Globotriose-functionalized gold nanoparticles as multivalent probes for Shiga-like toxin.

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.

Unusual nondispersive ambipolar carrier transport and high electron mobility in amorphous ter(9,9-diarylfluorene)s.

Nondispersive ambipolar carrier transport with comparably high electron and hole mobilities for amorphous molecular solids that are composed of only a single type of chromophores was observed for the first time in amorphous ter(9,9-diarylfluorene)s. High hole and electron mobilities over 10-3 cm2/(V.s) can be achieved with these terfluorenes. In particular, the electron mobility observed represents the highest ever reported for amorphous molecular solids.

Syntheses and spectroscopic studies of spirobifluorene-bridged bipolar systems; photoinduced electron transfer reactions.

Some 9,9'-spirobifluorene-bridged bipolar systems 1-3 containing 1,3,4-oxadiazole-conjugated oligoaryl and triarylamine moieties have been synthesized, in which 1 exhibits remarkable solvent-polarity dependent fluorescence properties due to a highly efficient photoinduced electron transfer reaction.

Ter(9,9-diarylfluorene)s: highly efficient blue emitter with promising electrochemical and thermal stability.

Novel ter(9,9-diarylfluorene)s were synthesized by a Suzuki-coupling reaction of 2-bromofluorene (1) and 2,7-fluorenediboronic ester derivatives (3) with high isolated yields (63-86%). The X-ray structure analysis of ter(9,9'-spirobifluorene) (4aa) revealed that the conjugated chromophore adopts a helical conformation. This conformation effectively releases the steric interaction between the fluorene moieties and prevents inter-chromophore interactions. The introduction of aryl groups at the C9 position of fluorene was highly beneficial to the thermal and morphological stability of these oligomers. These terfluorenes exhibit intense blue fluorescence with excellent quantum yields both in solution ( approximately 100%) and in solid state (66-90%), and possess interesting reversible redox properties. Highly efficient blue light-emitting OLED devices were fabricated using 4aa and 4cc as emitters as well as hole transporters. The devices exhibit low turn-on voltage ( approximately 3 V) and high EL external quantum efficiency (2.5-3%).

Efficient and convenient nonaqueous workup procedure for the preparation of arylboronic esters.

An efficient one-pot synthetic protocol for the synthesis of arylboronic esters has been established. The concentrated addition mixture of trimethylborate with aryl Grignard reagents was treated with low molecular weight diols (ethylene glycol, 1,3-propandiol) and toluene, the corresponding arylboronic esters were isolated in a convenient way with high yields. The diols not only serve as water replacement for the workup step, but also as well as the reagent for the preparation of arylboronic esters.