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Research Progress in Synthesization, Coating, and Characterization of Magnetic Nanoparticles
Published in Francisco Torrens, A. K. Haghi, Tanmoy Chakraborty, Chemical Nanoscience and Nanotechnology, 2019
Lavanya Tandon, Poonam Khullar
Sugar ligands can be introduced for targeting of receptors and binding of bacteria. PEG microgels can be functionalized by the use of peptide coupling chemistry and also by use of high excess of a protected mannose ligand with a short amine-linker at the anomeric position ((2-aminoethyl)-2,3,4,6-tetra-O-acetyl-a-D-mannopyranoside hydrochloride). Galactose functionalized particles (PEG-Gal, 6) can also be synthesized as a negative control for ligand-receptor binding. The carbohydrates were deprotected after coupling with sodium methoxide (MeONa) and the final PEG-sugar microgels can be redispersed in water readily. The particles which have been obtained have shown an increase in ζ-potential from -50.8 ± 5.9 mV for the PEG-COO- particles to -19.4 ± 4.7 mV for the PEG-mannose particles (PEG-Man, 5). This has indicated successful functionalization of carboxylate groups with sugar ligands. The sugar ligands have the ability to bind specifically the protein receptors and this distribution of sugar ligands can be visualized by incubation with fluorescently labeled Concanavalin A (ConA), which is a mannose-binding protein. The uniform fluorescence of PEG-Man microgels have been revealed by the confocal microscopy and it also depicted the binding of FITC-ConA and in this, no fluorescence has been observed with nonfunctionalized PEG, PEG-Gal, and PEGCOOH particles. It is depicted in Figure 10.17.
Gold Nanoparticles
Published in Jay L. Nadeau, Introduction to Experimental Biophysics, 2017
Edward S. Allgeyer, Gary Craig, Sanjeev Kumar Kandpal, Jeremy Grant, Michael D. Mason
Lectins are sugar-binding proteins that bind specifically to a glycoprotein or glycolipid. They are ubiquitous in the natural world and show differing degrees of specificity for species or classes of cells or organisms. Some lectins are used in blood typing, others for protein purification (concanavalin A is very widely used), and others can be used to tag bacteria. Wheat germ agglutinin (WGA) is specific for Gram-positive over Gram-negative bacteria, and is also taken up by a wide variety of mammalian cells, including neurons, where it is synaptically transported from one cell to another and so can be used to trace neural pathways. We will use this one in this particular example because of its wide usefulness, though the procedure described should apply to any lectin.
Microcarrier Culture Systems
Published in Anthony S. Lubiniecki, Large-Scale Mammalian Cell Culture Technology, 2018
A major problem encountered in scaling up a MC culture system is the sensitivity of cells to mechanical damage. This sensitivity is the result of lack of a protective cell wall, the relatively large size of the animal cells, and the fact that the cells are anchored to the MC and are not freely suspended. In large volumes this sensitivity may hamper the supply of sufficient oxygen to the cells in the conventional manner (i.e., by sparging of air through the medium and by dispersion of the air bubbles by means of stirring). The sensitivity of ADC to detachment from their growth surface depends on the type of the propagated cells, functional groups on the growth surface, and the type and strength of the shear stress to which the cells are subjected. Weiss (114) found that the mean minimal detachment forces for an established epithelial cell line is 1.06–1.36 N/m2 and for rat skin fibroblasts 0.73 N/m2, thus showing that the sensitivity to shear depends on the type of cell. Moreover, it was shown that the functional groups located on MC growth surface play a major role in the sensitivity of cells to detachment from their growth surface. Treatment of the growth surface with concanavalin A enhanced the adhesiveness of cells. The minimal detachment force was increased from 1.44 to 3.30 N/m2 (115, 116). The effect of shear stress on ADCs (embryonic kidney cells) was studied by Stathopoulos and Helluns (117). They found that shear stress of 0.26 N/m2 has no effect on cell viability, at intermediate stress levels (0.65–1.03 N/m2) there are morphological changes of the cells and a loss of cell viability (10–20% detachment), and at higher stress levels (2.6 N/m2 and higher) marked cell reduction was observed (75–85% cell detachment). Nerem (118) showed that moderate shear stress, which has no effect on cell viability, induces changes in cell shape and orientation, cytoskeletal structure, and membrane potential.
Static electric field inhibits the proliferation and secretion functions of splenic lymphocytes in mice
Published in International Journal of Environmental Health Research, 2023
Li Dong, Jiahong Wu, Guoqing Di
Based on the detection method adopted by Bai et al. (2011), some modifications have been made to detect the proliferation levels of splenic lymphocytes. The concentration of splenic lymphocytes suspension was adjusted to 1 × 107 cells/ml. Concanavalin A (ConA) can specifically bind to CD3 molecules and stimulate the proliferation of T lymphocytes (Kanellopoulos et al. 1985). Lipopolysaccharides (LPS) can trigger signal transduction by recognizing TLR4 and CD180 and stimulate the proliferation of B lymphocytes (Hebeis et al. 2005). ConA and LPS were used to stimulate T and B lymphocytes, respectively. The detection experiments were divided into three groups: unstimulated group, ConA stimulated group and LPS stimulated group. The 96-well plate containing cells was put into the cell incubator. After 24 h, 20 ul MTT solution was added to each well. After the 96-well plate was placed in the cell incubator for 4 h, 200 ul formazan solution was added to each well. After 96-well plate was put into the cell incubator for 4 h again, the absorbance at 570 nm was detected by a multifunctional microplate reader (Infinite M200 Pro, TECAN, Austria). The lymphocyte proliferation index (LPI) was used to represent the proliferation levels of lymphocytes (Singh et al. 2016). The calculation formula of LPI was as follows.