Flow cytometric analysis of the physical and protein-binding characteristics of solid drug nanoparticle suspensions.

Aim: Oral and intramuscular sustained-release antiretroviral solid drug nanoparticles (SDNs) are in development but there is limited understanding of whether nanoparticles or dissolved drug predominate systemically.

Materials & Methods: A flow cytometric method was developed to analyze SDNs in biological fluids such as plasma, including the putative formation of a protein corona.

Results: SDNs were found to be stable in plasma and could be observed using the techniques developed here.