Microemulsion and diafiltration approaches: an attempt to maximize the global yield of DNA-loaded nanospheres

The yield of DNA-loaded nanospheres in its widest definition includes encapsulation efficiency and the integrity of the loaded molecules plus the production yield of fabricated nanospheres. The former aspect could be considerably improved by adopting the microemulsion concept to enhance the stability of the primary emulsion during the preparation of nanospheres by the double emulsion solvent-removal method. The droplet size of the mentioned emulsion was monitored by means of photon electron correlation spectroscopy and could serve as an index for emulsion fineness and stability. DNA stability as a function of applied mechanical stress was monitored by horizontal agarose gel electrophoresis. The impact of the primary emulsion on nanosphere porosity was assessed as well. Regarding the second aspect of the global yield of nanospheres, i.e. production yield, a modified diafiltration technique was adopted for the washing and recovery processes in comparison with the traditional and for the conservation of particle size characteristics of the recovered nanospheres.