Phage display biopanning is used to identify peptides that show material-selective adsorption, effectively distinguishing between the cellulose of paper and the printed toner of standard office laser printers. These genetically selected 12mer peptides can selectively coat either non-printed cellulose or printed toner patterns. Furthermore, triazolindione ligation chemistry is exploited to introduce, for example, dyes or functional peptides selectively to the coatings. The strategy offers an easy access towards the patterned functionalization of paper-based materials, which potentially is of relevance for low-cost diagnostics or biomedical devices. [ABSTRACT FROM AUTHOR]