Nanoparticles (NPs) have been gaining growing interest in the biomedical scene thanks to unique characteristics such as high surface-to-volume ratio and tuneable surface chemistry, that allows them to be a first-line-strategy for cancer treatment, overcoming limitations related to the patient-to-patient variability and off-target side effects. NPs can be categorized based on the constitutive material, identifying polymeric, inorganic and lipid-based NPs, each one with his own pros and cons regarding cargo, delivery and related immune-response. Additionally, hybrid nano-systems are increasingly being studied to create biomimetic NPs with enhanced characteristics in terms of cell targeting and chemical stability in biological environment. When in contact with biological fluids, such as blood, plasma or serum, protein absorption takes place on the surface of the NP, forming what has been defined as protein corona (PC).