Structural modifications of biocompatible and biodegradable polymers with thiol moiety can result in improved properties and numerous biomedical application including targeted drug delivery, mucoadhesion, P-gp inhibition, permeation enhancement, enzyme inhibition, capping agent and enveloping agent for other nanocarriers. Thus, these thiolated polymers can serve as a novel multifunctional platform for successful delivery of therapeutic as well as diagnostic agents to achieve desired outcomes.