Schematic representation of the recombinant DNA strategy used to make spider silk block copolymers for the study. NcoI, NheI, SpeI, XhoI are restriction enzymes (RE). A box above/below a specific RE indicates an oligonucleotide sequence recognized by this RE. pet30a(+) plasmid is in blue, cloning linker is in yellow, silk hydrophobic block A is in magenta, and silk hydrophilic block B is in green. Steps are the following: (1) digestion, (2) ligation of a linker, (3) ligation of A block, (4) ligation of B block.