In situ formation of viruses tagged with quantum dots

Quantum dots (QDs) have great potential for applications in bio-related fields, due to their high photoluminescence, photochemical stability and size-dependent emission. QDs used for the construction of QD-virus hybrids can be harnessed as an imaging probe to reveal viral infection pathways and screen antiviral agents. In the study, human embryonic kidney (HEK) 293T cells were transfected with three plasmids, pSIN-EGFP, pMDG, and p8.91, to produce lentiviruses which can make infected cells express enhanced green fluorescent protein (EGFP). The QDs employed were CdSe-ZnS semiconductor nanocrystals emitting red fluorescence. The QD-virus hybrids, constructed as lentiviruses, were budding from the membrane surface of HEK 293T producer cells on which QDs encapsulated with alkylated chitosan (chitosan-QDs) were pre-adsorbed via electrostatic attraction force. Such in situ formation of QD-virus hybrids was confirmed by TEM micrographs indicating the lentivirus was capped with chitosan-modified QDs. To further illustrate the effectiveness (i.e., infectivity and photoluminescence) of the constructed QD-virus hybrids, NIH 3T3 cells were infected with the in situ fabricated QD-virus hybrids. Our results showed QDs were indeed entering NIH 3T3 cells along with lentiviruses as hybrids. Moreover, photoluminescence and infectivity of QD-virus hybrids remained intact, as compared to QDs and lentivirus alone. The unique approach of constructing QD-virus hybrids taking advantage of the viral budding process offers a feasible tool to create enveloped virus incorporated with nanomaterials for the study of fundamental and applied virology.