Disclosed herein are peptide-grafted compounds that irreversibly deactivate bacteriophages or influenza virus depending on the peptide and remain safe for bacteria and mammalian cells. The active compounds comprise a core (cyclodextrin or gold nanoparticle) coated with a hydrophobic chain terminated with a peptide selective for bacteriophages or for influenza. Further, said compounds can be used directly inside the environment of the bioreactor, but they are also a safe additive to stocks of antibiotics and expression inducers (such as isopropyl ß-D-1-thiogalactopyranoside, i.e., IPTG), that cannot be autoclaved and are a common source of phage infections. The anti-influenza compound may be used as a drug to be given in therapeutic or prophylactic mode to fight influenza infection.