Dear Adam Milsom et al.

Thank you for dealing with the referee comments so detailed. I'm happy to accept the revised manuscript for publication. I however noticed that title and abstract could be improved to fully agree with ACP's guidelines and ask you to change accordingly (https://www.atmospheric-chemistry-and-physics.net/policies/guidelines_for_authors.html). For this step, the manuscript will not be send to referees but one more round of review by the editor is required.

Title: For research articles, ACP prefers titles that highlight the scientific results/findings or implications of the study. A possible title might be "Experimental observation of the impact of nanostructure on hygroscopicity and reactivity of fatty acid atmospheric aerosol proxies".

Abstract: Please add a statement on the "The gap in knowledge being addressed"