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Paper-based platforms for biological studies have received significant attention given that cellulose is ubiquitous, biocompatible, and can be readily organized into tunable fibrous structures. In the latter form, effect of complexity in surface morphologies (roughness, porosity and fiber organization) on cell-substrate interaction has not been thoroughly explored. We infer that altering the properties of a fibrous material should lead to significant changes in cellular microenvironment and direct the deposition of structurally analogous extracellular matrix (fiber-fiber templating) like collagen. Here, we elucidate the effect of varying paper roughness and surface chemistry on NIH/3T3 fibroblasts via organization of excreted collagen. Collagen intensity was found to increase linearly with paper porosity, indicating a 3D culture platform. The intensity, however, decays over time due to biodegradation of the substrate. Stability can be improved by introducing fluorinated alkyl silanes to yield hydrophobic paper. This process concomitantly transforms the substrate to a 2D-like scaffold where collagen is predominantly assembled on the surface, thus changing the cellular microenvironment. Altering surface energy also led to fluctuations in collagen intensity and organization over time for smooth (calendered) paper substrates. We infer that the increased roughness improves collagen adsorption through capillary driven petal effect. In general, the influence of the substrate simultaneously affects its ability to host collagen and guide orientation. These findings offer insights into the effects of secondary structures and chemistry of fibrous polymeric materials on cell culture, which we propose as vital parameters when using paper-based platforms. Unlabelled Image • Collagen secreted from NIH/3T3 fibroblast cells increases linearly with paper porosity. • Paper transitions from 3D to 2D cell culture scaffold when rendered hydrophobic. • Hydrophobic paper relies on capillary driven petal effect for collagen adsorption. [ABSTRACT FROM AUTHOR]

An anisotropic aerogel hot-extrusion strategy is designed to convert polyimide aerogels into aerogel-based paper. The multilayer interconnected aerogel-based paper exhibits excellent thermal stability and mechanical properties, and the mechanical properties remain great at high temperatures. This aerogel-based paper has huge application potential in the aerospace field. [Display omitted] • Multi-layer interconnected aerogel based paper was successfully prepared by anisotropic aerogel hot extrusion strategy. • Aerogel-based papers exhibit excellent thermal stability and stable mechanical properties (PI-1: 216.28 MPa at 25 °C). • The tensile strength of PI-1 was 3 times that of commercial polyimide paper and 24 times that of aramid paper at 400 °C. • Aerogel-based paper maintain stable mechanical property after 5000 cycles. The continuous improvement of papermaking technology has attracted widespread attention. However, the prevention of high-temperature decomposition and a subsequent decline in mechanical strength is still a significant challenge with current papermaking technology. Herein, a newly developed multilayer interconnected polyimide aerogel-based paper was successfully prepared via an anisotropic aerogel hot-extrusion strategy. Precursor solutions of highly rigid benzimidazole units containing intermolecular hydrogen bonds and linear rod-like benzimide units were first prepared. Anisotropic precursor polyimide (PAAS) aerogels with a thickness of 3 mm were then manufactured by unidirectional freeze-drying. Then, aerogel-based papers with a thickness of 40 μm and microstructure multilayer interconnected properties were obtained by a hot extrusion strategy and a thermal imidization process. This polyimide structural paper exhibited excellent thermal and mechanical properties. Through the design of micro and macro structures, the tensile strength of the aerogel-based paper was much higher than that of commercial paper at both room temperature and 400 ℃. This aerogel-based paper also exhibited high-temperature cycle stability, high flexibility, and good stretchable bending properties. The successful preparation of this aerogel-based paper demonstrates the feasibility of the hot extrusion strategy. This work provides a new papermaking technology method and broadens the application field of paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • An amphiphobic paper was fabricated via internal sizing technology. • The modified paper exhibited high resistance to moisture and water vapor. • The modified paper maintained high fracture stress in high humidity environment. • The modified paper exhibited notable self-cleaning and antibacterial activity. Paper-based materials have been used in every aspect of social life. However, the current paper-based materials face unprecedented challenges, such as limited lifespan and poor mechanical strength, owing to the deformation after absorbing a large amount of water and bacterial erosion. Herein, superhydrophobic and lyophobic paper was fabricated using internal sizing technology. Hydrophobically modified starch and Ag@SiO 2 particles were added as two functional additives to paper pulp to promote a hierarchical structure formation with low surface energy. Consequently, the water and linseed oil contact angles of the obtained paper reached 154.8° and 138.4°, respectively. The resistance to moisture and water vapor also improved under high-humidity condition, the relative moisture content decreased from 511% to 278% and water vapor transmission rate also decreased from 97.44 to 21.23 g/m2·h. Furthermore, its mechanical properties could also be well maintained with a high fracture stress of 4.91 MPa. Besides, some liquid food, such as honey, easily rolled off the surface without leaving behind any residue, which demonstrated its self-cleaning ability. Furthermore, the modified paper exhibited notable bacterial repellency and antibacterial activity. This study provides an innovative method for endowing conventional paper with superhydrophobic and antibacterial properties, which can effectively expand their application scope. [ABSTRACT FROM AUTHOR]

A robust superhydrophobic ZnO coating on a filter paper substrate was successfully prepared for the first time by using a successive deposition process and chemical modification. The surface morphology, chemical composition, wetting property, mechanical stability, chemical stability and durability of the filter papers were examined. The as-prepared papers exhibited an improved rough surface topography compared with the uncoated paper due to the uniform ZnO microclusters decorated on the reticular fibers. More importantly, it was found that the wettability of papers was dependent on the surface roughness, which was governed by the number of ZnO microcluster deposition cycles. After the chemical modification with stearic acid, the resulting paper with 4 cycles presented the optimized superhydrophobicity with a water contact angle (WCA) of 158°, a slide angle (SA) of 3°, a low adhesion and good bounce performance. The chemical resistance of the superhydrophobic paper to corrosive liquids was studied. Moreover, the superhydrophobicity of paper was not affected after the water drops impact test or it was kept for 6 months, indicating its high impact resistance and long-term stability. The excellent superhydrophobicity of paper can be attributed to the synergistic effect of the suitable micro/nanoscale hierarchical roughness and the low surface energy modification. Unlabelled Image • A novel superhydrophobic paper modified with ZnO microclusters was fabricated. • The resulting paper presented the optimized superhydrophobicity, good bounce performance, and high impact resistance. • The superhydrophobicity is attributed to suitable micro/nanoscale hierarchical roughness and low surface energy modification. [ABSTRACT FROM AUTHOR]