Abstract
Polyelectrolyte complex gel beads have been used for wide-spread application, including use in medical, pharmaceutical, and bioengineering fields. Many of these applications of polyelectrolyte complex gel beads require narrow size distribution as well as strict control of particle shape. A calcium alginate beads or an alginate poly-L-lysine alginate system is the most commonly employed system in these polyelectrolyte complex systems. In this study, we demonstrated novel method for preparing monodispersed calcium alginate beads with small diameter (less than 300 µm) using microfabricated nozzle (MN) array. The MNs with an inner witdth of 30 x 30 µm and outer witdth of 60 x 60 µm were fabricated by photolithography and deep reactive ion etching process. Alginate droplets with narrow size distribution were formed by extruding the alginate aqueous solution into the flow of soybean oil through MNs. Monodispersed alginate droplets with an average diameter of 88.4 µm and a coefficient of variation of 5.9% were formed from MNs. The CaCl2 droplets were formed in the same manner at the downstream of the soybean oil flow. Calcium alginate beads were prepared by the immediate contact between alginate droplets and CaCl2 droplets. Most of the prepared beads had spherical shape. The number-average diameter and coefficient of variation of the prepared beads was 77.4 µm and 11.1%. The method proposed in this study is expected to be applicable for the various polyelectrolyte complex systems.
