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Despite recent advances in biofabrication, recapitulating complex architectures of cell-laden vascular constructs remains challenging. To date, biofabricated vascular models have not yet realized four fundamental attributes of native vasculatures simultaneously: freestanding, branching, multilayered, and perfusable. In this work, a microfluidics-enabled molding technique combined with coaxial bioprinting to fabricate anatomically relevant, cell-laden vascular models consisting of hydrogels is developed. By using 3D porous molds of poly(ethylene glycol) diacrylate as casting templates that gradually release calcium ions as a crosslinking agent, freestanding, and perfusable vascular constructs of complex geometries are fabricated. The bioinks can be tailored to improve the compatibility with specific vascular cells and to tune the mechanical modulus mimicking native blood vessels. Crucially, the integration of relevant vascular cells (such as smooth muscle cells and endothelial cells) in a multilayer and biomimetic configuration is highlighted. It is also demonstrated that the fabricated freestanding vessels are amenable for testing percutaneous coronary interventions (i.e., drug-eluting balloons and stents) under physiological mechanical states such as stretching and bending. Overall, a versatile fabrication technique with multifaceted possibilities of generating biomimetic vascular models that can benefit future research in mechanistic understanding of cardiovascular diseases and the development of therapeutic interventions is introduced.

eparation of low viscous oil from water has attracted immense attention in recent times due to the ever-increasing amount of oily industrial wastewater discharge and frequent oil spill accidents. Hence, there is a persistent demand for the fabrication of robust oil–water separation membranes. Herein, robust oil–water separation membranes are successfully fabricated by direct electrospinning of poly(vinylidene fluoride-co-hexafluoropropylene) and fluorinated polyhedral oligomeric silsesquioxane composite mixture. These hybrid membranes exhibit differential wetting (highly hydrophobic/superoleophilic) behavior for water and oil. The contact angle made by water and low viscous oil (hexane) with the membrane are measured to be 145 and 0° respectively. The nanofiber membranes efficiently separate low viscous oil from water in a single-step with separation efficiency of nearly 100%. Furthermore, the results demonstrate that the membranes are robust and durable exhibiting differential wettability even after several oil–water separation cycles. The results reveal the potential of their use for real-time industrial wastewater treatment applications.

Herein, the fabrication of poly(vinylidene fluoride) (PVDF) fibrous membrane using electrospinning is reported and its use for dry-adhesive applications is demonstrated. The shear and normal adhesion performance of the samples was investigated using an Instron tensile tester and an atomic force microscope (AFM) respectively. For shear adhesion measurements, the electrospun membrane was finger pressed on to a glass slide and pulled in shear mode using a tensile tester. The thickness of the electrospun membrane was varied and the effect of thickness on shear adhesion was investigated. The shear adhesion strength increased when the thickness of the samples was reduced. Shear adhesion strength of a 200 µm thick sample was determined to be approximately 0.165 N/cm. For normal adhesion measurements, a flat tipless cantilever was used to indent the sample and then retract back to measure the pull-off force. High shear adhesion strength and normal pull-off force recorded are attributed to the fine size of the fibers that conform to the asperities present on the surfaces of the glass slide and the AFM cantilever. The durability of the adhesive was also verified by repeating the AFM adhesion measurements over 1000 consecutive attachment–detachment cycles. The pull-off force was seen to be constant over 1000 attachment–detachment cycles. Our results indicate that these electrospun fibrous membranes can potentially be used as reusable dry-adhesives. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44393.

Quest for efficient fog harvesting methods has drawn immense attention in recent times. In this study, electrospinning is used to fabricate three different sets of membranes that are based on pristine poly(N-isopropylacrylamide) (PNIPAM) fibers, pristine polyvinylidene fluoride (PVDF) fibers, and PNIPAM-PVDF bead-on-string fibers. The wettability of these membranes is investigated as a function of temperature and the effect of their wettability on the fog collection efficiency is determined. Membranes based on pristine PNIPAM and pristine PVDF fibers are fabricated using conventional electrospinning and are shown to have a smooth surface morphology. On the other hand, PNIPAM-PVDF bead-on-string fibers are fabricated using core–shell electrospinning. Water collection efficiency of the membranes is compared to investigate the influence of microstructures and wettability gradient on fog harvesting ability of the samples. Among the three samples, the bead-on-string hierarchical fibrous membrane demonstrates the highest fog harvesting rate of 1150 ± 28 mg cm−2 h−1 at 25 °C and 909 ± 31 mg cm−2 h−1 at 40 °C. Furthermore, the results demonstrate that the presence of microstructures on the nanofibers improve the fog harvesting efficiency of PNIPAM-PVDF bead-on-string fibers.

Collection of clean water from humid air has attracted immense attention in recent years due to the lack of access to pure drinking water among large section of population in several parts of the world. Hence, there is a persistent demand for the fabrication of robust, scalable membranes for efficient harvesting of pure water, especially in fog-laden areas. Herein, three different membranes based on neat nanofibers, nanofibers with microparticles, and nanofibers with hierarchical structures (nanopillars) are successfully fabricated using poly(vinylidene fluoride-co-hexafluoropropylene) and fluorinated polyhedral oligomeric silsesquioxane composite mixture. Neat nanofibers and nanofibers with microparticles are fabricated by employing direct electrospinning and electrospinning combined with electrospraying process, respectively. Hierarchical structured fibers are fabricated by growing nanopillars on the surface of the fibers using electrospinning combined with template-wetting method. The wettability properties including water contact angle and hysteresis of these membranes are investigated. Due to the increased surface roughness and low surface energy, the hierarchical fibers exhibit higher contact angle (153°) and lower hysteresis (3°) compared to the neat nanofibers and nanofibers with microparticles. Furthermore, the results demonstrate that the presence of nanopillars on the surface of the nanofibers improves the membrane's water collection efficiency when exposed to humid air.