A 13 nm GNP (G13) was synthesized by citrate reduction of H[AuCl4] (SI, Section 5) and used to construct antiviral PNLs in two steps. First, G13 was partially PEGylated with a hepta(ethylene glycol) thiol (HS-EG7-OH) to prevent aggregation during lectin conjugation. This was achieved by overnight incubation of G13 with 2000 molar equivalents of HS-EG7-OH in water to yield ppG13-OH. Second, ppG13-OH was incubated with 100 molar equivalents of linker labeled lectins overnight to make G13-lectin based PNLs via self-assembly (Fig.