Multi-arginyl-poly-aspartate (MAPA), also known as cyanophycin, containing a backbone of poly-aspartate with arginine and lysine as side chains was prepared with recombinant <i>Escherichia coli</i>. The insoluble part (iMAPA) was conjugated with polyethylene glycol (PEG) of different molecular weights by a reductive reaction between the aldehyde group of PEG acetaldehyde and the amine group of lysine of iMAPA. In contrast to the unmodified iMAPA which has limited solubility in phosphate buffered saline (PBS), the conjugates exhibited UCST-type responses, and the cloud-point temperature of each conjugate also showed a positive correlation with concentration after PEG conjugation. Hysteresis was observed to follow approximate paths under the same condition during repeated heating and cooling. Reversible formation of vesicles with different morphologies appeared at room temperature, depending on the molecular weight of PEG. Some core-shell structures of size ranging from micron to submicron can be observed under TEM. These vesicles are expected to construct a drug delivery system with temperature regulation.

Thermal responses of multi-L-arginyl-poly-L-aspartate conjugated with polyethylene glycol

2019 Fall National Meeting

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