Height images were collected under ambient conditions (22◦C, 50% humidity)using a silicon tip (OMCL-AC160TS, Olympus Corp.). The reported roughnesses were determined from the root mean square (RMS)values of 2 m × 2 m, 5 m × 5 m, or 10 m × 10 m scan areas.In order to observe the morphology of chitin NCs, chitin NCs were deposited onto SAM-NH2 coated gold surfaces through spincoating of an aqueous 0.005% by mass chitin NC suspension at 4000 rpm for 1 min. The samples were then dried overnight at 70◦C before imaging.