China
Africa
Explore chapters and articles related to this topic
Quantum Dots:
Published in Vineet Kumar, Praveen Guleria, Nandita Dasgupta, Shivendu Ranjan, Functionalized Nanomaterials II, 2021
Kulvinder Singh, Shikha Sharma
The present methodology is a little bit difficult and can be achieved through many steps as shown in Figure 9.14. Firstly, the activation of the surface has been done by the first layer of silane molecules. This step involves the exchange of organic ligand with silane than can help the dispersion in water or ethanol. Maximum research is dedicated to the surface activation process, e.g. a citrate group on quantum dots has been exchanged with (3-sulfanylprosulfanylpropyl), then by the solvent (Correa-Duarte et al. 2001). The silica layer on the surface of quantum dots is then grown with the aid of tetraethyl orthosilicate as per Stober’s process. Similarly, (3-sulfanylprosulfanylpropyl) trimethoxysilane has been used for the phase transfer of quantum dots that are capped with trioctylphosphine oxide and hexadecylamine in tetrahydrofuran (Nann 2005). These (3-sulfanylprosulfanylpropyl) trimethoxysilane coated quantum dots are stable in polar solvent (methanol, ethanol). The silica thickness over the quantum dots has been controlled by varying the tetra ethyl orthosilicate concentration, reaction time, water content, base (ammonia) concentration, etc. An illustration of some selected surface chemistries and conjugation strategies that are applied to QDs. The grey periphery around the QD represents a general coating. This coating can be associated with the surface of the QD via (e) hydrophobic interactions, or ligand coordination. Examples of the latter include: (a) mono dentate or bidentate thiols; (b) imidazole, polyimidazole (e.g. polyhistidine), or dithiocarbamate (not shown) groups. The exterior of the coating mediates aqueous solubility by the display of (c) amine or carboxyl groups; or (d) functionalized PEG. Common strategies for bioconjugation include: (a) thiol modifications; or (b) polyhistidine or metallothionein (not shown) tags that penetrate the coating and interact with the surface of the QD; (f) electrostatic association with the coating; (g) nickel mediated assembly of polyhistidine to carboxyl coatings; (h) maleimide activation and coupling; (i) active ester formation and coupling; (j) biotin-labeling and streptavidin–QD conjugates. Figure not to scale. (Source: Algar et al. 2010)Demonstration of surface silanization of ZnO Quantum Dots.Demonstration of amide coupling (in reactant sp hybridized C is taken as bent due to sake of simplicity)
Preparation monoclonal β-type anti-idiotype antibody of zearalenone and development of green ELISA quantitative detecting technique
Published in Preparative Biochemistry & Biotechnology, 2020
Luhuai Shi, Tao Yu, Miner Luo, Hong Wang
Indirect ELISA was carried out as follows: 100 μl ZEN-BSA, which was prepared by active ester method[22], 0.5 μg/ml, for F(ab)’2 fragments of 1G4 detection or F(ab)’2 fragments of 1G4 (1 μg/ml) were added into a micro-titer plate and incubated overnight at 4 °C. The plates were washed 3 times with PBST (phosphate-buffered saline containing 0.05% Tween-20, v/v) and blocked overnight at 4 °C with 5.0% (w/v) skimmed milk in PBST (200 μl/well), then washed 3 times with PBST. The antibody (in sera, hybridoma supernatant), or F(ab)’2 fragments of 1G4, anti-idiotype monoclonal antibodies (100 μl/well) were added. The mixture incubated at 37 °C for 1 h and washed again (as described above). HRP-labeled goat anti-mouse IgG (Fab specific) antibody (Sigma Co., Ltd, diluted 1:2000 in PBST, 100 μl, for Fab fragments of 1G4 detection) or HRP-labeled goat anti-mouse IgG (Fc specific) antibody (Sigma Co., Ltd, diluted 1:10,000 in PBST, 100 μl) was added and then incubated at 37 °C for 40 min. The wells were washed again 5 times and the TMB substrate solution (100 μl/well) was used to measure the peroxidase activity in a dark place for 10 min. The enzyme reaction was terminated by adding 2 M H2SO4 (50 μl/well) and the absorbance at 450 nm was measured with a micro-plate reader.
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.
Water-soluble and amphiphilic phospholipid copolymers having 2-methacryloyloxyethyl phosphorylcholine units for the solubilization of bioactive compounds
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Kazuhiko Ishihara, Mingwei Mu, Tomohiro Konno
Functionalization of the side chains of PMB has been performed using reactive polymers with active ester groups. The resulting polymers, such as poly(MPC-random-BMA-random-ω-(p-nitrophenyloxycarbonyl oligo (ethylene glycol)) methacrylate (MEONP)) (PMBN), and poly(MPC-random-BMA-random-N-succinimidylloxycarbonyl oligo(ethylene glycol) methacrylate (PENHS)) (PMBS), can react with primary amino groups in bioactive compounds [60,61], and they require very mild reaction conditions: 10–24 h in phosphate buffered saline (pH 7.8) at 4 °C. Proteins and oligonucleotides can then be bound to the polymer. This multi-functionalization improves the solubility and site-specific transportation of the bioactive compound, and helps maintaining its bioactivity. The PMB segments improve the solubility and stability of the proteins bound to the polymer. These polymers form aggregates in the same way as PMB does; they can directly penetrate the cell membrane, while carrying bioactive compounds bound to the polymer chains. The functionalization of PMB with various bioactive compounds applied in vivo studies is shown in Table 2 [62–64].