Fig. 1: Spontaneous assembly of an azobenzene diguanidinium nucleotide binder (AzoDiGua) and adenosine 5’-triphosphate (ATP) into multi-stimuli-responsive micrometer-sized aggregates.

A Molecular structure and essential characteristics of ATP (left) and AzoDiGua (right). B Scheme depicting the assembly set-up and resulting stimulus-responsive behavior. C Photographs of an ATP solution (top left), an AzoDiGua solution (top right) and the resulting mixture after 10 min of incubation at room temperature (bottom). Each tube has a diameter 1 cm and contains 500 µL of solution. The enlarged image is a transmission optical microscopy image of the aggregates (scale bar: 50 µm). D, E Morphological analysis of the supramolecular aggregates as a function of incubation time with a number of analyzed objects n = 839 (5 min), 1078 (10 min), 1122 (15 min), 644 (30 min), 507 (45 min), and 565 (60 min). D Box plots of Feret diameter (left) and circularity (middle). Blue box: range from first to third quartile; horizontal blue bars: minimum and maximum (outliers excluded); horizontal black line: median; red cross: mean. E Cumulative apparent area of the aggregates as a function of their Feret diameter, normalized by the total apparent area of the aggregates. The shift to the right (arrow) shows the progressive aggregation. All experiments are done using 1 mM ATP and 1 mM AzoDiGua at room temperature in 50 mM Tris HCl buffer solutions (pH = 7.4).