1. Drug content: Generally, you can determine the loading% or loading capacity of the nanoparticles(NPs) by first degrading them (e.g. 1mg of NPs) in an organic solvent or DMSO, then precipitating and removing the polymers after a centrifugation step, and finally measuring the drug concentration via UV/Vis absorption, Fluorescence spectroscopy, or HPLC (depended on the drug nature).
2. Polymer content: If you could precipitate the polymer and phospholipid and separate them from the drug as I stated above, thereby U can perform HPLC on the pelleted lipid+polymer and determine their quantity and then calculate their weight or molar ratio (Polymer:Lipid) ====> This was just an idea!