“…The conjugation of RGD peptide was verified by mass spectrometry by the method reported by Desu [236] with slight modifications using Micromass Q-tof-2 TM mass spectrometer (Micromass, Manchester, UK). The cRGD peptide and maleimide DSPE-PEG 2000 were dissolved separately in 50 mM HEPES buffer pH 6.5, and mixed in equimolar ratio.…”