- Naphthalimide based fluorescent organic nanoparticles in selective sensing of Fe3+and as a diagnostic probe for Fe2+/Fe3+transition
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Fluorescent organic nanoparticles (FONPs) have attracted considerable attention as a practical and effective platform for sensing and imaging applications. The present article delineates the fabrication of FONPs derived from the naphthalimide based histidine appended amphiphile, NID. The self-assembly of NID in 99 vol% water in DMSO led to the formation of FONPs through J-type aggregation. Aggregation-induced emission (AIE) was observed due to the pre-associated excimer of NID with bluish green emission at 470 nm along with intramolecular charge transfer (ICT). The emission of NID FONPs was utilized for selective sensing of Fe3+ and bioimaging of Fe3+ inside mammalian cells. The fluorescence intensity of the FONPs was quenched with the gradual addition of Fe3+ due to the formation of a 1?:?1 stoichiometric complex with the histidine residue of NID. The morphology of the FONPs transformed from spherical to spindle upon the complex formation of NID with Fe3+. The limit of detection (LOD) of this AIE based turn-off chemosensor for Fe3+ was found to be 12.5 ± 1.2 μM having high selectivity over other metal ions. On the basis of the very low cytotoxicity and selective sensing of Fe3+, NID FONPs were successfully employed for bioimaging of Fe3+ ions through fluorescence quenching within mammalian cells (NIH3T3, B16F10). Considering the varying oxidative stress inside different cells, NID FONPs were used for detecting Fe2+ to Fe3+ redox state transition selectively inside cancer cells (B16F10) in comparison to non-cancerous cells (NIH3T3). Selective sensing of cancer cells was substantiated by co-culture experiment and flow cytometry. Hence, NID FONPs can be a selective diagnostic probe for cancer cells owing to their higher H2O2 content. This journal is
- Sarkar, Deblina,Chowdhury, Monalisa,Das, Prasanta Kumar
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- Synthesis method of N-carbobenzoxy-L-histidine
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The invention provides a synthesis method of N-carbobenzoxy-L-histidine, which comprises the following steps: step S1, enabling N-carbobenzoxy succinimide to react with L-histidine, so as to generate dicarbobenzoxy-L-histidine; and step S2, removing carbobenzoxy on an imidazolyl group in the bis (carbobenzoxy)-L-histidine, so as to obtain the N-carbobenzoxy-L-histidine. According to the synthesis method disclosed by the embodiment of the invention, N-benzyloxycarbonyloxy succinimide is used for replacing benzyl chloroformate, so that the problems that an intermediate is very sticky and is difficult to purify are solved; furthermore, the intermediate obtained by the first-step reaction is good in quality and free of unnecessary byproducts, and the second-step reaction can be carried out without purification of the first-step product, so that the process is simplified; moreover, when the carbobenzoxy group on the imidazolyl group is removed in the second step, ammonia gas is creatively adopted to replace common potassium hydroxide, sodium ethoxide and the like, the reaction condition is mild, removal of the alpha-amino protecting group can be avoided, and the problem of destroying the optical rotation of the product is avoided.
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Paragraph 0047; 0055; 0058-0063; 0067-0071; 0074-0079
(2021/06/06)
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- Aqueous phase mono-protection of amines and amino acids as N-benzyloxycarbonyl derivatives in the presence of β-cyclodextrin
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A simple and selective protection of amines/amino acids with Cbz-Cl has been achieved in aqueous phase with catalytic amounts of β-cyclodextrin in high yields at room temperature. This reaction proceeds without the formation of any by-products and has advantages over existing methods.
- Pavan Kumar,Somi Reddy,Narender,Surendra,Nageswar,Rama Rao
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p. 6393 - 6396
(2007/10/03)
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- PH-sensitive polymeric micelles for drug delivery
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Mixed micelles containing poly(L-histidine)-poly(ethylene glycol) block copolymer and poly(L-lactic acid)-poly(ethylene glycol) block copolymer are a pH-sensitive drug carrier that release the drug in an acidic microenvironment, but not in the blood. Since the microenvironment of solid tumors is acidic, these mixed micelles are useful for treating cancer, including those cancers exhibiting multidrug resistance. Targeting ligands, such as folate, can also be attached to the mixed micelles for enhancing drug delivery into cells. Methods of making poly(L-histidine), synthetic intermediates, and block copolymers are also described.
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Page/Page column 5; 6
(2008/06/13)
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- Surface functionalization of cadmium sulfide quantum-confined nanoclusters. 4. Formation and reactivity of an aniline surface quantum dot
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The preparation, characterization, properties, and reactivity of a novel quantum-confined CdS nanocluster containing a chemically active aniline surface are described, along with three general methods for the covalent attachment of a wide scope of molecular moieties to the cluster surface. The formation of facile covalent linkages via DCC mediated amidization, secondary amine formation, and thiourea condensation is discussed and, as the introduction of surface functionality is crucial for the eventual realization of molecular electronic devices fabricated from such nanoclusters, several derivatized nanoclusters bearing interesting chromophoric, fluorescent, electroactive, and chiroptical tethered species are described. All three derivatization techniques occur under very mild conditions that have been demonstrated not to disturb the integrity of the nanocluster core. The preparation, characterization, properties, and reactivity of a novel quantum-confined CdS nanocluster containing a chemically active aniline surface are described, along with three general methods for the covalent attachment of a wide scope of molecular moieties to the cluster surface. The formation of facile covalent linkages via DCC mediated amidization, secondary amine formation, and thiourea condensation is discussed and, as the introduction of surface functionality is crucial for the eventual realization of molecular electronic devices fabricated from such nanoclusters, several derivatized nanoclusters bearing interesting chromophoric, fluorescent, electroactive, and chiroptical tethered species are described. All three derivatization techniques occur under very mild conditions that have been demonstrated not to disturb the integrity of the nanocluster core.
- Veinot, Jonathan G.C.,Galloro, Josie,Pugliese, Linda,Bell, Valerie,Pestrin, Robert,Pietro, William J.
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p. 1530 - 1539
(2007/10/03)
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- Protease-catalysed synthesis of peptides containing histidine and lysine
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The kinetically controlled α-chymotrypsin- and trypsin-catalysed syntheses of peptides starting from simple acyl donor esters containing histidine at the P1-position (nomenclature according to Schechter and Berger) and lysine derivatives as amino components were examined on the basis of their kinetic parameters. Despite higher specificity constants (k(cat)/K(M)) of trypsin-catalysed ester hydrolysis, α-chymotrypsin- catalysed acyl transfer to N(ε)unprotected lysine derivatives gave higher peptide yields as compared to trypsin-catalysed reactions, whereas in acyl transfer to N(ε)-protected lysine derivatives the trypsin-catalysed reaction gave higher yields. α-Chymotrypsin-catalysed acyl transfer reactions in frozen systems demonstrated the yield-enhancing effect of freezing. Using specific ester leaving groups, both the amount of enzyme and the reaction time can be reduced. In frozen systems the ε-amino function of H-Lys-OH acts as an acyl acceptor at pH ≤9.
- Beck-Piotraschke, Karin,Jakubke, Hans-Dieter
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p. 1505 - 1518
(2007/10/03)
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- ONE-POT N-PROTECTION OF AMINO ACIDS
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Attention is called on the extreme simple procedure for N-protection of amino acids mediated through previous silylation.Although the methodology is known, it has rather scarcely been used.Some examples show the versatility of a one-pot procedure.Selective Boc and Z- Nα-protections of His were also worked out.
- Becu, Chr.,Reyniers, M.-F.,Anteunis, M. J. O.,Callens, R.
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p. 779 - 782
(2007/10/02)
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- NOVEL 5-AMINO-4-HYDROXYVALERYL DERIVATIVES
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Compounds of the formula STR1 in which R 1 represents hydrogen or acyl, A represents an optionally N-alkylated α-amino acid residue which is bonded N-terminally to R 1 and C-terminally to the group--NR 2--, R 2 represents hydrogen or lower alkyl, R 3 represents hydrogen, lower alkyl, optionally etherified or esterified hydroxy-lower alkyl, cycloalkyl, cycloalkyl-lower alkyl, bicycloalkyl-lower alkyl, tricycloalkyl-lower alkyl, aryl or aryl-lower alkyl, R 4 represents hydroxy or etherified or esterified hydroxy, R 5 represents lower alkyl having 2 or more carbon atoms, optionally etherified or esterified hydroxy-lower alkyl, cycloalkyl, cycloalkyl-lower alkyl, bicycloalkyl, bicycloalkyl-lower alkyl, tricycloalkyl, tricycloalkyl-lower alkyl, aryl, aryl-lower alkyl, optionally substituted carbamoyl, optionally substituted amino, optionally substituted hydroxy or optionally substituted mercapto and R 6 represents substituted amino, and salts of such compounds having salt-forming groups inhibit the blood pressure-increasing action of the enzyme renin and can be used as antihypertensives.
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- EXPERIENCES IN Z-DEPROTECTION. SIMPLE PREPARATIONS OF Z-His and diZ-His.
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A systematic investigation about the possibilities of removing benzyloxycarbonyl groupings in some model peptides acids that resist easy deprotection, have led to some interesting and efficient modified procedures.One-pot synthetic methods for Zα-His-OH and Zα,ZIm-His-OH are also reported.
- Anteunis, M. J. O.,Becu, Chr.,Becu, F.,Reyniers, M.-F.
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p. 775 - 782
(2007/10/02)
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