Fig. 3: Properties of melanated BC.
a, A melanated (mel+) and unmelanated (mel−) swatch, from the same original K. rhaeticus ptyr1 pellicle. These swatches had been dried and used as demonstration pieces. b, SEM of mel+ and mel− K. rhaeticus ptyr1 BC. The top and bottom surfaces pertain to the air-facing and media-facing pellicle surfaces, respectively. Images shown are representative of at least five images per condition. c, The sessile drop method was used to measure the contact angle on K. rhaeticus ptyr1 mel− (beige) and mel+ (black) pellicles. An unpaired t test result gave a value of P < 0.005 and error bars represent s.d. from eight mel− and nine mel+ drop measurements. Representative water drop shapes for mel+ and mel− pellicles are shown above the graph. d, Comparative tensile tests of melanated and unmelanated BC sheets were conducted using BC sheets prepared from halves of the same K. rhaeticus ptyr1 pellicle. Representative images of BC breaks are given for mel− and mel+ BC as well as stress–strain curves of the technical repeats from three biological replicates of mel+ and mel− pellicles. e–g, Tensile strength (e), Young’s modulus (f) and strain at break (g) for mel+ and mel− pellicles—the P values from paired t tests between mel+ and mel− BC were 0.17, 0.92 and 0.85, respectively. Error bars show s.d. from three biological replicates and each biological replicate is the average of three or more technical replicates.
