Development of Microspheres Based on Thiol-Modified Sodium Alginate for Intestinal-Targeted Drug Delivery

The bioactive peptides drugs are mostly delivered by parenteral administration, which brings great pain and risks to patients. Oral administration is an acceptable alternative form. However, the peptides drugs are extremely sensitive to strong acid environment in stomach after oral administration. They would be degraded by pepsin and trypsin in gastrointestinal tract. Herein, we present microspheres for intestinal-targeted peptides drugs delivery through oral administration. Sodium alginate was reacted with L-cysteine to bring into thiol groups. Then sodium alginate-L-cysteine conjugates were mixed with native sodium alginate and emulsified by an improved method. Ca2+ was used to fix the emulsion to get the microspheres. Bovine serum albumin was used as the simulating drug to assess the feasibility of microspheres as intestinal delivery carriers. The results showed that the microspheres exhibited spherical properties and narrow size distribution. The drug-loading capacity of microspheres was not compromis...