China
Africa
Explore chapters and articles related to this topic
What Are Polymeric Carriers?
Published in Mesut Karahan, Synthetic Peptide Vaccine Models, 2021
Gülderen Karakuş, Dolunay Şakar Daşdan
As seen in the example of polyethylene, a large, chain-like coarse molecule has been formed by the binding of numerous small ethylene monomer (–C2H4–) repeated along the chain with chemical bonds. Therefore, polymer molecule, polymer chain, or macro molecule expressions are often used instead of each other. The formation of polymerization consists of three parts: these are the start, multiplication, and termination steps. The methods used in the synthesis of polymers are divided into two groups by taking their mechanisms into account (chain) and condensation polymerization. Radical polymerization and ionic addition polymerization due to radicalization or ionicity of the active center providing chain growth can be examined in two groups. In addition, the ionic addition polymerization takes place in different categories according to the cationic or anionic state of the active center (Nesvadba 2012) (Table 6.1).
Polymers as Conditioning Agents for Hair and Skin
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
Two major types of polymerization methods are used to convert small molecules (monomers) into polymers. These methods were originally referred to as addition and condensation polymerization. Addition polymerization is now called chain, chain-growth, or chain-reaction polymerization. Condensation polymerization is now referred to as step-growth or step-reaction polymerization.
Biomaterials
Published in Manoj Ramachandran, Tom Nunn, Basic Orthopaedic Sciences, 2018
Subhamoy Chatterjee, John Stammers, Gordon Blunn
Polymers are synthesized by either condensation polymerization or addition polymerization. PMMA and UHMWPE are formed by addition polymerization where an initiator, such as a free radical or catalyst, breaks the monomer double bond activating it to react with an adjacent monomer. This process continues through the propagation phase until termination.
Polymer drug conjugates containing memantine, tacrine and cinnamic acid: promising nanotherapeutics for the treatment of Alzheimer’s disease
Published in Journal of Microencapsulation, 2023
Tobeka Naki, William Morwa Reagile Matshe, Mohammed Olusegun Balogun, Suprakas Sinha Ray, Samuel Ayodele Egieyeh, Blessing Atim Aderibigbe
Michael addition polymerisation is a flexible synthetic approach useful for generating polymers ranging from linear to hyperbranched polymers (Sun et al. 2017). Aqueous Michael’s addition polymerisation technique was used to synthesise the polymer-drug conjugates in this study. The conjugates are prepared in water in a one-pot process and are characterised by linear architectures. The reaction involves a nucleophilic addition of a nucleophile to an α, β-unsaturated carbonyl compound. Under mild reaction conditions, the reaction is useful for forming C–C bonds. The advantages of Michael addition reactions are high conversions, the capability to accommodate high functional groups and favourable reaction rates (Aderibigbe et al. 2020). The aza Michael polyaddition of prim-monoamines or bis-sec-amines with bis-acrylamides yields a synthetic polymer called linear polyamidoamines (PAAs) (Marcioni et al. 2021). PAAs are polymeric carriers with high structural flexibility. They can be engineered to be biodegradable and biocompatible, and are mostly highly water-soluble and hydrophilic. Their capability to hydrolytically degrade in aqueous systems arise from the amide bond on their backbone. Most of them have demonstrated promising antiviral activity, useful as sensor constituents, heparin complexing agents, heavy metal ion complexing agents, transfection promoters and drug delivery systems (Coué and Engbersen 2011, Marcioni et al. 2021). Polymer-drug conjugates are nanoscale systems in which a drug molecule is covalently attached to a polymer backbone (Duro-Castano et al.2015).
Fluorinated vectors for gene delivery
Published in Expert Opinion on Drug Delivery, 2022
Yu Wan, Yuhan Yang, Mingyu Wu, Shun Feng
Unlike the conventional PAMAM, linear dendronized polymers using click chemistry were established that performed well in large pDNA delivery in difficult-to-transfect cells [72]. Fluorination can further enhance the transfection capacity of this demonized polymer, outperforming both G5 PAMAM and Lipofectamine 2000. This fluorinated polymer proved to be capable of delivering zinc fingers, TALEs, and CRISPR/dCas9 platforms [72]. Similarly, the linear form of poly(amido amine)s (PAAs) is another kind of polycations obtained by the Michael addition polymerization of primary or secondary aliphatic amines to bis(acrylamide)s. The degradable backbone, such as disulfide, was often introduced into PAAs to facilitate the disassembly of the polyplexes. On this basis, a series of fluorinated PAAs to deliver siRNA were developed, which achieved enhanced cellular uptake and endosomal escape in vitro and improved gene silencing in vivo [26,73,74].
A dual-functional buformin-mimicking poly(amido amine) for efficient and safe gene delivery
Published in Journal of Drug Targeting, 2020
Mei Lu, Haonan Xing, Lin Cheng, Hui Liu, Lang Lang, Tianzhi Yang, Xiaoyun Zhao, Hui Xu, Pingtian Ding
A linear cationic polymer CBA-Bu with pedant buformin-mimicking side chains was synthesised based on our previous work [25]. The synthetic route was shown in Figure 1(A). Briefly, DAB and CBA were used to construct the polymer scaffold by Michael addition polymerisation. Of note, one of the two primary amino groups of DAB was protected by a Boc group to avoid being oxidised in this step. As a result, a linear structure with pendent chains was obtained. Then the Boc groups were removed in an acidic condition to expose the primary amino groups at the edge of the side chains. The obtained product in this step was marked as an intermediate product, and named as CBA-DAB according to a previous study [29]. The final product CBA-buformin (CBA-Bu) containing buformin-like side chains was obtained by an additional reaction of dicyandiamide with the primary amino groups [15].