Coding Macromolecules: Inputting Information in Polymers Using Monomer-Based Alphabets

The monomer units of a polymer can be used to encode a Message. This property is used, for instance, by nature to store genetic information in DNA macromolecules. Therefore, dining the past decades, many researchers have aimed to recreate in vitro or in vivo the properties of nucleic acids. Peptide nucleic acids, or more generally speaking xeno-nucleic acids, are interesting examples of man-made genetic polymers. However, the genetic code is surely not the only type of code that can be "written" in a polymer. In principle, many other monomer-based codes,could be developed: For example, a binary code can be potentially implemented in a synthetic macromolecule using two comonomers defined as 0 and 1 bit. This possibility is exciting because it would permit to develop a full new class of synthetic polymers, which contain sequence-coded information. Such polymers could be interesting for a variety of new applications, for example in the field of data storage and product identification. However, these tempting options are currently underexplored: It should be clarified that the development of information-containing macromolecules is not trivial. First of all, in order to contain "readable" information, Such polymers should possess perfectly controlled comonomer sequences. Moreover, chemical and analytical methods that allow deciphering of sequence-coded information have to be developed. The aim of the present Perspective is to Show that significant progress has been done in that direction during the past two years. For instance, convenient strategies have been reported for the preparation of monodisperse sequence-defined macromolecules. In addition, encouraging advances have been made for the sequencing of non-natural polymers. These recent results are discussed and critically analyzed herein. Altogether, monomer-based information storage should be regarded as a new property of synthetic matter.