1. Quantum dot and gold nanoparticle immobilization for biosensing applications using multidentate imidazole surface ligands
Eleonora Petryayeva, Ulrich J Krull Langmuir. 2012 Oct 2;28(39):13943-51. doi: 10.1021/la302985x. Epub 2012 Sep 19.
A facile approach for modification of solid substrates with multidentate imidazole ligands was developed for immobilization of high densities of quantum dots (QDs) that were capped with hydrophilic thiol-based ligands, and for immobilization of noble metal nanoparticles. Imidazole polymer was synthesized using poly(acrylic acid) as a backbone, and grafted on amine functionalized substrate in a two-step approach. The polymer-modified surface was characterized using ellipsometry, water contact angle, and X-ray photoelectron spectroscopy. Fluorescence spectroscopy and scanning electron microscopy were used to evaluate nanoparticle immobilization. Homogeneous, high density (ca. 5 × 10(11) cm(-2)) QD films formed via self-assembly were obtained within 4-6 h. Similarly, the imidazole polymer was also shown to be effective for immobilization of gold nanoparticles as a uniform film. By making use of the pH-sensitive affinity of the imidazole rings to zinc on the surface of QDs, it was possible to achieve regeneration of functional ligands suitable for subsequent immobilization of new QDs. Immobilized QDs were used as a platform for bioconjugation with oligonucleotides and peptides. The transduction of nucleic acid hybridization and enzyme activity using QDs as energy donors in interfacial fluorescence resonance energy transfer (FRET) indicated that the immobilization strategy preserved the functional properties of the QDs. The multidentate imidazole ligands used for QD immobilization offer the highest denticity of binding in comparison to the currently available approaches without compromise in their optical properties and ability to interact with biomolecules in solution.
2. Imidazole-based potential Bi- and tridentate nitrogen ligands: synthesis, characterization and application in asymmetric catalysis
Roman Sívek, Filip Bures, Oldrich Pytela, Jirí Kulhánek Molecules. 2008 Sep 25;13(9):2326-39. doi: 10.3390/molecules13092326.
Twelve new imidazole-based potential bi- and tridentate ligands were synthesized and characterized. Whereas in the first series the alpha-amino acid and imidazole moieties were linked by an amino bond, in the second series the tridentate ligands, containing two imidazole groups, were separated by an amide bond. The first series was obtained by the reductive amination of 2-phenylimidazole-4-carboxaldehyde with alpha-amino acid esters. The tridentate ligands were prepared from 2-phenylimidazole-4-carboxylic acid and chiral amines. In the Henry reaction, the amines were revealed as a more reactive species than the less nucleophilic amides, however the enantiomeric excesses were generally poor.
3. Efficient synthesis of a porphyrin-N-tripod conjugate with covalently linked proximal ligand: toward new-generation active-site models of cytochrome c oxidase
J P Collman, M Zhong, Z Wang, M Rapta, E Rose Org Lett. 1999 Dec 30;1(13):2121-4. doi: 10.1021/ol9911730.
[formula: see text] A new-generation cytochrome c oxidase active-site model compound (4) featuring both a trisimidazolyl moiety and a proximal base has been designed and efficiently synthesized. During this study, a facile method based on the chemistry of a 4-magnesioimidazole derivative to synthesize 4-imidazolyl-containing tripodal ligands (7) has been developed.
