Influences of Size and Amount of Colloidal Template and Droplet Diameter on the Formation of Porous-structured Hyaluronic Acid Particles

Combination of spray drying and templating method has been reported as one of the best method to produce porous pharmaceutical particles. However, current development reports have shown successful formation of porous particles with improper information on what mechanism occurs during the synthesis process and what process parameters involve the creation of particles with controllable pore structures and morphologies. In this report, influences of spray-drying parameters (i.e., size and amount of colloidal template, and droplet diameter) on porous particle fabrication were investigated. Hyaluronic acid (as a model of pharmaceutical drug host component) and polystyrene spheres (as a model of template) were used. The experimental results showed that the spray-drying parameters strongly influenced the external morphology (i.e., spherical and doughnut-shaped), particle outer diameter (from 300 to 2000 nm), and porous configuration (i.e., number of hole cavities and pore sizes (from 100 to 300 nm)) of particles. To qualitatively explain our synthesis strategies to get porous structure, the proposal of the particle formation mechanism was added.