A1 region, the habenula, and the arcuate nucleus than control or active coping rats. Additionally, we identified corticotropin-releasing hormone and vesicular glutamate transporter 2 positive neurons in the A1 medullary region that contained Prrp, suggesting a modulatory role of PrRP in these excitatory neurons involved in stress regulation. Our findings reinforce the hypothesis that PrRP plays a role in stress coping, a process closely linked to depression. However its effect is brain region-specific. Full article

The valorization of cheese whey, a rich by-product of the dairy industry that is rich in lactose (approx. 70%), proteins (14%), and minerals (9%), represents a promising approach for microbial fermentation. With global whey production exceeding 200 million tons annually, the high biochemical oxygen demand underlines the important need for sustainable processing alternatives. This review explores the biotechnological potential of whey as a fermentation medium by examining its chemical composition, microbial interactions, and ability to support the synthesis of valuable metabolites. Functional microorganisms such as lactic acid bacteria (Lactobacillus helveticus, L. acidophilus), yeasts (Kluyveromyces marxianus), actinobacteria, and filamentous fungi (Aspergillus oryzae) have demonstrated the ability to efficiently convert whey into a wide range of bioactive compounds, including organic acids, exopolysaccharides (EPSs), bacteriocins, enzymes, and peptides. To enhance microbial growth and metabolite production, whey fermentation can be carried out using various techniques, including batch, fed-batch, continuous and immobilized cell fermentation, and membrane bioreactors. These bioprocessing methods improve substrate utilization and metabolite yields, contributing to the efficient utilization of whey. These bioactive compounds have diverse applications in food, pharmaceuticals, agriculture, and biofuels and strengthen the role of whey as a sustainable biotechnological resource. Patents and clinical studies confirm the diverse bioactivities of whey-derived metabolites and their industrial potential. Whey peptides provide antihypertensive, antioxidant, immunomodulatory, and antimicrobial benefits, while bacteriocins and EPSs act as natural preservatives in foods and pharmaceuticals. Also, organic acids such as lactic acid and propionic acid act as biopreservatives that improve food safety and provide health-promoting formulations. These results emphasize whey’s significant industrial relevance as a sustainable, cost-efficient substrate for the production of high-quality bioactive compounds in the food, pharmaceutical, agricultural, and bioenergy sectors. Full article

Gold nanoparticles (AuNPs) have surface plasmon resonance (SPR) and catalytic activity that are not found in bulk gold and have been studied in various fields. Among these, immobilization of AuNPs on various solid-phase substrates is known to produce stable catalytic activity and specific SPRs and research on the immobilization of AuNPs has been conducted actively. However, the conventional method requires the preparation and immobilization of AuNPs in separate processes, making it difficult to prepare immobilized AuNPs in a one-pot process. In this study, we attempted to synthesize and immobilize AuNPs using peptidyl beads, which are microbeads having immobilized a peptide capable of reducing gold ions. We successfully reduced Au ions from 0.5 to 1000 µM of HAuCl₄ and immobilized them on peptidyl beads in the form of AuNPs. The immobilized AuNPs have a constant particle size independent of the HAuCl₄ concentration. Furthermore, the peptidyl beads with AuNPs have catalytic activity. The quantity of the AuNPs on the peptidyl beads and, subsequently, the catalytic reaction rate of the sample, could be controlled. This study would also be expected to be applied to the immobilization of metallic nanomaterials other than AuNPs by modifying the peptide sequence. Full article

Dengue is a neglected disease mainly affecting tropical and subtropical countries. The diagnosis of dengue fever is still a problem since most of it is made from whole or recombinant DENV proteins, which present cross-reactions with other members of the Flavivirus family. Therefore, there is still a huge demand for new diagnostic methods that provide rapid, low-cost, easy-to-use confirmation. Thus, in this study, we developed an affordable electrochemical biosensor for rapidly detecting immunoglobulin G (IgG) serological antibodies in the sera of DENV-infected patients. An identified linear B-cell epitope (DENV/18) specific for DENV 1–4 serotypes recognized by IgG in patient sera was selected as a target molecule after a microarray of peptides using the SPOT-synthesis methodology. After chemical synthesis, the DENV/18-peptide was immobilized on the surface of the working electrode of a commercially available screen-printed gold electrode (SPGE). The capture of DENV-specific IgG allowed for the formation of an immunocomplex that was measured by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) using a potassium ferrocyanide/ferricyanide ([Fe(CN)₆]^3−/4−) electrochemical probe. An evaluation of the biosensor’s performance showed a detection limit of 100 µg mL⁻¹ for the synthetic peptides (DENV/18) and 1.21 ng mL⁻¹ in CV and 0.43 ng mL⁻¹ in DPV for human serum, with a sensitivity of 7.21 µA in CV and 8.79 µA in DPV. The differentiation of infected and uninfected individuals was possible even at a high dilution factor that reduced the required sample volumes to a few microliters. The final device proved suitable for diagnosing DENV by analyzing real serum samples, and the results showed good agreement with molecular biology diagnostics. The flexibility to conjugate other antigenic peptides to SPEs suggests that this technology could be rapidly adapted to diagnose other pathogens. Full article

The global market increasingly demands alternative rapid diagnostic tools, such as disposable biosensors, to meet the growing need for point-of-care clinical testing of infectious diseases. Bacterial vaginosis (BV), a common infection caused by Gardnerella vaginalis, requires efficient and accurate detection methods to improve patient outcomes and prevent complications. However, existing diagnostic approaches often lack sensitivity, specificity, or rapid response times, highlighting the need for innovative biosensing solutions. In response to this challenge, we developed a peptide-based electrochemical biosensor for the specific detection of Gardnerella vaginalis. The sensor was designed to achieve high sensitivity, selectivity, and stability, with detection performed through electrochemical techniques. Cyclic voltammetry (CV) was employed to monitor electron transfer kinetics at the electrode surface, while electrochemical impedance spectroscopy (EIS) provided insights into changes in resistance and capacitance during peptide binding. The sensor fabrication involved covalently bonding anti-Gardnerella vaginalis peptides to a gold nanoparticle (AuNP)-modified graphene electrode, significantly enhancing bioreceptor immobilization stability and increasing the surface area for target binding interactions. The incorporation of AuNPs improved signal amplification due to their high surface-to-volume ratio and excellent conductivity, leading to enhanced sensor performance. The biosensor demonstrated a low detection limit (LOD) of 0.02305 μg/mL, with a rapid response time of 5 min across various concentrations of the target Gardnerella vaginalis antigen. The results confirmed specific and selective binding to the pathogen marker, with minimal interference from non-target species, ensuring high accuracy. The combination of graphene, AuNPs, and peptide bioreceptors resulted in robust signal enhancement, making this biosensor a promising tool for fast and reliable point-of-care diagnostics in clinical settings. Full article

The quantitative determination of conotoxins has great potential in the development of natural marine peptide pharmaceuticals. Considering the time-consuming sample pretreatment and expensive equipment in MS or LC-MS/MS analysis, an electrochemical sensor combined with molecularly imprinted polymer (MIP) is fabricated for the rapid monitoring of conotoxin αB-VxXXIVA to promote its pharmaceutical value and eliminate the risk of human poisoning. Electrochemically reduced graphene oxide–gold composite (rGO-Au) is modified with chitosan (CS) and glutaraldehyde (GA) to immobilize the macromolecular peptide, conotoxin αB-VxXXIVA. Subsequently, acrylamide (AAM) with a cross-linking agent, N,N′-methylene-bisacrylamide (NNMBA), is introduced into the rGO-Au electrode to form MIPs by electro-polymerization. The proposed MIP-based electrochemical sensor, PAM/αB-CTX/CS-GA/rGO-Au/SPE, exhibits satisfactory sensing performance in the detection of αB-VxXXIVA. Based on current change versus logarithm concentration, a wide linear range from 0.1 to 10,000 ng/mL and a low detection limit (LOD) of 0.014 ng/mL for this sensor are obtained. This work provides a promising method in electrochemical determination combined with MIP for the determination of macromolecular peptides. Full article

Throughout the last 5 years, extensive research has been carried out towards the development of effective treatments for coronavirus disease 2019 (COVID-19). Regardless of the worldwide efforts, only a few drugs have passed clinical trials, and there is still a need to develop therapies, especially for those who are particularly vulnerable to a severe disease course. Maleimide-functionalized liposomes are proposed to serve as a platform for the immobilization, stabilization, and delivery of a short peptide sequence with high affinity towards severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, extensive optimizations should be performed in order to achieve features required for a reliable drug candidate, such as homogeneity of physical parameters and their long-term stability. Here, we present a step-by-step development process for maleimide-functionalized liposomes, which—once decorated with the SARS-CoV-2-binding peptide—could inhibit the infection progress of COVID-19. The main emphasis is placed on defining optimal lipid composition and formation conditions of PEGylated liposomes. We propose that the developed nanocarrier technology can be used as a universal platform for the construction of multiple antiviral agents. Full article