<i>Retracted</i>: Synthesis, Characterization, and <i>In vitro</i> Studies of <scp>PLGA</scp>–<scp>PEG</scp> Nanoparticles for Oral Insulin Delivery

Therapeutic proteins and peptides are corresponding to a major area of research in biotechnology companies and current pharmaceutical. Because of their natural instability, the enormous majority of these drugs require parentéral administration. Oral insulin delivery would be a highly attractive alternative process of administration, though it continues to be a mysterious target due to the enzymatic digestion of insulin and low levels of absorption from the gastrointestinal region. Hydrogel polymers can be considered as potential carriers for oral insulin delivery. In particular, a pH responsive hydrogel composed of PLGA-PEG has shown the ability to protect insulin from enzymes in the gastric environment and release in small intestines. However, this material has not shown similar potential for oral protein delivery of further model drugs. To date, the unique interaction between PLGA-PEG and insulin, as a potential drug for oral delivery, is not completely understood. The focus of this research is synthetization and characterization of hydrogels PLGA-PEG insulin nanoparticles and also pH sensitivity of insulin nanoparticles was investigated.