Complex sentence: Significant problems with producing nanoparticles initially arise once these nanoparticles are generated in solution because without the use of a stabilizing agent, the nanoparticles tend to stick together once the stirring is stopped.
Split into simpler sentences: Significant problems with producing nanoparticles initially arise once these nanoparticles are generated in solution. Without the use of a stabilizing agent, nanoparticles tend to stick together once the stirring is stopped.