(top) The normalized VIP fluorescence intensity, I/I0, as a function of the clip/cVIP ratio, where I and I0 are fluorescence intensities observed for VIP in solutions with and without DSPE-PEG2000 monomers, respectively. A steady-state approximation (arrows) is used to obtain the Nmon:NVIP saturation molar ratio, shown in the table (bottom). The VIP concentration is cVIP = 4 μM, while the concentration of DSPE-PEG2000 is varied. The table also shows dh, determined by DLS, and estimated SSM aggregation numbers, Nagg [17], which are used to determine the VIP loading efficiency (Neff = NVIP/NSSM).