Herein, we report a 3D printable ink made of a peptide-polysaccharide hybrid hydrogel composed of fluorenylmethyloxycarbonyl-diphenylalanine (Fmoc-FF) peptide and TEMPO-oxidized cellulose nanofibrils (ToCNF), synthesized using a pH-dependent sol–gel transition method. The ToCNF suspension is synthesized through the mechanical breakdown of a cellulose pulp using a microfluidizer, followed by its oxidation mediated with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). The properties of the hybrid inks are compared in the presence (ToCNF/Fmoc-FF-Ca²⁺) and absence (ToCNF/Fmoc-FF) of the divalent cation Ca²⁺, which acts as the cross-linker, at two optimized weight ratios (r) of ToCNF and Fmoc-FF (r = 4.5 and 6.5). The rheological measurements show that the yield strength of the ToCNF/Fmoc-FF-Ca²⁺ gel is almost double that of the hydrogel composite without Ca²⁺ ions, especially at the concentration (C) of 10 mM CaCl₂. This finding is further verified by 3D gel printing, which produced good quality prints with the cation cross-linked hydrogel. The structural analysis by Field Emission Scanning Electron Microscopy shows that the calcium ions can cross-link the ToCNF and also enhance the self-assembly of Fmoc-FF, which leads to the formation of rigid compact nanofibers even at physiological pH. The electrostatic interaction of the positively charged Ca²⁺ions onto the negatively charged surface carboxylate groups of ToCNF and Fmoc-FF is analyzed by zeta potential (ζ) measurements. Small-angle X-ray scattering measurements give deeper structural insights into the interaction of Fmoc-FF with ToCNF. Cell responses to the hydrogels are studied in human dermal fibroblasts (NHDFs) in a direct contact test using a live/dead assay and in extract test using Alamar Blue and lactate dehydrogenase assays. The results show that high loading of Fmoc-FF decreases cell viability, while additional cross-linking with calcium reduces this cytotoxic effect.

Artificial nerves that are capable of sensing, processing and memory functions at bio-realistic frequencies are of potential use in nerve repair and brain-machine interfaces. n-type organic electrochemical transistors are a possible building block for artificial nerves, as their positive-potential-triggered potentiation behaviour can mimic that of biological cells. However, the devices are limited by weak ionic and electronic transport and storage properties, which leads to poor volatile and non-volatile performance and, in particular, a slow response. We describe a high-frequency artificial nerve based on homogeneously integrated organic electrochemical transistors. We fabricate a vertical n-type organic electrochemical transistor with a gradient-intermixed bicontinuous structure that simultaneously enhances the ionic and electronic transport and the ion storage. The transistor exhibits a volatile response of 27 mu s, a 100-kHz non-volatile memory frequency and a long state-retention time. Our integrated artificial nerve, which contains vertical n-type and p-type organic electrochemical transistors, offers sensing, processing and memory functions in the high-frequency domain. We also show that the artificial nerve can be integrated into animal models with compromised neural functions and that it can mimic basic conditioned reflex behaviour.

The acetosolv extraction, allylation and subsequent cross-linking of wheat straw lignin to thermoset biomaterials is herein described. The extraction temperature proved to be of great importance for the quality of the resulting lignin, with moderate temperature being key for preservation of β-O-4’ linkages. The allylation of the acetosolv lignin was carried out using three different synthetic strategies, resulting in selective installation of either benzylic or phenolic allyl ethers, or unselective allylation of various hydroxyl groups via etherification and carboxyallylation. The different allylation protocols employed either allyl alcohol, allyl chloride, or diallylcarbonate as allyl precursors, with the latter resulting in the highest degree of functionalization. Selected allylated acetosolv lignins were cross-linked using a thiol-ene approach and the lignin with the highest density of allyl groups was found to form a cross-linked thermoset material with properties comparable to kraft lignin-based analogues.

Reactive ion beam sputtering is an efficient tool to produce modifications in the surface topography in the form of periodic nanoripples with controlled modulation period and amplitude. In the present work, the atomic level processes responsible for nanoripple formation on silicon surface by oblique angle irradiation with molecular nitrogen ions have been studied. A variety of complementary techniques have been used to elucidate the structural and compositional changes occurring in the surface and sub-surface regions with irradiation fluence. It is shown that the implanted nitrogen ions react with the Si substrate to form Si3N4 phase in the subsurface region. GI-SAXS measurements suggest that the buried nitride layer gets phase separated to generate periodic variation in the density at nanometer length scale. With increasing fluence, the surface layer of Si gets sputtered out and the nitride layer reaches the surface. At this stage an unequal sputtering of nitride-rich and nitride-depleted regions results in development of surface instability which is already periodic in nature. Further irradiation results in development of well-defined surface ripples as a combined effect of composition-dependent and curvature-dependent sputtering. A direct chemical evidence for the phase separation of the nitride layer comes from the Auger electron scanning microscopy.

We here explore confinement-induced assembly of whey protein nanofibrils (PNFs) into microscale fibers using micro-focused synchrotron X-ray scattering. Solvent evaporation aligns the PNFs into anisotropic fibers and the process is followed in situ by scattering experiments in a droplet of PNF dispersion. We find an optimal temperature at which the order of the protein fiber has a maximum, suggesting that the degree of order results from a balance between the time scales of the forced alignment and the rotational diffusion of the fibrils. Moreover, we observe that the assembly process depends on the nano-scale morphology of the PNFs. Stiff PNFs with a persistence length in the micrometer scale are aligned at the air-water interface and the anisotropy gradually decrease towards the center of the droplet. Marangoni flows often increase entanglements toward the center, leading to complex patterns in the droplet. Flexible fibrils with a short persistence length (< 100 nm) tends to align uniformly throughout the droplet, possibly due to stronger local entanglements. Straight PNFs form smaller clusters with shorter inter-cluster distances due to their tight packing and consistent linear structure. In contrast, curved PNFs form intricate networks with larger characteristic distances and more varied structures because of their flexibility and adaptability.

Biobased cellulose nanofibrils (CNFs) constitute important building blocks for biomimetic, nanostructured materials, and considerable potential exists in their hybridization with tailorable polymeric nanoparticles. CNFs naturally assemble into oriented, fibrillar structures in their cross-section. This work shows that polymeric nanoparticle additives have the potential to increase or decrease orientation of these cellulose structures, which allows the control of bulk mechanical properties. Small amounts of these additives (<1 wt%) are shown to promote the alignment of CNFs, and the particle size is found to determine a tailorable maximum feature size which can be modified. Herein, X-ray scattering allows for the quantification of orientation at different length scales. This newly developed method of measuring cross-sectional orientation allows for understanding the influence of nanoparticle characteristics on the CNF network structure at different length scales in hybrid cellulose-nanoparticle materials, where previously quantitative description has been lacking. It thus constitutes an important foundation for further development and understanding of nanocellulose materials on the level of their nanoscale building blocks and their interactions, which in turn are decisive for their macroscopic properties.

Metal halide perovskites, particularly quasi-2D perovskites, have emerged as promising candidates for next-generation laser diode gain media due to their exceptional optoelectronic properties. However, conventional quasi-2D perovskites suffer from inefficient exciton funneling and pronounced efficiency roll-off at high carrier densities. Here, a quasi-2D/3D perovskite structure is proposed with a high-efficient energy cascade, modulated through molecular engineering strategy. The C─O─C functional groups in PEO form hydrogen bonds with PEA⁺, thereby delaying the assembly of PEA⁺ with the [PbBr₆]⁴⁻ octahedra inorganic layer. This modification led to refined grain size, enhanced crystallinity, and improved surface flatness in the resulting films. Furthermore, the engineered quasi-2D/3D thin film exhibits an increased exciton binding energy while alleviating efficiency roll-off at high carrier density, achieved by effectively suppressing Auger recombination through directional energy transfer from the quasi-2D to the 3D phase. Consequently, the amplified spontaneous emission threshold of quasi-2D/3D films is reduced to 16.6 µJ cm⁻², and obtained a higher net modal gain coefficient (892 cm⁻¹). These findings provide critical insights for developing low-threshold perovskite lasers.

The growing interest in gel-based additive manufacturing, also known as three-dimensional (3D) gel-printing technology, for research underscores the crucial need to develop robust biobased materials with excellent printing quality and reproducibility. The main focus of this study is to prepare and characterize some composite gels obtained with a low-molecular-weight gelling (LMWG) peptide called Fmoc-diphenylalanine (Fmoc-FF) and two types of cellulose nanofibrils (CNFs). The so-called Fmoc-FF peptide has the ability to self-assemble into a nanowire shape and therefore create an organized network that induces the formation of a gel. Despite their ease of preparation and potential use in biological systems, unfortunately, those Fmoc-FF nanowire gel systems cannot be 3D printed due to the high stiffness of the gel. For this reason, this study focuses on composite materials made of cellulose nanofibrils and Fmoc-FF nanowires, with the main objective being that the composite gels will be suitable for 3D printing applications. Two types of cellulose nanofibrils are employed in this study: (1) unmodified pristine cellulose nanofibrils (uCNF) and (2) chemically modified cellulose nanofibrils, which ones have been grafted with polymers containing the Fmoc unit on their backbone (CNF-g-Fmoc). The obtained products were characterized through solid-state cross-polarization magic angle-spinning 1H NMR and confocal laser scanning microscopy. Within these two CNF structures, two composite gels were produced: uCNF/Fmoc-FF and CNF-g-Fmoc/Fmoc-FF. The mechanical properties and printability of the composites are assessed using rheology and challenging 3D object printing. With the addition of water, different properties of the gels were observed. In this instance, CNF-g-Fmoc/Fmoc-FF (c = 5.1%) was selected as the most suitable option within this product range. For the composite bearing uCNF, exceptional print quality and mechanical properties are achieved with the CNF/Fmoc-FF gel (c = 5.1%). The structures are characterized by using field emission scanning electron microscopy (FESEM) and small-angle X-ray scattering (SAXS) measurements.

Despite significant advancements in the power conversion efficiency (PCE) of FAPbI<inf>3</inf>-based perovskite solar cells (PSCs), their commercialization remains hindered by stability issues. These challenges arise primarily from the phase transition of the α-phase to the δ-phase under operation. Alloying FAPbI<inf>3</inf> with Cs to form FA-Cs perovskite (FACsPbI<inf>3</inf>) emerged as a promising approach to enhance phase and thermal stability. In this study, it is demonstrated that adding a Cs source to the PbI<inf>2</inf> solution promotes the formation of a structurally stable α-phase in the PbI<inf>2</inf> film. This stabilization reduces cation diffusion but leads to Cs accumulation at the surface of the perovskite layer. To address this issue, a δ-phase perovskite in the PbI<inf>2</inf> film by predepositing the Cs source before PbI<inf>2</inf> deposition is constructed. This approach facilitates the uniform vertical distribution of FA and Cs cations, resulting in a homogeneous perovskite (h-perovskite) device. The h-perovskite device achieves a higher PCE of 24.59%, compared to 22.96% for the inhomogeneous perovskite (i-perovskite) device. Operando GIWAXS measurements reveal that the h-perovskite exhibits a slower degradation rate than the i-perovskite during device operation. This difference is attributed to the formation of the δ-phase and a stronger crystal lattice contraction observed in the i-perovskite during the operando measurements.

Laminated structural batteries present a transformative solution to reducing weight constraints in electric vehicles. These structural batteries are based on a multifunctional material that incorporates an energy storage function within a carbon fiber-reinforced polymer. Despite the potential of this technology, the intricate morphology of fiber-matrix or electrode-electrolyte interfaces and the impact of long-term cycling at low current rates (C-rates) on these interfaces remain insufficiently understood. This study addresses these critical knowledge gaps by examining the influence of matrix composition on the long-term electrochemical performance of structural battery electrodes and exploring advanced techniques to investigate carbon fiber-matrix interfaces. Localized imaging and X-ray scattering techniques were used to characterize morphological changes at the electrode-electrolyte interfaces by analyzing negative structural electrodes. The findings revealed that the matrix composition influences long-term electrochemical behavior and fiber-matrix interface formation. While the intrinsic properties of carbon fibers largely remain unaffected by long-term cycling, cycling promotes debonding at fiber-matrix interfaces. Nonetheless, residual regions of adhesion persist, underscoring the potential for preserving multifunctionality even under prolonged cycling conditions. These insights advance the understanding of interface dynamics, which is critical for optimizing structural battery technologies.