Alginate microbeads production
Microencapsulation is one of the most interesting fields in the area of pharmaceutical technology since its inception many years ago. Microencapsulation products (microparticles, microbeads) can be defined as small entities that contain an active agent or core material surrounded by a shell or embedded into a matrix structure.  Among all these materials, alginate appears as a good candidate for many applications. Alginate spheres are one of the most widely investigated cell encapsulation materials as they are biocompatible, non-toxic, biodegradable, and relatively cheap. 
Following is a method for encapsulation of reagent into alginate microbeads with total control of bead formation. A droplet-based microfluidic method is used to precisely control the production of microbeads without the drawbacks of large size distribution that present other methods.
Materials and methods
In this application note we have demonstrated that alginate beads can be successfully produced using the RayDrop with precise control of droplet size. Microbeads of 95-160µm diameter were generated with standard RayDrop configuration (Nozzle of 30µm and outlet capillary 150µm) using alginate solution at 1% in water. Other concentrations of alginate such as 2%, which is widely used in biological application, have also successfully tested by following the same process. In this last case, higher internal diameter tubing has to be used to deal with a more viscous solution. As a consequence, this setup and protocol can be used for encapsulation of mammalian cells, bacteria and other reagents into alginate beads. We have successfully demonstrated that using Fluigent product allow to control precisely alginate beads formation with high monodispersity. As presented, using the RayDrop with different nozzle size allow to have better flexibility. Changing capillary size can be easily done by the user to target different droplet sizes.
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