A versatile approach for the synthesis of sequence-controlled multiblock copolymers, using a combination of solid phase synthesis and step-growth polymerization by photoinduced thiol-ene coupling (TEC) is presented. Following this strategy, a series of sequence-controlled glycopolymers is derived from the polymerization of a hydrophilic spacer macromonomer and different glycomacromonomers bearing between one to five α-d-Mannose (Man) ligands. Through the solid phase assembly of the macromonomers, the number and positioning of spacer and sugar moieties is controlled and translates into the sequence-control of the final polymer. A maximum M̅ of 16 kDa, corresponding to a X̅ of 10, for the applied macromonomers is accessible with optimized polymerization conditions. The binding behavior of the resulting multiblock glycopolymers toward the model lectin Concanavalin A (ConA) is studied via turbidity assays and surface plasmon resonance (SPR) measurements, comparing the ability of precision glycomacromolecules and glycopolymers to bind to and cross-link ConA in dependence of the number of sugar moieties and overall molecular weight. The results show that there is a clear correlation between number of Man ligands and Con A binding and clustering, whereas the length of the glycooligomer- or polymer backbone seems to have no effect.

This work presents the translation of sequence-controlled synthesis of macromonomers into sequence-defined and selectively degradable precision polymers.

Sequence-control in synthetic polymers is an important contemporary research area because it provides the opportunity to create completely novel materials for structure-function studies. This is especially relevant for biomimetic polymers, bioactive and information security materials. The level of control is strongly dependent and inherent upon the polymerization technique utilized. Today, the most established method yielding monodispersity and monomer sequence-definition is solid-phase synthesis. This Focus Review highlights recent advances in solid-phase strategies to access synthetic, sequence-defined macromolecules. Alternatives strategies towards sequence-defined macromolecules are also briefly summarized.

Ag 2 S semiconductor nanoparticles (NPs) are near-infrared luminescent probes with outstanding properties (good biocompatibility, optimum spectral operation range, and easy biofunctionalization) that make them ideal probes for in vivo imaging. Ag 2 S NPs have, indeed, made possible amazing challenges including in vivo brain imaging and advanced diagnosis of the cardiovascular system. Despite the continuous redesign of synthesis routes, the emission quantum yield (QY) of Ag 2 S NPs is typically below 0.2%. This leads to a low luminescent brightness that avoids their translation into the clinics. In this work, an innovative synthetic methodology that permits a 10-fold increment in the absolute QY from 0.2 up to 2.3% is presented. Such an increment in the QY is accompanied by an enlargement of photoluminescence lifetimes from 184 to 1200 ns. The optimized synthetic route presented here is based on a fine control over both the Ag core and the Ag/S ratio within the NPs. Such control reduces the density of structural defects and decreases the nonradiative pathways. In addition, we demonstrate that the superior performance of the Ag 2 S NPs allows for high-contrast in vivo bioimaging.

A synthesis toward sequence-controlled multiblock glycopolymers, presenting a mannopyranoside (Man) glyco­(oligoamide) block followed by a poly­(ethylene glycol) (PEG) (M̅ n of 6 kDa) block, is shown. Therefore, monodisperse and sequence-defined glyco­(oligoamide) macromonomers derived from solid phase synthesis (SPS) are polymerized with dithiol-functionalized PEG via thiol–ene coupling (TEC) in a step-growth fashion. For the polymerization, a novel building block introducing a norbornene moiety is developed which is used for end-functionalization of the glyco­(oligoamide) macromonomers. As a highly reactive alkene moiety in photoinduced TEC, this gives access to X̅ n of up to 45. A total of 12 glyco­(oligoamide)–PEG multiblock copolymers with maximum M̅ n of 200 kDa are obtained and subjected to a series of purification steps decreasing overall dispersity. In different binding studies toward model lectin Concanavalin A, despite their high number of Man ligands, we see rather weak binding of glycopolymers that we attribute to the introduction of higher molecular weight PEG blocks.