Incorporation Of Peptides Research Articles

Lipid-mediated adaptation of proteins and peptides in cell membranes

The paper overviews the results of computational studies of the molecular mechanisms underlying the adaptation of model cell membranes taking place during their interaction with proteins and peptides. We discuss changes in the structural and dynamic parameters of the water–lipid environment, the hydrophobic/hydrophilic organization of the lipid bilayer surface (the so-called “mosaicity”), etc. Taken together, these effects are called the “membrane response” (MR) and constitute the most important ability of the cell membranes to respond specifically and consistently to the incorporation of extraneous agents, primarily proteins and peptides, and their subsequent functioning. The results of the authors’ long-term research in the field of molecular modeling of MR processes with various spatial and temporal characteristics are described, from the effects of binding of individual lipid molecules to proteins to changes in the integral macroscopic parameters of membranes. The bulk of the results were obtained using the “dynamic molecular portrait” approach developed by the authors. The biological role of the observed phenomena and potential ways of rationally designing artificial membrane systems with specified MR characteristics are discussed. This, in turn, is important for targeted changes in the activity profile of proteins and peptides exerting action on biomembranes, not least as promising pharmacological agents.

Using a Supramolecular Monomer Formulation Approach to Engineer Modular, Dynamic Microgels, and Composite Macrogels.

Microgels show advantages over bulk hydrogels due to convenient control over microgel size and composition, and the ability to use microgels to modularly construct larger hierarchical scaffold hydrogel materials. Here, supramolecular chemistry is used to formulate supramolecular polymer, dynamic microgels solely held together by non-covalent interactions. Four-fold hydrogen bonding ureido-pyrimidinone (UPy) monomers with different functionalities are applied to precisely tune microgel properties in a modular way, via variations in monomer concentration, bifunctional crosslinker ratio, and the incorporation of supramolecular dyes and peptides. Functionalization with a bioactive supramolecular cell-adhesive peptide induced selectivity of cells toward the bioactive microgels over non-active, non-functionalized versions. Importantly, the supramolecular microgels can also be applied as microscale building blocks into supramolecular bulk macrogels with tunable dynamic behavior: a robust and weak macrogel, where the micro- and macrogels are composed of similar molecular building blocks. In a robust macrogel, microgels act as modular micro-building blocks, introducing multi-compartmentalization, while in a weak macrogel, microgels reinforce and enhance mechanical properties. This work demonstrates the potential to modularly engineer higher-length-scale structures using small molecule supramolecular monomers, wherein microgels serve as versatile and modular micro-building units.

The αvβ6 integrin specific virotherapy, Ad5NULL-A20.FCU1, selectively delivers potent "in-tumour" chemotherapy to pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) represent an unmet clinical need. Approximately 90% of PDACs express high levels of αvβ6 integrin. We have previously described Ad5NULL-A20, an adenovirus vector with ablated native means of cell entry and retargeted to αvβ6 integrin by incorporation of an A20 peptide. Here, we incorporate suicide genes FCY1 and FCU1 encoding for cytosine deaminase (CDase) or a combination of CDase and UPRTase, capable of catalysing a non-toxic prodrug, 5-FC into the chemotherapeutic 5-FU and downstream metabolites, into replication-deficient Ad5 and Ad5NULL-A20. We show that Ad5NULL-A20 enables the transfer of suicide genes to αvβ6 integrin-positive PDAC cells which, in combination with 5-FC, results in cell death in vitro which is further mediated by a bystander effect in non-transduced cells. Intratumoural delivery of Ad5NULL-A20.FCU1 in combination with intraperitoneal delivery of 5-FC further results in tumour growth inhibition in a cell line xenograft in vivo. Using clinically-relevant 3D organoid models, we show selective transduction and therapeutic efficacy of FCU1 transgenes in combination with 5-FC. Taken together these data provide the preclinical rationale for combined Ad5NULL-A20.FCU1 plus 5-FC as a promising targeted therapy to mediate "in-tumour chemotherapy" and merits further investigation for the treatment of PDAC patients.

Programmed Cascade Polydopamine Nanoclusters for Pyroptosis-Based Tumor Immunotherapy.

Pyroptosis, an inflammatory cell death, plays a pivotal role in activating inflammatory response, reversing immunosuppression and enhancing anti-tumor immunity. However, challenges remain regarding how to induce pyroptosis efficiently and precisely in tumor cells to amplify anti-tumor immunotherapy. Herein, a pH-responsive polydopamine (PDA) nanocluster, perfluorocarbon (PFC)@octo-arginine (R8)-1-Hexadecylamine (He)-porphyrin (Por)@PDA-gambogic acid (GA)-cRGD (R-P@PDA-GC), is rationally design to augment phototherapy-induced pyroptosis and boost anti-tumor immunity through a two-input programmed cascade therapy. Briefly, oxygen doner PFC is encapsulated within R8 linked photosensitizer Por and He micelles as the core, followed by incorporation of GA and cRGD peptides modified PDA shell, yielding the ultimate R-P@PDA-GC nanoplatforms (NPs). The pH-responsive NPs effectively alleviate hypoxia by delivering oxygen via PFC and mitigate heat resistance in tumor cells through GA. Upon two-input programmed irradiation, R-P@PDA-GC NPs significantly enhance reactive oxygen species production within tumor cells, triggering pyroptosis via the Caspase-1/GSDMD pathway and releasing numerous inflammatory factors into the TME. This leads to the maturation of dendritic cells, robust infiltration of cytotoxic CD8+ T and NK cells, and diminution of immune suppressor Treg cells, thereby amplifying anti-tumor immunity.

Peptide-Induced Division of Polymersomes for Biomimetic Compartmentalization.

Polymersomes are synthetic vesicles that mimic the architecture of cellular compartments such as the cell membrane and organelles. These biomimetic compartments facilitate the creation of cell-like chemical systems, including microreactors and synthetic organelles. However, the construction of hierarchical multi-compartment systems remains challenging and typically requires the encapsulation of pre-formed vesicles within a host compartment. Here, we report the formation of multicompartment polymersomes with a vesicle-in-vesicle architecture achieved through self-division induced by short peptides incorporated into the vesicle membrane. A phenylalanine-phenylalanine-methionine (FFM) tripeptide was designed and encapsulated into the polymersome via microfluidics. We demonstrate that vesicle self-division occurs due to peptide incorporation into the membrane in response to pH changes. This self-division creates internal vesicles capable of colocalizing enzymes. The hybrid polymer-peptide system described here provides a straightforward method for developing subcompartmentalized systems, paving the way for engineering microreactors with life-like properties.

Synthetic Strategies to Prepare Bioactive Lysine and Peptide Conjugates With Triazolium Derivatives

AbstractPeptides conjugated with organic molecules can be useful tools for the development of novel bioactive compounds. The lysine side‐chain is an interesting functional group to act as a linker to connect small molecules in peptide conjugates. Herein we present the design and synthesis of four Safirinium derivatives, their facile conjugation to lysine in solid phase, and incorporation in peptides. The compounds differing in the functionalization of nitrogen N2 of the condensed triazolyl moiety are novel building blocks to design conjugates to perform structure‐activity relationship studies of elastase inhibitors. Consequently, structural investigations of the lysine building blocks and of the corresponding peptide conjugates were performed. We present herein the potential of the Safirinium analogs to act as elastase inhibitors in assays performed on porcine pancreas elastase.

Peptide incorporation in frozen dough and steamed bread: Characteristics and structure-function relationship

Antarctic krill peptide (AKP), a bioactive compound, has garnered significant attention in recent years. This study aimed to explore the effects of varying levels of AKP addition (ranging from 0% to 2.0%, based on the flour, w/w) and different freezing time (0, 1, 2, 4, and 6 weeks) on the rheological properties, rheo-fermentation properties, water distribution, and microstructure of dough. The results revealed that the addition of AKP led to a reduction in the freezable water content, T2 relaxation time, and free sulfhydryl content of frozen dough. After 6 weeks of freezing, the viscoelastic properties of the dough with AKP were higher than those of the control. Additionally, the fermentation height of dough containing 1.5% AKP increased by 25.85% compared with the control, resulting in increased springiness and specific volume, and decreased hardness in the resulting steamed bread. Pearson correlation analysis showed a positive correlation between freezable water content and free sulfhydryl groups, while a negative correlation was observed with springiness. Furthermore, springiness showed a positive correlation with the DPPH free radical scavenging rate. These findings highlight the potential of AKP as a novel food cryoprotectant capable of significantly enhancing the quality and nutritional value of frozen wheat products.

Alignment of lyotropic liquid crystals using magnetic nanoparticles improves ionic transport through built-in peptide ion channels

Hypothesis: We hypothesize that simultaneous incorporation of ion channel peptides (in this case, potassium channel as a model) and hydrophobic magnetite Fe3O4 nanoparticles (hFe3O4NPs) within lipidic hexagonal mesophases, and aligning them using an external magnetic field can significantly enhance ion transport through lipid membranes.Experiments: In this study, we successfully characterized the incorporation of gramicidin membrane ion channels and hFe3O4NPs in the lipidic hexagonal structure using SAXS and cryo-TEM methods. Additionally, we thoroughly investigated the conductive characteristics of freestanding films of lipidic hexagonal mesophases, both with and without gramicidin potassium channels, utilizing a range of electrochemical techniques, including impedance spectroscopy, normal pulse voltammetry, and chronoamperometry.Findings: Our research reveals a state-of-the-art breakthrough in enhancing ion transport in lyotropic liquid crystals as matrices for integral proteins and peptides. We demonstrate the remarkable efficacy of membranes composed of hexagonal lipid mesophases embedded with K+ transporting peptides. This enhancement is achieved through doping with hFe3O4NPs and exposure to a magnetic field. We investigate the intricate interplay between the conductive properties of the lipidic hexagonal structure, hFe3O4NPs, gramicidin incorporation, and the influence of Ca2+ on K+ channels. Furthermore, our study unveils a new direction in ion channel studies and biomimetic membrane investigations, presenting a versatile model for biomimetic membranes with unprecedented ion transport capabilities under an appropriately oriented magnetic field. These findings hold promise for advancing membrane technology and various biotechnological and biomedical applications of membrane proteins.

Redefining vascular repair: revealing cellular responses on PEUU-gelatin electrospun vascular grafts for endothelialization and immune responses on in vitro models.

Tissue-engineered vascular grafts (TEVGs) poised for regenerative applications are central to effective vascular repair, with their efficacy being significantly influenced by scaffold architecture and the strategic distribution of bioactive molecules either embedded within the scaffold or elicited from responsive tissues. Despite substantial advancements over recent decades, a thorough understanding of the critical cellular dynamics for clinical success remains to be fully elucidated. Graft failure, often ascribed to thrombogenesis, intimal hyperplasia, or calcification, is predominantly linked to improperly modulated inflammatory reactions. The orchestrated behavior of repopulating cells is crucial for both initial endothelialization and the subsequent differentiation of vascular wall stem cells into functional phenotypes. This necessitates the TEVG to provide an optimal milieu wherein immune cells can promote early angiogenesis and cell recruitment, all while averting persistent inflammation. In this study, we present an innovative TEVG designed to enhance cellular responses by integrating a physicochemical gradient through a multilayered structure utilizing synthetic (poly (ester urethane urea), PEUU) and natural polymers (Gelatin B), thereby modulating inflammatory reactions. The luminal surface is functionalized with a four-arm polyethylene glycol (P4A) to mitigate thrombogenesis, while the incorporation of adhesive peptides (RGD/SV) fosters the adhesion and maturation of functional endothelial cells. The resultant multilayered TEVG, with a diameter of 3.0cm and a length of 11cm, exhibits differential porosity along its layers and mechanical properties commensurate with those of native porcine carotid arteries. Analyses indicate high biocompatibility and low thrombogenicity while enabling luminal endothelialization and functional phenotypic behavior, thus limiting inflammation in in-vitro models. The vascular wall demonstrated low immunogenicity with an initial acute inflammatory phase, transitioning towards a pro-regenerative M2 macrophage-predominant phase. These findings underscore the potential of the designed TEVG in inducing favorable immunomodulatory and pro-regenerative environments, thus holding promise for future clinical applications in vascular tissue engineering.

Milk-derived antimicrobial peptides incorporated whey protein film as active coating to improve microbial stability of refrigerated soft cheese

Nisin is the first FDA-approved antimicrobial peptide and shows significant antimicrobial activity against Gram-positive bacteria, but only a weakly inhibitory effect on Gram-negative bacteria. The aim of this study was to prepare whey protein-based edible films with the incorporation of milk-derived antimicrobial peptides (αs2-casein151–181 and αs2-casein182–207) and compare their mechanical properties and potential application in cheese packaging with films containing nisin. These two antimicrobial peptides showed similar activity against B. subtilis and much higher activity against E. coli than bacteriocin nisin, representing that these milk-derived peptides had great potential to be applied as food preservatives. Antimicrobial peptides in whey protein films caused an increase in film opaqueness and water vapor barrier properties but decreased the tensile strength and elongation at break. Compared to other films, the whey protein film containing αs2-casein151–181 had good stability in salt or acidic solution, as evidenced by the results from scanning electron microscope and Fourier transform infrared spectroscopy. Whey protein film incorporated with αs2-casein151–181 could inhibit the growth of yeasts and molds, and control the growth of psychrotrophic bacteria present originally in the soft cheese at refrigerated temperature. It also exhibited significant inhibitory activity against the development of mixed culture (E. coli and B. subtilis) in the cheese due to superficial contamination during storage. Antimicrobial peptides immobilized in whey protein films showed a higher effectiveness than their direct application in solution. In addition, films containing αs2-casein151–181 could act as a hurdle inhibiting the development of postprocessing contamination on the cheese surface during the 28 days of storage. The films in this study exhibited the characteristics desired for active packaging materials.

Fully synthetic, tunable poly(α-amino acids) as the base of bioinks curable by visible light

Bioinks play a crucial role in tissue engineering, influencing mechanical and chemical properties of the printed scaffold as well as the behavior of encapsulated cells. Recently, there has been a shift from animal origin materials to their synthetic alternatives. In this context, we present here bioinks based on fully synthetic and biodegradable poly(α,L-amino acids) (PolyAA) as an alternative to animal-based gelatin methacrylate (Gel-Ma) bioinks. Additionally, we first reported the possibility of the visible light photoinitiated incorporation of the bifunctional cell adhesive RGD peptide into the PolyAA hydrogel matrix. The obtained hydrogels are shown to be cytocompatible, and their mechanical properties closely resemble those of gelatin methacrylate-based scaffolds. Moreover, combining the unique properties of PolyAA-based bioinks, the photocrosslinking strategy, and the use of droplet-based printing allows the printing of constructs with high shape fidelity and structural integrity from low-viscosity bioinks without using any sacrificial components. Overall, presented PolyAA-based materials are a promising and versatile toolbox that extends the range of bioinks for droplet bioprinting.

Development of Ac2-26 Mesoporous Microparticle System as a Potential Therapeutic Agent for Inflammatory Bowel Diseases.

Inflammatory bowel diseases (IBDs) disrupt the intestinal epithelium, leading to severe chronic inflammation. Current therapies cause adverse effects and are expensive, invasive, and ineffective for most patients. Annexin A1 (AnxA1) is a pivotal endogenous anti-inflammatory and tissue repair protein in IBD. Nanostructured compounds loading AnxA1 or its active N-terminal mimetic peptides improve IBD symptomatology. To further explore their potential as a therapeutic candidate, the AnxA1 N-terminal mimetic peptide Ac2-26 was incorporated into SBA-15 ordered mesoporous silica and covered with EL30D-55 to deliver it by oral treatment into the inflamed gut. The systems SBA-Ac2-26 developed measurements revealed self-assembled rod-shaped particles, likely on the external surface of SBA-15, and 88% of peptide incorporation. SBA-15 carried the peptide Ac2-26 into cultured Raw 264.7 macrophages and Caco-2 epithelial cells. Moreover, oral administration of Eudragit-SBA-15-Ac2-26 (200 μg; once a day; for 4 days) reduced colitis clinical symptoms, inflammation, and improved epithelium recovery in mice under dextran-sodium sulfate-induced colitis. The absorption of SBA-15 in gut epithelial cells is typically low; however, the permeable inflamed barrier can enable microparticles to cross, being phagocyted by macrophages. These findings suggest that Ac2-26 is successfully delivered and binds to its receptors in both epithelial and immune cells, aligning with the clinical results. Our findings demonstrate a simple and cost-effective approach to delivering Ac2-26 orally into the inflamed gut, highlighting its potential as non-invasive IBD therapy.

Incorporation of spray-dried encapsulated bioactive peptides from coconut (Cocos nucifera L.) meal by-product in bread formulation.

This study aimed to stabilize and mask the bitterness of peptides obtained from the enzymatic hydrolysis of coconut-meal protein with maltodextrin (MD) and maltodextrin-pectin (MD-P) as carriers via spray-drying. Essential (~35%), hydrophobic (~32%), antioxidant (~15%), and bitter (~45%) amino acids comprised a significant fraction of the peptide composition (with a degree of hydrolysis of 33%). The results indicated that the peptide's production efficiency, physical and functional properties, and hygroscopicity improved after spray-drying. Morphological features of free peptides (fragile and porous structures), spray-dried with MD (wrinkled with indented structures), and MD-P combination (relatively spherical particles with smooth surfaces) were influenced by the process type and feed composition. Adding free and microencapsulated peptides to the bread formula (2% W/W) caused changes in moisture content (35%-43%), water activity (0.89-0.94), textural properties (1-1.6 N), specific volume (5.5-6 cm3/g), porosity (18%-27%), and color indices of the fortified product. MD-P encapsulated peptides in bread fortification resulted in thermal stability and increased antioxidant activity (DPPH and ABTS+ radical scavenging: 4.5%-39.4% and 31.6%-46.8%, respectively). MD-P (as a carrier) could maintain sensory characteristics and mask the bitterness of peptides in the fortified bread. The results of this research can be used to produce functional food and diet formulations.

Silk fibroin-based dressings with antibacterial and anti-inflammatory properties

Silk fibroin is a fibrillar protein obtained from arthropods such as mulberry and non-mulberry silkworms. Silk fibroin has been used as a dressing in wound treatment for its physical, chemical, mechanical, and biological properties. This systematic review analyzed studies from PubMed, Web of Science, and Scopus databases to identify the molecules preferred for functionalizing silk fibroin-based dressings and to describe their mechanisms of exhibiting anti-inflammatory and antibacterial properties. The analysis of the selected articles allowed us to classify the dressings into different conformations, such as membranes, films, hydrogels, sponges, and bioadhesives. The incorporation of various molecules, including antibiotics, natural products, peptides, nanocomposites, nanoparticles, secondary metabolites, growth factors, and cytokines, has allowed the development of dressings that promote wound healing with antibacterial and immunomodulatory properties. In addition, silk fibroin-based dressings have been established to have the potential to regenerate wounds such as venous ulcers, arterial ulcers, diabetic foot, third-degree burns, and neoplastic ulcers. Evaluation of the efficacy of silk fibroin-based dressings in tissue engineering is an area of great activity that has shown significant advances in recent years.

Mussel-inspired electroactive, antibacterial and antioxidative composite membranes with incorporation of gold nanoparticles and antibacterial peptides for enhancing skin wound healing

Large skin wounds are one of the most important health problems in the world. Skin wound repair and tissue regeneration are complex processes involving many physiological signals, and effective wound healing remains an enormous clinical challenge. Therefore, there is an urgent need for a strategy to rapidly kill bacteria, promote cell proliferation and accelerate wound healing. At present, electrical stimulation (ES) is often used in the clinical treatment of skin wounds and can simulate the endogenous biological current of the body and accelerate the repair process of skin wounds. However, a single ES strategy has difficulty covering the entire wound area, which may lead to unsatisfactory therapeutic effects. To overcome this deficiency, it is essential to develop a collaborative treatment strategy that combines ES with other treatments. In this study, gold nanoparticles and antibacterial peptides (Os) were loaded on the surface of poly(lactic-co-glycolic acid) (PLGA) material through the reducibility and adhesion of polydopamine (PDA) and improved the electrical activity, anti-inflammatory, antibacterial and biocompatibility properties of the polymer material. At the same time, this composite membrane material (Os/Au-PDA@PLGA) combined with ES was used in wound therapy to improve the wound healing rate. The results show that the new wound repair material has good biocompatibility and can effectively promote cell proliferation and migration. Through the combined application of gold nanoparticles and antibacterial peptides Os, the polymer materials have more efficient bactericidal and antioxidant effects. The antibacterial experiment results showed that gold nanoparticles could further enhance the antibacterial activity of antibacterial peptides. Furthermore, the Os/Au-PDA@PLGA composite membrane has good hydrophilicity and electrical activity, which can provide a more favorable cell microenvironment for wound healing. In vivo studies using a full-thickness skin defect model in rats showed that the Os/Au-PDA@PLGA composite membrane had a better therapeutic effect than the pure PLGA material. More importantly, the combination of the Os/Au-PDA@PLGA composite with ES significantly accelerated the rate of vascularization and collagen deposition and promoted wound healing compared with non-ES controls. Therefore, the combination of the Au/Os-PDA@PLGA composite membrane with ES may provide a new strategy for the effective treatment of skin wounds.

Sequential Immunizations with Influenza Neuraminidase Protein Followed by Peptide Nanoclusters Induce Heterologous Protection.

Enhancing cross-protections against diverse influenza viruses is desired for influenza vaccinations. Neuraminidase (NA)-specific antibody responses have been found to independently correlate with a broader influenza protection spectrum. Here, we report a sequential immunization regimen that includes priming with NA protein followed by boosting with peptide nanoclusters, with which targeted enhancement of antibody responses in BALB/c mice to certain cross-protective B-cell epitopes of NA was achieved. The nanoclusters were fabricated via desolvation with absolute ethanol and were only composed of composite peptides. Unlike KLH conjugates, peptide nanoclusters would not induce influenza-unrelated immunity. We found that the incorporation of a hemagglutinin peptide of H2-d class II restriction into the composite peptides could be beneficial in enhancing the NA peptide-specific antibody response. Of note, boosters with N2 peptide nanoclusters induced stronger serum cross-reactivities to heterologous N2 and even heterosubtypic N7 and N9 than triple immunizations with the prototype recombinant tetrameric (rt) N2. The mouse challenge experiments with HK68 H3N2 also demonstrated the strong effectiveness of the peptide nanocluster boosters in conferring heterologous protection.

Matrix metalloproteinase degradable, in situ photocrosslinked nanocomposite bioinks for bioprinting applications

The development of suitable bioinks with high printability, mechanical strength, biodegradability, and biocompatibility is a key challenge for the clinical translation of 3D constructs produced with bioprinting technologies. In this work, we developed a new type of nanocomposite bioinks containing thiolated mesoporous silica nanoparticles (MSN) that act as active fillers within norbornene-functionalized hydrogels. The MSNs could rapidly covalently crosslink the hydrogels upon exposure to UV light. The mechanical properties of the gels could be modulated from 9.3 to 19.7 kPa with increasing concentrations of MSN. The ability of the MSN to covalently crosslink polymeric networks was, however, significantly influenced by polymer architecture and the number of functional groups. Modification of the outer surface of MSNs with matrix metalloproteinase (MMP) sensitive peptides (MSN-MMPs) resulted in proteinase K and MMP-9 enzyme responsive biodegradable bioinks. Additional cysteine modified RGD peptide incorporation enhanced cell-matrix interactions and reduced the gelation time for bioprinting. The nanocomposite bioinks could be printed by using extrusion-based bioprinting. Our nanocomposite bioinks preserved their shape during in vitro studies and encapsulated MG63 cells preserved their viability and proliferated within the bioinks. As such, our nanocomposite bioinks are promising bioinks for creating bioprinted constructs with tunable mechanical and degradation properties.

Difluoroalanine: Synthesis, Incorporation in Peptides, and Hydrophobic Contribution Assessment.

The straightforward synthesis of chiral (R)- and (S)-difluoroalanine is reported. The key step is a Strecker-type reaction followed by hydrogenolysis, Fmoc protection, and acidic hydrolysis. Peptide coupling reactions at its N- and C-terminal positions provide diastereomerically pure tripeptides. On the basis of hydrophobicity index measurements, the hydrophobic contribution of difluoroalanine in a peptide chain was found to be similar to that of isoleucine for a smaller van der Waals volume of the side chain.

Synthesis, Enzymatic Peptide Incorporation, and Applications of Diazirine-Containing Isoprenoid Diphosphate Analogues.

Prenylated proteins contain C15 or C20 isoprenoids linked to cysteine residues positioned near their C-termini. Here we describe the preparation of isoprenoid diphosphate analogues incorporating diazirine groups that can be used to probe interactions between prenylated proteins and other proteins that interact with them. Studies using synthetic peptides and whole proteins demonstrate that these diazirine analogues are efficient substrates for prenyltransferases. Photo-cross-linking experiments using peptides incorporating the diazirine-functionalized isoprenoids selectively cross-link to several different proteins. These new isoprenoid analogues should be broadly useful in the studies of protein prenylation.

An antifouling biosensor with dual modality readouts for detection of patulin in complex fruit juice

Herein, an antifouling sensing platform with electrochemical and fluorometric dual-signal readouts is proposed for the reliable detection of patulin (PAT) in orange and apple juice. The incorporation of an antifouling peptide of D-amino acids endows sensing surface with a sustained antifouling capability in complex detection system, effectively preventing nonspecific adsorption at the sensing interface. Moreover, the integration of both electrochemical and fluorescent signal readouts addresses the limitations inherent in each signal channel. And both electrochemical and fluorescent signal readouts would make up for the drawbacks of each signal channel and merge with the benefits of each transduction channel, ensuring mutual complementation of the detection results. In the sensing process, antifouling peptides and PAT-binding aptamers tagged with methylene blue (Mb-Apta) are covalently attached to gold nanoparticles (AuNPs), forming antifouling monolayers and sensing probes, respectively. Subsequently, SiO2-polyamidoamine (SiO2-PAMAM) will integrate with aptamers through electrostatic attraction. In the presence of PAT in the detection system, the Mb-Apta selectively bind with PAT molecules, resulting in Mb near to electrode surface and release SiO2-PAMAM into sample systems. Consequently, noticeable electrochemical and robust aggregation-induced emission (AIE) dual-signals are generated. The combined utilization of both electrochemical and fluorescent signal readouts offers enhanced detection sensitivity and an extended linear range.