Unexpected increase in structural integrity caused by thermally induced dwarfism in large benthic foraminifera.

Climate change is predicted to negatively impact calcification and change the structural integrity of biogenic carbonates, influencing their protective function. We assess the impacts of warming on the morphology and crystallography of Amphistegina lobifera, an abundant benthic foraminifera species in shallow environments. Specimens from a thermally disturbed field area, mimicking future warming, are about 50% smaller compared with a control location. Differences in the position of the ν1 Raman mode of shells between the sites, which serves as a proxy for Mg content and calcification temperature, indicate that calcification is negatively impacted when temperatures are below the thermal range facilitating calcification. To test the impact of thermal stress on the Young's modulus of calcite which contributes to structural integrity, we quantify elasticity changes in large benthic foraminifera by applying atomic force microscopy to a different genus, Operculina ammonoides, cultured under optimal and high temperatures. Building on these observations of size and the sensitivity analysis for temperature-induced change in elasticity, we used finite element analysis to show that structural integrity is increased with reduced size and is largely insensitive to calcite elasticity. Our results indicate that warming-induced dwarfism creates shells that are more resistant to fracture because they are smaller.

Self-Healing Composite Coating Fabricated with a Cystamine Cross-Linked Cellulose Nanocrystal-Stabilized Pickering Emulsion.

A gelled Pickering emulsion system was fabricated by first stabilizing linseed oil droplets in water with dialdehyde cellulose nanocrystals (DACNCs) and then cross-linking with cystamine. Cross-linking of the DACNCs was shown to occur by a reaction between the amine groups on cystamine and the aldehyde groups on the CNCs, causing gelation of the nanocellulose suspension. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the cystamine-cross-linked CNCs (cysCNCs), demonstrating their presence. Transmission electron microscopy images evidenced that cross-linking between cysCNCs took place. This cross-linking was utilized in a linseed oil-in-water Pickering emulsion system, creating a novel gelled Pickering emulsion system. The rheological properties of both DACNC suspensions and nanocellulose-stabilized Pickering emulsions were monitored during the cross-linking reaction. Dynamic light scattering and confocal laser scanning microscopy (CLSM) of the Pickering emulsion before gelling imaged CNC-stabilized oil droplets along with isolated CNC rods and CNC clusters, which had not been adsorbed to the oil droplet surfaces. Atomic force microscopy imaging of the air-dried gelled Pickering emulsion also demonstrated the presence of free CNCs alongside the oil droplets and the cross-linked CNC network directly at the oil-water interface on the oil droplet surfaces. Finally, these gelled Pickering emulsions were mixed with poly(vinyl alcohol) solutions and fabricated into self-healing composite coating systems. These self-healing composite coatings were then scratched and viewed under both an optical microscope and a scanning electron microscope before and after self-healing. The linseed oil was demonstrated to leak into the scratches, healing the gap automatically and giving a practical approach for a variety of potential applications.

Multicolor Photoluminescent Carbon Dots à La Carte for Biomedical Applications.

Dual-emission fluorescence probes that provide high sensitivity are key for biomedical diagnostic applications. Nontoxic carbon dots (CDs) are an emerging alternative to traditional fluorescent probes; however, robust and reproducible synthetic strategies are still needed to access materials with controlled emission profiles and improved fluorescence quantum yields (FQYs). Herein, we report a practical and general synthetic strategy to access dual-emission CDs with FQYs as high as 0.67 and green/blue, yellow/blue, or red/blue excitation-dependent emission profiles using common starting materials such as citric acid, cysteine, and co-dopants to bias the synthetic pathway. Structural and physicochemical analysis using nuclear magnetic resonance, absorbance and fluorescence spectroscopy, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy in addition to transmission electron and atomic force microscopy (TEM and AFM) is used to elucidate the material's composition which is responsible for the unique observed photoluminescence properties. Moreover, the utility of the probes is demonstrated in the clinical setting by the synthesis of green/blue emitting antibody-CD conjugates which are used for the immunohistochemical staining of human brain tissues of glioblastoma patients, showing detection under two different emission channels.

Length-Controlled Nanofiber Micelleplexes as Efficient Nucleic Acid Delivery Vehicles.

Micelleplexes show great promise as effective polymeric delivery systems for nucleic acids. Although studies have shown that spherical micelleplexes can exhibit superior cellular transfection to polyplexes, to date there has been no report on the effects of micelleplex morphology on cellular transfection. In this work, we prepared precision, length-tunable poly(fluorenetrimethylenecarbonate)-b-poly(2-(dimethylamino)ethyl methacrylate) (PFTMC16-b-PDMAEMA131) nanofiber micelleplexes and compared their properties and transfection activity to those of the equivalent nanosphere micelleplexes and polyplexes. We studied the DNA complexation process in detail via a range of techniques including cryo-transmission electron microscopy, atomic force microscopy, dynamic light scattering, and ζ-potential measurements, thereby examining how nanofiber micelleplexes form, as well the key differences that exist compared to nanosphere micelleplexes and polyplexes in terms of DNA loading and colloidal stability. The effects of particle morphology and nanofiber length on the transfection and cell viability of U-87 MG glioblastoma cells with a luciferase plasmid were explored, revealing that short nanofiber micelleplexes (length < ca. 100 nm) were the most effective delivery vehicle examined, outperforming nanosphere micelleplexes, polyplexes, and longer nanofiber micelleplexes as well as the Lipofectamine 2000 control. This study highlights the potential importance of 1D micelleplex morphologies for achieving optimal transfection activity and provides a fundamental platform for the future development of more effective polymeric nucleic acid delivery vehicles.

Solution and interfacial self-assembly of Bacillus subtilis bacterial lipoteichoic acid (LTA): nanoclustering, and effects of Ca2+ and temperature.

Lipoteichoic acid (LTA) is a major structural and functional molecule in the Gram-positive bacteria membrane. Knowledge of LTA adsorption at interfaces and its solution self-assembly is crucial to understanding its role in bacterial adhesion and colonisation, infections and inflammations. Here, we report the self-assembly behaviour of LTA extracted from Bacillus subtilis, a Gram-positive bacterium, in an aqueous solution using cryogenic transmission electron microscopy (Cryo-TEM) and small-angle neutron scattering (SANS) and its adsorption behaviour at the solid-liquid interface using atomic force microscopy (AFM) imaging and quartz crystal microbalance with dissipation monitoring (QCM-D). The Cryo-TEM results indicated the formation of spherical LTA micelles that decreased in size on addition of calcium chloride (CaCl2), attributed to charge neutralisation and possible formation of stable Ca2+-bridges between the phosphate groups on neighbouring LTA chains. Analysis of the SANS data from the polydisperse LTA aggregates in solution using the two Lorentzian model revealed the existence of two correlation lengths, which could respectively account for the presence of LTA micelle clusters and the local structure arising from LTA intra-molecular interactions. In the presence of CaCl2, the decrease in the correlation lengths of the clusters indicated possible disruption of H-bonding by Ca2+, leading to poorer water-LTA interactions. At higher temperatures, the correlation length corresponding to the clusters increased, indicating a temperature assisted growth caused by the fluidization of micellar core and dehydration of the polar LTA chains. AFM imaging showed that adsorption of LTA aggregates at the SiO2-water interface was significantly prompted by the addition of CaCl2, also confirmed by QCM-D measurements. These unprecedented nanoscopic structural details on the morphology of LTA aggregates in solution and at the solid-liquid interface add to our fundamental understanding of its self-assembly behaviour hitherto underexplored.

Measuring the refractive index and sub-nanometre surface functionalisation of nanoparticles in suspension.

Direct measurements to determine the degree of surface coverage of nanoparticles by functional moieties are rare, with current strategies requiring a high level of expertise and expensive equipment. Here, a practical method to determine the ratio of the volume of the functionalisation layer to the particle volume based on measuring the refractive index of nanoparticles in suspension is proposed. As a proof of concept, this technique is applied to poly(methyl methacrylate) (PMMA) nanoparticles and semicrystalline carbon dots functionalised with different surface moieties, yielding refractive indices that are commensurate to those from previous literature and Mie theory. In doing so, it is demonstrated that this technique is able to optically detect differences in surface functionalisation or composition of nanometre-sized particles. This non-destructive and rapid method is well-suited for in situ industrial particle characterisation and biological applications.

Small variations in reaction conditions tune carbon dot fluorescence.

The development of robust and reproducible synthetic strategies for the production of carbon dots (CDs) with improved fluorescence quantum yields and distinct emission profiles is of great relevance given the vast range of applications of CDs. The fundamental understanding at a molecular level of their formation mechanism, chemical structure and how these parameters are correlated to their photoluminescence (PL) properties is thus essential. In this study, we describe the synthesis and structural characterization of a range of CDs with distinct physico-chemical properties. The materials were prepared under three minutes of microwave irradiation using the same common starting materials (D-glucosamine hydrochloride 1 and ethylenediamine 2) but modifying the stoichiometry of the reagents. We show that small variation in reaction conditions leads to changes in the fluorescent behaviour of the CDs, especially in the selective enhancement of overlapped fluorescence bands. Structural analysis of the different CD samples suggested different reaction pathways during the CD formation and surface passivation, with the latter step being key to the observed differences. Moreover, we demonstrate that these materials have distinct reversible response to pH changes, which we can be attribute to different behaviour towards protonation/deprotonation events of distinct emission domains present within each nanomaterial. Our results highlight the importance of understanding the reaction pathways that lead to the formation of this carbon-based nanomaterials and how this can be exploited to develop tailored materials towards specific applications.

Exploring the "Living" Growth of Block Copolymer Nanofibers from Surface-Confined Seeds by In Situ Solution-Phase Atomic Force Microscopy.

Living crystallization-driven self-assembly of polymeric and molecular amphiphiles is of growing interest as a seeded growth route to uniform 1D, 2D, and more complex micellar nanoparticles with controlled dimensions and a range of potential applications. Although most studies have been performed using colloidally stable seeds in bulk solution, growth of block copolymer (BCP) nanofibers from seeds confined to a surface is attracting increased attention. Herein, we have used atomic force microscopy (AFM) to undertake detailed studies of the growth of BCP nanofibers from immobilized seeds located on a Si surface. Through initial ex situ AFM studies and in situ AFM video analysis in solution, we determined that growth occurred in four stages, whereby an initial surface-bound growth regime transitions to surface-limited growth. As the nanofiber length increases, surface influence is diminished as the newly grown micelle segment is no longer bound to the Si substrate. Finally, a surface-independent regime occurs where nanofiber growth continues into bulk solution. In addition to the anticipated nanofiber elongation, our studies revealed occasional examples of AFM tip-induced core fragmentation. In these cases, the termini of the newly formed fragments were also active to further growth. Furthermore, unidirectional growth was detected in cases where the seed was oriented at a significant angle with respect to the surface, thereby restricting unimer access to one terminus.

Postsynthesis Self- And Coassembly of Enzymatically Produced Fluorinated Cellodextrins and Cellulose Nanocrystals.

The design of new functional materials and devices substantially relies on self-assembly of hierarchical structures. Formation of 2D platelets is known in the enzymatic synthesis of cellulose-like polymers. Here we demonstrate the feasibility of postsynthesis assembly of novel fluorinated cellodextrins. Highly ordered 2D structures of large lateral dimensions, unattainable in the polymerization process, can be formed because of postsynthesis assembly of the cellodextrins. These cellodextrins were also involved in coassembly with cellulose nanocrystals (CNCs) leading to hybrid systems. The hybrid architectures obtained depend on the content of fluorine atoms in the fluorinated cellodextrins. Monofluorinated cellodextrins coassemble with CNCs into a nanoweb, while multifluorinated cellodextrins assemble around the CNCs.

Structure, Nanomechanical Properties, and Wettability of Organized Erucamide Layers on a Polypropylene Surface.

Understanding the nanostructure and nanomechanical properties of surface layers of erucamide, in particular the molecular orientation of the outermost layer, is important to its widespread use as a slip additive in polymer materials. Extending our recent observations of nanomorphologies of erucamide layers on a hydrophilic silica substrate, here we evaluate its nanostructure on a more hydrophobic polypropylene surface. Atomic force microscopy (AFM) imaging revealed the molecular packing, thickness, and surface coverage of the erucamide layers, while peak force quantitative nanomechanical mapping (QNM) showed that erucamide reduced the adhesive response on polypropylene. Synchrotron X-ray reflectivity (XRR) was used to probe the out-of-plane structure of the surface layers. Static contact angle measurements further corroborated on the resulting wettability, also demonstrating the efficacy of erucamide physisorption in facilitating control over polypropylene surface wetting. The results show the formation of erucamide monolayers, bilayers and multilayers, depending on the concentration in the spin-cast solution. Correlation of AFM, XRR and wettability results consistently points to the molecular orientation in the outermost layer, i.e. with the erucamide tails pointing outward for the surface nanostructures with different morphologies (i.e., bilayers and multilayers). Rare occurrence of monolayers with exposed hydrophilic head groups were observed only at the lowest erucamide concentration. Compared with our previous observations on the hydrophilic surface, the erucamide surface coverage was much higher on the more hydrophobic propylene surface at similar erucamide concentrations in the spin-cast solution. Furthermore, the structure, molecular orientation and nanomechanical properties of the spin-cast erucamide multilayers atop polypropylene were also similar to those on industrially relevant polypropylene fibers coated with erucamide via blooming. These findings shed light on the nanostructural features of the erucamide surface layer underpinning its nanomechanical properties, relevant to many applications in which erucamide is commonly used as a slip additive.

Dendritic Micelles with Controlled Branching and Sensor Applications.

Although micelles derived from the solution self-assembly of amphiphilic molecules and polymers have been prepared with a wide variety of shapes, examples with well-defined branched structures have remained elusive. We describe a divergent, directed self-assembly approach to low dispersity dendritic micelles with a high degree of structural perfection and tailorable branch numbers and generations. We use block copolymer amphiphiles as precursors and a crystallization-driven seeded growth approach whereby the termini of fiber-like micelles function as branching sites. Different dendrimeric generations are accessible by adjusting the ratio of added unimers to pre-existing seed micelles where the branch positions are determined by the reduced coronal chain grafting density on the surface of the micelle crystalline core. We demonstrate the spatially defined decoration of the assemblies with emissive nanoparticles and utility of the resulting hybrids as fluorescent sensors for anions where the dendritic architecture enables ultrahigh sensitivity.

Towards a Fully Automated Scanning Probe Microscope for Biomedical Applications.

The increase in capabilities of Scanning Probe Microscopy (SPM) has resulted in a parallel increase in complexity that limits the use of this technique outside of specialised research laboratories. SPM automation could substantially expand its application domain, improve reproducibility and increase throughput. Here, we present a bottom-up design in which the combination of positioning stages, orientation, and detection of the probe produces an SPM design compatible with full automation. The resulting probe microscope achieves sub-femtonewton force sensitivity whilst preserving low mechanical drift (2.0±0.2 nm/min in-plane and 1.0±0.1 nm/min vertically). The additional integration of total internal reflection microscopy, and the straightforward operations in liquid, make this instrument configuration particularly attractive to future biomedical applications.

Exposure to hypergravity during zebrafish development alters cartilage material properties and strain distribution.

AIMS: Vertebrates have adapted to life on Earth and its constant gravitational field, which exerts load on the body and influences the structure and function of tissues. While the effects of microgravity on muscle and bone homeostasis are well described, with sarcopenia and osteoporosis observed in astronauts returning from space, the effects of shorter exposures to increased gravitational fields are less well characterized. We aimed to test how hypergravity affects early cartilage and skeletal development in a zebrafish model. METHODS: We exposed zebrafish to 3 g and 6 g hypergravity from three to five days post-fertilization, when key events in jaw cartilage morphogenesis occur. Following this exposure, we performed immunostaining along with a range of histological stains and transmission electron microscopy (TEM) to examine cartilage morphology and structure, atomic force microscopy (AFM) and nanoindentation experiments to investigate the cartilage material properties, and finite element modelling to map the pattern of strain and stress in the skeletal rudiments. RESULTS: We did not observe changes to larval growth, or morphology of cartilage or muscle. However, we observed altered mechanical properties of jaw cartilages, and in these regions we saw changes to chondrocyte morphology and extracellular matrix (ECM) composition. These areas also correspond to places where strain and stress distribution are predicted to be most different following hypergravity exposure. CONCLUSION: Our results suggest that altered mechanical loading, through hypergravity exposure, affects chondrocyte maturation and ECM components, ultimately leading to changes to cartilage structure and function. Cite this article: Bone Joint Res 2021;10(2):137-148.

Heads or tails: Nanostructure and molecular orientations in organised erucamide surface layers.

HYPOTHESIS: Despite the widespread industrial usage of erucamide as a slip additive to modify polymer surface properties, a controversy appears to have persisted regarding the nanostructure of erucamide surface layers, particularly the molecular orientation at the outermost layer. The erucamide nanostructure and molecular orientation, along with its surface coverage, hydrophobicity, and adhesive response, can be tuned by simply varying the erucamide concentration in the solution from which the spin coated layer is prepared. EXPERIMENTS: Synchrotron X-ray reflectivity (XRR) allowed a comprehensive characterisation of the out-of-plane structural parameters (e.g. molecular packing and thickness) of the erucamide layers prepared via spin coating from nonaqueous solution on silica. Complementary Atomic Force Microscopy (AFM) imaging with high lateral resolution revealed localised in-plane structures. Contact angle measurements provided information on the wettability of erucamide-coated surfaces. Peak Force Quantitative Nanomechanical Mapping (QNM) allowed a correlation between the erucamide nanostructure with the surface nanomechanical properties (i.e. adhesive response). FINDINGS: Our results reveal erucamide surface nanostructures on silica as patchy monolayers, isolated circular bilayers/rounded rectangle-like aggregates and overlapping plate-like multilayers as the erucamide concentration in the spin coating solution was varied. In all the cases, XRR and AFM results were consistent with the picture that the erucamide tails were oriented outwards. The QNM adhesion force mapping of all the observed morphologies also supported this molecular orientation at the outermost erucamide monolayer. The wettability study further confirmed this conclusion with the observed increase in the surface hydrophobicity and coverage upon increasing erucamide concentration, with the macroscopic water contact angle θ = 92.9° ± 2.9° at the highest erucamide concentration of 2 wt%.

De Novo Designed Peptide and Protein Hairpins Self-Assemble into Sheets and Nanoparticles.

The design and assembly of peptide-based materials has advanced considerably, leading to a variety of fibrous, sheet, and nanoparticle structures. A remaining challenge is to account for and control different possible supramolecular outcomes accessible to the same or similar peptide building blocks. Here a de novo peptide system is presented that forms nanoparticles or sheets depending on the strategic placement of a "disulfide pin" between two elements of secondary structure that drive self-assembly. Specifically, homodimerizing and homotrimerizing de novo coiled-coil α-helices are joined with a flexible linker to generate a series of linear peptides. The helices are pinned back-to-back, constraining them as hairpins by a disulfide bond placed either proximal or distal to the linker. Computational modeling indicates, and advanced microscopy shows, that the proximally pinned hairpins self-assemble into nanoparticles, whereas the distally pinned constructs form sheets. These peptides can be made synthetically or recombinantly to allow both chemical modifications and the introduction of whole protein cargoes as required.

Chemoenzymatic Synthesis of Fluorinated Cellodextrins Identifies a New Allomorph for Cellulose-Like Materials*.

Understanding the fine details of the self-assembly of building blocks into complex hierarchical structures represents a major challenge en route to the design and preparation of soft-matter materials with specific properties. Enzymatically synthesised cellodextrins are known to have limited water solubility beyond DP9, a point at which they self-assemble into particles resembling the antiparallel cellulose II crystalline packing. We have prepared and characterised a series of site-selectively fluorinated cellodextrins with different degrees of fluorination and substitution patterns by chemoenzymatic synthesis. Bearing in mind the potential disruption of the hydrogen-bond network of cellulose II, we have prepared and characterised a multiply 6-fluorinated cellodextrin. In addition, a series of single site-selectively fluorinated cellodextrins was synthesised to assess the structural impact upon the addition of one fluorine atom per chain. The structural characterisation of these materials at different length scales, combining advanced NMR spectroscopy and microscopy methods, showed that a 6-fluorinated donor substrate yielded multiply 6-fluorinated cellodextrin chains that assembled into particles presenting morphological and crystallinity features, and intermolecular interactions, that are unprecedented for cellulose-like materials.

Tailored self-assembled photocatalytic nanofibres for visible-light-driven hydrogen production.

The creation of efficient artificial systems that mimic natural photosynthesis represents a key current challenge. Here, we describe a high-performance recyclable photocatalytic core-shell nanofibre system that integrates a cobalt catalyst and a photosensitizer in close proximity for hydrogen production from water using visible light. The composition, microstructure and dimensions-and thereby the catalytic activity-of the nanofibres were controlled through living crystallization-driven self-assembly. In this seeded growth strategy, block copolymers with crystallizable core-forming blocks and functional coronal segments were coassembled into low-dispersity, one-dimensional architectures. Under optimized conditions, the nanofibres promote the photocatalytic production of hydrogen from water with an overall quantum yield for solar energy conversion to hydrogen gas of ~4.0% (with a turnover number of >7,000 over 5 h, a frequency of >1,400 h-1 and a H2 production rate of >0.327 µmol h-1 with 1.34 µg of catalytic polymer (that is, >244,300 µmol h-1 g-1 of catalytic polymer)).

Solid-State Donor-Acceptor Coaxial Heterojunction Nanowires via Living Crystallization-Driven Self-Assembly.

The creation of organic heterojunctions from conjugated polymers on the nanoscale has attracted recent attention as a consequence of their considerable potential in optoelectronic devices. Herein, we report proof-of-concept results on a versatile synthetic strategy to access various linearly segmented nanowire heterojunctions with controlled dimensions using the seeded growth "living crystallization-driven self-assembly" method followed by a secondary crystallization step. Specifically, we describe the creation of coaxial and also segmented coaxial B-A-B and A-B-A nanowires with a solvophilic poly(ethylene glycol) (PEG) corona, an inner crystalline core that consists of poly(di-n-hexylfluorene) (PDHF), which functions as a donor, and an outer crystalline core of poly(3-(2'-ethylhexyl)thiophene) (P3EHT), which acts as an acceptor. The latter is present either along the entire nanowire or solely in the central or terminal segments. These assemblies were created by seeded growth of two types of π-conjugated polymeric building blocks, the triblock copolymer PDHF-b-P3EHT-b-PEG and the diblock copolymer PDHF-b-PEG, by using fiber-like seeds derived from either material. The nanowires with both solid-state donor and acceptor blocks exhibit Förster resonance energy transfer (FRET) from the PDHF inner core to the P3EHT outer core which was characterized by fluorescence spectroscopy and laser confocal scanning fluorescence microscopy (LCSM). The FRET in the solid-state coaxial heterojunctions with an inner PDHF core and an outer P3EHT core was enhanced relative to the directly analogous system in which the P3EHT block was solvated.

Multiscale characterisation of single synthetic fibres: Surface morphology and nanomechanical properties.

HYPOTHESIS: Thermal through-air bonding process and slip additive treatment affect fibre surface structure and nanomechanical properties, which is extremely difficult to characterise on a single-fibre level. EXPERIMENTS: Optical microscopy (OM) was applied to study the effect of air-through bonding, spunbonding, and crimping on fibre geometry and general appearance. A "spray-on" method developed here using a custom-designed fibre holder allowed a direct measurement of static contact angles of water droplets on single fibres. Scanning electron microscopy (SEM) showed different morphological features on the fibre due to the nonwoven fabric-making process and additive treatment. Synchrotron X-ray diffraction (XRD) was applied to study the effect of erucamide presence on polypropylene (PP) fibre crystal structure. Atomic force microscopy (AFM) imaging provided complementary characterization of fibre topographic features such as average surface roughness, along with adhesion force mapping by quantitative nanomechanical (QNM) AFM imaging. FINDINGS: Our results show the effect of nonwoven making process and surfactant additive treatment on the fibre surface structure and nanomechanical properties. Wettability experiment on the single fibre revealed the hydrophobic nature of all the synthetic fibres. For polyethylene/polyethylene terephthalate (PE/PET) bicomponent single fibres, the polyethylene sheath was found to possess fibrillar microstructure - typical for drawn fibres, whereas the fibres entangled in nonwoven fabrics exhibited a uniform, porous surface morphology attributed to the through-air process. Adhesion force mapping allowed us to correlate fibre nanomechanical properties with its topography, with surface pore interiors showing higher adhesion than the flat polyethylene region. Furthermore, on the polypropylene (PP) fibre surface treated with erucamide (13-cis-docosenamide; a common slip additive used in polyolefin film processing), we observed overlapping multilayers consisting of 4 nm erucamide bilayers, attributed to the slip additive migration onto the fibre surface. XRD measurements of the fibres did not detect the presence of erucamide; however, AFM imaging provided evidence for its migration to the fibre surface, imparting influence on the surface structure and adhesive properties of the fibre. Single-fibre AFM imaging also allowed a detailed analysis of different surface roughness parameters, revealing that both through-air bonding in the nonwoven making process and the slip additive (erucamide) treatment affected the fibre surface roughness. The wettability, surface morphology, and adhesion properties from this study, obtained with unprecedented resolution and details on single fibres, are valuable to informing rational design of fibre processing for fibre optimal properties, critically important in many industrial applications.

Uniform Biodegradable Fiber-Like Micelles and Block Comicelles via "Living" Crystallization-Driven Self-Assembly of Poly(l-lactide) Block Copolymers: The Importance of Reducing Unimer Self-Nucleation via Hydrogen Bond Disruption.

Fiber-like micelles based on biodegradable and biocompatible polymers exhibit considerable promise for applications in nanomedicine, but until recently no convenient methods were available to prepare samples with uniform and controllable dimensions and spatial control of functionality. "Living" crystallization-driven self-assembly (CDSA) is a seeded growth method of growing importance for the preparation of uniform 1D and 2D core-shell nanoparticles from a range of crystallizable polymeric amphiphiles. However, in the case of poly(l-lactide) (PLLA), arguably the most widely utilized biodegradable polymer as the crystallizable core-forming block, the controlled formation of uniform fiber-like structures over a substantial range of lengths by "living" CDSA has been a major challenge. Herein, we demonstrate that via simple modulation of the solvent conditions via the addition of trifluoroethanol (TFE), DMSO, DMF and acetone, uniform fiber-like nanoparticles from PLLA diblock copolymers with controlled lengths up to 1 µm can be prepared. The probable mechanism involves improved unimer solvation by a reduction of hydrogen bonding interactions among PLLA chains. We provide evidence that this minimizes undesirable unimer aggregation which otherwise favors self-nucleation that competes with epitaxial crystallization from seed termini. This approach has also allowed the formation of well-defined segmented block comicelles with PLLA cores via the sequential seeded-growth of PLLA block copolymers with different corona-forming blocks.