Breath figures-mediated microprinting allows for versatile applications in molecular biology

Softlithographic processes are currently applied in different fields ranging from microelectronics to biology. One of the main advantages of these techniques stands in the low cost and in its easy use without the need of expensive apparatus. The available procedure is simple and particularly suitable for biological tests: a biomolecule is printed on a suitable substrate and its presence can be further recognized with a given reactants. The use of polydimethylsiloxane (PDMS) is a key step in this technology because printing from PDMS mould is an easy process. We have recently shown that the hexagonal ordered pattern which is obtained by breath figure method on a polystyrene film, generated by arrangements of micrometric holes on the film surface, can be reproduced by PDMS obtaining a positive mould, formed by regularly arranged micrometric protuberances. This mould can be "inked" with a suitable biomolecule solution which is subsequently printed on the desired substrate. With this method no photolithographic step is necessary; regular spots of a few microns can be easily produced without the need of sophisticated apparatus. We report some examples of printing with different molecules which are then recognized by specific reactants. A further advantage of the method we present in this work is related to the multiple printing of the same labelled molecule with the same mould onto several substrates without significant loss of signal.