Response to “Comment on Bulk Nanobubbles or Not Nanobubbles: That is the Question”

Advanced techniques which combine high spatial resolution with chemical sensitivity to directly probe the observed nano-entities and provide direct evidence that they are truly gas-filled nanobubbles do not exist. Therefore, in our paper we focused on providing, for the first time, multiple indirect evidence using a variety of physical and chemical techniques, that the nano-entities are not due to contamination and, hence, they must be bulk nanobubbles (BNBs). It should be noted that such techniques require good experimental skills, sound protocols, good scientific expertise and reliable equipment. Whilst no single piece of indirect evidence on its own can be considered as conclusive proof, we estimate that our results combined provide strong evidence that bulk nanobubbles do exist and they are stable. The work presented in our paper is the culmination of a series of studies, and many authors have either directly or indirectly confirmed our findings. Nonetheless, in their Comment, Rak & Sedlak reject all of the work we reported. We here address their comments point by point and show that their criticisms are unwarranted and unfounded, as follows.