Assembling Complex Macromolecules and Self-Organizations of Biological Relevance with Cu(I)-Catalyzed Azide-Alkyne, Thio-Bromo, and TERMINI Double "Click" Reactions

In 2022, the Nobel Prize in Chemistry was awarded to Bertozzi, Meldal, and Sharpless "for the development of click chemistry and biorthogonal chemistry". Since 2001, when the concept of click chemistry was advanced by Sharpless laboratory, synthetic chemists started to envision click reactions as the preferred choice of synthetic methodology employed to create new functions. This brief perspective will summarize research performed in our laboratories with the classic Cu(I)-catalyzed azide-alkyne click (CuAAC) reaction elaborated by Meldal and Sharpless, with the thio-bromo click (TBC) and with the less-used, irreversible TERminator Multifunctional INItiator (TERMINI) dual click (TBC) reactions, the last two elaborated in our laboratory. These click reactions will be used to assemble, by accelerated modular-orthogonal methodologies, complex macromolecules and self-organizations of biological relevance. Self-assembling amphiphilic Janus dendrimers and Janus glycodendrimers together with their biological membrane mimics known as dendrimersomes and glycodendrimersomes as well as simple methodologies to assemble macromolecules with perfect and complex architecture such as dendrimers from commercial monomers and building blocks will be discussed. This perspective is dedicated to the 75th anniversary of Professor Bogdan C. Simionescu, the son of my (VP) Ph.D. mentor, Professor Cristofor I. Simionescu, who as his father, took both science and science administration in his hands, and dedicated his life to handling them in a tandem way, to their best.

PVDF-Based Fluoropolymer Modifications via Photoinduced Atom Transfer Radical Polymerizations

Graft modifications of PVDF fluoropolymers have been identified as the efficient route to improve the properties and expand the applications. Taking advantage of C-F and C-Cl bonds in the repeat units, atom transfer radical polymerizations (ATRP) were widely used for graft modification. Recently, photoinduced ATRP has shown good spatial and temporal control over the polymerization process in contrast to thermal activation mode. This minireview highlights the progress in PVDF-based fluoropolymer modifications by using photoinduced Cu(II)-mediated ATRP and organocatalyzed ATRP. The challenges and opportunities are proposed with the aim at advancing the development of synthesis and applications of fluoropolymer.

State-of-art review on preparation, surface functionalization and biomedical applications of cellulose nanocrystals-based materials

Cellulose nanocrystals (CNCs) are a class of sustainable nanomaterials that are obtained from plants and microorganisms. These naturally derived nanomaterials are of abundant hydroxyl groups, well biocompatibility, low cost and biodegradable potential, making them suitable and promising candidates for various applications, especially in biomedical fields. In this review, the recent advances and development on the preparation, surface functionalization and biomedical applications of CNCs-based materials have been summarized and outlined. The main context of this paper could be divided into the following three parts. In the first part, the preparation strategies based on physical, chemical, enzymatic and combination techniques for preparation of CNCs have been summarized. The surface functionalization methods for synthesis CNCs-based materials with designed properties and functions were outlined in the following section. Finally, the current state about applications of CNCs-based materials for tissue engineering, medical hydrogels, biosensors, fluorescent imaging and intracellular delivery of biological agents have been highlighted. Moreover, current issues and future directions about the above aspects have also pointed out and discussed. We believe this review will attract great research attention of scientists from materials, chemistry, biomedicine and other disciplines. It will also provide some important insights on the future development of CNCs-based materials especially in biomedical fields.

Electrochemistry for Atom Transfer Radical Polymerization

Atom Transfer Radical Polymerization (ATRP) is the most powerful and most employed technology of Controlled Radical Polymerization (CRP) to produce polymers with well-defined architecture, that is, composition, topology, and functionality. Several hundreds of papers are published every year on ATRP processes, mainly based on empiric experimental procedures. Electrochemistry powerfully entered in the field of ATRP about 10 years ago, providing important contributions both to the further development of the process and to a better understanding of its mechanism. Five main issues took advantage of electrochemistry and/or its synergism with ATRP: i) understanding the mechanism of ATRP activation; ii) determination of thermodynamic parameters; iii) determination of activation and deactivation rate constants; iv) the SARA ATRP vs SET-LRP dispute: the role of Cu⁰ ; v) electrochemically-mediated ATRP.

Surface-Initiated Controlled Radical Polymerization Approach to In Situ Cross-Link Cellulose Nanofibrils with Inorganic Nanoparticles

This paper investigates a strategy to convert hydrophilic cellulose nanofibrils (CNF) into a hydrophobic highly cross-linked network made of cellulose nanofibrils and inorganic nanoparticles. First, the cellulose nanofibrils were chemically modified through an esterification reaction to produce a nanocellulose-based macroinitiator. Barium titanate (BaTiO₃, BTO) nanoparticles were surface-modified by introducing a specific monomer on their outer-shell surface. Finally, we studied the ability of the nanocellulose-based macroinitiator to initiate a single electron transfer living radical polymerization of stearyl acrylate (SA) in the presence of the surface-modified nanoparticles. The BTO nanoparticles will transfer new properties to the nanocellulose network and act as a cross-linking agent between the nanocellulose fibrils, while the monomer (SA) directly influences the hydrophilic-lipophilic balance. The pristine CNF and the nanoparticle cross-linked CNF are characterized by FTIR, SEM, and solid-state ¹³C NMR. Rheological and dynamic mechanical analyses revealed a high dregee of cross-linking.

Understanding the effect of monomer structure of oligoethylene glycol acrylate copolymers on their thermoresponsive behavior for the development of polymeric sensors

Oligoethylene glycol acrylate (OEGA) polymers are a class of thermoresponsive polymers. Three new OEGA monomer combinations were investigated, which revealed three different types of thermoresponsive behavior as a function of copolymer composition.

Lipidated polymers for the stabilization of cubosomes: nanostructured drug delivery vehicles

Lipidated polymers, like their protein counterparts, may be useful in fields as diverse as biochemistry and drug delivery. As such, strategies for preparing lipidated polymers with defined molecular architecture are clearly warranted. Herein, we describe a broadly-applicable methodology for synthesizing such lipidated materials, and demonstrate how they can be applied to the preparation of nanostructured drug delivery vehicles.

Highly reactive α-bromoacrylate monomers and Michael acceptors obtained by Cu(ii)Br2-dibromination of acrylates and instantaneous E2 by a ligand

The importance of the order of addition of reagents in SET-LRP.

Acetone: a solvent or a reagent depending on the addition order in SET-LRP

The importance of reagent order in biphasic SET-LRP in acetone/water mixtures is shown.

Supported Cu0 nanoparticles catalyst for controlled radical polymerization reaction and block-copolymer synthesis

The synthesis of Cu⁰ nanoparticles on different supports and their activity in controlled living radical polymerization processes is presented. The type of support influences the final size of the copper nanoparticles as well as their adhesion to the support. These aspects have a direct influence on the characteristics of the polymers obtained. The best results were obtained for SiO₂ particles, which afforded a good molecular weight distribution (Mw/Mn = 1.25). The activity, recovery and recycling of the catalyst was explored for ultrafast polymerization reaction of butyl acrylate. Further, the terminal bromine reactivity was used for the synthesis of a block poly(n butyl acrylate-block-styrene). The influence of ligand type on the control of the reaction was studied. Also, a straightforward polymerization procedure without any ligand afforded a polydispersity value of 1.38.

Polymer Brush-Functionalized Chitosan Hydrogels as Antifouling Implant Coatings

Implantable sensor devices require coatings that efficiently interface with the tissue environment to mediate biochemical analysis. In this regard, bioinspired polymer hydrogels offer an attractive and abundant source of coating materials. However, upon implantation these materials generally elicit inflammation and the foreign body reaction as a consequence of protein fouling on their surface and concomitant poor hemocompatibility. In this report we investigate a strategy to endow chitosan hydrogel coatings with antifouling properties by the grafting of polymer brushes in a "grafting-from" approach. Chitosan coatings were functionalized with polymer brushes of oligo(ethylene glycol) methyl ether methacrylate and 2-hydroxyethyl methacrylate using photoinduced single electron transfer living radical polymerization and the surfaces were thoroughly characterized by XPS, AFM, water contact angle goniometry, and in situ ellipsometry. The antifouling properties of these new bioinspired hydrogel-brush coatings were investigated by surface plasmon resonance. The influence of the modifications to the chitosan on hemocompatibility was assessed by contacting the surfaces with platelets and leukocytes. The coatings were hydrophilic and reached a thickness of up to 180 nm within 30 min of polymerization. The functionalization of the surface with polymer brushes significantly reduced the protein fouling and eliminated platelet activation and leukocyte adhesion. This methodology offers a facile route to functionalizing implantable sensor systems with antifouling coatings that improve hemocompatibility and pave the way for enhanced device integration in tissue.

Recent Developments in the Synthesis of Biomacromolecules and their Conjugates by Single Electron Transfer-Living Radical Polymerization

Single electron transfer-living radical polymerization (SET-LRP) represents a robust and versatile tool for the synthesis of vinyl polymers with well-defined topology and chain end functionality. The crucial step in SET-LRP is the disproportionation of the Cu(I)X generated by activation with Cu(0) wire, powder, or nascent Cu(0) generated in situ into nascent, extremely reactive Cu(0) atoms and nanoparticles and Cu(II)X₂. Nascent Cu(0) activates the initiator and dormant chains via a homogeneous or heterogeneous outer-sphere single-electron transfer mechanism (SET-LRP). SET-LRP provides an ultrafast polymerization of a plethora of monomers (e.g., (meth)-acrylates, (meth)-acrylamides, styrene, and vinyl chloride) including hydrophobic and water insoluble to hydrophilic and water soluble. Some advantageous features of SET-LRP are (i) the use of Cu(0) wire or powder as readily available catalysts under mild reaction conditions, (ii) their excellent control over molecular weight evolution and distribution as well as polymer chain ends, (iii) their high functional group tolerance allowing the polymerization of commercial-grade monomers, and (iv) the limited purification required for the resulting polymers. In this Perspective, we highlight the recent advancements of SET-LRP in the synthesis of biomacromolecules and of their conjugates.

Acetone–water biphasic mixtures as solvents for ultrafast SET-LRP of hydrophobic acrylates

Transformation of SET-LRP catalyzed with Cu(0) wire from single phase (acetone/water = 9/1, v/v) into biphase (acetone/water = 8/2, v/v).

PDMAEMA-b-PPOA-b-PDMAEMA double-bond-containing amphiphilic triblock copolymer: synthesis, characterization, and pH-responsive self-assembly

This article reports a new pH-responsive double-bond-containing ABA triblock copolymer synthesized via a combination of free radical polymerization and SET-LRP.

Searching for efficient SET-LRP systems via biphasic mixtures of water with carbonates, ethers and dipolar aprotic solvents

Screening biphasic mixtures of water with carbonates, ethers and dipolar aprotic solvents to discover new SET-LRP solvent systems.

Glass surface modification via Cu(0)-mediated living radical polymerization of fluorinated and non-fluorinated acrylates

The glass surface was modified via Cu(0)-mediated living radical polymerization of butyl acrylate and trifluoroethyl methacrylate by using the grafting from and grafting to methodologies.

The stirring rate provides a dramatic acceleration of the ultrafast interfacial SET-LRP in biphasic acetonitrile–water mixtures

The rate of interfacial SET-LRP in biphasic acetonitrile–water mixtures is stirring rate dependent.

Understanding Polymer-Cell Attachment

The development of polymeric materials with cell adhesion abilities requires an understanding of cell-surface interactions which vary with cell type. To investigate the correlation between cell attachment and the nature of the polymer, a series of random and block copolymers composed of 2-(dimethylamino)ethyl acrylate and ethyl acrylate are synthesized through single electron transfer living radical polymerization. The polymers are synthesized with highly defined and controlled monomer compositions and exhibited narrow polydispersity indices. These polymers are examined for their performance in the attachment and growth of HeLa and HEK cells, with attachment successfully modeled on monomer composition and polymer chain length, with both cell lines found to preferentially attach to moderately hydrophobic functional materials. The understanding of the biological-material interactions assessed in this study will underpin further investigations of engineered polymer scaffolds with predictable cell binding performance.

Recent developments in polydopamine: an emerging soft matter for surface modification and biomedical applications

After more than four billion years of evolution, nature has created a large number of fascinating living organisms, which show numerous peculiar structures and wonderful properties. Nature can provide sources of plentiful inspiration for scientists to create various materials and devices with special functions and uses. Since Messersmith proposed the fabrication of multifunctional coatings through mussel-inspired chemistry, this field has attracted considerable attention for its promising and exiciting applications. Polydopamine (PDA), an emerging soft matter, has been demonstrated to be a crucial component in mussel-inspired chemistry. In this review, the recent developments of PDA for mussel-inspired surface modification are summarized and discussed. The biomedical applications of PDA-based materials are also highlighted. We believe that this review can provide important and timely information regarding mussel-inspired chemistry and will be of great interest for scientists in the chemistry, materials, biology, medicine and interdisciplinary fields.

Grafting of functional methacrylate polymer brushes by photoinduced SET-LRP

The growth of polymer brushes from a variety of methacrylate monomers was accomplished using UV light as a polymerization trigger.

Polymerisation of 2-acrylamido-2-methylpropane sulfonic acid sodium salt (NaAMPS) and acryloyl phosphatidylcholine (APC) via aqueous Cu(0)-mediated radical polymerisation

The scope of aqueous Cu(0)-mediated living radical polymerisation has been expanded with the preparation of poly(2-acrylamido-2-methylpropane sulfonic acid)sodium salt (P(NaAMPS)) and poly(acryloyl phosphatidycholine) (PAPC).

Quantitative end-group functionalization of PNIPAM from aqueous SET-LRP via in situ reduction of Cu(ii) with NaBH4

Rapid in situ azidation and CuAAC ‘click’ reaction demonstrating very high chain-end functionality.

Surface-initiated SET-LRP mediated by mussel-inspired polydopamine chemistry for controlled building of novel core–shell magnetic nanoparticles for highly-efficient uranium enrichment

Surface-initiated SET-LRP integrated with polydopamine chemistry to prepare core–shell magnetic nanoparticles for uranium enrichment.

First double hydrophilic graft copolymer bearing a poly(2-hydroxylethyl acrylate) backbone synthesized by sequential RAFT polymerization and SET-LRP

This article reports the first synthesis of well-defined double hydrophilic graft copolymers with a PHEA backbone, by the combination of RAFT polymerization, SET-LRP, and a grafting-from strategy.

Cu(0)-mediated living radical polymerization: recent highlights and applications; a perspective

Cu(0)-mediated living radical polymerization or single electron transfer living radical polymerization (Cu(0)-mediated LRP or SET-LRP) is a versatile polymerization technique that has attracted considerable interest during the past few years for the facile preparation of advanced materials.

Ultrafast SET-LRP of hydrophobic acrylates in multiphase alcohol–water mixtures

A multiphase SET-LRP system using thein situgenerated Cu(0) by reduction of Cu(ii)Br₂with NaBH₄in various alcohols containing water was developed and used for SET-LRP of hydrophobic acrylates. From left to right: a solution of methanol/water containing Cu(ii)Br₂, the same solution after addition of BA and its SET-LRP.

SET-LRP of NIPAM in water via in situ reduction of Cu(ii) to Cu(0) with NaBH4

The direct and quantitative reduction of the air-stable Cu(ii)Br₂/Me₆TREN to Cu(0) by NaBH₄ represents a new method for the aqueous single electron transfer-living radical polymerization (SET-LRP) of water soluble polymers.

Ultrafast SET-LRP in biphasic mixtures of the non-disproportionating solvent acetonitrile with water

The two kinetic regime, low conversion and low chain end functionality seen in copper catalyzed polymerization of acrylates in acetonitrile was transformed into a SET-LRP kinetic, to complete conversion and quantitative chain end functionality in a biphasic mixture containing 10% water.

PHEA-g-PDMAEA well-defined graft copolymers: SET-LRP synthesis, self-catalyzed hydrolysis, and quaternization

This article reports the synthesis of well-defined graft copolymers containing a PHEA backbone and degradable PDMAEA side chains, by the combination of RAFT polymerization, SET-LRP, and the grafting-from strategy.

A multiple-stage activation of the catalytically inhomogeneous Cu(0) wire used in SET-LRP

The surface of a Cu(0) wire used as a catalyst in SET-LRP is inhomogeneous since it contains a combination of Cu(111) and Cu(100) faces of the FCC unit cell whose ratio is dependent on the fabrication method. A method to activate this inhomogeneous Cu(0) wire for SET-LRP is reported.

Pentablock star shaped polymers in less than 90 minutes via aqueous SET-LRP

The synthesis of core-first multi-block star-shaped copolymers via aqueous SET-LRP has been reported for the first time.

Design of a hydrophilic ruthenium catalyst for metal-catalyzed living radical polymerization: highly active catalysis in water

A novel hydrophilic phosphine ligand for a ruthenium catalyst was synthesized towards useful living radical polymerization in water.

Lights on! A significant photoenhancement effect on ATRP by ambient laboratory light

The influence of ambient laboratory light from common fluorescent lamps on AGET, ARGET, and classical ATRP reactions was investigated and significant differences were found except for ARGET ATRP.

Continuous flow SET-LRP in the presence of P(VDF-co-CTFE) as macroinitiator in a copper tubular reactor

A green, highly effective and energy-saving route to the grafting modification of P(VDF-co-CTFE) was developedviacontinuous flow SET-LRP with significant advantages over batch reactors.

The synergistic effect during biphasic SET-LRP in ethanol–nonpolar solvent–water mixtures

Adding a nonpolar solvent to ethanol–water reaction mixtures transforms SET-LRP of BA from triphasic to biphasic exhibiting a synergistic effect.