China
Africa
Explore chapters and articles related to this topic
Synthesis and Functionalization of Magnetic Particles
Published in Jeffrey N. Anker, O. Thompson Mefford, Biomedical Applications of Magnetic Particles, 2020
Erika C. Vreeland, Dale L. Huber
The most popular approach for covalent linkage takes advantage of reactive side chains of amino acid residues found within proteins and conjugates them to appropriately functionalized nanoparticles. The most common of these include primary amines found in the lysine residue and the N-terminus of the protein, carboxylic acid in aspartic and glutamic residues and the C-terminus of the protein, and sulfhydryl in the cysteine residue. Amines react with activated carboxylate moieties to form amide bonds, where sulfhydryl moieties react with haloacetyl, alkyl halide derivatives, maleimide, pyridyl disulfide, among others, to form thioester or disulfide linkages (Hermanson 2013). Crosslinker reagents are chosen for their reactivity to the functional moieties on proteins and nanoparticle surfaces. Homobifunctional crosslinkers have the same reactivity at both ends and have the potential to link neighboring molecules, resulting in protein polymerization or nanoparticle agglomeration. In this case, heterobifunctional crosslinkers may be chosen to reduce undesired reactions. The most common “zero-length” crosslinker of this type, EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide), can be used to couple primary amines to carboxylic acid functionalized nanoparticles in an aqueous environment. In a simple one-step reaction, EDC is used to activate carboxylate moieties on particles, forming a reactive ester intermediate. This ester is reactive with primary amines, promoting the formation of a stable amide bond between the protein and the nanoparticle surface. NHS (N-hydroxysuccinimide) or sulfo-NHS is often used in conjunction with EDC to form a more stable NHS ester or sulfo-NHS ester intermediate that can improve reaction yield (Hermanson 2013). This approach is straightforward yet results in proteins bound to the surface in a variety of orientations. For conjugated antibodies, this means that a portion will have its active binding sites in the Fab region oriented in a way that will inhibit binding with the target. Directional conjugation strategies have been developed to better control the orientation of immobilized antibodies by linking antibodies through the non-binding Fc region (Vijayendran and Leckband 2001). Antibodies typically contain glycosylated residues in the Fc region that can be oxidized under mild conditions to create a hydrazide-reactive aldehyde moiety. A hydrazide-terminated heterobifunctional linker can then be used to link the antibody to the nanoparticle surface (Kumar, Aaron, and Sokolov 2008).
In vitro biocompatibility study of EDC/NHS cross-linked silk fibroin scaffold with olfactory ensheathing cells
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Shengwen Li, Peng Wu, Zhongqing Ji, Yu Zhang, Peng Zhang, Yongqing He, Yixin Shen
1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide (EDC/NHS) are commonly used as carboxylic acid activation reagents in amide synthesis [41]. A previous study reported that Hyaluronic acid/EDC/NHS-crosslinking is a good choice for improving the tensile properties of electrospun SF nanofibers serving as engineering scaffolds [42]. EDC and NHS were catalysts and can be removed by dialysis and the cross-linking process would just produce urea derivative by-products, such as ammonia [25].Nevertheless, EDC/NHS over certain concentrations may pose a risk of cytotoxicity [43]. It had been proved that 9.5% (0.5 mol/L) EDC used in collagen and 3% EDC/NHS used in SF did not reduce cell viability of odontoblast-like cells and fibroblast cells, separately [42, 44]. However, few studies have explored the influences of different EDC/NHS concentrations on SF scaffold structures and the biocompatibility with OECs.
A review of immobilization techniques to improve the stability and bioactivity of lysozyme
Published in Green Chemistry Letters and Reviews, 2021
Paul T. Anastas, Alina Rodriguez, Tamara M. de Winter, Philip Coish, Julie B. Zimmerman
Saeki et al. (41) investigated the immobilization of lysozyme to polyamide reverse osmosis (RO) membranes. Lysozyme was covalently immobilized on the surface of the RO membranes by an interfacial polymerization method. The method involves a polymerization reaction between 1, 3,5-benzenetricarbonyl trichloride and 6-amino caproic acid (ACA). ACA was used as a spacer to minimize steric hindrance between lysozyme and the membrane. Lysozyme was then immobilized to the ACA-modified polyamide layer through an amine coupling reaction with EDC and N-hydroxysuccinimide (NHS). The immobilized lysozyme was tested for antibacterial activity against two gram-positive bacteria, B. subtilis and M. luteus. The results indicated that the B. subtilis was completely lysed and the antibacterial activity of the membrane lasted up to 5 months, although it decreased by 30% compared to that of free lysozyme likely due to denaturation of the immobilized lysozyme via hydrolysis.
Two-component organogelators: combination of Nε-alkanoyl-L-lysine with various N-alkanoyl-L-amino acids: additional level of hierarchical control
Published in Soft Materials, 2018
Mehmet Çolak, Deniz Barış, Murat Evcil, Nadir Demirel, Halil Hoşgören
The synthesis of Nε-alkanoyl-L-lysine derivatives is the key step because there is very limited literature. Synthesis of Nε-acetyl derivatives of these compounds to be used in the synthesis of target molecules was first made and patented by Takizawa K., Yoshida R., in 1975 (29). The use of these compounds is owned by Japanese Ajinomoto Co., Inc., Tokyo, Japan. Another synthesis method is to convert the Thallium (I) salt of N-hydroxysuccinimide to its corresponding N-hydroxysuccinimide active ester with the corresponding acid chlorides; based on the acylation of the Nε −lysine amino acid with the active esters formed. This method provides a selective (chemoselective) acylation of the amino group in the side chain of basic amino acids such as lysine (30,31). Another method is to form complex between the α-amino group of lysine with the copper (II). Then acylation of Nε of lysine. The procedure is completed by removal of the copper (II) ion with the 8-hydroxyquinoline from the acylated amino acid complex. In this method, only acetic anhydride is used as an acylating agent. Acetyl lysine 15N labeled was prepared according to this procedure (32). Our method has advantages that the synthesis procedure is simple and forward. And, the synthesis step is short when compared with the literature methods.