Staff member

The growing threat of antibiotic-resistant pathogens has intensified the demand for alternative antibacterial materials. Quatsomes-nanovesicles composed of cholesterol and quaternary ammonium surfactants (QAS)- emerge as promising candidates due to their intrinsic antimicrobial properties and tunable physicochemical characteristics. Here, we investigate the antibacterial activity of quatsomes incorporating QAS with either tetradecyl (C14) or hexadecyl (C16) alkyl chains against Staphylococcus aureus, a leading cause of hospital-acquired infections. Both quatsome types exhibited potent bactericidal activity in planktonic cultures, with C16containing formulations showing a 2.5-fold lower minimum bactericidal concentration than C14 counterparts. Confocal microscopy suggested a partial penetration of cationic quatsomes into the bacterial peptidoglycan layer, accompanied by significant increases in zeta-potential, suggesting strong electrostatic interactions without visible membrane disruption, as confirmed by scanning electron microscopy. Both formulations also demonstrated high efficacy against mature S. aureus biofilms, with no significant differences between alkyl chain lengths, indicating a mechanism primarily targeting the extracellular biofilm matrix. In addition, they showed a good antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA). A preliminary safety assessment using reconstructed human epidermis (EpiskinTM) confirmed the non-irritant nature of both formulations. These findings highlight the potential of QAS-based quatsomes as effective and biocompatible nanocarriers for topical antibacterial applications, offering a promising platform for combating antibiotic-resistant infections in both planktonic and biofilm states.

JTD Keywords: Antibacterial materials, Antimicrobial activity, Biofilm, Gram-positive bacteria, Growth, Nanovesicles, Quaternary ammonium surfactants, Quatsomes, Silver nanoparticles, Staphylococcus aureus

Targeting therapeutic nanocarriers (NCs) to endothelial receptors favours transport across the blood-brain barrier (BBB), a main obstacle to access the brain. While these strategies compel validation in animals, quantitative sub-cellular resolution is non-viable in vivo. BBB-on-chip (BBB-oC) devices can help. Illustrating this, we used a BBB-oC comprising a lateral channel containing a human brain endothelial lining and a central chamber containing hydrogel-embedded pericytes and astrocytes. We studied NCs targeting intercellular adhesion molecule-1 (ICAM-1), a cell-surface protein overexpressed in pathology and involved in CAM-mediated transport. Brain access was validated in vivo after injection of NCs coated with anti-ICAM-1 vs. control IgG. ICAM-1 expression was verified in vitro using endothelial cells, pericytes, and astrocytes (756-, 511-, 690-fold over non-specific signal under TNF alpha). VE-cadherin presence and lack of dextran leakage demonstrated a restrictive BBB-oC barrier. Data showed endothelial targeting of anti-ICAM-1 NCs (428 NCs/cell at 1 h), uptake (60% of cell-interacting NCs), and transcytosis (90%; 24 h) downregulated by a CAM-pathway inhibitor (88% decay; 1 h). Non-transcyosed NCs trafficked to lysosomes, while transcytosed NCs interacted with pericytes and astrocytes (2643 NCs/cell; 24 h) and entered them (90% of transcytosed NCs). This BBB-oC represents a valuable model to evaluate ICAM-1-mediated transcytosis, complementing animal studies.

JTD Keywords: Blood-brain barrier, Design, Drug-delivery, Endothelial and basolateral interactions, Endothelium, Icam-1 targeting, Icam-1-targeted nanocarriers, Nanoparticles, Organ-on-a-chip, Targeted nanocarriers, Transcytosis mechanism, Transport

Pons, Miquel

JTD

Changes in the mechanical properties of the extracellular matrix (ECM) are a hallmark of disease. Due to its relevance, several in vitro models have been developed for the ECM, including cell-derived matrices (CDMs). CDMs are decellularized natural ECMs assembled by cells that closely mimic the in vivo stromal fibre organization and molecular content. Here, we applied atomic force microscopy-force spectroscopy (AFM-FS) to evaluate the nanomechanical properties of CDMs obtained from patients diagnosed with collagen VI-related congenital muscular dystrophies (COL6-RDs). COL6-RDs are a set of neuromuscular conditions caused by pathogenic variants in any of the three major COL6 genes, which result in deficiency or dysfunction of the COL6 incorporated into the ECM of connective tissues. Current diagnosis includes the genetic confirmation of the disease and categorization of the phenotype based on maximum motor ability, as no direct correlation exists between genotype and phenotype of COL6-RDs. We describe differences in the elastic modulus (E) among CDMs from patients with different clinical phenotypes, as well as the restoration of E in CDMs obtained from genetically edited cells. Results anticipate the potential of the nanomechanical analysis of CDMs as a complementary clinical tool, providing phenotypic information about COL6-RDs and their response to gene therapies.

JTD Keywords: Atomic force microscopy-based force spectroscopy, Bethlem myopathy, Cell-derived matrices, Collagen vi-related congenital muscular dystrophies, Elastic modulus, Extracellular matrix, Extracellular-matrix, Fibroblasts, Gene editin, Microenvironment, Migration, Mode, Muscle, Position, Progenitors, Stiffness

The precise mechanisms underlying the cellular response to static electric cues remain unclear, limiting the design and development of biomaterials that utilize this parameter to enhance specific biological behaviours. To gather information on this matter we have explored the interaction of collagen type-I, the most abundant mammalian extracellular protein, with poly(vinylidene fluoride) (PVDF), an electroactive polymer with great potential for tissue engineering applications. Our results reveal significant differences in collagen affinity, conformation, and interaction strength depending on the electric charge of the PVDF surface, which subsequently affects the behaviour of mesenchymal stem cells seeded on them. These findings highlight the importance of surface charge in the establishment of the material-protein interface and ultimately in the biological response to the material. The development of new tissue engineering strategies relies heavily on the understanding of how biomaterials interact with biological tissues. Although several factors drive this process and their driving principles have been identified, the relevance and mechanism by which the surface potential influences cell behaviour is still unknown. In our study, we investigate the interaction between collagen, the most abundant component of the extracellular matrix, and poly(vinylidene fluoride) with varying surface charges. Our findings reveal substantial variations in the binding forces, structure and adhesion of collagen on the different surfaces, which collectively explain the differential cellular responses. By exposing these differences, our research fills a critical knowledge gap and paves the way for innovations in material design for advanced tissue regeneration strategies. (c) 2024 Acta Materialia Inc. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

JTD Keywords: Adhesion, Atomic-force microscope, Biomaterials, Collagen, Collagen fibril, Electroactive material, Energ, Nanofibers, Osteogenic differentiation, Polyvinylidene fluoride, Pvdf, Stimuli, Surface charge, Surface coating, Systems

A deficiency in omega-3 fatty acids ( to 3 FAs) in the brain has been correlated with cognitive impairment, learning deficiencies, and behavioral changes. In this study, we provided to 3 FAs as a supplement to spontaneously hypertensive rats (SHR+ to 3). Our focus was on examining the impact of dietary supplementation on the physicochemical properties of the brain-cell membranes. Significant increases in to 3 levels in the cerebral cortex of SHR+ to 3 were observed, leading to alterations in brain lipid membranes molecular packing, elasticity, and lipid miscibility, resulting in an augmented phase disparity. Results from synthetic lipid mixtures confirmed the disordering effect introduced by to 3 lipids, showing its consequences on the hydration levels of the monolayers and the organization of the membrane domains. These findings suggest that dietary to 3 FAs influence the organization of brain membranes, providing insight into a potential mechanism for the broad effects of dietary fat on brain health and disease.

JTD Keywords: Behavio, Bilayers, Docosahexaenoic acid, Metabolism, Molecular packing, Phosphatidylcholine, Phosphatidylethanolamine, Polyunsaturated fatty-acids, Raft, Spectroscopy, Sphingomyelin

Charge exchange is the fundamental process that sustains cellular respiration and photosynthesis by shuttling electrons in a cascade of electron transfer (ET) steps between redox cofactors. While intraprotein charge exchange is well characterized in protein complexes bearing multiple redox sites, interprotein processes are less understood due to the lack of suitable experimental approaches and the dynamic nature of the interactions. Proteins constrained between electrodes are known to support electron transport (ETp) through the protein matrix even without redox cofactors, as the charges housed by the redox sites in ET are furnished by the electrodes. However, it is unknown whether protein ETp mechanisms apply to the interprotein medium present under physiological conditions. We study interprotein charge exchange between plant photosystem I (PSI) and its soluble redox partner plastocyanin (Pc) and address the role of the Pc copper center. Using electrochemical scanning tunneling spectroscopy (ECSTS) current-distance and blinking measurements, we quantify the spatial span of charge exchange between individual Pc/PSI pairs and ETp through transient Pc/PSI complexes. Pc devoid of the redox center (Pcapo) can exchange charge with PSI at longer distances than with the copper ion (Pcholo). Conductance bursts associated with Pcapo/PSI complex formation are higher than in Pcholo/PSI. Thus, copper ions are not required for long-distance Pc/PSI ETp but regulate its spatial span and conductance. Our results suggest that the redox center that carries the charge in Pc is not necessary to exchange it in interprotein ET through the aqueous solution and question the canonical view of tight complex binding between redox protein partners.

JTD Keywords: azurin, binding, blinking, crystal-structure, cupredoxin, current distance spectroscopy, electrochemical tunneling microscopy, proteinconductance, reduction, single metalloprotein, single molecule measurements, site, spectroscopy, Blinking, Cupredoxin, Current distance spectroscopy, Electrochemical tunneling microscopy, Interprotein electron transfer, Protein conductance, Single molecule measurements, State electron-transport

Lysosomes play a central role in cellular homeostasis and alterations in this compartment associate with many diseases. The most studied example is that of lysosomal storage disorders (LSDs), a group of 60 + maladies due to genetic mutations affecting lysosomal components, mostly enzymes. This leads to aberrant intracellular storage of macromolecules, altering normal cell function and causing multiorgan syndromes, often fatal within the first years of life. Several treatment modalities are available for a dozen LSDs, mostly consisting of enzyme replacement therapy (ERT) strategies. Yet, poor biodistribution to main targets such as the central nervous system, musculoskeletal tissue, and others, as well as generation of blocking antibodies and adverse effects hinder effective LSD treatment. Drug delivery systems are being studied to surmount these obstacles, including polymeric constructs and nanoparticles that consti-tute the focus of this article. We provide an overview of the formulations being tested, the diseases they aim to treat, and the results observed from respective in vitro and in vivo studies. We also discuss the advantages and disadvantages of these strategies, the remaining gaps of knowledge regarding their per-formance, and important items to consider for their clinical translation. Overall, polymeric nanocon-structs hold considerable promise to advance treatment for LSDs.(c) 2023 Elsevier B.V. All rights reserved.

JTD Keywords: cellular and animal models, enzyme replacement therapy, lysosomal storage disorders, nanoemulsions, nanoparticles, Beta-glucuronidase deficiency, Blood-brain-barrier, Cellular and animal models, Central-nervous-system, Drug delivery systems, Enzyme replacement therapy, Feline gm1 gangliosidosis, Human acid sphingomyelinase, Human alpha-galactosidase, Humans, Lysosomal storage diseases, Lysosomal storage disorders, Lysosomes, Mucopolysaccharidosis type-ii, Nanoemulsions, Nanoparticles, Neuronal ceroid-lipofuscinosis, Niemann-pick-disease, Pluripotent stem-cells, Polymer-based drug delivery systems, Polymers, Tissue distribution

The synthesis and study of the tripeptide Arg-Gly-Asp (RGD), the binding site of different extracellular matrix proteins, e.g., fibronectin and vitronectin, has allowed the production of a wide range of cell adhesive surfaces. Although the surface density and spacing of the RGD peptide at the nanoscale have already shown a significant influence on cell adhesion, the impact of its hierarchical nanostructure is still rather unexplored. Accordingly, a versatile colloidal system named quatsomes, based on fluid nanovesicles formed by the self-assembling of cholesterol and surfactant molecules, has been devised as a novel template to achieve hierarchical nanostructures of the RGD peptide. To this end, RGD was anchored on the vesicle's fluid membrane of quatsomes, and the RGD-functionalized nanovesicles were covalently anchored to planar gold surfaces, forming a state of quasi-suspension, through a long poly(ethylene glycol) (PEG) chain with a thiol termination. An underlying self-assembled monolayer (SAM) of a shorter PEG was introduced for vesicle stabilization and to avoid unspecific cell adhesion. In comparison with substrates featuring a homogeneous distribution of RGD peptides, the resulting hierarchical nanoarchitectonic dramatically enhanced cell adhesion, despite lower overall RGD molecules on the surface. The new versatile platform was thoroughly characterized using a multitechnique approach, proving its enhanced performance. These findings open new methods for the hierarchical immobilization of biomolecules on surfaces using quatsomes as a robust and novel tissue engineering strategy.

JTD Keywords: activation, arg-gly-asp (rgd), cell adhesion, extracellular-matrix, growth, integrins, ligands, nanopatterns, quatsomes, scaffolds, self-assembled monolayers, surface engineering, tissue engineering, Arg-gly-asp (rgd), Cell adhesion, Integrins, Nano-structured surfaces, Nanovesicles, Quatsomes, Self-assembled monolayers, Surface engineering, Tissue engineering

Charge separation and transport through the reaction center of photosystem I (PSI) is an essential part of the photosynthetic electron transport chain. A strategy is developed to immobilize and orient PSI complexes on gold electrodes allowing to probe the complex's electron acceptor side, the chlorophyll special pair P700. Electrochemical scanning tunneling microscopy (ECSTM) imaging and current-distance spectroscopy of single protein complex shows lateral size in agreement with its known dimensions, and a PSI apparent height that depends on the probe potential revealing a gating effect in protein conductance. In current-distance spectroscopy, it is observed that the distance-decay constant of the current between PSI and the ECSTM probe depends on the sample and probe electrode potentials. The longest charge exchange distance (lowest distance-decay constant ?) is observed at sample potential 0 mV/SSC (SSC: reference electrode silver/silver chloride) and probe potential 400 mV/SSC. These potentials correspond to hole injection into an electronic state that is available in the absence of illumination. It is proposed that a pair of tryptophan residues located at the interface between P700 and the solution and known to support the hydrophobic recognition of the PSI redox partner plastocyanin, may have an additional role as hole exchange mediator in charge transport through PSI.© 2021 Wiley-VCH GmbH.

JTD Keywords: azurin, current distance decay spectroscopy, cytochrome c(6), electrochemical scanning tunneling microscopy (ecstm), electrochemistry, photosystem i, photosystem-i, plastocyanin, protein electron transfer, recognition, single metalloprotein, single molecules, structural basis, tunneling spectroscopy, 'current, Amino acids, Charge transfer, Chlorine compounds, Chlorophyll, Current distance decay spectroscopy, Decay spectroscopies, Distance decay, Electrochemical scanning tunneling microscopy, Electrochemical scanning tunneling microscopy (ecstm), Electrodes, Electron transfer, Electron transport, Electron transport properties, Gold compounds, Kinetics, Oxidation-reduction, Photosynthesis, Photosystem i, Photosystem i protein complex, Photosystems, Protein electron transfer, Protein electron-transfer, Proteins, Scanning tunneling microscopy, Silver halides, Single molecule, Single molecules

© 2021 The Authors. Published by American Chemical Society. Lateral compartmentalization of the plasma membrane is a prominent feature present at multiple spatiotemporal scales that regulates key cellular functions. The extracellular glycocalyx matrix has recently emerged as an important player that modulates the organization of specific receptors and patterns the lipid bilayer itself. However, experimental limitations in investigating its impact on the membrane nanoscale dynamics have hampered detailed studies. Here, we used photonic nanoantenna arrays combined with fluorescence correlation spectroscopy to investigate the influence of hyaluronic acid (HA), a prominent glycosaminoglycan, on the nanoscale organization of mimetic lipid bilayers. Using atomic force microscopy and force spectroscopy, we further correlated our dynamic measurements with the morphology and mechanical properties of bilayers at the nanoscale. Overall, we find that HA has a profound effect on the dynamics, nanoscale organization, and mechanical properties of lipid bilayers that are enriched in sphingolipids and/or cholesterol, such as those present in living cells.

JTD

The purpose of this systematic study was to investigate the effects of specific substrates and potential conditions applied while tailoring the morphology and chemical composition of nanostructured Co films. In particular, Co electrodeposition in sustainable choline chloride-urea deep eutectic solvent was assessed, using glassy carbon and two metals widely employed in electrocatalysis and biocompatible purposes, Pt and Au, as substrates for modification with Co. Various in situ electrochemical techniques were combined with a broad range of ex-situ characterization and chemical-composition techniques for a detailed analysis of the prepared Co films. Among the results, nanostructured Co films with high extended active surface areas and variable composition of oxo and hydroxyl species could be tuned by simply modulating the applied potential limits, and without using additives or surfactant agents. The study highlights the effectiveness of using deep eutectic solvent as suitable electrolyte for surface modification by controlled deposition of nanostructured Co films with further application in electrocatalysis.

JTD Keywords: Cobalt electrodeposition, Deep eutectic solvent, First growth stages, Substrate influence

Lipid membranes are involved in many physiological processes like recognition, signaling, fusion or remodeling of the cell membrane or some of its internal compartments. Within the cell, they are the ultimate barrier, while maintaining the fluidity or flexibility required for a myriad of processes, including membrane protein assembly. The physical properties of in vitro model membranes as model cell membranes have been extensively studied with a variety of techniques, from classical thermodynamics to advanced modern microscopies. Here we review the nanomechanics of solid-supported lipid membranes with a focus in their phase behavior. Relevant information obtained by quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM) as complementary techniques in the nano/mesoscale interface is presented. Membrane morphological and mechanical characterization will be discussed in the framework of its phase behavior, phase transitions and coexistence, in simple and complex models, and upon the presence of cholesterol.

JTD Keywords: Lipid phase behavior, Phase transition, Phase coexistence, Nanomechanics, Thermodynamics, Atomic force microscopy (AFM), Quartz crystal microbalance with dissipation monitoring (QCM-D)