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Bovine serum albumin (BSA) was reacted with linear and newly synthesized branched oligothiophene N-hydroxysuccinimidyl ester fluorophores (TSEs) in moderately basic carbonate buffer solution. Optically stable BSA-TSE conjugates were obtained with a degree of labeling depending on experimental conditions. Conjugates with high fluorophore to BSA ratios (F/BSA = 8) displayed fluorescence quantum yields in the range of 10-30% in water at pH = 7.2, comparable to the quantum yield (25%) of the BSA-FITC conjugate prepared under the same conditions and with the same degree of labeling.

Oligomers of thiophene are widely studied compounds for their electronic and optoelectronic properties. Despite their strong fluorescence, their use as markers for biomolecules, especially for oligonucleotides (ONs), is still largely unexplored. Here, we describe the synthesis of a series of ON molecular beacons employing different oligothiophenes as fluorescent probes and discuss their fluorescence emissions in comparative experiments with and without dabcyl as a quencher, in their hairpin and linear conformations, and as duplexes after hybridization with a complementary target.

The design, synthesis and properties of liquid-crystalline semiconducting oligothiophenes containing dithienothiophene (DTT), benzothiadiazole (BTZ) and carbazole (CBZ) rigid cores are described. The effect of molecular structure (shape, size and substitution) on their thermal behaviour and electrical properties has been investigated. Polarised optical microscopy (POM) and differential scanning calorimetry (DSC) analyses have revealed highly ordered smectic mesophases for most of the newly synthesised compounds. X-ray diffraction (XRD) studies performed at various temperatures have shown that the smectic order is retained in the crystalline state upon cooling across the transition temperature, affording cast films with a more favourable morphology for FET applications.