Microneedles are promising devices for transdermal delivery and diagnostic applications, due to their minimally invasive and painless nature of application. However, so far, applications are limited to small scale research projects. Material selection and production for larger projects remain a challenge. In vitro testing using human cell culture could bridge the gap between cost effective screening of suitable materials and concerns for safety and ethics. In this study, materials were tested for effects on viability and morphology of human endothelial cells and keratinocytes. In addition, materials were assessed for their potential to influence cellular differentiation and barrier formation. Elution‐based testing of inflammatory markers revealed no negative effects in all applied tests, whereas the assessment of differentiation markers on cells in direct contact with the material showed differences and allowed the selection of candidate materials for future medical device applications. This study illustrates that elution‐based biocompatibility testing can paint an incomplete picture. Advanced staining techniques and cell types specific for the application of the medical device improve material selection to reduce and replace animal testing at an early stage in the development process. © 2018 The Authors. journal Of Biomedical Materials Research Part A Published By Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 505–512, 2019.

Nanostructured surfaces and nanoparticles are already widely employed in many different fields of research, and there is an ever-growing demand for reliable, reproducible and scalable nanofabrication methods. This is especially valid for multifunctional nanomaterials with physical properties that are tailored for specific applications. Here, we report on the fabrication of two types of nanomaterials. Specifically, we present surfaces comprising a highly uniform array of elliptical pillars as well as nanoparticles with the shape of nanopockets, possessing nano-cavities. The structures are fabricated by nanoimprint lithography, physical and wet-chemical etching and sputter deposition of thin films of various materials to achieve a multifunctional nanomaterial with defined optical and magnetic properties. We show that the nanopockets can be transferred to solution, yielding a nanoparticle dispersion. All fabrication steps are carefully characterized by microscopic and optical methods. Additionally, we show optical simulation results that are in good agreement with the experimentally obtained data. Thus, this versatile method allows to fabricate nanomaterials with specific tailor-made physical properties that can be designed by modelling prior to the actual fabrication process. Finally, we discuss possible application areas of these nanomaterials, which range from biology and medicine to electronics, photovoltaics and photocatalysis.

Nanoimprinting is a well-established replication technology for optical elements, with the capability to replicate highly complex micro- and nanostructures. One of the main challenges, however, is the generation of the master structures necessary for stamp fabrication. We used UV-based Nanoimprint Lithography to prepare hierarchical master structures. To realize structures with two different length scales, conventional nanoimprinting of larger structures and conformal reversal nanoimprinting to print smaller structures on top of the larger structures was performed. Liquid transfer imprint lithography proved to be well suited for this purpose. We used the sample prepared in such a way as a master for further nanoimprinting, where the hierarchical structures can then be imprinted in one single nanoimprinting step. As an example, we presented a diffusor structure with a diffraction-grating structure on top.