Mansour Rojabian - Chemistry group, Department of Science, University of Zanjan, Zanjan, Iran
Kobra Rostamizadeh - Department of Medicinal Chemistry, School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran,
Ali Ramazani - Chemistry group, Department of Science, University of Zanjan, Zanjan, Iran

Nowadays, there are many bioactive molecules for potential applications in treatment of various diseases, but unfortunately their extensive use have been limited due to low aqueoussolubility, rapidly clearance from circulation, giving rise to immunological problems, and burst release. For overcomingthese problems, one of the solutions is to attach macromolecules such as polymers to bioactive agents. Poly(ethylene glycol) (PEG) is a highly investigated polymerfor covalent and surfaces modification of bioactive molecules and encapsulation of different drugs [l]. PEG possesses many useful properties including wide range of solubility in both organic and aqueous media, lack of toxicity and immunogenicity [2], no biodegradability, and ease ofexcretion from living organisms [2, 3]. This study was aimed to fabricate alternative copolymer of PEG and L-lysine with pendent carboxyl groups in order to increase PEG drug attachment ability with high solubility in aqueous solutions.