Compared to monovalent carbohydrates, multivalent carbohydrate ligands exhibit significantly enhanced binding affinities to their interacting proteins. Here, we report globotriose (P(k) ligand)-functionalized gold nanoparticle (AuNP) probes for the investigation of multivalent interactions with the B(5) subunit of Shiga-like toxin I (B-Slt). Six P(k)-ligand-encapsulated AuNPs (P(k)-AuNPs) of varying particle size and linker length were synthesized and evaluated for their potential as multivalent affinity probes by using a surface plasmon resonance competition assay. The affinity of these probes for the interacting proteins was greatly affected by nanoparticle size, linker length, and ligand density on nanoparticle surface. For example, the 20-nm 20-P(k)-l-AuNP, which had a relatively long linker showed a >10(8)-fold increase in affinity compared with the mono P(k) ligand. This intrinsic high-affinity AuNP probe specifically captured the recombinant B-Slt from Escherichia coli lysate, and the resulting purity of the B-Slt was >95 %. We also developed a robust P(k)-AuNP-based detection method for Slt-I by combining the technique with silver enhancement.

A series of chiral vanadyl(V) methoxides bearing 3-t-butyl-5-substituted N-salicylene-L-valinate and L-t-leucinate as chiral auxiliaries has been prepared. In all cases except the 3,5-di-t-butyl analogue, they exist as monomers both in solution and in the single crystal state. In the case of the 3,5-di-t-butyl analogue, the architectural nature of the vanadyl(V) complex highly depends on the base used during the complex formation event. A pentanuclear C4-symmetric complex was formed when potassium salts were employed instead of the corresponding sodium salts. A central vanadate(V) unit serves to grip four identical chiral monomeric vanadyl(V) units together, by which a potassium ion sits on top of the four flanking units through carbonyl coordinations and serves to hold the whole cluster by cooperation with the central vanadate(V) unit. In comparison with the corresponding monomeric vanadyl(V) methoxide complex, the cluster complex was utilized to facilitate the asymmetric aerobic oxidations of various racemic alpha-hydroxyesters, -amides, and -thioesters with excellent selectivity factors (krel 40 to >500).

Functionalized N-2-mercaptoethyl-gallamides bearing three or five hydroxyl units that are tethered with diethylene glycol ether(s) allow for transferring hydrophobically pyridine-capped CdSe/ZnS core/shell nanoparticles from an organic to an aqueous layer with intact fluorescent profiles.

The nuclearity of two preViously prepared nickel complexes, [LNiCl(µ-Cl)] 2 • 2CH 3 OH (1) and L′NiCl 2 (2) (L ) bis(1-methylbenzimidazoyl-2-methyl)amine and L′ ) bis(1-methylbenzimidazoyl-2-methyl)-10-camphorsulfonamide), was found to be temperature-dependent. Mononuclear [LNi(CH 3 OH) 2 Cl]Cl • 2H 2 O (3) and dinuclear [L′NiCl(µ-Cl)] 2 (4) were obtained as crystals at -20 °C. It is noteworthy that complex 2 can catalyze the conjugate addition of thiophenols to R,β-enones in high yields; in contrast, the same reaction catalyzed by NiCl 2 • THF or complex 3 was far less effectiVe.