Tailored Branched Polymer–Protein Bioconjugates for Tunable Sieving Performance

Protein–polymer conjugates combine the unique properties of both proteins and synthetic polymers, making them important materials for biomedical applications. In this work, we synthesized and characterized protein-branched polymer bioconjugates that were precisely designed to retain protein functionality while preventing unwanted interactions. Using chymotrypsin as a model protein, we employed a controlled radical branching polymerization (CRBP) technique utilizing a water-soluble inibramer, sodium 2-bromoacrylate. The green-light-induced atom transfer radical polymerization (ATRP) enabled the grafting of branched polymers directly from the protein surface in the open air. The resulting bioconjugates exhibited a predetermined molecular weight, well-defined architecture, and high branching density. Conformational analysis by SEC-MALS validated the controlled grafting of branched polymers. Furthermore, enzymatic assays revealed that densely grafted polymers prevented protein inhibitor penetration, and the resulting conjugates retained up to 90% of their enzymatic activity. This study demonstrates a promising strategy for designing protein–polymer bioconjugates with tunable sieving behavior, opening avenues for applications in drug delivery and biotechnology

Dialkylgallium Complexes with Alkoxide and Aryloxide Ligands Possessing N‑Heterocyclic Carbene Functionalities: Synthesis and Structure

Methods for the synthesis of dialkylgalium compounds with alkoxide or aryloxide ligands possessing N-heterocyclic carbene functionalities have been established. As a result, the synthesis of a series of dialkylgallium complexes Me₂Ga­(O,C) (<b>1</b>, <b>3</b>–<b>5</b>), and Me₂Ga­(O,C)·Me₃Ga (<b>2</b>, <b>6</b>) is described, where (O,C) represents an alkoxide or aryloxide monoanionic chelate ligand with an N-heterocyclic carbene functionality. All complexes have been fully characterized using spectroscopic and X-ray techniques. The presence of a strongly basic NHC functionality in alkoxide or aryloxide ligands resulted in the formation of monomeric Me₂Ga­(O,C) species. The reaction of those complexes with the Lewis acid Me₃Ga leads to Me₂Ga­(O,C)·Me₃Ga adducts (<b>2</b> and <b>6</b>) with a strong Me₃Ga–O dative bond. The effect of (O,C) ligands with various steric and electronic properties on the structure of obtained Me₂Ga­(O,C) and Me₂Ga­(O,C)·Me₃Ga has been discussed on the basis of spectroscopic data. Finally, the bond valence vector model has been used to estimate the effect of a chelating (O,C) ligand on strains in complexes <b>1</b>–<b>6</b> on the basis of X-ray data

Dialkylgallium Complexes with Alkoxide and Aryloxide Ligands Possessing N‑Heterocyclic Carbene Functionalities: Synthesis and Structure

Methods for the synthesis of dialkylgalium compounds with alkoxide or aryloxide ligands possessing N-heterocyclic carbene functionalities have been established. As a result, the synthesis of a series of dialkylgallium complexes Me₂Ga­(O,C) (<b>1</b>, <b>3</b>–<b>5</b>), and Me₂Ga­(O,C)·Me₃Ga (<b>2</b>, <b>6</b>) is described, where (O,C) represents an alkoxide or aryloxide monoanionic chelate ligand with an N-heterocyclic carbene functionality. All complexes have been fully characterized using spectroscopic and X-ray techniques. The presence of a strongly basic NHC functionality in alkoxide or aryloxide ligands resulted in the formation of monomeric Me₂Ga­(O,C) species. The reaction of those complexes with the Lewis acid Me₃Ga leads to Me₂Ga­(O,C)·Me₃Ga adducts (<b>2</b> and <b>6</b>) with a strong Me₃Ga–O dative bond. The effect of (O,C) ligands with various steric and electronic properties on the structure of obtained Me₂Ga­(O,C) and Me₂Ga­(O,C)·Me₃Ga has been discussed on the basis of spectroscopic data. Finally, the bond valence vector model has been used to estimate the effect of a chelating (O,C) ligand on strains in complexes <b>1</b>–<b>6</b> on the basis of X-ray data

Dialkylgallium Complexes with Alkoxide and Aryloxide Ligands Possessing N‑Heterocyclic Carbene Functionalities: Synthesis and Structure

Methods for the synthesis of dialkylgalium compounds with alkoxide or aryloxide ligands possessing N-heterocyclic carbene functionalities have been established. As a result, the synthesis of a series of dialkylgallium complexes Me₂Ga­(O,C) (<b>1</b>, <b>3</b>–<b>5</b>), and Me₂Ga­(O,C)·Me₃Ga (<b>2</b>, <b>6</b>) is described, where (O,C) represents an alkoxide or aryloxide monoanionic chelate ligand with an N-heterocyclic carbene functionality. All complexes have been fully characterized using spectroscopic and X-ray techniques. The presence of a strongly basic NHC functionality in alkoxide or aryloxide ligands resulted in the formation of monomeric Me₂Ga­(O,C) species. The reaction of those complexes with the Lewis acid Me₃Ga leads to Me₂Ga­(O,C)·Me₃Ga adducts (<b>2</b> and <b>6</b>) with a strong Me₃Ga–O dative bond. The effect of (O,C) ligands with various steric and electronic properties on the structure of obtained Me₂Ga­(O,C) and Me₂Ga­(O,C)·Me₃Ga has been discussed on the basis of spectroscopic data. Finally, the bond valence vector model has been used to estimate the effect of a chelating (O,C) ligand on strains in complexes <b>1</b>–<b>6</b> on the basis of X-ray data

Impact of Organometallic Intermediates on Copper-Catalyzed Atom Transfer Radical Polymerization

In atom transfer radical polymerization (ATRP), radicals (R^•) can react with Cu^I/L catalysts forming organometallic complexes, R–Cu^II/L (L = N-based ligand). R–Cu^II/L favors additional catalyzed radical termination (CRT) pathways, which should be understood and harnessed to tune the polymerization outcome. Therefore, the preparation of precise polymer architectures by ATRP depends on the stability and on the role of R–Cu^II/L intermediates. Herein, spectroscopic and electrochemical techniques were used to quantify the thermodynamic and kinetic parameters of the interactions between radicals and Cu catalysts. The effects of radical structure, catalyst structure and solvent nature were investigated. The stability of R–Cu^II/L depends on the radical-stabilizing group in the following order: cyano > ester > phenyl. Primary radicals form the most stable R–Cu^II/L species. Overall, the stability of R–Cu^II/L does not significantly depend on the electronic properties of the ligand, contrary to the ATRP activity. Under typical ATRP conditions, the R–Cu^II/L build-up and the CRT contribution may be suppressed by using more ATRP-active catalysts or solvents that promote a higher ATRP activity