The mucosal pellicle (MP) is a biological film protecting the oral mucosa. It is composed of bounded salivary proteins and transmembrane mucin MUC1 expressed by oral epithelial cells. Previous research indicates that MUC1 expression enhances the binding of the main salivary protein forming the MP, MUC5B. This study investigated the influence of MUC1 structure on MP formation. A TR146 cell line, which does not express MUC1 natively, was stably transfected with genes coding for three MUC1 isoforms differing in the structure of the two main extracellular domains: the VNTR domain, exhibiting a variable number of tandem repeats, and the SEA domain, maintaining the two bound subunits of MUC1. Semi-quantification of MUC1 using dot blot chemiluminescence showed comparable expression levels in all transfected cell lines. Semi-quantification of MUC5B by immunostaining after incubation with saliva revealed that MUC1 expression significantly increased MUC5B adsorption. Neither the VNTR domain nor the SEA domain was influenced MUC5B anchoring, suggesting the key role of the MUC1 N-terminal domain. AFM-IR nanospectroscopy revealed discernible shifts indicative of changes in the chemical properties at the cell surface due to the expression of the MUC1 isoform. Furthermore, the observed chemical shifts suggest the involvement of hydrophobic effects in the interaction between MUC1 and salivary proteins.

We have investigated the self-assembly of a strong dipolar molecule (LDipCC) on the semiconducting Si(111)-B surface with scanning tunneling microscopy (STM), density functional theory (DFT) calculations and STM simulations. Although the formation of an extended two-dimensional network was clearly revealed by STM under ultra-high vacuum, the assignment of a specific STM signature to the different terminal groups from the LDipCC molecular unit required a complete analysis by numerical simulations. The overall observed assembly is explained in terms of STM contrasts associated with the molecular structure of LDipCC and the molecule-surface interactions. To distinguish the relative arrangement of the dipolar molecules within the assembly, a rational combination of experimental results and electronic structure calculations allows us to identify a single adsorbed LDipCC phase in which the molecular dipoles are homogeneously arranged into a parallel fashion on the Si(111)-B surface.

On-surface synthesis of graphene nanoribbons (NRG), as prototypical polymers, has emerged contemporary interest in two last decades due to their promising optical, electronic and mechanical properties. The main strategy to obtain these nanoribbons is based on homo-coupling of halogenated molecules induced by thermal activation followed by on-surface assisted cyclo-dehydrogenation. [1] However, this strategy leads only to the formation of non-functionalized NRG because the lateral active sites of precursors are occupied by halogen atoms, while functional NRG can be relevant of interest in many applications (spintronic, optoelectronics etc.). Nevertheless, Sanchez et al. [2] reported that unhalogenated molecules can be used as precursors of graphene nanoribbons but the length of resulting nanoribbons is restricted to 10 nm. Herein, we present 30 nm long NRG fabricated using pristine NRG precursor by optimizing experimental parameters such as coverage and heating’s rate and time, investigated by STM under UHV. Moreover, we propose two NRG precursors bearing lateral functional groups (like cyano or pyridyl moieties) as starting points for the formation of 1D and 2D functionalized NRG.

The growth of an extended supramolecular network using dipolar molecules as the building blocks is of great technological interest. We investigated the self-assembly of a dipolar molecule on an Au(111) surface. The formation of an extended two-dimensional network was demonstrated by scanning tunnelling microscopy under ultra-high vacuum and explained in terms of molecule–molecule interactions. This 2D-network is still stable under the pressure of one atmosphere of nitrogen, which demonstrated its interest for the development of submolecular-precisely polyfunctional smart surfaces.

The fabrication of robust and conjugated organic nano-architectures deposited on surfaces is a key-challenge in order to build smart components. Most of covalent nano-architectures are obtained by thermally-induced on surface chemistry with an effective catalytic role of surfces (Ulmann cross-coupling, Glaser crosscoupling, etc.). Nevertheless, as molecular diffusion is also promoted by an increasing of the temperature, it is very difficult to achieve well-ordered covalently-bounded nano-architectures by these on-surface reactions. Photopolymerization of molecules is a powerful method to obtain organic polymers, because photopolymerization is not thermally-induced and does not require any catalytic role of the surface. Nevertheless, this strategy is still rare on surfaces despite of its interests. Here, we investigate the photopolymerization of supramolecular networks adsorbed on different surfaces (Si(111)-B, Cu(111), HOPG) by illumination with an ultra-violet (UV) light. All experiments were monitored by Ultra-High Vaccum Scanning Tunneling Microscopy (UHV-STM). We observe the formation of covalently-bounded nano-architectures, like nanowires, depending of geometry of the starting supramolecular networks. The properties of obtained polymers (airstability, charge transport abilities, etc.) are currently under investigation with Atomic Force Microscopy (AFM) under ambient conditions.