Because of their wide range of applications in food and health industries, the interest for oligosaccharides is growing very rapidly. The challenge is to develop synthetic routes, easy to scale-up, based on the use of low-cost bio-resources, and able to cope with the diversity of desired oligosaccharides. Living cell factories stand as a very promising approach to produce efficiently oligosaccharides through sustainable processes. OLIGOMET aims at developing a versatile metabolic chassis for efficient production of added-value oligosaccharides. The chassis will be designed using Escherichia coli as platform organism using system-level approaches for metabolic optimization. The versatility of the metabolic chassis will be evaluated by plugging two types of native or engineered carbohydrate enzymes, namely glycosyl-transferases and glycosyde-phosphorylase, to produce two types of high-added value oligosaccharides, Human Milk Oligosaccharides (HMO) and core human glycan oligosaccharides.

Glycoconjugates, defined here as carbohydrates attached to a lipid or a protein, are ubiquitous in Nature. They are present on all cell membranes through a dense coating named Glycocalyx. They play critical roles in a wide variety of biological and pathological processes acting as signaling, recognition, and bacterial adhesion, etc. Consequently, major scientific and biotechnological interests in accessing glycoconjugates derive from the promise to use them as probes for biological research, as well as lead compounds for developing drugs, vaccines, and diagnostic tools. These endeavors are however complicated by a lack of general methods for the straightforward preparation of these key-enabling carbohydrate derivatives. This is a major scientific challenge for glycochemists worldwide. The transdisciplinary (Chemistry/Biology/Nano-science/technology) SWEET-DISPLAY project aims at developing a new modular chemical platform based on barbituric acid, allowing direct access to a wide range of glyco-amphiphiles (GAs) or glycolipids analogues through Knoevenagel condensation on protecting group-free carbohydrates. These GAs will act as active recognition layers of pathogenic lectins in liquid crystal (LC) biosensors. In fact, Prof. N.L. Abbott’s group has pioneered, and successfully developed over the past two decades, the smart use of LCs to transduce and amplify molecular events at an aqueous/LC interface; allowing their detection though optical signals and images visible to the naked eye. This LC biosensor technology is capable of delivering a simple, high-sensitivity, and label-free detection without the requirement of complex instrumentations, making it well-suited for the primary screening assay of analytes performed away from central laboratories. LC biosensors have already been designed with many amphiphilic species (e.g. surfactants and lipids) to detect a hand full of biological analytes (e.g. including proteins, nucleic acids, viruses, endotoxins, and cells to name few) but never challenged till date for probing carbohydrate/pathogenic lectin (a carbohydrate-binding protein) interactions, pointing out toward the inherently innovative application of this Public Collaborative Research (PRC) exploratory project. Lectins such as LecA (galactophilic) and LecB (fucophilic) from Pseudomonas aeruginosa, a bacterium that have become a real concern in hospital-acquired infections will be first covered. Other biotargets of interests are RSL (fucophilic) from the plant pathogen Ralstonia solanacearum that leads to lethal wilt in many agricultural crops or its homolog BambL from human pathogen Burkholderia ambifaria that was identified in clinical isolates from cystic fibrosis patients. SWEET-DISPLAY is a low TRL (1-3) PRC project grounded on the unification of cross-fertilizing knowledge and complementary expertise of two internationally recognized labs uniting for the first time under a PRC: CERMAV, in glycosciences, and SyMMES, in functional liquid crystals. Backed on preliminaries results, its core novelty lies in an original access to a large range of GAs characterized by hydrophobic tails that will penetrate into the hydrophobic LC phase while the hydrophilic carbohydrate heads will remain exposed to the aqueous phase, defining a functional self-assembled monolayer at the LC/GA/water interface. Pathogenic lectins will cause local disruptions of this sensing interface that will propagate through the bulk of LCs providing an optical readout through polarizing microscopy images (with nematic LCs-Generation 1). A 2nd generation, even more appealing and easy to implement, enabling a color-indicating assay (with cholesteric (chiral nematic LCs-Generation 2) will be proposed and will rely on the sensitivity of Bragg reflections (induced by the helical self-assembly of cholesteric LCs) to temperature and pathogen concentration when sense with a fiber optic-based UV-Vis-NIR spectrophotometer.

Antibiotic resistance is a major global public health issue and a WHO priority since 2015. The majority of current antibiotics inhibit the biosynthesis of peptidoglycan, an essential structural component of the bacterial wall. The fight against antibiotic resistance thus requires a better understanding of the proteins involved in the biosynthesis of peptidoglycan. This study is hampered by the lack of well-defined ligands allowing a fine structural and mechanistic analysis. Glyco_SWIM aims to develop an innovative and convenient access to peptidoglycan oligomers of well-defined size and structure. The originality will lie in the use of an enzyme obtained molecular engineering capable of polymerizing a simple disaccharide precursor. The bacterial wall mimics thus obtained will allow a fine analysis by X-ray crystallography, nuclear magnetic resonance and enzymology of major proteins acting on the peptidoglycan.

Novel applications in the biomedical field could come from exploiting the electroactive properties of conducting polymers and the biocompatibility and biodegradability of natural polysaccharides towards the development of flexible, stretchable and bioresorbable electronic biointerfaces. Such devices are promising for electrical stimulation and recording in vivo, because of their mechanically permissive structures that conform to curvilinear structures found in native tissue. Moreover, their transient character enables opportunities to develop advanced biomedical devices such as monitoring systems that eliminate risks associated with surgical explantation, stimulators to accelerate tissue repair and temporary drug delivery systems. The main goal of the STRETCH project is to design and study new electrode materials, of which originality lies in the combination of two crosslinked polysaccharide networks incorporating a conducting polymer. These all-polymeric materials will be integrated in an implantable electrode array dedicated to neurophysiological monitoring. The focus on such an application will allow close collaboration with clinicians, guaranteeing consideration of the physico-chemical and biological requirements early in the design stage of the materials. For this specific application, the new device is expected to i) optimize tissue integration mainly due to its ability to mechanically match its biological environment; ii) operate over a short period of time (about 3 weeks) and dissolve afterwards to generate biologically safe products. The strategy for material selection focuses on designing water-borne dispersions based on poly(3,4-ethylenedioxythiophene) (PEDOT), a biocompatible and electrically conductive polymer, and photocrosslinkable sulfated polysaccharides (sulfated dextran (DexS) and sulfated hyaluronic acid (HAS)) to obtain processable polymer formulations ("inks") combining conductivity, printability, controllable biological and degradation properties. Besides acting as dopant and dispersing agent of PEDOT in water (instead of commonly used poly(styrene sulfonate)), these functional polysaccharides will allow i) the design of conductive tracks showing self-healability, ii) the fabrication of soft conducting hydrogels with properties beneficial for interacting with living systems, and iii) the processing and integration of these active components into a bioresorbable electrode array. Here, crosslinked chitosan (CHI) thin films will be used as the insulating material taking advantage of the low conductivity, biocompatibility, biodegradability, adhesive and film-forming properties of CHI. The proposed method to engineer the STRETCH electrode array involves the chemical modification of dextran, HA and CHI, the development of new photocrosslinkable PEDOT/DexS and PEDOT/HAS inks and their localized deposition on soft CHI substrates, and the device integration combining microtechnology and photolithography techniques. Fundamental studies will be performed to fully characterize the different materials in terms of mechanical properties, electrical conductivity at rest and under stretching, bioresorption in physiological media and stability to sterilization conditions. The biocompatibility and behavior (adhesion, proliferation, spreading) of cells cultured on these hybrid materials will also be investigated in vitro and the best candidates will be selected to assess their performance in vivo in a cortical rodent model.

Colored structural materials found in nature are of great interest and their fascinating properties have stimulated the design of bioinspired functional photonic materials. Due to their intrinsic ability to modify the propagation of visible light, they are potential candidates for various optoelectronic applications, including as filters, low and high reflection coatings, or resonant gratings and cavities. Nowadays, scientists have reached a level of understanding that allows the development of various types of colored structural materials using bottom-up self-assembly approaches. These materials are composed of elementary building blocks such as organic-inorganic nanoparticles, or synthetic high molecular weight linear block copolymers (BCPs). Very recently, another class of nanostructured systems has emerged, based on the self-assembly of brush-like block copolymers (BBCPs). These copolymers present attractive properties due to their high density of functional groups, their low entanglement and their ability to self-assemble rapidly into highly ordered nanostructures. It is thus possible to form lamellar organizations with inter-domain spaces of a few hundred nanometers, generating structural colors. However, at present, all available systems are made from petroleum-based polymers. The SUGARCOLORS project proposes to use fully biobased BBCPs, elaborated from sugars and polyesters, sustainable constituents that are attracting increasing interest due to their "green" characteristics: biocompatibility, biodegradability and biorecognition properties. Various industrial sectors are particularly interested and applications at the macroscopic level offer solutions to create new biomaterials based on modified sugars with several available hydroxyl groups. These materials have promising characteristics that should allow advanced electronic devices and their applications in various sectors such as food, packaging, cosmetics, health and microelectronics to become more environmentally friendly and biocompatible. To better understand these systems and incorporate them into new devices (bio-nanoelectronics) in response to the transition to a bio-based economy, it is important to control the mechanisms of self-assembly at the nanoscale. Based on a multidisciplinary consortium with complementary expertise (CERMAV and LTM), the SUGARCOLORS project proposes an innovative strategy for the elaboration of carbohydrate-based brush-like block copolymer systems. It aims at designing colored structural materials and to study them systematically according to the state of the art in order to design photonic crystals based on colored biomaterials that are reflective and responsive to external stimuli. Such a project constitutes a "green technology platform" to design new biosourced materials, and creating a significant opportunity for the valorization of these new bio-nanomaterials especially for optoelectronic applications.