Nanomedicine is the application of nanotechnology to medicine and it is enabled by the use of nanosized materials. Many current applications of nanomedicine provide enhanced drug delivery for different therapeutic approaches such as in nucleic acid delivery for cancer gene therapy. Because of the distinct optical, magnetic and structural properties of nanomaterials, nanotechnology has also been applied to promote diagnostic imaging strategies such in the case of fluorescence (FI), magnetic resonance (MRI), computed tomography (CT) or positron emission tomography (PET) modalities. Finally, due to its overall properties, nanotechnology results particularly suitable for the preparation of materials showing at the same time both imaging and therapeutic behaviors. These multifunctional nanomaterials have been defined theranostics (therapeutic+diagnostic) and they represent the key elements for the application of personalized medicine. Attending at continuous demand for the development of more efficient nanocarriers with therapeutic and/or molecular imaging-based diagnostic application, we focus our research toward the design and preparation of novel multifunctional hybrid nanocarriers for the theranosis of cardiovascular, cancer, respiratory and immune-based diseases.