Accesing node material values (properties) into VIEW_3D - TOOLS

Hi guys, any clue about how to access values from a node (for example diffuse) of a material into the VIEW_3D - TOOLS panel?

Do I need to create an operator?

I don´t need to save or assign a new property to the object in context, I just want to access a node from a material in special.

I hope you can guide me, thanks a lot in advance!