Photo-editable macromolecular information

Abstract

Light-induced alteration of macromolecular information plays a central role in biology and is known to influence health, aging and Darwinian evolution. Here, we report that light can also trigger sequence variations in abiotic information-containing polymers. Sequence-coded poly(phosphodiester)s were synthesized using four phosphoramidite monomers containing either photo-sensitive or photo-inert substituents. These monomers allow different sequence manipulations. For instance, using two light-cleavable monomers containing o-nitrobenzyl ether and o-nitroveratryl ether motifs, photo-erasable digital polymers were prepared. These polymers can be decoded by tandem mass spectrometry but become unreadable after UVA exposure. The opposite behavior, i.e. photo-revealable sequences, was obtained with polymers made of two isobaric monomers containing light-cleavable o-nitrobenzyl ether and light-inert p-nitrobenzyl ether substituents. Furthermore, when the latter two monomers were used in conjunction with a third monomer bearing a light-inert OH group, site-directed photo-mutations were induced in synthetic polymers. This was used herein to change the meaning of binary sequences.

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

Fig. 2

Example of a photo-erasable digital polymer. ESI-HRMS spectra obtained in the negative ion mode for polymer P1 before (a) and after (b) light exposure. Open and full dark gray circles indicate clusters of trifluoroacetic acid and trichloroacetic acid, respectively. Open and full dark gray diamonds indicate photo-deprotection by-products. See Supplementary Figs. 6, 7 and 15 for interpretation. c MS/MS sequencing of the coded polymer P1 before photo-erasing. This spectrum was obtained by collision-induced dissociation of the [P1-4H]^4- precursor ion. The inset schematizes the fragmentation pattern of a phosphate repeat unit. Dark gray stars indicate secondary fragments including deprotonated repeat units at m/z 288.0 and m/z 348.1

Fig. 3

Characterization of a digital polymer coded with an invisible monomer ink. ESI-HRMS spectra obtained in the negative ion mode for polymer P10 before (a) and after (b) light exposure. Squares and circles indicate synthesis impurities. Open and full dark gray diamonds indicate photo-deprotection by-products. See Supplementary Fig. 6 for interpretation. c MS/MS sequencing of the irradiated polymer P10′. This spectrum was obtained by collision-induced dissociation of the [P10′-3H]³⁻ precursor ion. The inset schematizes the fragmentation pattern of a phosphate repeat unit. Dark gray stars indicate secondary fragments including deprotonated repeat units at m/z 153.0 and m/z 288.0

Fig. 4

Photo-induced sequence mutation. MS/MS sequencing spectra obtained for polymer P12 before (a) and after (b) light exposure. The top and bottom spectra were obtained by collision-induced dissociation of the [P12-2H]²⁻ and [P12′-2H]²⁻ precursor ions, respectively. In these conditions, a phosphate repeat unit leads to different fragments, as indicated by the gray fragmentation pattern on the right side of panel a. However, for clarity, only w_i^z− fragments are highlighted in this figure. The corresponding peaks were intentionally thickened and colored (blue before- and red after irradiation) with the help of the Origin software. All other fragments are intentionally displayed in light gray. A detailed interpretation of all peaks can be found in Supplementary Table 6. Black hashtags indicate deprotonated repeat units at m/z 153.0 and m/z 288.0