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What Are Polymeric Carriers?
Published in Mesut Karahan, Synthetic Peptide Vaccine Models, 2021
Gülderen Karakuş, Dolunay Şakar Daşdan
In emulsion polymerization medium there are water, monomer, micelle builders, and initiators. The monomer is stabilized by a surfactant (such as soap) and these droplets are called micelles. One end of the micelles is hydrophobic, and the other end is of a hydrophilic character. Polymerization is carried out quickly and at very low temperatures in micelles. Measurements showed that the micelles were in the form of a rod. Each micelle consists of 50–100 emulsifying molecules. The hydrocarbon tails of these molecules, forming myelin, are oriented into the micelle and the ionic ends are facing towards the water. Micelles and water are mixed at the beginning of emulsion polymerization. A part of the micelles in the mixture is water soluble, and some of them collect together to form spherical micelles. After dissolving the micelles in the water, the monomer is added to the medium by mixing.
Engineered Nanoparticles for Drug Delivery in Cancer Therapy *
Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Tianmeng Sun, Yu Shrike Zhang, Pang Bo, Dong Choon Hyun, Miaoxin Yang, Younan Xia
Many recent studies have examined different techniques for the fabrication of polymer nanoparticles, including polyelectrolyte complex formation, double emulsion and solvent evaporation, and emulsion polymerization [268]. An oppositely charged polymer can be used to entrap drugs in the polymeric matrix of a nanoparticle, which then releases the drug through a combination of drug diffusion and polymer degradation. The double emulsion and solvent evaporation techniques involve dissolution of the polymer and drug in an organic solvent, followed by emulsification in an aqueous solution. The organic solvent diffuses from the polymer phase to the aqueous phase, and evaporates from the aqueous phase, leaving behind drug-loaded polymer nanoparticles. The drawback of this method lies in the poor uniformity of the nanoparticles that are produced. By contrast, the emulsion polymerization approach is able to generate uniform, nanosized particles based on the polymerization of monomers in emulsified droplets. However, only a few kinds of materials can be used for the fabrication of nanoparticles using this method.
Pharmaceutical and Methodological Aspects of Microparticles
Published in Neville Willmott, John Daly, Microspheres and Regional Cancer Therapy, 2020
Yan Chen, Mark A. Burton, Bruce N. Gray
Emulsion polymerization is a method most frequently employed for the preparation of nanoparticles (10 to 1000 nm), for example, polymethyl methacrylate and polyalkylcyanoacrylate nanoparticles. The technique involves emulsification of a hydrophobic monomer in an aqueous phase with the monomer polymerized using either a free radical initiator or high energy irradiation.82
Self-assembling peptides-based nano-cargos for targeted chemotherapy and immunotherapy of tumors: recent developments, challenges, and future perspectives
Published in Drug Delivery, 2022
Xue-Jun Wang, Jian Cheng, Le-Yi Zhang, Jun-Gang Zhang
Peptide nanoparticles (PNPs) and nanospheres are examples of 0D peptide nanostructures that have a size range from 1 to 100 nm and are extensively used for various biomedical applications. Target-specific ligands can produce stimuli-responsive nanoparticles and could be ideally designed for the release of payload in the desired area of the body, i.e. tumor sites (Wang et al., 2021b). The driving forces for the SA of PNPs are the interactions between α-helices hydrophobic amino acids and ionic interactions between parallel dimers and trimers which stabilize coiled-coil interfaces (Doll et al., 2015). Emulsion polymerization in an aqueous medium is a handy method for the synthesis of 0D PNPs with the use of initiators, monomers, and surfactants. Polypeptide nanoparticles preparation with monomer emulsion polymerization of amino acids has been reported by Jacobs et al. (2019). The monomer which was UV light-sensitive was selected for the construction of PNPs. Subsequently, a block of glycosylation peptide was used for achieving aggregation of particles after cross-linking.
Microencapsulation of reactive isocyanates for application in self-healing materials: a review
Published in Journal of Microencapsulation, 2021
Amanda N. B. Santos, Demetrio J. dos Santos, Danilo J. Carastan
An initial attempt to microencapsulate an isocyanate involved the use of blocked isocyanates (Yang et al.2008). This strategy relied on their lower reactivity, since they differ from other isocyanates for presenting inactive –NCO groups (R–C=N–O–C(O)–NH), which can be activated under thermal treatment. For the system studied the deblocking occurred at temperatures around 140 °C and was dependent on time. This strategy aimed to avoid the undesirable reaction of –NCO with the reactional medium (water), a challenge that increased with the addition of amines and/or polyols in the reaction environment. Yang’s group was able to successfully encapsulate a commercial blocked isocyanate in polystyrene (PS) nanocapsules using an aqueous emulsion polymerisation process. First, a pre-emulsion was obtained using two mixtures: part I [styrene, divinylbenzene (DVB), 2,2′-azobisisobutyronitrile (AIBN) and a blocked aliphatic polyisocyanate (BNCO)]; and part II [water, sodium dodecyl sulphate (SDS), and nonyl phenol ethoxylate (Igepal® CO-887)]. Under mechanical stirring, part II was added into part I, and the pre-emulsion was cooled and then sonicated. Emulsion polymerisation was carried out under nitrogen atmosphere at 70 °C. Functionalised PS nanocapsules were also produced by adding specific reagents into part I of the pre-emulsion. Hydroxyl functionalization was prepared by the reaction of PS with 2-hydroxyethyl methacrylate (HEMA), and or 2-(tert-butylamino)ethyl methacrylate was used for amine functionalization (Yang et al.2008).
Preparation and use of nanogels as carriers of drugs
Published in Drug Delivery, 2021
Cuixia Li, Sreekanth Reddy Obireddy, Wing-Fu Lai
In this method, polymers are first dissolved in water. Under the action of oil-soluble surfactants, appropriate emulsion methods are applied to form an aqueous dispersion of polymers in an organic solvent to obtain W/O inverse emulsions in the presence of a surfactant. As shown in Figure 3, an aqueous solution of gelatin was emulsified into a fine emulsion under the action of an ultrasonic wave. Then glutaraldehyde was added as a crosslinking agent to generate nanogels (Mitra et al., 2001). Mitra et al. (2001) dispersed the aqueous solution of dextran-doxorubicin (DOX) conjugate and chitosan in organic solvents to form microemulsions. After adding a crosslinking agent, pH-responsive nanogels that can be used to deliver anti-cancer drugs were prepared. The crosslinking reaction between polymers occurs in tiny droplets of an aqueous solution under mild reaction conditions. Therefore, it can be used to generate nanogels loaded with fragile bioactive agents. Similar to inversion emulsion polymerization, this method involves the use of organic solvents, emulsifiers and co-emulsifiers. This brings great difficulties to the purification of nanogels.