Author(s): I. Lynch, A. Afantitis, T. Exner, M. Himly, V. Lobaskin, P. Doganis, D. Maier, N. Sanabria et al.

Source: Nanomaterials 2020, 10, 2493; doi:10.3390/nano10122493

Abstract: Chemoinformatics has developed efficient ways of representing chemical structures for small molecules as simple text strings, simplified molecular‐input line entry system (SMILES) and the IUPAC International Chemical Identifier (InChI), which are machine‐readable. In particular, InChIs have been extended to encode formalized representations of mixtures and reactions, and work is ongoing to represent polymers and other macromolecules in this way. The next frontier is encoding the multi‐component structures of nanomaterials (NMs) in a machine readable format to enable linking of datasets for nanoinformatics and regulatory applications. A workshop organized by the H2020 research infrastructure NanoCommons and the nanoinformatics project NanoSolveIT analyzed issues involved in developing an InChI for NMs (NInChI). The layers needed to capture NM structures include but are not limited to: core composition (possibly multi – layered); surface topography; surface coatings or functionalization; doping with other chemicals; and representation of impurities. NM distributions (size, shape, composition, surface properties, etc.), types of chemical  linkages connecting surface functionalization and coating molecules to the core, and various  crystallographic  forms  exhibited  by  NMs  also  need  to  be  considered.  Six case studies were conducted to elucidate requirements for unambiguous description of NMs. The suggested NInChI layers are intended to stimulate further analysis that will lead to the first version of a “nano” extension to the InChI standard.

Keywords: molecular structure; machine‐readable; nanomaterials descriptors; core; surface; surface functionalization; complex nanostructures