Chitosan-based Polyelectrolyte Complexes: Characteristics and Application in Formulation of Particulate Drug Carriers

Abstract

Over the past few decades, chitosans have gained great attention in the field of biomedicine. Unique cationic nature, biocompatibility, biodegradability, origin from renewable sources, and diversity make these biopolymers good candidates for micro- and nanoencapsulation of cells, genes, proteins, and structurally different drugs. Under suitable conditions, these polycations can interact with various polyanions, creating assemblies known as polyelectrolyte complexes (PECs) with physicochemical properties that significantly differ from those of the individual polymers. The reversible nature of interaction between comprising polymers and stimuli-responsive nature, particularly the pH sensitivity, makes PECs suitable for drug delivery applications. This chapter summarizes basic principles of polyelectrolyte complexation and discusses the importance of experimental conditions (e.g., pH value and ionic strength of the reaction medium, concentration, and ratio of individual polymers) and the influence of relevant functional properties of chitosans (e.g., molecular weight, degree of deacetylation, and viscosity) on this process. The chapter discusses in detail the overall effect of chitosan-based PECs on morphology, encapsulation efficiency, stability, and drug release properties of anionic-based particulate drug carriers. Finally, a brief overview of various physicochemical and biopharmaceutical techniques that can be applied for characterization of these complexes and related particulate drug carriers is presented.