Fig. 1.

Monomer and polymer design. a Molecular structures of the different phosphoramidite monomers that were synthesized and used in the present work. b Strategy for the preparation of photo-erasable digital polymers. In this case, monomers M1 and M2 are used as 0- and 1-bits, respectively. These monomers have different molar mass and therefore allow construction of digital sequences that can be decoded by MS/MS. Upon light irradiation, both 0 and 1 units are photo-cleaved, thus leading to a non-decodable homopolymer (depicted in gray). c Strategy for the preparation of polymers containing hidden messages. In this case, isobaric monomers M1 and M3 are used as an invisible binary ink, which lead to MS/MS non-decodable sequences. Light is then used as a revealer. Photo-irradiation cleaves selectively ortho-nitrobenzyl units, thus leading to a MS/MS decodable binary sequence. d Strategy for photo-induced site-directed mutations. In this case, the polymers are constructed using monomers M1, M3, and M4. After TIPS deprotection, the formed digital polymer contains isobaric 1-bits (depicted in red and blue). Light irradiation allows selective 1→0 mutation of a single type of 1 unit (i.e. only the blue one). The letter T symbolizes a terminal thymidine nucleoside unit in panels b, c, and d