End-functionalization of polystyrene by malto-oligosaccharide generating aggregation-tunable polymeric reverse micelle

Development of Improved Synthetic Routes to Pixatimod (PG545), a Sulfated Oligosaccharide-Steroid Conjugate

The heparan sulfate (HS) mimetic pixatimod (PG545) is a highly potent inhibitor of angiogenesis, tumor growth, and metastasis currently in clinical trials for cancer. PG545 has also demonstrated potent antiviral activity against numerous HS-dependent viruses, including SARS-CoV-2, and shows promise as an antiviral drug for the treatment of COVID-19. Structurally, PG545 consists of a fully sulfated tetrasaccharide conjugated to the steroid 5α-cholestan-3β-ol. The reported synthesis of PG545 suffers from a low yield and poor selectivity in the critical glycosylation step. Given its clinical importance, new efficient routes for the synthesis of PG545 and analogues were developed. Particular attention was given to improving the key glycosylation step by using more stable protecting groups and optimized glycosyl donors.

Dictating Nanoparticle Assembly via Systems-Level Control of Molecular Multivalency

Nanoparticle assembly can be controlled by multivalent binding interactions between surface ligands, indicating that more precise control over these interactions is important to design complex nanoscale architectures. It has been well-established in natural materials that the arrangement of different molecular species in three dimensions can affect the ability of individual supramolecular units to coordinate their binding, thereby regulating the strength and specificity of their collective molecular interactions. However, in artificial systems, limited examples exist that quantitatively demonstrate how changes in nanoscale geometry can be used to rationally modulate the thermodynamics of individual molecular binding interactions. As a result, the use of nanoscale design features to regulate molecular bonding remains an underutilized design handle to control nanomaterials synthesis. Here we demonstrate a polymer-coated nanoparticle material where supramolecular bonding and nanoscale structure are used in conjunction to dictate the thermodynamics of their multivalent interactions, resulting in emergent bundling of supramolecular binding groups that would not be expected on the basis of the molecular structures alone. Additionally, we show that these emergent phenomena can controllably alter the superlattice symmetry by using the mesoscale particle arrangement to alter the thermodynamics of the supramolecular bonding behavior. The ability to rationally program molecular multivalency via a systems-level approach therefore provides a major step forward in the assembly of complex artificial structures, with implications for future designs of both nanoparticle- and supramolecular-based materials.

Syntheses of sugar poly(orthoesters) through reverse anomeric effect

The syntheses of high molecular weight sugar poly(orthoesters) were achieved by using reverse anomeric effect (RAE)-enabled promoters.

Modification of polysaccharides through controlled/living radical polymerization grafting-towards the generation of high performance hybrids

This review covers the literature concerning the modification of polysaccharides through controlled radical polymerizations (NMP, ATRP and RAFT). The different routes to well-defined polysaccharide-based macromolecules (block and graft copolymers) and graft-functionalized polysaccharide surfaces as well as the applications of these polysaccharide-based hybrids are extensively discussed.

Micelles and polymersomes obtained by self-assembly of dextran and polystyrene based block copolymers

The self-assembly of dextran-block-polystyrene (dex-b-PS) block copolymers was investigated in solution. The hydrophobic PS weight fraction in these block copolymers ranges from 7 to 92% w/w, whereas the average number molar mass of dextran was kept constant at 6600 gmol(-1). Self-assembly by direct dissolution in water could be performed only for block copolymers with a low hydrophobic content (7% w/w), whereas mixtures of tetrahydrofuran and dimethylsulfoxide were required for higher PS content, before transferring the structures into water. Core-shell micelles, ovoïds, and vesicles could be identified upon characterization by light and neutrons scattering, atomic force microscopy, and transmission electron microscopy. Most of the morphologies observed were not expected considering the chemical composition of the block copolymers. Finally, the size and shape of these nanoparticles were fixed upon cross-linking the dextran block through reaction of the hydroxyl groups with divinylsulfone. The role of the dextran conformation on the self-assembly process is discussed.

Synthesis of ATRP-induced dextran-b-polystyrene diblock copolymers and preliminary investigation of their self-assembly in water

Dextran-b-polystyrene diblock copolymers forming miscellaneous spherical self-assemblies in water were obtained by chemical modification of the anomeric extremity of a commercial dextran followed by atom transfer radical polymerisation of styrene.