Glyco-nanoobjects elaboration using ecofriendly process – GlyNanEP

Soft nanostructures obtained by self-assembly of amphiphilic copolymers (ACP) are of great relevance for nanomedecine, where they are used as Drug Delivery Systems (DDS). Among these DDS, those with vesicular morphology (polymersomes) are under intense scrutiny given their interesting multi-compartmental morphology, owing the simultaneous encapsulation of hydrophilic and/or hydrophobic drugs.

For many decades, nanostructures covered with poly(ethylene oxide) (PEO) have emerged as “gold” standard DDS approved by the FDA. However, many reports currently describe the non-immunogenicity of PEO. Owing to their high water-solubility, non-toxicity and tunable biocompatibility, neutral polysaccharides and particularly dextran have been reported as suitable alternatives to PEO. However, unlike PEO-based ACP, which can easily self-assemble into a broad set of morphologies, spherical micelles and core/shell nanoparticles have been frequently reported for amphiphilic glycopolymers (AGP), which associate hydrophilic polysaccharides and hydrophobic polymers. Reports on advanced glyco-nanostructures (GNS) morphologies are actually scarce. This limitation may be attributed to the unsuitable classical self-assembly techniques currently used, i.e. solvent displacement and film rehydration, which favorite the formation of kinetically frozen aggregates.

The first objective of the GlyNanEP project is to fill the lack of AGP in terms of self-assembly by developing a modern and versatile strategies i) to easily design well-defined AGP, as well as ii) to carry out their self-assembly using iii) a clean and straightforward process allowing the obtaining of GNS with advanced morphologies in reproducible manner.

The method that will be involved in this project is an emerging one-pot technique named Polymerization-Induced Self-Assembly (PISA), which enables to produce nanostructures based on self-assembled ACP directly in aqueous media at high solids concentration (>5 wt% and 50 wt%) without using organic solvent. In PISA, a water-soluble macroinitiator or macromolecular Chain Transfer Agent (macro-CTA) is used to polymerize suitable monomer, which forms a water-insoluble polymer. ACPs are progressively obtained when the hydrophobic block/graft reaches a critical size and self-assemble in situ to generate a diverse set of nanostructures morphologies.

Here, a model system based on dextran derivative as macro-CTA and 2- hydroxypropyl methacrylate (HPMA) as water-soluble monomer will be used at initial investigations to reveal the ability of the PISA approach to offer new high-ordered GNS so far never obtained with AGP. In addition, such GNS will be prepared from AGP having two macromolecular architectures (grafted and diblock) in order to understand and establish relationships between the structural parameters of AGP and the nature of GNS generated in water. After optimizing the different parameters influencing the self-assembly of the AGPs in PISA process, the second objective of this project will be to demonstrate the versatility/ability of this technique to produce in one step smart pH-sensitive glyco-polymersomes (GPs), functionalized by targeting ligands and loaded with hydrophilic and/or hydrophobic drugs. Such smart GPs can be interesting for cancer treatment, since they can disassemble at acidic pH (at the cells vicinity or within intracellular tumor) to release the encapsulated drugs. As a proof of concept, polymersomes based on a biocompatible pH-sensitive amphiphilic dextran /poly(hydroxypropyl methacrylate-co-4-vinylpyridine) (Dex/ P(HPMA-co-4VP)) glycopolymers, surface-functionalized by model peptide (DKPPR) and loaded with a model drug (Doxorubicin) will be produced in situ using PISA. Cytotoxicity and cell adhesion will be performed in order to demonstrate the real potential of such smart nanostructures for biomedical applications. All nanostructures produced will be characterized using advanced techniques such as DLS, TEM, AFM and SEM.