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Iron-containing poly(ionic liquid) membranes were prepared by Cu(0)-mediated reversible deactivation radical polymerization, which was achieved to catalyze a heterogeneous Fenton reaction and realize self-cleaning of the membrane surface.

Cationic glycopolymers have attracted great attention as a new type of antibacterial material.

A claw-type Schiff base, tris[N-(2-pyridylmethyl)-2-iminoethyl]amine (Py3Tren), is used as an active ligand for photoinduced atom transfer radical polymerization (Photo-ATRP). CuBr2/Py3Tren was employed as a catalyst for Photo-ATRP of methyl methacrylate (MMA) under the irradiation of ultraviolet or visible light. Well-defined poly(MMA) could be synthesized with high chain-end functionality confirmed by in situ chain extension. Temporal control of Photo-ATRP was successfully demonstrated by switching the light on and off. The polymerization mechanism was finally discussed through UV/vis spectroscopy and electrospray ionization mass spectrometry (ESI-MS) experiments.

Nondegradable PEGylated protein drugs are known to cause accumulation in the tissue and accelerated blood clearance effect, which inspire people to develop alternative polymers such as polyesters for bioconjugation. However, the hydrophobicity and slow degradation rate of polyesters remain as challenges for typical therapeutic applications. Here, we report the facile synthesis of biodegradable protein–poly(e-caprolactone) conjugates via enzymatic ring opening polymerization (eROP). Candida antarctica lipase B (CALB)–poly(N-hydroxyethyl acrylamide) conjugates with pendent hydroxyl groups were utilized as initiators and catalysts simultaneously for the eROP of e-caprolactone to form amphiphilic graft copolymers. The enzymatic degradation of ester-containing polymers in the conjugates could be significantly accelerated by lipase, leading to total degradation in several days.

Protein-loaded hydrogels were synthesized via biocatalytic atom transfer radical polymerization (ATRP) for the first time. Laccase from Trametes versicolor acted as the ATRPase for the enzymatic polymerizations and was in situ loaded into the porous network of poly(ethylene glycol)-based hydrogels. The use of additional ligands such as tris(2-(dimethylamino)ethyl)amine could significantly increase the polymerization conversion, allowing the polymerizations to occur at ambient or even lower temperature. The rheology and water uptake ratio of hydrogels could be tuned by using different cross-linkers. Immobilized enzymes in the hydrogels have shown decreased yet considerable activity compared with pristine laccase. The hydrogels could be facilely recovered and reused up to six times with no significant decrease in enzyme activity. Such hydrogels were successfully used for the oxidative polymerization of hydroquinone and may find potential applications in protein delivery and water treatment.

The use of a tripodal heptadentate Schiff base, tris[N-(2-pyridylmethyl)-2-iminoethyl]amine (Py3Tren), as an active ligand for atom transfer radical polymerization (ATRP) is reported. The coordination between Py3Tren and CuBr2 in solution is investigated by electrospray ionization mass spectrometry, which reveals the generation of a tripod claw-shaped complex by using equimolar quantities of CuBr2 and Py3Tren. Electrochemical studies of CuBr2/Py3Tren complexes demonstrate more negative redox potentials and higher activities compared with those of bidentate CuBr2/N-ethyl-2-pyridylmethanimine (PyEthyl) complexes. Subsequently, CuBr/Py3Tren is employed as a catalyst for the normal ATRP of methyl methacrylate (MMA). Well-defined poly(MMA) with controlled molecular weight and narrow polydispersity could be synthesized with high conversions and fast rates even at ambient temperature (30 °C). Activators regenerated by electron transfer (ARGET) ATRP and supplemental activators and reducing agents (SARA) ATRP of acrylate monomers using Py3Tren as the ligand are also performed to reduce the amounts of metal catalysts for polymerizations.

Polymerization-induced self-assembly (PISA) has evolved as a facile pathway for the in situ formation of polymeric nanomaterials with unique morphologies. However, aqueous PISA by atom transfer radical polymerization (ATRP) for the generation of protein-based nanoassemblies is still challenging. In this research, Candida antarctica lipase B (CALB) is modified as the macroinitiator for Cu(0)-mediated reversible deactivation radical polymerization (Cu(0)-RDRP) of both hydrophilic and hydrophobic monomers in water or water/methanol mixtures. Different acrylamides and acrylates are successfully polymerized in the presence of lipase-based macroinitiators under mild reaction conditions and it is found that the lipase-catalyzed hydrolysis of ester bonds from poly(acrylates) is very significant. The PISA of lipase–hydrophobic polymer conjugates could directly generate spherical nanoparticles in aqueous solution without further processing. Activity tests further demonstrate preservation or even a significant increase of the enzymatic activity for the conjugates, indicating the potential application of aqueous PISA in protein delivery and enzyme immobilization.

Covalent coupling of hydrophobic polymers to the exterior of hydrophilic proteins would mediate unique macroscopic assembly of bioconjugates to generate amphiphilic superstructures as novel nanoreactors or biocompatible drug delivery systems. The main objective of this study was to develop a novel strategy for the synthesis of protein-polymer giant amphiphiles by the combination of copper-mediated living radical polymerization and azide-alkyne cycloaddition reaction (CuAAC). Azide-functionalized succinimidyl ester was first synthesized for the facile introduction of azide groups to proteins such as albumin from bovine serum (BSA) and laccase from Trametes versicolor. Alkyne-terminal polymers with varied hydrophobicity were synthesized by using commercial copper wire as the activators from a trimethylsilyl protected alkyne-functionalized initiator in DMSO under ambient temperature. The conjugation of alkyne-functionalized polymers to the azide-functionalized laccase could be conducted even without additional copper catalyst, which indicated a successful self-catalyzed CuAAC reaction. The synthesized amphiphiles were found to aggregate into spherical nanoparticles in water and showed strong relevance to the hydrophobicity of coupled polymers. The giant amphiphiles showed decreased enzyme activity yet better stability during storage after chemical modification and self-assembly. These findings will deepen our understanding on protein folding, macroscopic self-assembly, and support potential applications in bionanoreactor, enzyme immobilization, and water purification.

It is challenging to regenerate enzyme carriers when covalently immobilized enzymes suffered from inactivation during continuous operations. Hence, it is urgent to develop a facile strategy to immobilize enzymes reversibly. Herein, the non-covalent interaction between protein and carbohydrate was used to adsorb and desorb enzymes reversibly. Laccase was immobilized onto glycopolymer microspheres via protein-carbohydrate interaction using lectins as the intermediates. The enzyme loading and immobilization yield were up to 49 mg/g and 77.1% with highly expressed activity of 107.9 U/mg. The immobilized laccase exhibited enhanced pH stability and high activity in catalyzing the biodegradation of paracetamol. During ten successive recoveries, the immobilized laccases could be recycled while maintaining relatively high enzyme activity. The glycopolymer microspheres could be efficiently regenerated by elution with an aqueous solution of mannose or acid for further enzyme immobilization. This glycopolymer microspheres has excellent potential to act as reusable carriers for the non-covalent immobilization of different enzymes.