Current Standing on Radical Ring‐Opening Polymerizations of Cyclic Ketene Acetals as Homopolymers and Copolymers with one anotherDeng, Yiyi; Mehner, Fabian; Gaitzsch, Jens
doi: 10.1002/marc.202200941pmid: 36881376
Radical Ring‐opening polymerization (RROP) of cyclic ketene acetals (CKAs) emerges to be a valuable polymerization technique. In attracting more attention, RROP has seen a new spike in publications, which the authors will put into perspective. This review will hence address the progress made on the number of available CKAs and the synthetic strategies to get them. In grouping, the available monomers into distinct categories, the enormous variety of available CKAs will be highlighted. Polymerizations of CKAs without vinylenes have the potential to yield fully biodegradable polymers, which is why this kind of polymerization is the focus of this review. Detailing the current understanding of the mechanism, the various side reactions will be noted and also their effect on the overall properties of the final polymers. Current attempts to control the ring‐retaining and branching reactions will be discussed as well. In addition to the polymerization itself, the available materials will be discussed as well as homopolymers, copolymers of CKAs, and block‐copolymers with pure CKA‐blocks have significantly widened the range of possible applications of materials from RROP. Altogether this review highlights the progress in the entire field of RROP just of CKAs to give a holistic overview of the field.
Synthesis of Multifunctional Protein‐Polymer Conjugates via Oxygen‐tolerant, Aqueous Copper‐Mediated Polymerization, and Bioorthogonal Click ChemistryVoutyritsa, Errika; Gryparis, Charis; Theodorou, Alexis; Velonia, Kelly
doi: 10.1002/marc.202200976pmid: 37002553
Oxygen‐tolerant, aqueous copper‐mediated polymerization approaches are combined with click chemistry in either a sequential or a simultaneous manner, to enable the synthesis of multifunctional protein‐polymer conjugates. Propargyl acrylate (PgA) and propargyl methacrylate (PgMA) grafting from a bovine serum albumin (BSA) macroinitiator is thoroughly optimized to synthesize chemically addressable BSA‐poly(propargyl acrylate) and BSA‐poly(propargyl methacrylate) respectively. The produced multifunctional bioconjugates bear pendant terminal 1‐alkynes which can be readily post‐functionalized via both [3+2] Huisgen cycloaddition and thiol‐yne click chemistry under mild reaction conditions. Simultaneous oxygen‐tolerant, aqueous copper‐catalyzed polymerization, and click chemistry mediate the in situ multiple chemical tailoring of biomacromolecules in excellent yields.
Reversible Molecular Capture and Release in Microfluidics by Host–Guest Interactions in Hydrogel MicrodotsJiao, Chen; Liubimtsev, Nikolai; Zagradska‐Paromova, Zlata; Appelhans, Dietmar; Gaitzsch, Jens; Voit, Brigitte
doi: 10.1002/marc.202200869pmid: 36702804
The integration of microscopic hydrogels with high specific surface area and physically reactive groups into microfluidic systems for selective molecular interactions is attracting increasing attention. Herein, the reversible capture and release of molecules through host–guest interactions of hydrogel dots in a microfluidic device is reported, which translates the supramolecular chemistry to the microscale conditions under continuous flow. Polyacrylamide (PAAm) hydrogel arrays with grafted β‐cyclodextrin (β‐CD) modified poly(2‐methyl‐2‐oxazoline) (CD‐PMOXA) chains are fabricated by photopolymerization and integrated into a polydimethylsiloxane (PDMS)‐on‐glass chip. The β‐CD/adamantane (β‐CD/Ada) host–guest complex is confirmed by two dimensional Nuclear Overhauser Effect Spectroscopy NMR (2D NOESY NMR) prior to transfer to microfluidics. Ada‐modified molecules are successfully captured by host–guest interaction formed between the CD‐PMOXA grafted chains in the hydrogel network and the guest molecule in the solution. Furthermore, the captured molecules are released by perfusing free β‐CD with higher binding affinity than those grafted in the hydrogel array. A small guest molecule adamantane‐fluorescein‐isothiocyanate (Ada‐FITC) and a macromolecular guest molecule (Ada‐PMOXA‐Cyanine 5 (Cy5)) are separately captured and released for three times with a release ratio up to 46% and 92%, respectively. The reproducible capture and release of functional molecules with different sizes demonstrates the stability of this hydrogel system in microfluidics and will provide an opportunity for future applications.
Compartmentalized Intracellular Click Chemistry with Biodegradable PolymersomesOerlemans, Roy A. J. F.; Shao, Jingxin; Huisman, Sander G. A. M.; Li, Yudong; Abdelmohsen, Loai K. E. A.; van Hest, Jan C. M.
doi: 10.1002/marc.202200904pmid: 36607841
Polymersome nanoreactors that can be employed as artificial organelles have gained much interest over the past decades. Such systems often include biological catalysts (i.e., enzymes) so that they can undertake chemical reactions in cellulo. Examples of nanoreactor artificial organelles that acquire metal catalysts in their structure are limited, and their application in living cells remains fairly restricted. In part, this shortfall is due to difficulties associated with constructing systems that maintain their stability in vitro, let alone the toxicity they impose on cells. This study demonstrates a biodegradable and biocompatible polymersome nanoreactor platform, which can be applied as an artificial organelle in living cells. The ability of the artificial organelles to covalently and non‐covalently incorporate tris(triazolylmethyl)amine‐Cu(I) complexes in their membrane is shown. Such artificial organelles are capable of effectively catalyzing a copper‐catalyzed azide‐alkyne cycloaddition intracellularly, without compromising the cells’ integrity. The platform represents a step forward in the application of polymersome‐based nanoreactors as artificial organelles.
Selective Colloid Transport across Planar Polymer BrushesLaktionov, Mikhail Y.; Zhulina, Ekaterina B.; Klushin, Leonid; Richter, Ralf P.; Borisov, Oleg V.
doi: 10.1002/marc.202200980pmid: 36915225
Polymer brushes are attractive as surface coatings for a wide range of applications, from fundamental research to everyday life, and also play important roles in biological systems. How colloids (e.g., functional nanoparticles, proteins, viruses) bind and move across polymer brushes is an important yet under‐studied problem. A mean‐field theoretical approach is presented to analyze the binding and transport of colloids in planar polymer brushes. The theory explicitly considers the effect of solvent strength on brush conformation and of colloid‐polymer affinity on colloid binding and transport. The position‐dependent free energy of the colloid insertion into the polymer brush which controls the rate of colloid transport across the brush is derived. It is shown how the properties of the brush can be adjusted for brushes to be highly selective, effectively serving as tuneable gates with respect to colloid size and affinity to the brush‐forming polymer. The most important parameter regime simultaneously allowing for high brush permeability and selectivity corresponds to a condition when the repulsive and attractive contributions to the colloid insertion free energy nearly cancel. This theory should be useful to design sensing and purification devices with enhanced selectivity and to better understand mechanisms underpinning the functions of biological polymer brushes.
Influence of the Degree of Swelling on the Stiffness and Toughness of Microgel‐Reinforced HydrogelsKessler, Michael; Yuan, Tianyu; Kolinski, John M.; Amstad, Esther
doi: 10.1002/marc.202200864pmid: 36809684
The stiffness and toughness of conventional hydrogels decrease with increasing degree of swelling. This behavior makes the stiffness‐toughness compromise inherent to hydrogels even more limiting for fully swollen ones, especially for load‐bearing applications. The stiffness‐toughness compromise of hydrogels can be addressed by reinforcing them with hydrogel microparticles, microgels, which introduce the double network (DN) toughening effect into hydrogels. However, to what extent this toughening effect is maintained in fully swollen microgel‐reinforced hydrogels (MRHs) is unknown. Herein, it is demonstrated that the initial volume fraction of microgels contained in MRHs determines their connectivity, which is closely yet nonlinearly related to the stiffness of fully swollen MRHs. Remarkably, if MRHs are reinforced with a high volume fraction of microgels, they stiffen upon swelling. By contrast, the fracture toughness linearly increases with the effective volume fraction of microgels present in the MRHs regardless of their degree of swelling. These findings provide a universal design rule for the fabrication of tough granular hydrogels that stiffen upon swelling and hence, open up new fields of use of these hydrogels.
Recent Research Progress of 19F Magnetic Resonance Imaging Probes: Principle, Design, and Their ApplicationMo, Yongyi; Huang, Chixiang; Liu, Changjiang; Duan, Ziwei; Liu, Juan; Wu, Dalin
doi: 10.1002/marc.202200744pmid: 36512446
Visualization of biomolecules, cells, and tissues, as well as metabolic processes in vivo is significant for studying the associated biological activities. Fluorine magnetic resonance imaging (19F MRI) holds potential among various imaging technologies thanks to its negligible background signal and deep tissue penetration in vivo. To achieve detection on the targets with high resolution and accuracy, requirements of high‐performance 19F MRI probes are demanding. An ideal 19F MRI probe is thought to have, first, fluorine tags with magnetically equivalent 19F nuclei, second, high fluorine content, third, adequate fluorine nuclei mobility, as well as excellent water solubility or dispersity, but not limited to. This review summarizes the research progresses of 19F MRI probes and mainly discusses the impacts of structures on in vitro and in vivo imaging performances. Additionally, the applications of 19F MRI probes in ions sensing, molecular structures analysis, cells tracking, and in vivo diagnosis of disease lesions are also covered in this article. From authors’ perspectives, this review is able to provide inspirations for relevant researchers on designing and synthesizing advanced 19F MRI probes.