Polybead hollow microspheres (5.21% solids, 1 μm in diameter) were purchased from Polysciences. Texas-Red-conjugated dextran (Mw = 3 kDa, 10 kDa) and anti-fade agent were purchased from Invitrogen. THF, mineral oil, and glycerol were purchased from EMD Biosciences. Solvable was purchased from Perkin-Elmer. Dialysis cassettes (MWCO = 2500) were purchased from Thermo Scientific. Syringes (1 mL) were purchased from BD and 23 guage, 1.5-inch-long single capillary stainless steel tip was from EFD. Iron oxide nanoparticles of 30-nm diameter suspended in chloroform with oleic acid stabilization were purchased from Ocean Nanotech. Filters (5–8 μm) were purchased from Millipore.