Effect of manufacturing parameters on the characteristics of vitamin C encapsulated tripolyphosphate-chitosan microspheres prepared by spray-drying

Abstract

To prepare the sustained release vitamin C carriers, vitamin C was successfully encapsulated in tripolyphosphate (TPP) cross-linked chitosan (TPP-chitosan) microspheres by the spray-drying method at different manufacturing conditions. Manufacturing parameters (inlet temperature, liquid flow rate, chitosan concentration and volume of 1% w/v TPP solution) had a significant influence on the characteristics of thus prepared microspheres. The optimum spray-drying conditions such as inlet temperature, liquid flow rate and compressed air flow rate for the encapsulation of vitamin C in TPP-chitosan microspheres was found to be 170°C, 2 ml min⁻¹ and 10 l min⁻¹, respectively. The size and yield of the TPP-chitosan microspheres ranged from 3.9–7.3 µm and 54.5–67.5%, respectively. The encapsulation efficiency of TPP-chitosan microspheres ranged from 45.72–68.7% and it decreased with the increasing volume of 1% w/v TPP solution. At the same cross-linking extent, the encapsulation efficiency of TPP-chitosan microspheres increased when the concentration of chitosan was increased from 0.5–1% w/v. Effect of volume of 1% w/v TPP solution on the surface morphology of chitosan microspheres was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These studies revealed that chitosan solution (250 ml) cross-linked with 15 ml 1% w/v TPP solution produced more porous microspheres than that cross-linked with 5 and 10 ml TPP solution. The release rate of vitamin C from TPP-chitosan microspheres decreased when the concentration of chitosan was increased from 0.5–1.0% w/v. Vitamin C release rate was also modulated by varying the volume of 1% w/v TPP solution. The release rate of vitamin C from TPP-chitosan microspheres decreased with increasing volume (5–15 ml) of 1% w/v TPP solution.

Key Words: :

• Vitamin C
• chitosan
• encapsulation
• microspheres
• tripolyphosphate
• controlled release