Disclosed is a nanoparticular formulation comprising 1) a compound comprising polyethylene glycol (PEG) or methoxypolyethylene glycol as hydrophilic structural element and an alkyl chain as lipophilic structural element and 2) a near fluorescent dye which is indocyanine green, wherein the alkyl chain has 3 to 30 carbon atoms, which can be independently mono- or poly-substituted with C1-C3 alkyl, hydroxyl or phenyl, wherein the hydrophilic and lipophilic structural element are connected via a covalent bond,and and wherein the nanoparticular formulation forms micelles in aqueous media. A process for preparing the formulation is also disclosed.
