Desorption Electrospray Ionization (Desi) Of Digital Polymers: Direct Tandem Mass Spectrometry Decoding And Imaging From Materials Surfaces

Sequence-defined synthetic polymers have recently emerged as an attractive medium to store information at the molecular level, where comonomers of the chains are defined as letters of an alphabet. The main read-out methodology employed to retrieve such molecularly encoded information is tandem mass spectrometry (MS/MS), but a major current limitation remains the low storage capacity of readable chains. Ordering short oligomers at discrete locations onto surfaces to compose long messages is an attractive alternative to the difficult synthesis of long coded polymers. Yet, such surface storage requires a reliable sampling technique to be coupled on-line with MS/MS. Because it combines fast surface extraction with efficient analyte ionization in ambient conditions, desorption electrospray ionization (DESI) is shown here to be perfectly suited to envisage bidimensional data storage. The present study demonstrates performances of DESI-MS/MS at mapping oligomers used to write letters of a word, extracting digital labels from materials tagged for anticounterfeiting purposes, and imaging text written with coded polymeric inks.