Abstract: Disclosed herein are nanostructures comprising a polymeric framework comprising at least five geminal bisphosphonate groups, wherein the geminal bisphosphonate groups independently of each other are incorporated as —R3R4C(P?O(OR1)(OR2))2, wherein R1 and R2 are independently selected from the group consisting of a negative charge, H, alkyl and aryl, and wherein at least one of R3 and R4 is a group connected to the polymeric framework with the proviso that when only one of R3 and R4 is such a connected group, the other of R3 and R4 is either a group being able to connect to the polymeric framework, or the residue of such a group, or selected from the group consisting of H, OH, OR5 and R5, wherein R5 is a lower alkyl. The polymeric framework may comprise manganese ions. Disclosed are also methods for producing such manganese containing nanostructures, compositions comprising such manganese containing nanostructures and use of such manganese containing nanostructures, i.a. as MRI contrasting agents.

Abstract: The present invention relates to branched polyethyleneglycol (PEG) derivatives consisting of a molecule with a quaternary carbon connected to three PEG chains, wherein all three PEG chains are of equal length and each comprises 1-30 —OCH2CH2— units, and one group with at least one carbon atom, wherein said at least one carbon atom is attached to the quaternary carbon. Also compositions containing such derivatives and use of such derivatives are disclosed.