Plasma-assisted multiscale topographic scaffolds for soft and hard tissue regeneration

The design of transplantable scaffolds for tissue regeneration requires gaining precise control of topographical properties. Here, we propose a methodology to fabricate hierarchical multiscale scaffolds with controlled hydrophilic and hydrophobic properties by employing capillary force lithography in combination with plasma modification. Using our method, we fabricated biodegradable biomaterial (i.e., polycaprolactone (PCL))-based nitrogen gas (N-FN) and oxygen gas plasma-assisted flexible multiscale nanotopographic (O-FMN) patches with natural extracellular matrix-like hierarchical structures along with flexible and controlled hydrophilic properties. In response to multiscale nanotopographic and chemically modified surface cues, the proliferation and osteogenic mineralization of cells were significantly promoted. Furthermore, the O-FMN patch enhanced regeneration of the mineralized fibrocartilage tissue of the tendon–bone interface and the calvarial bone tissue in vivo in rat models. Overall, the PCL-based O-FMN patches could accelerate soft- and hard-tissue regeneration. Thus, our proposed methodology was confirmed as an efficient approach for the design and manipulation of scaffolds having a multiscale topography with controlled hydrophilic property.

Polymeric Nanostructures for Prospective Tribological Application in Min-iaturized Devices: A Review

Background:: Tribological issues severely confound smooth operation of moving elements in actuators-based miniaturized devices e.g. micro-electro-mechanical systems. At micro/nano scales, surface forces namely adhesion and friction manifest strongly and oppose relative mechanical motion of actuator elements. Topographical modification of sur-faces via surface patterning has emerged as a potential route to mitigate surface forces at small-scales. Methods:: Capillary force lithography is a simple yet robust technique to fabricate polymer nanostructures with varying shapes/sizes. This paper presents a brief review on the capillary force lithography technique, its salient features and tribo-logical performance of nanostructures fabricated by the technique. Conclusion:: Capillary force lithography has several attractive salient features, in particular the ability of the technique to create polymer nanopatterns of varying shapes/sizes without the need for molds with different shapes/sizes. Polymer nanostructures fabricated by the technique effectively reduce surface forces at micro/nano-scales, and are of interest for tribological application in small-scale devices.

Continuous Tip Widening Technique for Roll-to-Roll Fabrication of Dry Adhesives

In this study, we reported continuous partial curing and tip-shaped modification methods for continuous production of dry adhesive with microscale mushroom-shaped structures. Typical fabrication methods of dry adhesive with mushroom-shaped structures are less productive due to the failure of large tips on pillar during demolding. To solve this problem, a typical pillar structure was fabricated through partial curing, and tip widening was realized through applying the proper pressure. Polyurethane acrylate was used in making the mushroom structure using two-step UV-assisted capillary force lithography (CFL). To make the mushroom structure, partial curing was performed on the micropillar, followed by tip widening. Dry adhesives with properties similar to those of typical mushroom-shaped dry adhesives were fabricated with reasonable adhesion force using the two-step UV-assisted CFL. This production technology was applied to the roll-to-roll process to improve productivity, thereby realizing continuous production without any defects. Such a technology is expected to be applied to various fields by achieving the productivity improvement of dry adhesives, which is essential for various applications.