Controlled synthesis of multifunctional dome-shaped micro- and nano-structures via a robust physical route for biological applications.

Micro- and nano-particles are elemental for many current and developing technologies. Specifically, these particles are being used extensively in biological studies and applications, which include imaging, drug delivery and therapeutics. Recent advances have led to the development of multifunctional particles, which have the potential to further enhance their effectiveness, enabling novel applications. Therefore, many efforts have been devoted to producing well-defined particles for specific needs. However, the conventional fabrication methodologies used to develop particles are time consuming, making it extremely challenging to fine-tune the properties of the particles for multifunctional applications. Herein, we present a simple and facile method to fabricate dome-shaped micron- and nano-sized particles via a robust physical route. The presented method enables particles to be designed using a vast range of materials, with different sizes and compositions. The versatility of this method enables the engineering of multifunctional particles with pre-defined properties that can be adjusted to a specific biological application. We demonstrate the fabrication of dome-shaped particles using physical vapor deposition (PVD) and a polystyrene-bead-monolayer-based mechanical mask. We show domes from several materials and coatings; in particular, we demonstrate the development process for biocompatible magnetic iron oxide domes. We find that our magnetic domes exhibit an Fe3O4 structure with a high magnetization saturation. In addition, we examine the biocompatibility of the magnetic domes by performing viability tests and morphological analysis. The ability to design and fabricate micro- and nano-particles upon request in a simple and relatively high-throughput manner opens possibilities for the development of new smart multifunctional particles for both therapeutic and diagnostic applications.