22.5 DMF + 2.5 H2O + 1.5 g MgCl2
The function of MgCl2 is to absorb water to improve the molecular transfer from the tip to the surface during the writing process.
The composition of the cocktail presented in Demers et al., Science 296, 1836 (2002) is as follows:
90% dimethylformamide/10% water solution containing 1 mM DNA and 0.3 M MgCl2
