Fig. 2: Light-regulated growth from HBA-based substrates.

a Time-dependent images (side view) of swollen substrates under UV irradiation (10 mW cm⁻²). A photomask with a diameter of 500 µm was used. The scale bar is 250 µm. b The height of the grown microstructures (grown height) of different samples vs treatment time. The data were obtained from three independent measurements. Error bars are s.e.m. The dashed boxes show the typical profiles of the grown structures before and after being stored in the dark. c Zeta potential of linear poly(HBA-co-NBA) copolymers at different irradiation times. The polymer concentration was 2 mg mL⁻¹, and an LED lamp (10 mW cm⁻²) was used for irradiation. The inset shows the photolytic reaction of the NBA units. d Profiles of a swollen seed-20% containing HB acetate, I-819, and BZSA under different conditions. Photomasks with a diameter of 5 mm were used. e Typical profiles of the grown structures obtained from the swollen seed with (top) or without (bottom) transesterification catalyst BZSA. Fluorescent cross-section images of the grown structure obtained from a nondyed seed and dyed nutrient (f) and a dyed seed and nondyed nutrient (g). The substrates used in (a), (d), (e), (f), and (g) contain 20% promoter (seed-20%). PDIDA was used to dye the seed in (f) and the nutrient in (g) with a concentration of 0.01 wt%.