Protein and peptide delivery through chitin, chitosan, and starch

A drug delivery system is a technique of administering drug substances/drug formulation in the body. It may function as a drug or serve as a vehicle to transport the drug to the appropriate site in the body. Enteral (oral, sublingual, buccal, and rectal), parenteral (intravenous, intramuscular, and subcutaneous), and topical (skin) methods account for the majority of drug administration. Depending upon the nature, severity, location of illness, molecular structure of drug, and desired pharmacological effects, the route of drug administration is decided. To alter half-life and bioavailability of drugs, which could be peptides, proteins, biomolecules, aptamers, antibodies, etc., these moieties can be modified or functionalized with polymers such as dextran, glycogen, starch, cellulose, chitosan, etc. However, these carrier systems may suffer from certain toxicities for which greener resources, that is, natural polymers are strong contenders as carrier systems in nano delivery systems. Researchers are tweaking around the functionalization methods for natural polymers such as starch, chitosan, dextran, and cellulose to make drug/peptide delivery more effective. This chapter primarily deals with the overview of natural polymers, viz., chitin, chitosan, and starch polymers, along with their characteristics and structural modifications of aforementioned polymers. The chapter then talks about the significance of proteins and peptides in therapeutic delivery. This chapter also expounds on different routes of administration by which the proteins and peptides could be delivered through myriad types of nanoformulations. The multifold therapeutic applications in peptide delivery have also been discussed at length. The importance of peptide delivery has also been emphasized in this chapter. The chapter is concluded with challenges in the path of peptide delivery.