[en] Different thermoplastic polymers were spin-coated to prepare smooth surfaces for the direct deposition of end-group modified oligonucleotides by Dip-Pen Nanolithography. A study of the diffusion process was done in order to investigate the dependence of calibration coefficient and quality of deposited features on environmental parameters (temperature, relative humidity) and ink's molecular weight and functionality. The optimization of the process parameters led to the realization of high quality and density nanoarrays on plastics.

[en] Highlights: • Microstructured molds are rapidly prototyped by combining stereolithography and replica molding • Surface fluorination of 3D printed masters ensures multiple fabrication of elastomeric replicas avoiding damages • Microtextured superhydrophobic bulk devices are obtained by casting a new low-surface tension polymer against the molds • High-performance self-cleaning luminescent solar concentrators are rapidly fabricated and up-scaled to different dimensions A strategy combining stereolithography (SL) and soft-lithography for the straightforward fabrication of superhydrophobic bulk devices is reported. Microtextured masters are rapidly prototyped by SL and passivated with a perfluorosilane. Such surface treatment enables the faultless fabrication of negative microstructured polydimethylsiloxane molds ultimately utilized to obtain bulk polymeric micropatterned structures by replica molding. As illustrative proof of concept, this approach is employed in the field of photovoltaics to realize the first example of superhydrophobic luminescent solar concentrators (LSCs) showing superior self-cleaning properties. Following our strategy, a new dye-doped acrylate mixture is developed and optimized to ensure complete wetting of the hollow microstructures present on the mold. By judiciously tailoring the photoinitiator concentration and by implementing a tailored double-step UV-irradiation process, complete UV-photopolymerization is achieved despite the significant thickness of the target samples. The high fidelity replication of the original SL-printed features on the daughter replicas as well as their super water-repellency are successfully demonstrated. The performance of the resulting superhydrophobic LSCs is investigated at varying device dimensions and found to be comparable with state-of-the-art systems. This study demonstrates the potential of high-resolution SL-printing in combination with replication techniques as a versatile tool to reproducibly fabricate microstructured superhydrophobic polymeric bulk devices in a straightforward fashion.

[en] This manuscript presents a study of physical and chemical properties of microchannels fabricated by femtosecond laser processing technology in thermoplastic polymeric materials, including poly(methyl methacrylate) (PMMA), polystyrene (PS) and cyclic olefin polymer (COP). By surface electron microscopy and optical profilometry, the dimensions of microchannels in the polymers were found to be easily tunable, with surface roughness values comparable to those obtained by standard prototyping techniques such as micromilling. Through colorimetric analysis and optical microscopy, PMMA was found to remain nearly transparent after ablation while COP and PS darkened significantly. Using infrared spectroscopy, the darkening in PS and COP was attributed to significant oxidation and dehydrogenation during laser ablation, unlike PMMA, which was found to degrade by a thermal depolymerization process. The more stable molecular structure of PMMA makes it the most viable thermoplastic polymer for femtosecond laser fabrication of microfluidic channels.

[en] Highlights: • Functionalized alginate hydrogels for pH controlled drug release are synthesized. • Functionalization is designed to allow sustained drug release only at pH lower than 4.5. • Hydrogels are applied on magnetically steerable devices able to navigate human body. • Hydrogel coating onto microrobots create drug carriers that can reach specific target sites. • Hydrogel coating functionalization can guarantee the release of drugs only in the target site. Targeted drug delivery is currently emerging as a promising approach to overcome the limits of currently employed administration techniques. The most convenient methodology to control drug delivery is the application of stimuli-responsive materials, which can release drugs only when required, to remotely controlled microdevices able to navigate human body. Thanks to this synergy, release can be controlled both spatially and temporally. Spatial control is guaranteed by the maneuverability of the devices, which can be precisely guided to release in targeted locations. Temporal control, conversely, is guaranteed by the functionalization introduced in the stimuli-responsive material. In this context, the present work describes the coating of magnetically controlled microdevices with functionalized alginate-based hydrogels able to release drugs at pH values lower than 4.5. Hydrogels are functionalized binding the drug with either an azidoethyl ester bond or an amidic bond, following an innovative synthesis route. After fabrication, release from hydrogel coated microdevices as a function of the environmental pH is characterized. Finally, devices are magnetically actuated and the possibility to achieve spatially and temporally controlled release is demonstrated. The functional microtransporters described in the present work are particularly promising for in-vivo applications in environments where pH differences are present, like the digestive apparatus.