Synthesis and characterization of magnetic chitosan-poly (acrylic acid) hydrogels as drug delivery system for 5-fluorouracil

Hydrogels are three-dimensional polymer networks that are able to retain a large amount of water in their swollen state. Hydrogels have become very popular due to their unique properties such as high water content, softness, flexibility and biocompatibility. These compounds have tendency to absorb water due to the presence of hydrophilic groups such as -SO3H, -CONH2, and -CONH. Gels can be hydrated in a variety of proportions, which in some cases it reach more than 1500-2000 percent by weight of polymer, and it can be due to the nature of the aqueous medium and the polymer structure [1]. Medications or electrophobic species are trapped in the pores structure of the hydrogels and released from their structure based on a mechanism that depends on the spreading coefficient of the drug or the electroactive species [2]. Hydrogel-based drug delivery systems are divided into two major groups: 1. Systems with time control. 2. Release systems due to the presence of a stimulus. Environmentally sensitive hydrogels, known as smart systems, are divided into three sub-branches: 1. Release system with physical stimulation such as temperature, electrical current, light and pressure. 2. Release system with chemical stimulation such as pH, the composition of solvents, ions, and special interactions that lead to identify the molecules. 3. Release systems with other stimuli [3]. Magnetic chitosan-poly (acrylic acid) hydrogels were synthesized and used as drug delivery system. The chemical structure and surface morphology of the magnetic chitosan-poly (acrylic acid) hydrogels were studied by FTIR, SEM, and XRD, techniques. The swelling properties of the hydrogels were investigated in pH 1.2 and 7.4 buffer solutions. 5-fluorouracil (5-FU) was selected as an anti-cancer model drug. The pH-responsive release was verified by in vitro release test at pH 1.2 and 7.4. The obtained results showed that the swelling ratio of hydrogels increased by decreasing of the pH from 7.4 to 1.2. The releasing behavior of 5-FU to the hydrogels, indicated that chitosan-poly (acrylic acid) hydrogels had better drug releasing under acidic conditions.