**5. Conclusions and Perspectives**

Nanotechnology has significantly impacted medicine. In the past decade, studies about the biological response to NPs are greatly investigated in parallel with nano-bio interactions, which have influenced NP design. Both were in concordance with the evolution of NPs for biomedical applications. Many studies have investigated and demonstrated that NPs can enter into the human system. Therefore, the NP characteristics on biological systems, such as their physicochemical properties (size, shape, surface, coating and morphology, surface charge, hydrophobicity, chemical composition, structure, and the state of agglomeration), the types of biomolecules present, and the bio-identity of NP protein corona are important issues to characterize in order to know how they interact with cells, organisms, biological medium, biomolecules, and other biological systems or even with other nanomaterials. These studies helped determine their possible biocompatibility and toxicity in biological micro-environments and to engineer nontoxic nanomaterials, which may be used in biomedical applications.

With the potentially wide application of NPs in the future, these may be extensively used in various fields, especially in immunotherapy for clinical diagnosis and therapy based on their size, biocompatibility, surface chemistry, and adjustable toxicity. Immunotherapy combined with nanomedicines may be used to treat di fferent types of cancer due to their excellent e fficacy in penetration, specific retention, and killing of tumor cells.

The human proteome study [133] can be an arduous and discouraging task due to the high number of proteins, encoded by around 25,000 di fferent genes, from which multiple protein variants are generated by post-translational modifications. The concept of proteomics involves a comprehensive study on the structures, localizations, post-translational modifications, functions, and interactions of all proteins expressed by an organism at a certain time and under certain conditions. The nanotechnology field has been expanded by providing innovative methods capable of responding to proteomic demands. In this sense, nanotechnology applications in proteomics have established a novel technical platform termed "nanoproteomics." Detection techniques without labels are useful in the study of protein interaction kinetics, thanks to avoiding steric impediments caused by the presence of labels. The design and development of new multi-functional platforms based on nanomedicine could be of grea<sup>t</sup> interest in the unlabeled detection of protein-protein interactions given the possibility of synthesizing de novo proteins "in vitro" in the presence of these nano-systems.

In conclusion, the progress in nano-bio studies can potentially improve nano-medical applications and ensure a sustainable future.

**Author Contributions:** C.A.-S., R.M.-R., M.F. writing original draft preparation. C.A.-S., T.N., A.L.-V., P.J.-V., H.F.-G., M.J.A.P., R.G., V.A.-F., R.M.-R., M.F. writing—review and editing. C.A.-S., T.N., A.L.-V., P.J.-V., H.F.-G., V.A.-F. designing figures. Conceptualization, R.G., M.J.A.P., R.M.-R. & M.F. The manuscript has been approved by all the co-authors.

**Funding:** We gratefully acknowledge financial support from the Spanish Health Institute Carlos III (ISCIII) for the grants: FIS PI17/01930 and CB16/12/00400. Fundación Solórzano FS/38-2017. The Proteomics Unit belongs to ProteoRed, PRB3-ISCIII, supported by gran<sup>t</sup> PT17/0019/0023, of the PE I + D + I 2017-2020, funded by ISCIII and FEDER.

**Acknowledgments:** We gratefully acknowledge financial support from the Spanish Health Institute Carlos III (ISCIII) for the grants: FIS PI17/01930 and CB16/12/00400. Fundación Solórzano FS/38-2017. The Proteomics Unit belongs to ProteoRed, PRB3-ISCIII, supported by gran<sup>t</sup> PT17/0019/0023, of the PE I + D + I 2017-2020, funded by ISCIII and FEDER. A. Landeira-Viñuela is supported by VIII Centenario USAL-BancoSantander PhD Grant. We also thank G.R.G. for language edition services.

**Conflicts of Interest:** The authors declare no conflict of interest.
