Bioadhesive capacity and immunoadjuvant properties of thiamine-coated nanoparticles.

The general aim of this work was to develop polymeric nanoparticle carriers with bioadhesive properties, and to evaluate its adjuvant potential for oral vaccination. Thiamine was used as specific ligand-nanoparticle conjugate (TNP) to target specific sites within the gastrointestinal tract, enterocytes and Peyer's patches. The affinity of nanoparticles to the gut mucosa was studied in orally inoculated rats. In contrast to conventional non-coated nanoparticles (NP), higher levels of TNP were found in the ileum tissue, showing a strong capacity to be captured by Peyer's patches. TNP were characterized by an AUCadh which was found to be three times higher than for control NP. To investigate the adjuvant capacity of TNP, ovalbumin (OVA) was used as standard antigen. Oral immunization of BALB/c mice with OVA-TNP induced stronger serum titers of specific IgG2a and IgG1 and mucosal IgA compared to OVA-NP. This mucosal immune response (IgA) was about 4-titers higher than that elicited by OVA-NP. These results suggest the use of thiamine-coated nanoparticles as particle vectors for oral vaccine and immunotherapy delivery strategies.