Plasmon-enhanced photocatalytic nanoreactors for selective inactivation of murine leukemia virus (MLV)

The lack of effective virucides that can eradicate viruses under mild conditions that do not harm mammalian cells or high value biologics poses risks for the food, health care, and pharmaceutical industries. Here, we examine plasmonic nanoreactors that contain the photocatalyst [Ru(bpy)₃]²⁺ localized in the evanescent electric (E-) field of a silver nanoparticle (AgNP) as a selective virucide. The AgNP is passivated by a lipid coating and functionalized with annexin V to target and bind enveloped viruses with surface-exposed phosphatidylserine and localize the light-driven reactivity of the plasmonic nanoreactor virucide (PNV) in the proximity of the virus to enhance inactivation efficacy and minimize collateral damage. The lipid coating prevents premature Ag⁺ release under "dark" conditions and minimizes cytotoxicity. Upon illumination at 470 nm, plasmon-enhanced excitation of [Ru(bpy)₃]²⁺ induces photoreactivity and generates reactive oxygen species (ROS) that damage the bound virus and increase the permeability of the lipid coating around the AgNP, facilitating the release of Ag⁺ ions. Using murine leukemia virus (MLV) as a model, annexin V-functionalized PNVs achieved over 85% viral inactivation after 30 minutes of illumination with 470 nm light (65 mW cm^-2) at a 1 : 1 virus : PNV ratio, with no measurable cytotoxicity in mammalian host cells. These results demonstrate that PNVs combine light-activated reactivity with targeting to achieve potent, selective virucidal activity under mild conditions, paving a path to safeguarding biologics and cell cultures against viral contamination.