Formation of particles prepared using chitosan and their trimethyl chitosan derivatives for oral vaccine delivery: Effect of molecular weight and degree of quaternization

The purpose of this study was to investigate the effect of molecular weight (MW) of chitosan and the degree of quaternization (DQ) of trimethyl chitosan (TMC) on the formation of particles. The amount of tripolyphosphate (TPP) was varied in order to optimize the preparation condition of particles. Particle size, zeta potential, loading efficiency (LE) of ovalbumin (OVA), a model antigen, and OVA release profiles were also investigated in order to select the best systems for oral vaccine delivery. The results showed that the amount of TPP added has an effect on the ability of chitosan and TMC polymer to form particles. The formation of chitosan particles required a higher amount of TPP than that of TMC particles. Using the same amount of TPP, the MW of chitosan did not have an effect on particle formation whereas the DQ of TMC had. Depending on the amount of TPP, the size of particles prepared from chitosan and their TMC were in the range of 0.5-2.3 m and their positive charges were in the range of 3-48 mV. Adding the same amount of TPP, the size of the chitosan particles was larger than that of their respective TMC particles. The size of the TMC particles was decreased with increasing of DQ. The zeta potential of the TMC particles was higher than that of their starting chitosan particles and it increased with increasing DQ. The loading efficiency (LE) of OVA onto the TMC particles was charge-dependent. MW did not affect the LE of chitosan particles. The OVA release from the particles prepared depended on the solubility and loading capacity of the particles.