Facile construction of multivalent targeted drug delivery system from Boltorn® series hyperbranched aliphatic polyester and folic acid

The conjugation of PAMAM dendrimer and folic acid is a well‐studied multivalent targeted drug delivery system, but it is expensive and difficult to be synthesized. To construct an inexpensive and well‐defined multivalent targeted drug delivery system, a cheap carrier — Boltorn® series hyperbranched aliphatic polyester — was proposed as the nanodevice to carry fluorescein, folic acid, and methotrexate. The construction follows a facile route: (1) synthesizing the carrier — a hybrid hyperbranched polymer with acyclic hydroxyls and cyclic carbonate, (2) linking fluorescein to the hyperbranched polymer via the acyclic hydroxyls, (3) opening the ring of the cyclic carbonate with the amino group of folic acid, and (4) attaching the drug methotrexate to the resulting hydroxyls by ring‐opening reaction. In this route, the peripheral hydroxyls of the hyperbranched polymer are divided into two groups and reacted with three reagents in sequence to form the desired multivalent targeted drug delivery system. Copyright © 2009 John Wiley & Sons, Ltd.