This thesis describes the efforts toward developing new molecular probes which can target and report on biological membranes. These probes employ sophisticated fluorescence or photothermal reporting group, and one or more high affinity ligands for receptors of biological importance. Specifically, four studies were conducted: Covalently conjugated far-red fluorescent probes employing one or two cRGDfk targeting ligands were shown to internalize into OVCAR-4 cells and tumors. Additional targeting and uptake studies into cancer cells were conducted with non-covalently preassembled fluorescent molecular probes created using Synthavidin (synthetic avidin) technology. Synthavidin technology was also used to functionalize the surface of liposomes, endowing them both with far-red fluorescence and affinity for either cationic or anionic biological membranes. Finally, photothermal croconaine dyes were incorporated into nanoparticles to create stable nanoparticles capable of far-red laser triggered payload release.