PH-responsive hydrolysis of salicylate-based polyanhydride copolymer fibers for targeted drug delivery

Periodontitis is a chronic inflammatory condition that leads to tissue damage, bone loss, and gingival recession. In this disease, pH levels in the mouth are affected by food and saliva as well as tissue inflammation and damage caused by periodontitis. Monitoring pH levels helps assess disease progression and treatment outcomes; therefore, it is important to study the degradation of the biomaterials under relevant pH conditions. Fibers are valuable in treating periodontal disease by enabling site-specific drug delivery to affected soft and hard tissues. In this work, we evaluate polyanhydride fibers that undergo hydrolysis to yield salicylic acid as a function of pH conditions. The physical properties of the polyanhydrides, specifically those based on ester-containing carboxyphenoxydecanoate (CPD), can be altered by copolymerization with ether-containing para-carboxyphenoxyhexane (pCPH) to affect degradation rates under specific pH conditions. Overall, we observed that the CPD:pCPH copolymer is more resistant to hydrolysis than the CPD homopolymer. We examined the effects of degradation media pH on the hydrolysis of 50:50 CPD:pCPH fibers (fibers containing 50% CPD and 50% pCPH) with pH values ranging from pH 6 to 9. This pH range was chosen as it covers the pH values typically observed in the gingival crevicular fluid (GCF) as well as in the gastrointestinal tract. As a general trend, increasing the pH of the degradation media increased the rate at which the copolymer fibers were hydrolyzed. This work will help enable targeted drug delivery to specific areas in the body, such as acidic tumors or the gastrointestinal tract, for efficient medication release.