Shenzhen based Esun company sells the filament they developed that should clean your extruder and nozzle.
Composition of this filament is unknown but it is probably similar to nylon. Nylon filament is used in a cleaning process where it is extruded at 200 C and then cooled to 135 C which hardens it and makes it attract and clean up all the particles that clog up the extruder. Like all similar cleaning methods, this one can also fail.
There is not much information or reviews available around, so if you know something more about this or have any practical experience with it let me know ...
If you want to see good guide on how to clean partially clogged nozzle take a look at: