Keywords: EPR; enhanced permeability and retention effect; DTPA; 2-[bis[2-[bis(carboxymethyl)amino]ethyl]amino]acetic acid; TFA; trifluoroacetic acid; Fmoc; 9-fluorenylmethoxycarbonyl; DMF; N,N-dimethylformamide; DCM; dichloromethane; OPfp; pentafluorophenyl ester;