Complete dissociation and reassembly behavior as studied by using poly(ethylene glycol)-block-poly(glutamate sodium) and kanamycin A
Kanamycin A, an amino modified sugar, can interact with poly(ethylene glycol)-block-poly(glutamate sodium) (PEG114–PGlu64) via electrostatic interactions (with PGlu) and hydrogen bonding (with PEG). The interplay of these two forces determines the assembly process and the resulting structure. In deionized water, kanamycin A and PEG114–PGlu64 form a spherical structure at [+]/[−] = 3.5. This structure dissociates instantly and completely in the presence of 30 mM NaCl. However, a new structure is reassembled in about 2 hours. A similar phenomenon is observed when the buffer pH is increased from 7.8 to 8.3. We attribute the distinct dissociation/reassembly process to the reestablishment of the balance between electrostatic interactions and hydrogen bonding. The dissociation/reassembly process in response to environmental changes offers a novel approach to release the loaded cargo in a controlled manner.