China
Africa
Explore chapters and articles related to this topic
Design of Bioresponsive Polymers
Published in Deepa H. Patel, Bioresponsive Polymers, 2020
Anita Patel, Jayvadan K. Patel, Deepa H. Patel
Industrially imperative products can be produced by the ROMP technique that is a kind of olefin metathesis chain-growth polymerization. The liberation of ring strain in cyclic olefins like cyclopentene or else norbornene is the instigator of the reaction and a broad variety of catalysts has been found.
Orders Norzivirales and Timlovirales
Published in Paul Pumpens, Peter Pushko, Philippe Le Mercier, Virus-Like Particles, 2022
Paul Pumpens, Peter Pushko, Philippe Le Mercier
The polymerization of oligo(ethylene glycol)-methacrylate and its azido-functionalized analog was performed directly from the outer surface of the Qβ VLPs by atom transfer radical polymerization (ATRP) (Pokorski et al. 2011a, b). The introduction of chemically reactive monomers during polymerization therefore provided a robust platform for post-synthetic modification via the CuAAC reaction. The ATRP methodology was developed further by Hovlid et al. (2014) and reviewed in an excellent minireview of Wallat et al. (2014), who specifically highlighted the concept of the grafting-from proteins as the new and efficient chemistry to polymerize directly from protein substrates in aqueous media, with the Qβ VLPs as the most successful story. The authors demonstrated efficient postpolymerization modification via the CuAAC reaction to introduce fluorophores, Gd-based contrast agents, and doxorubicin, a common anticancer drug. Then, Isarov et al. (2016) generated the graft-to protein/polymer conjugates using polynorbornene block copolymers, which were prepared via ring-opening metathesis polymerization (ROMP). The ROMP technique afforded low-dispersity polymers and allowed for the strict control over polymer molecular mass and architecture. Such polymers consisted of a large block of PEGylated monoester norbornene and were capped with a short block of norbornene dicarboxylic anhydride. This cap served as a reactive linker that facilitated attachment of the polymer to lysine residues under mildly alkaline conditions. As a result, the multivalent polynorbornene-modified Qβ VLPs were constructed.
Chimeric VLPs
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
The CuAAC reaction was used by the covering of the Qβ VLP surface by polymer chains, to which multiple connections were made, thereby crosslinking protein cage subunits (Manzenrieder et al. 2011). Such polymers could extend in vivo circulation lifetime, diminishing nonspecific adsorption or passivating the immune response. The poly(2-oxazoline)s were chosen for the role of such polymers because of their advantageous properties of versatile controlled syntheses by means of living cationic polymerization, aqueous-phase solubility, and chemical stability that made them attractive for a variety of biomedical and materials applications (Manzenrieder et al. 2011). The polymerization of oligo(ethylene glycol)-methacrylate and its azido-functionalized analog was performed directly from the outer surface of the Qβ VLPs by atom transfer radical polymerization (ATRP) (Pokorski et al. 2011a). The introduction of chemically reactive monomers during polymerization therefore provided a robust platform for post-synthetic modification via the CuAAC reaction. The ATRP methodology was developed further by Hovlid et al. (2014) and reviewed in an excellent minireview of Wallat et al. (2014), who specifically highlighted the concept of the grafting-from proteins as the new and efficient chemistry to polymerize directly from protein substrates in aqueous media, with the Qβ VLPs as the most successful story. The authors demonstrated efficient post-polymerization modification via the CuAAC reaction to introduce fluorophores, Gd-based contrast agents, and doxorubicin, a common anticancer drug. Then, Isarov et al. (2016) generated the graft-to protein/polymer conjugates using polynorbornene block copolymers, which were prepared via ring-opening metathesis polymerization (ROMP). The ROMP technique afforded low-dispersity polymers and allowed for the strict control over polymer molecular mass and architecture. Such polymers consisted of a large block of PEGylated monoester norbornene and were capped with a short block of norbornene dicarboxylic anhydride. This cap served as a reactive linker that facilitated attachment of the polymer to lysine residues under mildly alkaline conditions. Thus, the multivalent polynorbornene-modified Qβ VLPs were constructed. The conjugated nanoparticles showed no cytotoxicity to NIH 3T3 murine fibroblast cells. This study markedly expanded the toolbox for the protein bioconjugates (Isarov et al. 2016).
Tailoring the monomers to overcome the shortcomings of current dental resin composites – review
Published in Biomaterial Investigations in Dentistry, 2023
Jingwei He, Lippo Lassila, Sufyan Garoushi, Pekka Vallittu
In recent years, covalent adaptable networks (CANs) have been used to reduce shrinkage stress. When subjected to specific stimuli, the covalent bonds in the network dynamically break, relax, and rearrange to form new bonds, thus allowing stress to be released during network formation [88]. Using addition-fragmentation chain transfer monomers to reduce the shrinkage stress of DRCs is a. type of CANs mechanism. Park et al. [89] incorporated allyl sulfide monomers (as shown in Figure 10(a,b)) into norbornene-methacrylate systems to obtain low shrinkage stress DRCs. The new DRCs showed more than 96% stress reduction compared with Bis-GMA/TEGDMA-based DRCs but also exhibited lower flexural strength. Lamparth et al. [90] and Crob et al. [91] evaluated allyl sulfone urethanes (as shown in Figure 10(c–g)) and allyl sulfide methacrylates (as shown in Figure 10(h–l)) as addition-fragmentation chain transfer agents for low shrinkage stress DRCs. The results revealed that all these agents could reduce shrinkage stress while maintaining flexural strength, but the maximum stress reduction was only around 36% at an agent concentration of 20 mol% in the resin matrix.
In situ gelling and mucoadhesive polymers: why do they need each other?
Published in Expert Opinion on Drug Delivery, 2018
Forouhe Zahir-Jouzdani, Julian Dominik Wolf, Fatemeh Atyabi, Andreas Bernkop-Schnürch
Click chemistry comprises practical and reliable reactions allowing for modular synthesis of larger molecules. ‘Spring loaded’ reactants form carbon-heteroatom bonds via different mechanisms such as strain-promoted azide-alkyne cycloaddition (SPAAC), [3 + 2] cycloaddition or Diels-Alder cycloaddition. Within the last years this approach has aroused more and more interest for the development of in situ gelling systems. For example, azadibenzocyclooctyne and azide functionalized PEG chains were used to generate cross-linked polymer networks via SPAAC. Without need for catalysts or external stimuli these systems gelled within seconds and mechanical as well as rheological properties were adjustable by varying the molecular mass and degree of substitution of the PEG [45]. Truong et al. [11] chose a dual-click approach to achieve a tough double network under physiological conditions. A loose network was generated via tetrazine-norbornene inverse-electron demand Diels-Alder cycloaddition between norbornene-functionalized CS and PEG-ditetrazine, whereas nucleophilic thiol-alkyne addition between PEG-dithiol and PEG-tetraalkyne formed the dense network. In this way, they were able to prepare a hydrogel exhibiting high mechanical strength as well as small pore sizes being suitable for a range of applications.
Enzyme-triggered- and tumor-targeted delivery with tunable, methacrylated poly(ethylene glycols) and hyaluronic acid hybrid nanogels
Published in Drug Delivery, 2022
Wioletta Liwinska, Ewelina Waleka-Bagiel, Zbigniew Stojek, Marcin Karbarz, Ewelina Zabost
Poor stability and short biological half-life limit the usability of HA. HA contains carboxylic acid and hydroxyl-, and N-acetyl groups that can easily be combined with other chemicals. HA chemical modifications of carboxyl and primary alcohol groups, with either norbornene (NorHA), or methacrylate (MeHa), possess a significantly greater binding affinity to CD44. The CD44-HA interactions depend on the extent of modification, type of attacked chemical group, and the site of HA used for modification (Li et al., 2021). Amphiphilic HA derivatives can self-assemble into core-shell NGs. The internal hydrophobic core can accumulate anticancer compounds for diagnosis and treatment (Lee et al., 2012).