Facile fabrication of uniform size-controlled microparticles and potentiality for tandem drug delivery system of micro/nanoparticles.

This article describes a rapid and facile method for manufacturing various size-controlled gel particles with utilizing inkjet printing technology. Generally, the size of droplets could be controlled by changing nozzle heads of inkjet printer, from which ink solution is ejected. However, this method uses drying process before gelling microparticles, and with that, the size of microparticles was easily controlled by only altering the concentration of ejected solution. When sodium alginate solution with various concentrations was ejected from inkjet printer, we found that the concentration of alginate solution vs. the volume of dried alginate particle showed an almost linear relationship in the concentration range from 0.1 to 3.0%. After dried alginate particles were soaked into calcium chloride solution, the size of microgel beads were obtained almost without increasing their size. The microparticles including various sizes of nanoparticles were easily manufactured by ejecting nanoparticle-dispersed alginate solution. The release of 25-nm sized nanoparticles from alginate microgel beads was finished in a relatively-rapid manner, whereas 100-nm sized nanoparticles were partially released from those ones. Moreover, most of 250-nm sized nanoparticles were not released from alginate microgel beads even after 24-h soaking. This particle fabricating method would enable the tandem drug delivery system with a combination of the release from nano and microparticles, and be expected for the biological and tissue engineering application.