Figure 1: Principle of the combinatorial laser-induced forward transfer synthesis.

Donor slides bearing different monomer building blocks, embedded in a resin (different colours in b and c) are positioned on top of an acceptor slide (a). A laser scanning system transfers minute amounts of material to the acceptor slide. Repeating these steps with different donor slides results in a pattern of different amino acid types (d). The coupling reaction of monomers (e) is initiated by heating the surface. Next, uncoupled amino-acid building blocks are removed (f), uncoupled amino groups are blocked and then the protecting groups are removed (g). Repeating the cycle generates an array of combinatorially synthesized peptides (h).