“…Moreover, to investigate the stability of the bulk nanobubbles, the authors use other gases, including nitrogen, oxygen, helium, and argon. 133 They nd that under the same conditions, CO 2 nanobubbles are smaller than the other gases due to their higher solubility in water. The produced bulk nanobubbles have a concentration of approximately 6 Â 10 7 mL À1 , which is acceptable for several in vivo and in vitro biomedical applications.…”