An attempt to design and synthesize a new polymer displaying solubility over a broad pH range has been carried out. HEC–cysteamine can be synthesized and designed by ring opening of glucose subunits of unmodified HEC using sodium periodate followed by reductive amination of the oxidized HEC. The conjugate is a novel thiomer with positive charges which can be explored in the pharmaceutical field especially for intestinal drug delivery due to properties such as swelling behaviour, cohesive, mucoadhesive and permeation enhancing properties. Within this book, the nanoparticles based on HEC-cysteamine of various degrees of thiolation generated by oxidation and reductive amination improved the transport of model compounds as compared to the buffer control. According to the achieved results, the conjugates could be a promising tool for delivery of peptide/protein drugs to the gastrointestinal tract.
Novel designed preactivated thiomers were prepared by immobilizing 2MNA on the polymeric backbone polyacrylates. The influence of molecular mass and degree of preactivation with 2MNA on permeation enhancing properties of the thiolated polyacrylates was evaluated. Some preactivated thiomers could improve the permeation of model drug. Thiolated microparticles generated by spray drying method were shown to have mucoadhesion and controlled (VB 12) release properties compared with unmodified particles due to the presence of free and oxidized thiol groups as shown by PAA–cysteine conjugate. Transfection and bioavailability study of the other thiolated polymers were also discussed in this book.