Recently, viral infections have become the world’s biggest dilemma once again due to novel coronavirus disease 2019, which quickly turned into a global pandemic as declared by the World Health Organization on March 11, 2020, and has been affecting human life at great expenses since then. To fight with the emerging new enemy which is in nanosize, biomimetic nanotechnological approaches are quickly revisited to develop effective antiviral nanotherapeutics with reduced systemic toxicity and more precise targeting. Since multifunctional metal nanoparticles are one of the most important key players of the nanoworld, their synthesis methods and applications in antiviral therapeutic agents and nanovaccines against different viruses, that is, human immunodeficiency virus, hepatitis viruses, influenza A virus, herpes simplex virus, and severe acute respiratory syndrome coronavirus 2, are discussed in this chapter.
