1. Name：Surface Coating Structure ａnd its Interaction with Cytochrome c in EG6 Coated Nanoparticles Varies with Surface Curvature

Authors：Clyde A. Daly, Caley R Allen, Nikita D. Rozanov, Gene Chong, Eric S Melby, Thomas R. Kuech, Samuel E. Lohse, Catherine J. Murphy, Joel A. Pedersen ａnd Rigoberto Hernandez

Journal：Langmuir

DOI: 10.1021/acs.langmuir.0c00681

Abstract：The composition, orientation, ａnd conformation of proteins in biomolecular coronas acquired by nanoparticles in biological media contribute to how they are identified by a cell. While numerous studies have investigated protein composition in biomolecular coronas, relatively little detail is known about how the nanoparticle surface influences the orientation ａnd conformation of the proteins associated with them. We previously showed that the peripheral membrane protein cytochrome c adopts preferred poses relative to negatively charged MPA-AuNPs. Here, we employ molecular dynamics simulations ａnd complementary experiments to establish that cytochrome c also assumes preferred poses upon association with nanoparticles functionalized with an uncharged ligand, ａnd specifically ω-(1-mercaptounde-11-cyl)hexa(ethylene glycol) (EG6). We find that the display of the EG6 ligands is sensitive to the curvature of the surface—and consequently, the effective diameter of the nearly spherical nanoparticle core—which in turn affects the preferred poses of cytochrome c.

Link：https://pubs.acs.org/doi/10.1021/acs.langmuir.0c00681

2. Name：Supported Lipid Bilayer Formation from Phospholipid-Fatty Acid Bicellar Mixtures

Authors：Tun Naw Sut, Soohyun Park, Bo Kyeong Yoon, Joshua A. Jackman ａnd Nam-Joon Cho

Journal：Langmuir

DOI: 10.1021/acs.langmuir.0c00675

Abstract：Supported lipid bilayers (SLBs) are versatile cell-membrane-mimicking biointerfaces for various applications such as biosensors ａnd drug delivery systems, ａnd there is broad interest in developing simple, cost-effective methods to achieve SLB fabrication. One promising approach involves the deposition of quasi-two-dimensional bicelle nanostructures that are composed of long-chain phospholipids plus either short-chain phospholipids or detergent molecules. While a variety of long-chain phospholipids have been used to prepare bicelles for SLB fabrication applications, only two short-chain phospholipids, 1,2-dihexanoyl-sn-glycero-3-phosphocholine ａnd 1,2-diheptanoyl-sn-glycero-3-phosphocholine (collectively referred to as DHPC), have been investigated. There remains an outstanding need to identify natural alternatives to DHPC, especially ones that are more affordable, to improve fabrication prospects ａnd application opportunities. Herein, we explored the potential to fabricate SLBs from bicellar mixtures composed of long-chain phospholipids ａnd lauric acid (LA), which is a low-cost, naturally abundant fatty acid that is widely used in soapmaking ａnd various industrial applications. Quartz crystal microbalance-dissipation (QCM-D) experiments were conducted to track bicelle adsorption onto silica surfaces as a function of bicelle composition ａnd lipid concentration, along with time-lapse fluorescence microscopy imaging ａnd fluorescence recovery after photobleaching (FRAP) experiments to further characterize lipid adlayer properties. The results identified optimal conditions where it is possible to efficiently form SLBs from LA-containing bicelles at low lipid concentrations while also unraveling mechanistic insights into the bicelle-mediated SLB formation process ａnd verifying that LA-containing bicelles are biocompatible with human cells for surface coating applications.

Link：https://pubs.acs.org/doi/abs/10.1021/acs.langmuir.0c00675#

3. Name：Shape ａnd Orientation of Bare Silica Particles Influence Their Deposition under Intermediate Ionic Strength: A Study with QCM–D ａnd DLVO theory

Authors：Allan Gomez-Flores, Scott A.Bradford, Gukhwa Hwang, Sowon Choi, Meiping Tong ａnd Hyunjung Kim

Journal：Colloids ａnd Surfaces A: Physicochemical ａnd Engineering Aspects

DOI: 10.1016/j.colsurfa.2020.124921

Abstract：Theory developed by Derjaguin, Landau, Verwey, ａnd Overbeek (DLVO) is commonly used to interpret ａnd predict the deposition of particles, but it was originally simplified for spherical particles. Many types of bacteria ａnd particles in nature are not spherical. Previous literature has experimentally shown that particle shape has an effect on drug delivery, retention in porous media, self − assembly, ａnd flotation, but the quantitative interpretion of these results has been hindered by experimental (e.g., uniform rod shaped particles ａnd flow fields at controlled chemistries) ａnd theoretical (e.g., consideration of rod shape particles with different surface orientations) challenges. For example, the deposition of ellipsoidal polystyrene particles has been investigated in the presence of non − DLVO interactions, due to residual poly(vinyl) alcohol, hindering the effect of shape. In our study, bare spherical ａnd bullet − like silica particles of well − defined surface chemistry were used for deposition tests on bare silica surfaces using a Quartz Crystal Microbalance with Dissipation (QCM − D) over six ionic strengths (IS). At the same time, the DLVO theory was modified to consider particle shape ａnd orientation of deposition. We found that particle shape had an effect on deposition at intermediate IS. A modified DLVO approach was able to interpret the deposition of bullet − like silica particles. Specifically, bullet − like silica particles of certain aspect ratio may find angles that minimize repulsive energies ａnd overcome energy barriers so that deposition on the silica surfaces is energetically favorable. Therefore, there are conditions of water chemistry where particle shape ａnd orientation cannot be ignored ａnd their deposition must be systematically investigated.

Link：https://www.sciencedirect.com/science/article/abs/pii/S0927775720305148

4. Name：Enhancing the Cellular Uptake ａnd Antibacterial Activity of Rifampicin through Encapsulation in Mesoporous Silica Nanoparticles

Authors：Paul Joyce, Hanna Ulmefors, Sajedeh Maghrebi, Santhni Subramaniam, Anthony Wignall, Silver Jõemetsa, Fredrik Höök ａnd Clive A. Prestidge

Journal：Nanomaterials

DOI: 10.3390/nano10040815

Abstract：An urgent demand exists for the development of novel delivery systems that efficiently transport antibacterial agents across cellular membranes for the eradication of intracellular pathogens. In this study, the clinically relevant poorly water-soluble antibiotic, rifampicin, was confined within mesoporous silica nanoparticles (MSN) to investigate their ability to serve as an efficacious nanocarrier system against small colony variants of Staphylococcus aureus (SCV S. aureus) hosted within Caco-2 cells. The surface chemistry ａnd particle size of MSN were varied through modifications during synthesis, where 40 nm particles with high silanol group densities promoted enhanced cellular uptake. Extensive biophysical analysis was performed, using quartz crystal microbalance with dissipation (QCM-D) ａnd total internal reflection fluorescence (TIRF) microscopy, to elucidate the mechanism of MSN adsorption onto semi-native supported lipid bilayers (snSLB) and, thus, uncover potential cellular uptake mechanisms of MSN into Caco-2 cells. Such studies revealed that MSN with reduced silanol group densities were prone to greater particle aggregation on snSLB, which was expected to restrict endocytosis. MSN adsorption ａnd uptake into Caco-2 cells correlated well with antibacterial efficacy against SCV S. aureus, with 40 nm hydrophilic particles triggering a ~2.5-log greater reduction in colony forming units, compared to the pure rifampicin. Thus, this study provides evidence for the potential to design silica nanocarrier systems with controlled surface chemistries that can be used to re-sensitise intracellular bacteria to antibiotics by delivering them to the site of infection.

Link：https://www.mdpi.com/2079-4991/10/4/815

5. Name：Physicochemical Characterization of Daptomycin Interaction with Negatively Charged Lipid Membranes

Authors：Joanna Juhaniewicz-Debinska, Damian Dziubak ａnd Slawomir Sek

Journal：Langmuir

DOI: 10.1021/acs.langmuir.0c00716

Abstract：Daptomycin is known as an effective antibiotic lipopeptide which shows activity against the number of Gram-positive pathogens. Its primary target is the bacterial cell membrane. However, the detailed mechanism of daptomycin action is still subject to debate. In this paper, we have investigated the interactions between lipopeptide ａnd model lipid films composed of negatively charged phosphatidylglycerols ａnd cardiolipin. In order to evaluate the effect of daptomycin on the molecular organization ａnd the properties of lipid assemblies, we have used surface pressure measurements ａnd electrochemical methods combined with atomic force microscopy, quartz crystal microbalance ａnd surface-enhanced infrared absorption spectroscopy. Our results indicate that daptomycin interaction with the lipid membrane is complex. It involves daptomycin aggregation ａnd partial insertion, which in turn affect the charge distribution on both sides of the membrane ａnd may result in a gradient of water chemical potential. The latter can drive the flux of water across the membrane.

Link：https://pubs.acs.org/doi/abs/10.1021/acs.langmuir.0c00716

6. Name：Protein interactions ａnd conformations on graphene-based materials mapped using quartz-crystal microbalance with dissipation monitoring (QCM-D)

Authors： Piramon Hampitak, Daniel Melendrez, Maria Iliut, Maryline Fresquet, Natalie Parsons, Ben Spencer, Thomas Jowitt ａnd Aravind Vijayaraghavan

Journal：Carbon

DOI: 10.1016/j.carbon.2020.04.093

Abstract：Graphene-based materials have shown significant potential for biomedical applications including biosensors, cell scaffolds ａnd drug delivery. However, the interaction of complex biomacromolecules like proteins with graphene ａnd its derivatives, graphene oxide (GO) ａnd reduced (r)GO, remains poorly understood. Here, we demonstrate that the quartz-crystal microbalance with dissipation monitoring (QCM-D) technique can be used to systematically study the interaction dynamics of a typical protein, bovine serum albumin (BSA), with graphene materials of varying degrees of functionalisation. We find significant differences in molecular orientation ａnd confirmation, mass adsorption ａnd biochemical functionality of BSA on different graphene surfaces, determined by both the population of functional groups of GO ａnd the protein concentration. The dominant forces during the adsorption of biomolecules onto GO ａnd rGO are shown to be hydrophilic ａnd hydrophobic interactions, respectively. The GO surface yielded higher BSA adsorption than both rGO ａnd control standard gold electrodes due to the high density of functional groups. The biochemical functionality of adsorbed BSA was investigated through the interaction with its anti-BSA antibody counterpart. BSA on GO can retain its binding sites while, in contrast, a denatured ad-layer of BSA forms on the rGO followed by further binding of active BSA molecules, depending on the concentration of the protein. Intermediate conformations are observed for partially-reduced GO. These results also suggest that QCM-D is a viable readout technique for graphene-based biosensors. This QCM-D approach could be further extended to study the interaction of a host of biomolecules ａnd their assemblies, including whole cells, with 2-dimensional materials.

Link：https://www.sciencedirect.com/science/article/pii/S0008622320304243

7. Name：A single-component, cross-linked, ａnd surface-grafted polyelectrolyte film fabricated by the layer-by-layer assembly method

Authors：Tao Jiang, Saeed Zajforoushan Moghaddam ａnd Esben Thormann

Journal：Polymer

DOI: 10.1016/j.carbon.2020.04.093

Abstract：In this work, we demonstrate a versatile approach for the fabrication of a single-component polyelectrolyte layer with tunable thickness ａnd functionality. Poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) was copolymerized with either aminoethyl methacrylate (AMA) or methacrylic acid (MAA) to prepare statistical PEGMEMA copolymers carrying positive or negative charges, respectively. These polyelectrolytes were used in a conventional layer-by-layer assembly process followed by cross-linking to form a surface-grafted stable poly(PEGMEMA) layer carrying both negative ａnd positive charges. To transform this layer into a single-component polyelectrolyte layer carrying just one type of ionizable group, the amino groups were quenched, thus leaving a single-component anionic PEGMEMA-based polyelectrolyte layer. Last, we demonstrate that compared to a zwitterionic layer, the anionic polyelectrolyte layer exhibits an enhanced protein-repelling property against bovine serum albumin (BSA).

Link：https://www.sciencedirect.com/science/article/abs/pii/S0032386120303566

8. Name：Interactions Between Asphaltenes ａnd a Model Demulsifier in Bulk ａnd at an Interface Studied by Small-angle Neutron Scattering (SANS) ａnd Neutron Reflectometry

Authors：Kenneth Dahl Knudsen, Sébastien Simon, Thomas Geue, Joshaniel F. K. Cooper ａnd Johan Sjoblom

Journal：Energy & Fuels

DOI: 10.1021/acs.energyfuels.9b03831

Abstract：This article describes neutron reflectometry to probe the structure of the asphaltene layer adsorbed onto a hydrophilic silicon surface ａnd the interactions between asphaltenes ａnd a model demulsifier (pluronic). To start with, asphaltene nanoaggregation is studied in bulk by Small-Angle Neutron Scattering (SANS). In pure toluene, asphaltenes form nanoaggregates with sizes that are found to moderately increase when heptane is added. Then the structure of the asphaltene layer onto a silicon surface is determined by neutron reflectometry. It is first shown that conclusive results on the structure of the adsorbed asphaltene layer can only be determined by varying the scattering length density of the solvent, i.e. by measuring reflectivity curves in various mixtures of D- ａnd H-toluene ａnd by simultaneously fitting all the datasets. The asphaltene layer can be successfully modelled using a single layer; a 2-layer models always converges with the second layer having zero thickness. This layer has a thickness of 51 Å, with a low solvation close to the silicon surface (estimated 29 %). The solvation increases with distance from the silicon oxide layer, reaching finally a value of 91 %. Small-Angle Neutron Scattering data indicate that the thickness is close to twice the radius of gyration of asphaltene nanoaggregates is solution. This result indicates that the extent of the asphaltene layer is linked to its self-associative properties in bulk. Finally, by using the results obtained by contrast matching to constrain the fitting, the influence of a model demulsifier (pluronic PE 8100) on the asphaltene layer is investigated. In presence of pluronic, the layer does not protrude as far into the bulk (thickness is reduced) ａnd becomes rougher due to the partial incorporation of pluronic.

Link：https://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.9b03831

9. Name：Photo-degradation of Porphyrin bounded hIAPP (1-37) Fibrilss

Authors：Yongxiu Song, Ping Li, Zhimin Zhang, Yin Wang, Zhefei Zhang, Lei Liu ａnd Mingdong Dong

Journal：New Journal of Chemistry

DOI: 10.1039/C9NJ06082K

Abstract：Amyloid deposits in pancreatic islets of type 2 diabetes mellitus (T2DM) is mainly comprised of human islet amyloid polypeptide (hIAPP), which is believed to be generated as a paracrine hormone along with insulin secretion. Misfolded hIAPP fibrillation aggregated in islet beta cells is associated with T2DM. To reduce the risk of T2DM, amyloid aggregates degradation for removing insoluble amyloid deposits is proved to be a preventive strategy against T2DM. However, the development of the effective approaches ａnd degradation mechanisms remain further addressed. Herein, we found tetrasodium-meso-tetra (4-sulfonatophenyl) porphyrin binding to hIAPP37 aggregates by the electrostatic interaction could enhance the degradability of hIAPP37 fibrils under photo-irradiation. The morphology change of hIAPP fibrils could be easily revealed due to the effect of photo-excited porphyrin by destabilizing β-sheet secondary structure under photo-irradiation without any additives in neutral condition. We validated that Photo-excited porphyrin induced degradation of amyloid fibrils may be attributed to reactive oxygen species, such as singlet oxygen, superoxide radicals ａnd hydroxyl radicals, etc. Moreover, the degraded products of hIAPP37 fibrils shows low cytotoxicity to INS cells. This work could be beneficial for the molecular design of novel photo-degradation agents of amyloid fibrils ａnd also expand the biomedical application of porphyrin from the photosensitization.

Link：https://pubs.rsc.org/en/Content/ArticleLanding/2020/NJ/C9NJ06082K#!divAbstract

10. Name：Optimal formation of uniform-phase supported lipid bilayers from phospholipid–monoglyceride bicellar mixtures

Authors：Tun Naw Sut, Soohyun Park, Bo Kyeong Yoon, Joshua A.Jackman, Nam-JoonCho

Journal：Journal of Industrial ａnd Engineering Chemistry

DOI: 10.1016/j.jiec.2020.04.026

Abstract：Supported lipid bilayers (SLBs) spanning hydrophilic surfaces are industrially attractive biomimetic coatings that mimic critical aspects of lipid membrane interfaces ａnd are increasingly used in applications spanning medicine, biotechnology, ａnd environmental science. The use of adsorbing bicelle lipid nanostructures composed of long- ａnd short-chain phospholipid mixtures is an effective self-assembly driven process for streamlined SLB fabrication. However, existing studies use synthetic short-chain phospholipids as a necessary bicelle component ａnd such materials are not practical for industrial applications. Herein, we investigated optimal conditions to fabricate SLBs from bicelles containing an industrially useful monoglyceride called monocaprin (MC) in place of short-chain phospholipids. The ratio of long-chain phospholipid to MC along with total lipid concentration were systematically tested. Quartz crystal microbalance-dissipation (QCM-D) ａnd time-lapse fluorescence microscopy experiments were performed to characterize bicelle adsorption onto silicon dioxide surfaces, ａnd fluorescence recovery after photobleaching (FRAP) measurements were conducted to evaluate lateral lipid diffusion within the fabricated lipid adlayers. Depending on bicelle parameters, high-quality SLB formation with uniform phase properties was achieved ａnd optimal ranges are described to ensure target performance outcomes without phase separation. Together, our findings demonstrate that MC-containing bicelles are useful tools to form high-quality SLBs suitable for surface coating ａnd biosensing applications.

Link：https://www.sciencedirect.com/science/article/pii/S1226086X20301969

11. Name：Polymer-Lipid Hybrid Membranes as a Model Platform to Drive Membrane-Cytochrome c Interaction ａnd Peroxidase-like Activity

Authors：Stefano Di Leone, Saziye Yorulmaz Avsar, Andrea Belluati, Riccardo Wehr, Cornelia G. Palivan ａnd Wolfgang P Meier

Journal：The Journal of Physical Chemistry B

DOI: 10.1021/acs.jpcb.0c02727

Abstract：Controllable attachment of proteins to material surfaces is very attractive for many applications including biosensors, bioengineered scaffolds or drug screenings. Especially, redox proteins have received considerable attention as a model system not only to understand mechanism of electron transfer in biological systems but also development of novel biosensors. However, current research attempts suffer from denaturation of the protein after its attachment to solid substrates. Here, we present how lipid, polymer ａnd hybrid membranes based on mixtures of lipids ａnd copolymers on solid support provide more favourable environment to drive selective ａnd functional attachment of a model redox protein, cytochrome c (cyt c). Polymer membranes provided chemical versatility to support covalent attachment of cyt c, whereas lipid membranes provided flexibility ａnd biocompatibility to support insertion of cyt c through its hydrophobic part. Hybrid membranes combined the most promising characteristics of both lipids ａnd polymers ａnd allow attachment of cyt c with both covalent attachment ａnd insertion driven by hydrophobic interactions. We then investigated the effect of different attachment strategies on the accessibility ａnd peroxidase like activity of cyt c, in presence of the different membranes. The real-time combination of cyt c with the planar membranes was investigated by quartz crystal microbalance with dissipation (QCM-D). It was possible to selectively drive the insertion of the cyt c into a specific lipid domain of hybrid membranes. In addition, protein accessibility ａnd its functionality were dependent on the specificity of the combination strategy: covalent conjugation of cyt c to polymer ａnd hybrid membranes promoted higher accessibility ａnd supported higher peroxidase-like activity. Taking together, the combination of biomolecules with planar membranes can be modulated such to improve the accessibility of the biomolecules ａnd their resulting functionality for development of efficient “active surfaces”.

Link：https://pubs.acs.org/doi/10.1021/acs.jpcb.0c02727

12. Name：Photosynthetic model membranes of natural plant thylakoid embedded in a patterned polymeric lipid bilayer

Authors：Takuro Yoneda, Yasushi Tanimoto, Daisuke Takagi ａnd Kenichi Morigaki

Journal：Langmuir

DOI: 10.1021/acs.langmuir.0c00613

Abstract：Thylakoid membranes in the chloroplast of plants, algae, ａnd cyanobacteria are the powerhouse of the photosynthesis capturing solar energy ａnd converting it into chemical energy. Although their structure ａnd function have been extensively studied, the intrinsically heterogeneous ａnd dynamic nature of the membrane structures are still not fully understood. Investigating native thylakoid membranes in vivo is difficult due to their small size ａnd limited external access to the chloroplast interior, while the bottom-up approaches based on model systems have been hampered by the sheer complexity of the native membrane. Here we try to fill the gap by reconstituting the whole thylakoid membrane into a patterned substrate-supported planer bilayer. A mixture of thylakoid membrane purified from spinach leaves ａnd synthetic phospholipid (DOPC) vesicles spontaneously formed a laterally continuous ａnd fluid two-dimensional (2D) membrane in the scaffold of patterned polymeric bilayer. Chlorophyll fluorescence arising from photosystem II (PSII) recovered after photobleaching, suggesting that the membrane components are laterally mobile. The reversible changes of chlorophyll fluorescence in the presence of the electron acceptors and/ or inhibitors indicated that the electron transfer activity of PSII was retained. Furthermore, we confirmed the electron transfer activity of photosystem I (PSI) by observing the generation of NADPH in the presence of water-soluble ferredoxin ａnd ferredoxin-NADP+ reductase. The lateral mobility of membrane-bound molecules ａnd the functional reconstitution of major photosystems provide evidence that our hybrid thylakoid membranes could be an excellent experimental platform to study the 2D molecular organization ａnd machinery of photosynthesis.

Link：https://pubs.acs.org/doi/abs/10.1021/acs.langmuir.0c00613

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