The present invention relates to a hydroxyalkyl starch (HAS) derivative of formula (I) wherein F1 is a functional group comprising the group —NR′—, with R′ being H or alkyl L is a spacer bridging F1 and S wherein HAS′ is the remainder of the HAS molecule, Rb and Rc are —[(CR1R2)mO]n—H and are the same or different from each other Ra is —[(CR1R2)mO]n—H with HAS′ being the remainder of the hydroxyalkyl starch molecule, or Ra is HAS″ with HAS′ and HAS″ together being the remainder of the hydroxyalkyl starch molecule R1 and R2 are independently hydrogen or an alkyl group having from 1 to 4 carbon atoms, m is 2 to 4, wherein R1 and R2 are the same or different from each other in the m groups CR1R2 n is from 0 to 6.
