Uniform polymer-protein conjugate by aqueous AGET ATRP using protein as a macroinitiator

Recent Advances in the Application of ATRP in the Synthesis of Drug Delivery Systems

Advances in atom transfer radical polymerization (ATRP) have enabled the precise design and preparation of nanostructured polymeric materials for a variety of biomedical applications. This paper briefly summarizes recent developments in the synthesis of bio-therapeutics for drug delivery based on linear and branched block copolymers and bioconjugates using ATRP, which have been tested in drug delivery systems (DDSs) over the past decade. An important trend is the rapid development of a number of smart DDSs that can release bioactive materials in response to certain external stimuli, either physical (e.g., light, ultrasound, or temperature) or chemical factors (e.g., changes in pH values and/or environmental redox potential). The use of ATRPs in the synthesis of polymeric bioconjugates containing drugs, proteins, and nucleic acids, as well as systems applied in combination therapies, has also received considerable attention.

Oxygen tolerant, photoinduced controlled radical polymerization approach for the synthesis of giant amphiphiles

New families of amphiphilic protein–polymer bioconjugates readily synthesized via an oxygen tolerant, photoinduced RDRP approach.

Preparation of Biomolecule-Polymer Conjugates by Grafting-From Using ATRP, RAFT, or ROMP

Biomolecule-polymer conjugates are constructs that take advantage of the functional or otherwise beneficial traits inherent to biomolecules and combine them with synthetic polymers possessing specially tailored properties. The rapid development of novel biomolecule-polymer conjugates based on proteins, peptides, or nucleic acids has ushered in a variety of unique materials, which exhibit functional attributes including thermo-responsiveness, exceptional stability, and specialized specificity. Key to the synthesis of new biomolecule-polymer hybrids is the use of controlled polymerization techniques coupled with either grafting-from, grafting-to, or grafting-through methodology, each of which exhibit distinct advantages and/or disadvantages. In this review, we present recent progress in the development of biomolecule-polymer conjugates with a focus on works that have detailed the use of grafting-from methods employing ATRP, RAFT, or ROMP.

Up in the air: oxygen tolerance in controlled/living radical polymerisation

The requirement for deoxygenation in controlled/living radical polymerisation (CLRP) places significant limitations on its widespread implementation by necessitating the use of large reaction volumes, sealed reaction vessels as well as requiring access to specialised equipment such as a glove box and/or inert gas source. As a result, in recent years there has been intense interest in developing strategies for overcoming the effects of oxygen inhibition in CLRP and therefore remove the necessity for deoxygenation. In this review, we highlight several strategies for achieving oxygen tolerant CLRP including: "polymerising through" oxygen, enzyme mediated deoxygenation and the continuous regeneration of a redox-active catalyst. In order to provide further clarity to the field, we also establish some basic parameters for evaluating the degree of "oxygen tolerance" that can be achieved using a given oxygen scrubbing strategy. Finally, we propose some applications that could most benefit from the implementation of oxygen tolerant CLRP and provide a perspective on the future direction of this field.

Nanobiocatalysis: Nanostructured materials – a minireview

The field of nanobiocatalysis has experienced a rapid growth due to recent advances in nanotechnology. However, biocatalytic processes are often limited by the lack of stability of the enzymes and their short lifetime. Therefore, immobilization is key to the successful implementation of industrial processes based on enzymes. Immobilization of enzymes on functionalized nanostructured materials could give higher stability to nanobiocatalysts while maintaining free enzyme activity and easy recyclability under various conditions. This review will discuss recent developments in nanobiocatalysis to improve the stability of the enzyme using various nanostructured materials such as mesoporous materials, nanofibers, nanoparticles, nanotubes, and individual nanoparticles enzymes. Also, this review summarizes the recent evolution of nanostructured biocatalysts with an emphasis on those formed with polymers. Based on the synthetic procedures used, established methods fall into two important categories: “grafting onto” and “grafting from”. The fundamentals of each method in enhancing enzyme stability and the use of these new nanobiocatalysts as tools for different applications in different areas are discussed.

Multivalent 3D Display of Glycopolymer Chains for Enhanced Lectin Interaction

Synthetic glycoprotein conjugates were synthesized through the polymerization of glycomonomers (mannose and/or galactose acrylate) directly from a protein macroinitiator. This design combines the multivalency of polymer structures with 3D display of saccharides randomly arranged around a central protein structure. The conjugates were tested for their interaction with mannose binding lectin (MBL), a key protein of immune complement. Increasing mannose number (controlled through polymer chain length) and density (controlled through comonomer feed ratio of mannose versus galactose) result in greater interaction with MBL. Most significantly, mannose glycopolymers displayed in a multivalent and 3D configuration from the protein exhibit dramatically enhanced interaction with MBL compared to linear glycopolymer chains with similar total valency but lacking 3D display. These findings demonstrate the importance of the 3D presentation of ligand structures for designing biomimetic materials.

Visible light induced fast synthesis of protein–polymer conjugates: controllable polymerization and protein activity

Visible light induced fast and controllable RAFT polymerization from protein as a novel method for preparing protein–polymer conjugates at ambient temperature.

ATRP under Biologically Relevant Conditions: Grafting from a Protein

Atom transfer radical polymerization (ATRP) methods were developed in water-based media, to grow polymers from proteins under biologically relevant conditions. These conditions gave good control over the resulting polymers, while still preserving the protein's native structure. Several reaction parameters, such as ligand structure, halide species, and initiation mode were optimized in water and PBS buffer to yield well-defined polymers grown from bovine serum albumin (BSA), functionalized with cleavable ATRP initiators (I). The CuCl complex with ligand 2,2'-bipyridyne (bpy) provides the best conditions for the polymerization of oligo(ethylene oxide) methacrylate (OEOMA) in water at 30 °C under normal ATRP conditions (I/CuCl/CuCl₂/bpy = 1/1/9/22), while the CuBr/bpy complex gave better performance in PBS. Activators generated by electron transfer (AGET) ATRP gave well-controlled polymerization of OEOMA at 30 °C with the ligand tris(2-pyridylmethyl)amine (TPMA), (I/CuBr₂/TPMA = 1/10/11). The AGET ATRP reactions required slow feeding of a very small amount of ascorbic acid into the aqueous reaction medium or buffer. The reaction conditions developed were used to create a smart, thermoresponsive, protein-polymer hybrid.