Our previous research revealed that (E)-4-amino-3-methylbut-2-en-1-yl diphosphate (AMBPP) is one of the best inhibitors of IspH, a [4Fe–4S]-dependent enzyme involved in the methylerythritol phosphate pathway that is a valuable target for the discovery of new antibacterial and antiparasitic drugs as it is absent in humans. AMBPP has substantial limitations for drug development due to its poor metabolic stability. Here, we investigate the replacement of the diphosphate moiety of AMBPP by more stable mimics: sulfonate, phosphonate or phosphinophosphonate. After synthesis of the derivatives, enzymatic assays demonstrated that none of these AMBPP analogs is an efficient IspH inhibitor.

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.

IspH/LytB, an oxygen-sensitive [4Fe-4S] enzyme, catalyzes the last step of the methylerythritol phosphate (MEP) pathway, a target for the development of new antimicrobial agents. This metalloenzyme converts (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate (HMBPP) into the two isoprenoid precursors: isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Here, the synthesis of (S)-[4-2 H1 ]HMBPP and (R)-[4-2 H1 ]HMBPP is reported together with a detailed NMR analysis of the products formed after their respective incubation with E. coli IspH/LytB in the presence of the biological reduction system used by E. coli to reduce the [4Fe-4S] center. (S)-[4-2 H1 ]HMBPP was converted into [4-2 H1 ]DMAPP and (E)-[4-2 H1 ]IPP, whereas (R)-[4-2 H1 ]HMBPP yielded [4-2 H1 ]DMAPP and (Z)-[4-2 H1 ]IPP, hence providing the direct enzymatic evidence that the mechanism catalyzed by IspH/LytB involves a rotation of the CH2 OH group of the substrate to display it away from the [4Fe-4S].

Synthetic polymers prepared by solid-phase processes are often released from the solid support by hydrolysis, leading to an acidic alpha chain-end which can usefully be employed to perform mass spectrometry experiments in the negative ion mode. This is the case for sequence-defined polyurethanes, which exhibit very simple MS/MS pattern as deprotonated species in great contrast to data obtained in the positive ion mode. Indeed, after deprotonation of their acidic end-group, collision induced dissociation (CID) of these polymers proceeds via competitive cleavages of all carbamate bonds. This leads to a unique series of anionic fragments spaced by the mass of one of the other coding co-monomer, enabling their sequence to be readily deciphered. However, as their size increases, polyurethanes are best ionized in the positive mode but their dissociation pattern is far more complicated, with four to five fragmentation routes depending on the adducted cation. This spectral complexity could however be highly reduced when selecting precursor ions that have experienced H/Na (or any other alkali) exchange in their acidic alpha end-group: in these conditions, only one reaction is observed and yields pairs of complementary products. Mechanisms could be proposed to explain how, although part of an end-group, the acidic proton had a key role in the dissociation processes of polyurethane chains. Exchange of this proton was then further optimized by proper selection of the X- anion in the NaX salt supplemented to the electrosprayed solution. By allowing simplification of MS/MS data while avoiding signal dilution over multiple ion series, CID of these [M - H + zNa]((z-1)+) permitted to envisage reliable decoding of sequence-defined polyurethanes storing large amount of information. (C) 2019 Elsevier B.V. All rights reserved.

Sequence-defined poly(N-substituted urethanes) were synthesized via a solid-phase iterative protocol including two successive orthogonal coupling steps: the formation of an activated carbonate and its chemoselective reaction with the secondary amine group of amino alcohol building blocks. This simple method was used to write binary information on the formed polymers using four-coded molecules, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(propylamino)ethanol, and 2-(butylamino)ethanol, symbolizing binary dyads 00, 01, 10, and 11, respectively. The method is fast and allows synthesis of uniform oligomers and polymers with controlled lengths (4-mer to 28-mer) and digital information sequences. Furthermore, the coded poly(N-substituted urethanes) were easily characterized by electrospray mass spectrometry and decoded by tandem mass spectrometry. Overall, these digital macromolecules offer interesting advantages over conventional sequence-coded polyurethanes, i.e., synthesis of longer chains, reduced synthesis times, and better solubility and processing in common organic solvents.

The crystallization of digitally encoded polyurethanes was studied by electron diffraction. A series of oligomers with different primary structures was analyzed in this work. They all form hydrogen-bonding-directed lamellar single crystals with a base-centered orthorhombic unit cell. Although crystal morphology was the same in all cases, the digital coding of the oligomers has a small influence on the intersheet distance in the crystals. The crystal lattices allow calculation of the volume occupied by one basic information unit, which is in the range 148-188 Å3. Interestingly, this volume is about 3× smaller than that occupied by a coded nucleotide in a DNA double helix. Furthermore, crystallization of blends of oligourethanes with different coded primary structures was investigated. Oligomers with drastically different monomer compositions form structures that are not cocrystals but more probably segregated crystals containing distinct domains of different composition.

MS/MS sequencing is an unrivaled technique to decipher binary information chemically encoded in the backbone of sequence-controlled synthetic polymers constructed with two co-monomers of different mass, arbitrarily designated as the 0- and 1-bit of the ASCII alphabet. Efficiency of this "reading" step relies however on the simplicity of MS/MS patterns, which depends on both polymer chemistry and chain length. In this context, polyurethanes (PUs) were very promising candidates as dissociation of small deprotonated oligomers (n < 8) yielded a single fragment series. The carbamate bond cleavage reaction was hence studied in details to tentatively anticipate the CID behavior of longer chains prior to optimizing their synthesis. In spite of the simplicity of MS/MS spectra, three different mechanisms were evidenced; however, they were not expected to induce MS/MS complexity when activating longer chains, as verified for sequence-controlled PUs containing up to two bytes of information (i.e., 16 co-monomers). In contrast, the ionization step appeared to be an issue: deprotonation yield of the end-group in negative ion mode electrospray was observed to strongly decrease as PU chain length increases. This sensitivity issue was addressed by introducing a second acidic end-group to allow doubly deprotonated oligomers with no impact on their CID behavior. (C) 2017 Elsevier B.V. All rights reserved.

Sequence-defined oligourethanes were transformed into ATRP initiators and used for the synthesis of precision macromolecular architectures.

Sequence-coded polyurethanes are tested as anticounterfeiting tags for the labeling of methacrylate-based intraocular implants. These sequence-defined oligomers are prepared by solid-phase iterative chemistry using two co-monomers, allowing formation of a controlled 0/1 binary sequence. Tags with different sequences and chain lengths are synthesized and tested for lenses labeling. Two main methods are investigated for incorporating the tags in the intraocular implants. In the first approach, they are included in situ during the free-radical copolymerization of 2-ethoxyethyl methacrylate and ethylene glycol dimethylacrylate. In another strategy, premade lenses are swollen in a tetrahydrofuran solution containing the polyurethane tags and dried. Both approaches allow successful incorporation of the polyurethane labels in the methacrylate networks. In order to demonstrate this, the tags are extracted from the lenses using a solvent swelling protocol and analyzed by electrospray mass spectrometry. In all cases, the labels are found and their coded sequences can be identified by tandem mass spectrometry sequencing. These results indicate that sequence-coded polyurethane tags represent a valid option for the labeling of implants. Importantly, it is shown in this work that the use of small weight fractions of polyurethane tag (i.e., 0.1-0.4 wt%) do not alter significantly the biocompatibility and transparency properties of the intraocular lenses.

Polyurethanes (PUs) constitute a popular class of plastic materials with a wide range of applications in construction, coatings, and the automotive industry. PUs are usually synthesized by step-growth polymerization and, therefore, exhibit non-uniform molecular structures. Here, we show that uniform PUs can be prepared by a facile chemoselective multistep-growth approach. This strategy permits precise control of the chain lengths of the PUs formed and their primary structure, thus making the preparation of coded monomer sequences possible. Furthermore, it was found that these polymers are remarkably easy to analyze by tandem mass spectrometry sequencing. Thus, these precision polymers can potentially be used as molecular barcodes in various applications. As a proof of concept, their use as anti-counterfeiting tags for identification of materials is reported here.