**Preface to "Metal and Metal Oxide Nanoparticles: Design, Characterization, and Biomedical Applications"**

The current Special Issue entitled "Metal and Metal Oxide Nanoparticles: Design, Characterization, and Biomedical Applications"aims to present contributions from all scientists producing and/or applying metal and metal oxide nanoparticles in a diagnostic, therapeutic or theranostics context.

Developing new materials is usually a time-demanding and meticulous process, but at the same time, it is one of the more promising solutions to obtain a cleaner, safer, and smart future. In more detail, when referring to nanomaterials, an increasingly successfully tool of nanotechnologies, nanoparticles are categorized as materials in which at least one dimension is less than 100 nm in diameter. Among the various nanoparticle categories, metal and metal oxide nanoparticles stand out as emerging nanotechnological solutions for a wide range of biological and medical physio/pathological open questions. This Special Issue covers the fundamental science, design, characterization, and biomedical applications of metal and metal oxide nanomaterials and the five papers here presented embrace all the aspects determining the performance of these systems, ranging from their synthesis, design, chemical, physical, and biological functionalization, to their characterization and successful applications.

Metal-based nanoparticles (MNPs) include metal NPs, metal oxide NPs, quantum dots (QDs) and magnetic NPs and, thanks to their chemical physical properties, have gained much traction for their functional use in biomedicine.

> **Tania Limongi** *Editor*
