Figure 3:

Biotin-PLG particles can be efficiently conjugated with SA-FasL and induce apoptosis in mouse B lymphoma cell line. (A) Schematic of biotin-PLG particles being functionalized with SA-FasL. (B) The amount of fluorescently tagged SA bound to the particles was investigated by varying the protein concentration (0, 100, 200, 400, 800, and 40,000 ng SA/mL in 1 mL) incubated with 1 mg of biotin-PLG particles (“biotin particles”). As a control, 1 mg of unmodified PLG particles was incubated with the same SA concentrations (“blank particles”). After two spins and washes, particles were dissolved in DMSO and fluorescence was measured, n=3. (C) The loading efficiency was calculated by dividing the bound SA by the incubated SA, n=3. (D) Biotin-PLG particles functionalized with SA-FasL induce cell death in A20 cells. Particles were incubated with 400 ng / mL of SA-FasL in 1 mL with 1 mg of particles. After washing to remove unbound SA-FasL, particles were incubated with 1.5 × 10⁵ A20 cells for 18 hours and cell death was analyzed via propidium iodide stain and flow cytometry (n=3). For comparison, soluble FasL was added to cells (0, 10 ng) and demonstrated the ability to induce cell death at low concentrations (n=3).