Formation of monodisperse cross-linked nanospherial condensates based on flow-focusing and droplet diffusion techniques

By generating the monodisperse droplets of disperse phase in the continuous phase and keeping them stable during condensing process, it is possible to fabricate monodisperse spherical condensates using emulsification–diffusion technique. In this work we fabricated the monodispersive polylysine micro- and nano-spheres by using “flow-focusing” and droplets diffusion techniques. By keeping the flow rates of dispersed phase and continuous phase constant, the size of condensed and glutaraldehyde cross-linked polylysine spherical particles was tuned from tens micrometers to tens nanometers by varying the concentration of the polylysine solution. Near monodisperse spheres can form from tens micrometers to hundreds nanometers with similar size distribution. The luminescence experiment shows that the stability of small molecules trapped by cross-linked polymer can be stable over tens hours when sufficient aldehydization keeps the condensates stable.

Graphical abstractPolylysine microspheres and nanospheres condensed after “flow-focusing” and emulsion diffusion and cross-linking processes.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Fabricating a “Flow-Focusing” microfluid device. ► Condensing polylysine into monodisperse spheres through diffusion and cross-linking. ► Characterizating the monodispersity of spherical condensates.