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Hierarchical self-assemblies suggest routes for emerging structural complexities of soft matter towards multifunctional behaviors, however, involving challenges to design the balanced competing attractive and repulsive interactions required for the different length scales. Herein, self-assembly of zwitterionic amphiphiles were explored in the solvent-free state, where especially bis-n-tetradecylphosphobetaine shows temperature-driven reversible transition from low-temperature molecular-scale self-assemblies to high-temperature hierarchical self-assembly, combining colloidal and molecular order. The colloidal order results from layered molecular packing to 2D-nanoplatelets, which form well-defined oblique self-assemblies in several nanometer periodicity, allowing viscous fluidity upon shearing. The colloidal-scale structure emerges due to packing frustration between the tightly packed zwitterionic moieties and alkyl chains, and can be relieved by plasticizing with ionic liquids for purely smectic-A liquid crystallinity. Thus, even molecules with seemingly simple chemical structure can lead to structural hierarchy and tunable complexity by balancing the competing long-range electrostatics and short-range nanosegregations.

Optical fibers are a key component in modern photonics, where conventionally used polymer materials are derived from fossil-based resources, causing heavy greenhouse emissions and raising sustainability concerns. As a potential alternative, fibers derived from cellulose-based materials offer renewability, biocompatibility, and biodegradability. In the present work, we studied the potential of carboxymethyl cellulose (CMC) to prepare optical fibers with a core-only architecture. Wet-spun CMC hydrogel filaments were cross-linked using aluminum ions to fabricate optical fibers. The transmission spectra of fibers suggest that the light transmission window for cladding-free CMC fibers was in the range of 550–1350 nm, wherein the attenuation coefficient for CMC fibers was measured to be 1.6 dB·cm–1 at 637 nm. CMC optical fibers were successfully applied in touch sensing and respiratory rate monitoring. Finally, as a proof-of-concept, we demonstrate high-speed (150 Mbit/s) short-distance signal transmission using CMC fibers (at 1310 nm) in both air and water media. Our results establish the potential of carboxymethyl cellulose-based biocompatible optical fibers for highly demanding advanced sensor applications, such as in the biomedical domain. publishedVersion

Unlike classic synthetic stimulus-responsive and shape-memory materials, which remain limited to fixed responses, the responses of living systems dynamically adapt based on the repetition, intensity, and history of stimuli. Such plasticity is ubiquitous in biology, which is profoundly linked to memory and learning. Concepts thereof are searched for rudimentary forms of "intelligent materials." Here, we show plasticity of electroconductivity in soft ferromagnetic nickel colloidal supraparticles with spiny surfaces, assembling/disassembling to granular conducting micropillars between two electrodes driven by magnetic field

Cellulose is a new promising candidate for biodegradable optical fiber material for sensing applications. Cellulose-based optical fibers have features like fast wetting and drying that commercial glass optical fiber and polymer optical fibers does not have. We have recently demonstrated three different types of fibers viz., regenerated cellulose, methylcellulose and carboxymethyl cellulose. These fibers have attenuations in the range of 1.5-6 dB/cm, the transmission spectrum between 500-1400 nm and diameter 300 μm. More importantly, it is possible to transmit 150 Mbit/s signals using a few centimeters of fibers. The optical performances have been tested in water, humidity, touch, and respiratory rate applications.

openaire: EC/H2020/742829/EU//DRIVEN Funding Information: Dr. Hua Jiang is acknowledged for his assistance in TEM characterization. This work was supported by ERC (Advanced Grant DRIVEN, No. 742829), the Academy of Finland (No. 310799, 321443, 13332370 and 328942). This work was carried out under the Academy of Finland Center of Excellence Program (2022–2029) in Life‐Inspired Hybrid Materials (LIBER) (project numbers 346108 and 346109). The facilities and technical support provided by Aalto University Nanomicroscopy Center (Aalto‐NMC), and computing time from CSC‐IT Center for Science are gratefully acknowledged. Publisher Copyright: © 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH. Fluorescent supraparticles of gold, silver and copper nanoclusters are synthesized by simply drying of invert emulsions, resulting in a dozen-fold increase in photoluminescence quantum yield (up to ≈80 %) and a significant improvement in photostability. The inhibition of the ligand twisting during the intramolecular charge transfer is found to be responsible for the enhancement, especially for the gold nanocluster supraparticles. This research provides a general, flexible, and easy method for producing highly luminescent and photostable metal nanocluster-based materials that promise practical applications in white-light-emitting diodes.

International audience; The behavior of nanoparticles in solution is largely dominated by their shape and interaction potential. Despite considerable progress in the preparation of patchy and compartmentalized particles, access to nanoparticles with complex surface patterns and topographies remains limited. Here, we show that polyanionic brushes tethered to rod-like cellulose nanocrystals (CNCs) spontaneously develop a striped or helical topography through interpolyelectrolyte complexation with polycationic diblock copolymers. Using cryogenic transmission electron microscopy (cryo-TEM) and tomography (cryo-ET), we follow the complexation process and analyze the delicate 3D topography on the CNC surface. The described approach is facile and modular and can be extended to other block chemistries, nanoparticles, and surfaces, thereby providing a versatile platform toward surface-patterned particles with complex topographies and spatially arranged functional groups.

openaire: EC/FP7/291364/EU//MIMEFUN Biological structural materials offer fascinating models how to synergistically increase the solid-state defect tolerance, toughness, and strength using nanocomposite structures by incorporating different levels of supramolecular sacrificial bonds to dissipate fracture energy. Inspired thereof, we show how to turn a commodity acrylate polymer, characteristically showing a brittle solid state fracture, to become defect tolerant manifesting noncatastrophic crack propagation by incorporation of different levels of fracture energy dissipating supramolecular interactions. Therein, poly(2-hydroxyethyl methacrylate) (pHEMA) is a feasible model polymer showing brittle solid state fracture in spite of a high maximum strain and clear yielding, where the weak hydroxyl group mediated hydrogen bonds do not suffice to dissipate fracture energy. We provide the next level stronger supramolecular interactions toward solid-state networks by postfunctionalizing a minor part of the HEMA repeat units using 2-ureido-4[1H]-pyrimidinone (UPy), capable of forming four strong parallel hydrogen bonds. Interestingly, such a polymer, denoted here as p(HEMA-co-UPyMA), shows toughening by suppressed catastrophic crack propagation, even if the strength and stiffness are synergistically increased. At the still higher hierarchical level, colloidal level cross-linking using oxidized carbon nanotubes with hydrogen bonding surface decorations, including UPy, COOH, and OH groups, leads to further increased stiffness and ultimate strength, still leading to suppressed catastrophic crack propagation. The findings suggest to incorporate a hierarchy of supramolecular groups of different interactions strengths upon pursuing toward biomimetic toughening.

Layered nanomaterials fascinate researchers for their mechanical, barrier, optical, and transport properties. Nacre is a biological example thereof, combining excellent mechanical properties by aligned submicron inorganic platelets and nanoscale proteinic interlayers. Mimicking nacre with advanced nanosheets requires ultraconfined organic layers aimed at nacre-like high reinforcement fractions. We describe inorganic/polymer hybrid Bragg stacks with one or two fluorohectorite clay layers alternating with one or two poly(ethylene glycol) layers. As indicated by X-ray diffraction, perfect one-dimensional crystallinity allows for homogeneous single-phase materials with up to a 84% clay volume fraction. Brillouin light spectroscopy allows the exploration of ultimate mechanical moduli without disturbance by flaws, suggesting an unprecedentedly high Young's modulus of 162 GPa along the aligned clays, indicating almost ideal reinforcement under these conditions. Importantly, low heat conductivity is observed across films, κ

Cellulose materials offer new biodegradable alternatives for fabricating optical fibers for sensing applications. Unlike glass and polymer optical fibers, these environmentally friendly materials have intrinsic properties making them attractive candidates for functional optical fibers. Cellulose fibers are hygroscopic and thus can rapidly take water vapors from the surroundings and dry quickly. Cellulose-based optical fibers can be manufactured from regenerated cellulose or cellulose derivatives which offer a large property space. They can be resistant or soluble in water, and the refracting index of the material can be tuned as needed. In this work, feasibility for sensor applications of three different cellulose optical fibers have been tested: regenerated cellulose for water and humidity sensing, carboxymethyl cellulose for respiratory rate monitoring, and methylcellulose for short-range 150 Mbit/s signal transmission at 1310 nm. Therefore, fast signal transmission can be achieved with short cellulose-based sensor fibers. The work shows the scientific and technical potential of a novel optical material for photonics. acceptedVersion

We show ionically cross-linked, temperature-responsive reversible or irreversible hydrogels of anionic cellulose nanocrystals (CNCs) and methacrylate terpolymers by mixing them homogeneously in the initially charge-neutral state of the polymer, which was subsequently switched to be cationic by cleaving side groups by UV irradiation. The polymer is a random terpolymer poly(di(ethylene glycol) methyl ether methacrylate)-rnd-poly(oligo(ethylene glycol) methyl ether methacrylate)-rnd-poly(2-((2-nitrobenzyl)oxycarbonyl)aminoethyl methacrylate), that is, PDEGMA-rnd-POEGMA-rnd-PNBOCAEMA. The PDEGMA and POEGMA repeating units lead to a lower critical solution temperature (LCST) behavior. Initially, homogeneous aqueous mixtures are obtained with CNCs, and no gelation is observed even upon heating to 60 °C. However, upon UV irradiation, the NBOCAEMAs are transformed to cationic 2-aminoethyl methacrylate (AEMA) groups, as 2-nitrobenzaldehyde moieties are cleaved. The resulting mixtures of anionic CNC and cationic PDEGMA-rnd-POEGMA-rnd-PAEMA show gelation for sufficiently high polymer fractions upon heating to 60 °C due to the interplay of ionic interactions and LCST. For short heating times, the gelation is thermoreversible, whereas for long enough heating times, irreversible gels can be obtained, indicating importance of kinetic aspects. The ionic nature of the cross-linking is directly shown by adding NaCl, which leads to gel melting. In conclusion, the optical triggering of the polymer ionic interactions in combination with its LCST phase behavior allows a new way for ionic nanocellulose hydrogel assemblies.

Summary Responsive and shape-memory materials allow stimuli-driven switching between fixed states. However, their behavior remains unchanged under repeated stimuli exposure, i.e., their properties do not evolve. By contrast, biological materials allow learning in response to past experiences. Classical conditioning is an elementary form of associative learning, which inspires us to explore simplified routes even for inanimate materials to respond to new, initially neutral stimuli. Here, we demonstrate that soft actuators composed of thermoresponsive liquid crystal networks “learn” to respond to light upon a conditioning process where light is associated with heating. We apply the concept to soft microrobotics, demonstrating a locomotive system that “learns to walk” under periodic light stimulus, and gripping devices able to “recognize” irradiation colors. We anticipate that actuators that algorithmically emulate elementary aspects of associative learning and whose sensitivity to new stimuli can be conditioned depending on past experiences may provide new routes toward adaptive, autonomous soft microrobotics., Graphical Abstract, Highlights • A synthetic material that emulates algorithmically associative learning is disclosed • The present material learns to respond to an initially neutral stimulus by bending • A soft thermoresponsive strip can be conditioned to walk upon irradiation • Gripping devices can be conditioned to differentiate irradiation colors, Progress and Potential As described by Eric R. Kandel in his Nobel lecture, habituation, sensitization, and classical conditioning are the elementary forms of biological learning, which involves prohibitive complexity. Trying to capture even the slightest elements thereof in artificial materials is a grand challenge. We demonstrate soft actuators based on liquid crystal networks that show programmed associative learning behavior, inspired by the classical conditioning experiments on dogs. The thermoresponsive network evolves to respond to light upon conditioning, whereby the initially neutral light stimulus is applied together with heating. The conditioned actuator enables soft robotic devices that “learn” to translocate, or grippers that can be conditioned to differentiate irradiation colors. A modular artificial dog is also demonstrated that salivates upon a neutral stimulus. These findings suggest generalization from association of stimuli to soft systems that evolve depending on their history., Aiming toward bioinspired materials whose responsivity evolves depending on their history, we disclose programmable liquid crystal polymer networks that “learn” to respond to an initially neutral stimulus (light) after association with an intrinsically effective stimulus (heating). The concept is inspired by the Pavlovian conditioning and enables soft robots that learn to walk, grippers that recognize different irradiation colors, and an artificial Pavlov's dog. This is a step toward actuators that algorithmically mimic elementary aspects of learning.

Description, Electrically driven dissipative gradients of superparamagnetic nanoparticles allow voltage-controlled magnetism and patterns., It has been recognized that driving matter to nonequilibrium states can lead to emergent behaviors and functionalities. Here, we show that uniform colloidal dispersions can be driven into dissipative nonuniform states with emerging behaviors. We experimentally demonstrate this with electrically driven weakly charged superparamagnetic iron oxide nanoparticles in a nonpolar solvent. The driving leads to formation of nonequilibrium concentration gradients that further translate to nonequilibrium magnetism, including voltage-controlled magnetization and susceptibility. The concentration gradients also serve as diffuse interfaces that respond to external magnetic fields, leading to novel dissipative patterns. We identify the closest nondissipative analogs, discuss the differences, and highlight the ability to directly quantify the dissipation and link it to the pattern formation. Beyond voltage-controlled magnetism, we foresee that the concept can be generalized to other functional colloids to create, e.g., optical, electrical, catalytic, and mechanical responses that are not possible in thermodynamic equilibrium.

Funding Information: This work was carried out under the ERC Advanced grant (DRIVEN, ERC‐2016‐AdG‐742829), Academy of Finland's Centre of Excellence in Life‐Inspired Hybrid Materials (LIBER, 346108), Academy of Finland (No. 321443, 328942, 308647, and 318891) and Photonic Research and Innovation (PREIN) as well as FinnCERES flagships. L.F. and X.C. thanks for support from CSC (IT Center for Science, Finland) for providing computation resources. The authors acknowledge the provision of facilities and technical support by Aalto University OtaNano – Nanomicroscopy Center (Aalto‐NMC). | openaire: EC/H2020/742829/EU//DRIVEN Ultra-small luminescent gold nanoclusters (AuNCs) have gained substantial interest owing to their low photobleaching and high biocompatibility. While the substitution of silver for gold at the central core of AuNCs has shown significant augmentation of photoluminescence with enhanced photostability, selective replacement of the central atom by silver is, however, energetically inhibited. Herein, a new strategy for in situ site-selective Ag-doping exclusively at the central core of AuNCs using sulphated colloidal surfaces as the templates is presented. This approach exceedingly improves the photoluminescence quantum efficiency of AuNCs by eliminating nonradiative losses in the multi-step relaxation cascade populating the emissive state. Density functional theory predicts the mechanism of specific doping at the central core, endorsing the preferential bonding between Ag+ ions and sulphates in water. Finally, the generic nature of the templating concept to allow core-specific doping of nanoclusters is unraveled.

openaire: EC/H2020/834742/EU//ATOP | openaire: EC/H2020/742829/EU//DRIVEN Because of their lightweight structure, flexibility, and immunity to electromagnetic interference, polymer optical fibers (POFs) are used in numerous short-distance applications. Notably, the incorporation of luminescent nanomaterials in POFs offers optical amplification and sensing for advanced nanophotonics. However, conventional POFs suffer from nonsustainable components and processes. Furthermore, the traditionally used luminescent nanomaterials undergo photobleaching, oxidation, and they can be cytotoxic. Therefore, biopolymer-based optical fibers containing nontoxic luminescent nanomaterials are needed, with efficient and environmentally acceptable extrusion methods. Here, such an approach for fibers wet-spun from aqueous methylcellulose (MC) dispersions under ambient conditions is demonstrated. Further, the addition of either luminescent gold nanoclusters, rod-like cellulose nanocrystals or gold nanocluster-cellulose nanocrystal hybrids into the MC matrix furnishes strong and ductile composite fibers. Using cutback attenuation measurement, it is shown that the resulting fibers can act as short-distance optical fibers with a propagation loss as low as 1.47 dB cm−1. The optical performance is on par with or even better than some of the previously reported biopolymeric optical fibers. The combination of excellent mechanical properties (Young's modulus and maximum strain values up to 8.4 GPa and 52%, respectively), low attenuation coefficient, and high photostability makes the MC-based composite fibers excellent candidates for multifunctional optical fibers and sensors.

Methylcellulose/cellulose nanocrystal (MC/CNC) nanocomposite fibers showing high ductility and high modulus of toughness were prepared by a simple aqueous wet-spinning from corresponding nanocomposite hydrogels into ethanol coagulation bath followed by drying. The hydrogel MC aq. concentration was maintained at 1 wt-% while the CNC aq. loading was systematically varied in the range 0 - 3 wt-%. This approach resulted in MC/CNC fiber compositions from 25/75 wt-%/wt-% to 95/5 wt-%/wt-%. The optimal mechanical properties were achieved with the MC/CNC composition of 80/20 wt-%/wt-% allowing high strain (36.1 %) and modulus of toughness (48.3 MJ/m^3), still keeping a high strength (190 MPa). Further, we demonstrate that the continuous spinning of MC/CNC fibers is potentially possible. The results indicate possibilities to spin MC-based highly ductile composite fibers from environmentally benign aqueous solvents., 1 scheme, 7 figures, 1 table

openaire: EC/H2020/742829/EU//DRIVEN In the effort toward sustainable advanced functional materials, nanocelluloses have attracted extensive recent attention. Nanocelluloses range from rod-like highly crystalline cellulose nanocrystals to longer and more entangled cellulose nanofibers, earlier denoted also as microfibrillated celluloses and bacterial cellulose. In recent years, they have spurred research toward a wide range of applications, ranging from nanocomposites, viscosity modifiers, films, barrier layers, fibers, structural color, gels, aerogels and foams, and energy applications, until filtering membranes, to name a few. Still, nanocelluloses continue to show surprisingly high challenges to master their interactions and tailorability to allow well-controlled assemblies for functional materials. Rather than trying to review the already extensive nanocellulose literature at large, here selected aspects of the recent progress are the focus. Water interactions, which are central for processing for the functional properties, are discussed first. Then advanced hybrid gels toward (multi)stimuli responses, shape-memory materials, self-healing, adhesion and gluing, biological scaffolding, and forensic applications are discussed. Finally, composite fibers are discussed, as well as nanocellulose as a strategy for improvement of photosynthesis-based chemicals production. In summary, selected perspectives toward new directions for sustainable high-tech functional materials science based on nanocelluloses are described.

Nanorods consisting of a polystyrene core and a poly(4-vinylpyridine) shell produced via the self-assembly route of comb-shaped supramolecules exhibit very poor mechanical properties. Adding a sufficient amount of poly(2,6-dimethyl-1,4-diphenyl oxide) introduces entanglements to the PS-core resulting in nanorods with much better properties, which can be used as templates for e.g. transition metal oxide tubes.

Nanocellulose-based materials and nanocomposites show extraordinary mechanical properties with high stiffness, strength, and toughness. Although the last decade has witnessed great progress in understanding the mechanical properties of these materials, a crucial challenge is to identify pathways to introduce high wet strength, which is a critical parameter for commercial applications. Because of the waterborne fabrication methods, nanocellulose-based materials are prone to swelling by both adsorption of moist air or liquid water. Unfortunately, there is currently no best practice on how to take the swelling into account when reporting mechanical properties at different relative humidity or when measuring the mechanical properties of fully hydrated materials. This limits and in parts fully prevents comparisons between different studies. We review current approaches and propose a best practice for measuring and reporting mechanical properties of wet nanocellulose-based materials, highlighting the importance of swelling and the correlation between mechanical properties and volume expansion.

openaire: EC/H2020/788489/EU//BioELCell | openaire: EC/H2020/742829/EU//DRIVEN We introduce chitin nanofibers, nanochitin (ChNF), the cationic groups of which electrostatically complex in aqueous media with the anionic groups of a polyanion, seaweed alginate (SA). This allows the formation of continuous microfibers after drawing contacting suspensions. We elucidate the effect of the nanofiber aspect ratio (15, 25, and >60) on the mechanical performance of the composite microfibers after considering variables such as concentration, pH, and drawing rate. An automatic collector facilitated a constant spinning velocity of 30 mm/s upon interfacial complexation from aqueous media (using 0.3 to 1 wt % as mass fraction for each component and a pH between 4 and 7). The composite microfibers showed a core-shell structure in which ChNFs were preferentially axially aligned in the center and more randomly oriented in the shell. The degree of ChNF alignment in the core increased with the aspect ratio, as resolved by WAXS diffractograms. Consequently, ChNF with the largest aspect ratio (>60) was readily spun into microfibers that displayed the highest Young's modulus (4.5 GPa), almost double that measured for the shortest ChNF. The latter, however, presented the highest strain and flexibility and allowed continuous fiber spinning. Distinctively, tensile tests revealed mechanically stable microfibers even in wet conditions, with a strength loss of less than 50% and strain gains of up to 35%. The amino and carboxyl groups in the microfibers offer possibilities for functionalization, expanding their potential beyond that related to wound healing and antibacterial applications. Overall, we provide a new perspective toward dry spinning via interfacial complexation of biobased components and the effect of a particle's morphology on the detailed structuring of microfibers, which display a particular assembly that is discussed here for the first time.

The title of our recent paper should be corrected. The title should be changed from "Marcromolecular Architecture and Encapsulation of the Anticancer Drug Everolimus Control the Self-Assembly of Amphiphilic Polypeptide-Containing Hybrids" to "Macromolecular Architecture and Encapsulation of the Anticancer Drug Everolimus Control the Self-Assembly of Amphiphilic Polypeptide-Containing Hybrids". The Supporting Information was also changed to account for the correction of the title. © 2019 American Chemical Society. All rights reserved.

The availability of microbially-safe drinking water is a challenge in many developing regions. Due to the well-known antibacterial effect of silver ions, materials used for their controlled release have been widely studied for point-of-use water disinfection. However, even if it is in principle known that chloride anions can suppress the antibacterial efficiency of silver, the majority of previous studies, surprisingly, have not focused on chloride concentrations relevant for freshwaters and thus for practical applications. Here, we prepared low-cost nanocellulose-aluminium oxyhydroxide nanocomposites functionalized with silver nanoparticles. Field samples obtained from Chennai, India were used as a guideline for choosing relevant chloride concentrations for the antibacterial studies, i.e., 10, 90, and 290 ppm. The antibacterial performance of the material against Escherichia coli and Bacillus subtilis was demonstrated and the influence of chloride concentration on the antibacterial effect was studied with E.coli. A 1 h contact time led to bacterial reductions of 5.6 log10, 2.9 log10, and 2.2 log10, respectively. This indicates that an increase of chloride concentration leads to a substantial reduction of antibacterial efficiency, even within chloride concentrations found in freshwaters. This work enables further insights for designing freshwater purification systems that utilize silver-releasing materials.

Macromolecular architecture plays an important role in the self-assembly process of block copolymer amphiphiles. Herein, two series of stimuli-responsive amphiphilic 3-miktoarm star hybrid terpolypeptides and their corresponding linear analogues were synthesized exhibiting the same overall composition and molecular weight but different macromolecular architecture. The macromolecular architecture was found to be a key parameter in defining the morphology of the nanostructures formed in aqueous solutions as well as to alter the self-assembly behavior of the polymers independently of their composition. In addition, it was found that the assemblies prepared from the star-shaped polymers showed superior tolerance against enzymatic degradation due to the increased corona block density on the outer surface of the nanoparticles. Encapsulation of the hydrophobic anticancer drug Everolimus resulted in the formation of intriguing non-spherical and non-symmetric pH-responsive nanostructures, such as "stomatocytes" and "multi-compartmentalized suprapolymersomes", while the pH-triggered release of the drug was also investigated. Owing to the similarities of the developed "stomatocytes" with red blood cells, in combination with their pH-responsiveness and superior stability over enzymatic degradation, they are expected to present advanced drug delivery properties and have the ability to bypass several extra- and intracellular barriers to reach and effectively treat cancer cells.

ACS Macro Letters 7(3), 318-323 (2018). doi:10.1021/acsmacrolett.8b00023, Published by ACS, Washington, DC

Cellulose is a natural biomaterial harvested from regrowing resources and it is one of the most attractive components for the construction of functional materials with low adverse ecological impact. Among various nanocelluloses, cellulose nanocrystals (CNC) are rod-like nanoparticles whose high crystallinity and stiffness make them viable candidates for templating materials. We report here on CNC-based polymer brushes used as templates for the synthesis of porous inorganic nanorods with tunable diameters and aspect ratios. The CNC were modified with initiation sites for surface-initiated polymerisation (SI-ATRP) to act as a backbone for the grafting of poly(2-(dimethyl amino)ethyl methacrylate) (PDMAEMA) brushes. Controlled polymerisation conditions allowed for adjusting the brush length and consequently the morphology of the hybrid nanomaterials. The PDMAEMA brush served as coordination and nucleation sites for the mineralisation of tetramethyl orthosilicate (TMOS) into SiO2@CNC-g-PDMAEMA hybrids. After calcination, microscopy and N2-sorption measurements revealed hollow silica nanorods with accessible micro- and meso-pores. We foresee that this strategy can be adapted to other nanocelluloses to create high-aspect ratio porous silica nanotubes, or to achieve uniform depositions in the mineralisation of other inorganic metals or metal oxide compounds.

openaire: EC/H2020/742829/EU//DRIVEN We show that composite hydrogels comprising methyl cellulose (MC) and cellulose nanocrystal (CNC) colloidal rods display a reversible and enhanced rheological storage modulus and optical birefringence upon heating, i.e., inverse thermoreversibility. Dynamic rheology, quantitative polarized optical microscopy, isothermal titration calorimetry (ITC), circular dichroism (CD), and scanning and transmission electron microscopy (SEM and TEM) were used for characterization. The concentration of CNCs in aqueous media was varied up to 3.5 wt % (i.e, keeping the concentration below the critical aq concentration) while maintaining the MC aq concentration at 1.0 wt %. At 20 °C, MC/CNC underwent gelation upon passing the CNC concentration of 1.5 wt %. At this point, the storage modulus (G′) reached a plateau, and the birefringence underwent a stepwise increase, thus suggesting a percolative phenomenon. The storage modulus (G′) of the composite gels was an order of magnitude higher at 60 °C compared to that at 20 °C. ITC results suggested that, at 60 °C, the CNC rods were entropically driven to interact with MC chains, which according to recent studies collapse at this temperature into ring-like, colloidal-scale persistent fibrils with hollow cross-sections. Consequently, the tendency of the MC to form more persistent aggregates promotes the interactions between the CNC chiral aggregates towards enhanced storage modulus and birefringence. At room temperature, ITC shows enthalpic binding between CNCs and MC with the latter comprising aqueous, molecularly dispersed polymer chains that lead to looser and less birefringent material. TEM, SEM, and CD indicate CNC chiral fragments within a MC/CNC composite gel. Thus, MC/CNC hybrid networks offer materials with tunable rheological properties and access to liquid crystalline properties at low CNC concentrations.

Three-dimensional ex vivo cultures from patient-derived tumor tissue offer new opportunities for drug development and personalized treatment of cancer. However, one of the main challenges in establishing a tumor type faithful ex vivo tissue culture system is in optimization of biochemical and physical microenvironment to preserve desired phenotypic features. A collaboration with the Helsinki University Hospital enables us to receive live patient-derived breast cancer tissue samples from most breast cancer surgeries performed in the Southern Finland, typically samples arriving twice a week. Together with a group of materials scientists from Aalto Technical University we have explored seven different 3D culture matrices and defined their biomechanical properties and stiffness values with rheological measurements. Four investigated matrices preserved the luminal CK8+ cell phenotype of the luminal cancers they derived from, whereas rest of the matrices that included commonly used Matrigel and collagen scaffolds promoted a switch in the cell identity from luminal CK8+ to basal CK14+ phenotype. Furthermore, the genetic expression profiles examined with NGS corresponded to observed phenotypic switch. We noticed significant species-specific differences between mouse mammary and human breast samples in their morphology, phenotypic responses and ERα+ preservation to microenvironmental matrix stiffness. Furthermore, a combination of scaffold stiffness and composition of biochemical matrix constituency is required for long-term maintenance of ERα+ luminal tumour phenotype. Therefore, both physical properties and composition of the microenvironment need to be optimized for maintenance of breast tumor type specific phenotype and genetic profiles of ex vivo tumor explant cultures. Citation Format: Pauliina M. Munne, Lahja Martikainen, Iiris Räty, Kia Bertula, Nonappa Nonappa, Aino Peura, Minna Mutka, Marjut Leidenius, Tuomo Meretoja, Panu Kovanen, Johanna Mattson, Paivi Heikkila, Heikki Joensuu, Olli Ikkala, Juha T. Klefstrom. Novel ex vivo model for ERα positive breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2966.

openaire: EC/FP7/291364/EU//MIMEFUN The synthesis and spontaneous, reversible supracolloidal hydrogen bond-driven self-assembly of cobalt nanoparticles (CoNPs) into hollow shell-like capsids and their directed assembly to higher order superstructures is presented. CoNPs and capsids form in one step upon mixing dicobalt octacarbonyl (Co2CO8) and p-aminobenzoic acid (pABA) in 1,2-dichlorobenzene using heating-up synthesis without additional catalysts or stabilizers. This leads to pABA capped CoNPs (core ca. 5nm) with a narrow size distribution. They spontaneously assemble into tunable spherical capsids (d≈50-200nm) with a few-layered shells, as driven by inter-nanoparticle hydrogen bonds thus warranting supracolloidal self-assembly. The capsids can be reversibly disassembled and reassembled by controlling the hydrogen bonds upon heating or solvent exchanges. The superparamagnetic nature of CoNPs allows magnetic-field-directed self-assembly of capsids to capsid chains due to an interplay of induced dipoles and inter-capsid hydrogen bonds. Finally,self-assembly on air-water interface furnishes lightweight colloidal framework films.

This is the peer-reviewed version of the following article: Anaya‐Plaza, E., van de Winckel, E., Mikkilä, J., Malho, J. M., Ikkala, O., Gulías, O., ... & Kostiainen, M. A. (2017). Photoantimicrobial biohybrids by supramolecular immobilization of cationic phthalocyanines onto cellulose nanocrystals. Chemistry–A European Journal, 23(18), 4320-4326., which has been published in final form at https://doi.org/10.1002/chem.201605285. This article may be used for non-commercial purposes in accordance with Wiley-VCH Terms and Conditions for Self-Archiving, The development of photoactive and biocompatible nanostructures is a highly desirable goal to address the current threat of antibiotic resistance. Here, we describe a novel supramolecular biohybrid nanostructure based on the non-covalent immobilization of cationic zinc phthalocyanine (ZnPc) derivatives onto unmodified cellulose nanocrystals (CNC), following an easy and straightforward protocol, in which binding is driven by electrostatic interactions. These non-covalent biohybrids show strong photodynamic activity against S. aureus and E. coli, representative examples of Gram-positive and Gram-negative bacteria, respectively, and C. albicans, a representative opportunistic fungal pathogen, outperforming the free ZnPc counterparts and related nanosystems in which the photosensitizer is covalently linked to the CNC surface, A.d.l.E. acknowledges a Ramón y Cajal contract from the Spanish Ministry of Economy (MINECO). The work at Madrid was supported by the EU [SO2S (FP7‐PEOPLE‐2012‐ITN, 316975); and CosmoPHOS‐nano (FP7‐NMP‐2012‐6, 310337‐2)], the Spanish MINECO [CTQ‐2014‐52869‐P (T.T.) and CTQ‐2014‐53673‐P (A.d.l.E.)] and Comunidad de Madrid [FOTOCARBON (S2013/MIT‐2841)]. J.M., V.L., and M.A.K. acknowledge support through the Emil Aaltonen Foundation and the Academy of Finland (grants 267497, 273645 and 263504). This work was supported by the Academy of Finland through its Centers of Excellence Programme (2014–2019) and made use of the Aalto University Nanomicroscopy Centre (Aalto NMC). The work in Barcelona was supported by the Spanish MINECO (grant CTQ2013‐48767‐C3‐1‐R). R.B.‐O. thanks the European Social Funds and the SUR del DEC de la Generalitat de Catalunya for his predoctoral fellowship (2016 FI B1 00021).

openaire: EC/FP7/291364/EU//MIMEFUN Self-assembly of colloidal building blocks, like metal nanoparticles, is a rapidly progressing research area toward new functional materials. However, in-depth control of the colloidal self-assembly and especially hierarchical self-assembly is difficult due to challenges in controlling the size dispersities, shape/morphology, directionalities, and aggregation tendencies. Using either polydispersed or narrow-size dispersed nanoparticles, considerable progress has been achieved over the past few years. However, absolutely monodisperse nanoparticles could allow new options for rational designs of self-assemblies. Therein, atomically precise monolayer protected nanoclusters (d < 3 nm) have recently been synthesized with well-defined metal cores and surface ligands. Their dispersion behavior is commonly tuned by surfactant-like ligands. Beyond that, this study deals with approaches based on ligand-driven supramolecular interactions and colloidal monodispersity until atomic precision to tune the colloidal self-assembly and hierarchy from nanoscale to mesoscopic scale. Therein colloidal packing to self-assembled 2D crystals and closed virus capsid-inspired shells provide relevant research goals due to ever increasing potential of 2D materials and encapsulation. This study addresses the hydrogen bonding (H-bonding) directed self-assembly of atomically precise gold and silver nanoparticles and narrow size dispersed cobalt nanoparticles to free-standing 2D colloidal nanosheets, nanowire assemblies, capsid-like colloidal closed shells, as well as higher order structures.

Fiber spinning of anionic TEMPO-oxidized cellulose (TOCN) nanofibrils with polycations by interfacial polyelectrolyte complexation is demonstrated. The formed fibers were mostly composed of cellulose nanofibrils and the polycations were a minor constituent, leading to yield and ultimate strengths of ca. 100 MPa and ca. 200 MPa, and Young’s modulus of ca. 15 GPa. Stretching of the as-formed wet filaments of TOCN/polycation by 20% increased the Young’s modulus, yield strength, and ultimate tensile strength by approximately 45, 36, and 26%, respectively. Importantly, feasibility of compartmentalized wound bicomponent fibers by simultaneous spinning of two fibers of different compositions and entwining them together was shown. This possibility was further exploited to demonstrate reversible shape change of a bicomponent fiber directly by humidity change, and indirectly by temperature changes based on thermally dependent humidity absorption. The demonstrated route for TOCN-based fiber preparation is expected to open up new avenues in the application of nanocelluloses in advanced fibrous materials, crimping, and responsive smart textiles.

Currently, nanosystems have been developed and applied as promising vehicles for different biomedical applications. We have developed three lignin nanoparticles (LNPs): pure lignin nanoparticles (pLNPs), iron(III)-complexed lignin nanoparticles (Fe-LNPs), and Fe3O4-infused lignin nanoparticles (Fe3O4-LNPs) with round shape, narrow size distribution, reduced polydispersity and good stability at pH 7.4. The LNPs showed low cytotoxicity in all the tested cell lines and hemolytic rates below 12% after 12 h of incubation. Additionally, they induced hydrogen peroxide production in a small extent and time-dependent manner, and the interaction with the cells increased over time, exhibiting a dose-dependent cell uptake. Concerning the drug loading, pLNPs showed the capacity to efficiently load poorly water-soluble drugs and other cytotoxic agents, e.g. sorafenib and benzazulene (BZL), and improve their release profiles at pH 5.5 and 7.4 in a sustained manner. Furthermore, the BZL-pLNPs presented an enhanced antiproliferation effect in different cells compared to the pure BZL and showed a maximal inhibitory concentration ranging from 0.64 to 12.4 μM after 24 h incubation. Overall, LNPs are promising candidates for drug delivery applications, and the superparamagnetic behavior of Fe3O4-LNPs makes them promising for cancer therapy and diagnosis, such as magnetic targeting and magnetic resonance imaging.

openaire: EC/FP7/291364/EU//MIMEFUN Block copolymers microphase separate into a variety of bulk morphologies that serve as scaffolds, templates, masks and source for polymeric nano-particles. While supramolecular additives are common to complex within diblock copolymers to modify the morphology, the subtle effects of complexation on ABC triblock terpolymer morphologies are less explored. Here, we describe the manipulation of polystyrene-block-poly(4-vinylpyridine)-block-poly(tert-butyl methacrylate) (PS-b-P4VP-b-PT or S4VT) triblock terpolymer bulk morphologies through supramolecular complexation with rod-like 4-(4-pentylphenylazo)phenol (5PAP). The 5PAP molecule hydrogen bonds by phenolic groups to the 4VP repeating units and with increasing molar fraction of 5PAP, initially observed P4VP cylinders flatten into elliptic cylinders until a morphological transition occurs into a third (P4VP/5PAP) lamella. At sufficient 5PAP loadings, the cylinders can even merge into a perforated P4VP lamella located at the PS/PT interface. Quaternization of the P4VP phase and re-dispersion in organic solvent allows liberating S4VT Janus nanostructures from the bulk, including Janus cylinders, nanoporous Janus membranes and Janus sheets. The manipulation of “sandwiched” microphases through supramolecular binding motifs could allow the preparation of previously inaccessible terpolymer bulk morphologies and, in case of cross-linkable phases, lead to a larger library of Janus nano-objects.

Herein, it is discussed whether the complex biological concepts of (associative) learning can inspire responsive artificial materials. It is argued that classical conditioning, being one of the most elementary forms of learning, inspires algorithmic realizations in synthetic materials, to allow stimuli-responsive materials that learn to respond to a new stimulus, to which they are originally insensitive. Two synthetic model systems coined as "Pavlovian materials" are described, whose stimuli-responsiveness algorithmically mimics programmable associative learning, inspired by classical conditioning. The concepts minimally need a stimulus-triggerable memory, in addition to two stimuli, i.e., the unconditioned and the originally neutral stimuli. Importantly, the concept differs conceptually from the classic stimuli-responsive and shape-memory materials, as, upon association, Pavlovian materials obtain a given response using a new stimulus (the originally neutral one); i.e., the system evolves to a new state. This also enables the functionality to be described by a logic diagram. Ample room for generalization to different stimuli and memory combinations is foreseen, and opportunities to develop future adaptive materials with ever-more intelligent functions are expected.

Tunable and responsive surfaces offer routes to multiple functionalities ranging from superhydrophobic surfaces to controlled adhesion. Inspired by cilia structure in the respiratory pathway, magnetically responsive periodic arrays of flexible and magnetic thiol-ene micropillars are fabricated. Omnidirectional collective bending of the pillar array in magnetic field is shown. Local non-contact actuation of a single pillar is achieved using an electromagnetic needle to probe the responsiveness and the elastic properties of the pillars by comparing the effect of thiol-ene crosslinking density to pillar bending. The suitable thiol-ene components for flexible and stiff magnetic micropillars and the workable range of thiol-to-allyl ratio are identified. The wettability of the magnetic pillars can be tailored by chemical and topography modification of the pillar surface. Low-surface-energy self-assembled monolayers are grafted by UV-assisted surface activation, which is also used for surface topography modification by covalent bonding of micro- and nanoparticles to the pillar surface. The modified thiol-ene micopillars are resistant to capillarity-driven collapse and they exhibit low contact angle hysteresis, allowing water droplet motion driven by repeated bending and recovery of the magnetic pillars in an external magnetic field. Transport of polyethylene microspheres is also demonstrated.

openaire: EC/H2020/725513/EU//SuperRepel | openaire: EC/H2020/742829/EU//DRIVEN The ability to switch the hydrophilicity/hydrophobicity of nanoparticles promises great potential for applications. Here we report a generic approach that allows hydrophobization of cationic surfaces by light-induced photoacid switching from the unbound zwitterionic form to the electrostatically bound anionic form. Importantly, this allows reversible assembly and disassembly of cationic AuNPs, with disassembly kinetics controlled by temperature. The AuNPs can be repeatedly transferred between aqueous and non-polar solvents using light, showing potential in purification processes. In the macroscopic scale, nontrivially, light triggers the in situ hydrophobization of a flat cationized gold surface. The current approach is generic and opens up a new way to control the surface properties and self-assembly of nanoparticles.

Silk and cellulose are biopolymers that show a high potential as future sustainable materials.They also have complementary properties, suitable for combination in composite materials where cellulose would form the reinforcing component and silk the tough matrix. Therein, a major challenge concerns balancing structure and properties in the assembly process. We used recombinant proteins with triblock architecture combining structurally modified spider silk with terminal cellulose affinity modules. Flow-alignment of cellulose nanofibrils and triblock protein allowed a continuous fiber production.The protein assembly involved phase separation into concentrated coacervates, with subsequent conformational switching from disordered structures to beta sheets. This gave the matrix a tough adhesiveness, forming a new composite material with high strength and stiffness combined with increased toughness. We show that versatile design possibilities in protein engineering enable new fully biological materials, and emphasize the key role of controlled assembly at multiple length scales for realization.

openaire: EC/H2020/742829/EU//DRIVEN Strain-stiffening is one of the characteristic properties of biological hydrogels and extracellular matrices, where the stiffness increases upon increased deformation. Whereas strain-stiffening is ubiquitous in protein-based materials, it has been less observed for polysaccharide and synthetic polymer gels. Here we show that agarose, that is, a common linear polysaccharide, forms helical fibrillar bundles upon cooling from aqueous solution. The hydrogels with these semiflexible fibrils show pronounced strain-stiffening. However, to reveal strain-stiffening, suppressing wall slippage turned as untrivial. Upon exploring different sample preparation techniques and rheological architectures, the cross-hatched parallel plate geometries and in situ gelation in the rheometer successfully prevented the slippage and resolved the strain-stiffening behavior. Combining with microscopy, we conclude that strain-stiffening is due to the semiflexible nature of the agarose fibrils and their geometrical connectivity, which is below the central-force isostatic critical connectivity. The biocompatibility and the observed strain-stiffening suggest the potential of agarose hydrogels in biomedical applications.

Living systems are essentially out of equilibrium, where concentration gradients are kinetically controlled by reaction networks that provide spatial recognitions for biological functions. They have inspired life-like systems using supramolecular dynamic materials and systems chemistry. Upon pursuing ever more complex life-inspired systems, mimicking the ability to learn would be of great interest to be implemented in artificial materials. We demonstrate a soft hydrogel model system that is programmed to algorithmically mimic some of the basic aspects of classical Pavlovian conditioning, the simplest form of learning, driven by the coupling between chemical and physical processes. The gel can learn to respond to a new, originally neutral, stimulus upon classical conditioning with an unconditioned stimulus. Further subtle aspects of Pavlovian conditioning, such as forgetting and spontaneous recovery of memory, are also achieved by driving the system out-of-equilibrium. The present concept demonstrates a new approach towards dynamic functional materials with “life-like” properties.