Deep eutectic solvents (DESs) were developed 15 years ago and have been used for various purposes based on their unique chemical and physical properties. Recently, they have been highlighted as versatile media for the synthesis of noble metal nanomaterials. Although there are a few limitations, their vast chemical library of hydrogen bond donors and excellent solubility show great potential for their future applications for the synthesis of noble metal nanoparticles.

Nanoparticles (NPs) exposed to a biological milieu will strongly interact with proteins, forming “coronas” on the surfaces of the NPs. The protein coronas (PCs) affect the properties of the NPs and provide a new biological identity to the particles in the biological environment. The characterization of NP-PC complexes has attracted enormous research attention, owing to the crucial effects of the properties of an NP-PC on its interactions with living systems, as well as the diverse applications of NP-PC complexes. The analysis of NP-PC complexes without a well-considered approach will inevitably lead to misunderstandings and inappropriate applications of NPs. This review introduces methods for the characterization of NP-PC complexes and investigates their recent applications in biomedicine. Furthermore, the review evaluates these characterization methods based on comprehensive critical views and provides future perspectives regarding the applications of NP-PC complexes.