Controlled release of silica-coated insulin-loaded chitosan nanoparticles as a promising oral administration system

Oral insulin administration has recently become one of the most exciting research subjects. Different approaches have been carried out to get an effective oral insulin delivery system using nanotechnology. The development of a delivery system that overcomes the difficulties of oral insulin administration, achieving high stability and minimal side effects, is still an urgent need. Therefore, this study is considered one of the efforts to design a new prospective drug delivery nano-composite (silica-coated chitosan-dextran sulfate nanoparticles).

Chitosan-dextran sulfate nanoparticles (CS-DS NPs) were prepared via a complex coacervation method and then coated with silica. Uncoated and silica-coated CS-DS NPs were physically characterized via different techniques. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, and atomic force microscopy (AFM) have been used to investigate the chemical elements, size, morphology, and surface properties of the prepared formulations. Differential scanning calorimetry (DSC) to assess the thermal properties of formed nano-formulations. Fourier transform infrared (FT-IR) spectroscopy investigated the silica coat and chitosan interaction. The encapsulation efficiency was evaluated using high-performance liquid chromatography (HPLC) analysis. The insulin release profile of nano-formulations was performed with and without silica coat at two different pHs (5.5,7), nearly simulating the environment of the gastrointestinal tract (GIT).

The silica-coated CS-DS NPs revealed interesting physicochemical properties exemplified by suitable core particle size obtained by TEM images (145.31 ± 33.15 nm), hydrodynamic diameter (210 ± 21 nm), high stability indicated by their zeta potential value (-32 ± 3.2 mV), and adequate surface roughness assessed by AFM. The encapsulation efficiency of insulin-loaded chitosan nanoparticles (ICN) was (66.5%) higher than that of insulin-chitosan complex nanoparticles (ICCN). The silica-coated ICN demonstrated a controlled insulin release profile at pHs (5.5 and 7) compared with uncoated ICN.

The silica-coated ICN can be an efficient candidate as a desired oral delivery system, overcoming the common obstacles of peptides and proteins delivery and achieving high stability and controlled release for further applications.