Introduction: When intravenous or subcutaneous administration of insulin, various side effects or possible risks have been reported. Oral administration of insulin has significant advantages of convenience, painless and mimetic endogenous insulin pathway, and thus it presents patients compliance, protects pancreatic β cells and lessens adverse effects caused by long-term injection. This challenging oral delivery of insulin can be achieved by promising silica nanoparticles (SNs), especially mesoporous silica nanoparticles (MSNs), with controllable morphology and high loading efficiency. This review presents the synthesis and physiological behaviors of SNs such as in vivo and in vitro degradation, absorption, distribution, and excretion, as well as preparations of oral insulin based on SNs. As well, this review will provide insights for innovative oral delivery of SNs and insulin.
Areas covered: Promising SNs and MSNs have gained interests for application in oral drug delivery of insulin.
Expert opinion: After synthesis under proper conditions and methods, promising SNs with controllable structure and suitable stability can be synthesized. By improving permeability and penetration, achieving controlled release and adjusting physiological processes, functionalization on SNs by active groups, molecules, or polymers is necessary for oral delivery of insulin.
Keywords: Insulin; oral delivery; silica nanoparticles; therapeutic protein and peptide.