An experiment to introduce pH-responsive hydrogels for controlled drug delivery

Stimuli-responsive polymers are used in a variety of biomedical applications. For example, pH responsive hydrogels have been extensively investigated for controlled drug delivery. By responding to the pH environment in the body, which changes depending on location and metabolic state, a pH-sensitive drug dosage form is able to modulate drug delivery patterns to meet physiologic requirements and minimize side effects. This paper describes an experiment used to introduce freshmen engineering students to stimuli-responsive polymers for controlled release applications. Students produce a pH responsive hydrogel, made from polyethylene glycol grafted onto a polymethacrylic acid backbone p(MMA-EG) using free radical polymerization. These hydrogels were previously examined for oral delivery of insulin for diabetics by Nakamura et al. In our experiment, the swelling capabilities of the hydrogels in different pH environments are examined as a function of crosslink density. In future experiments, hydrogel mechanical properties and release properties, as a function of these variables, will be examined. In addition to learning about pH-responsive drug delivery, students will learn concepts of polymer chemistry, materials science, design of experiments, data analysis, and engineering design. An assessment plan will measure student mastery of learning outcomes specific to the field of biomaterials science and those set forth by ABET for undergraduate chemical engineering programs.