In vitro interactions between splenocytes and dansylamide dye-embedded nanoparticles detected by flow cytometry.

Engineered nanoparticles (NPs) possess a range of biological activity. In vitro methods for assessing toxicity and efficacy would be enhanced by simultaneous quantitative information on the behavior of NPs in culture systems and signals of cell response. We have developed a method for visualizing NPs within cells using standard flow-cytometric techniques and uniquely designed spherical siloxane NPs with an embedded (covalently bound) dansylamide dye. This method allowed NP visualization without obscuring detection of relevant biomarkers of cell subtype, activation state, and other events relevant to assessing bioactivity. We determined that NPs penetrated cells and induced a range of biological signals consistent with activation and costimulation. These results indicate that NPs may affect cell function at concentrations below those inducing cytotoxicity or apoptosis and demonstrate a novel method to image both localization of NPs and cell-level effects. FROM THE CLINICAL EDITOR: A method for visualizing NPs within cells using standard flow-cytometric techniques is reported in this paper. The novel method allowed NP visualization without obscuring detection of relevant biomarkers of cell subtype, activation state, and other events relevant to assessing bioactivity. NPs also induced a range of biological signals consistent with activation and costimulation.