Careful analysis and comparison of optical and electrochemical data available in recent literature for multi-thiophene molecular assemblies suggested a few basic rules for the design of structurally simple and easily accessible oligothiophenes endowed with properties not far from those exhibited by much more complex and synthetically demanding architectures. The synthesis and computational investigation of three examples of a class of oligothiophenes (spider-like) tailored according to these indications are reported together with their exhaustive optical and electrochemical characterization. The new compounds (T9 5, T14 6, T19 7) are characterized by a thiophene, a 2,2'-bithiophene and a 2,2',5',2''-terthiophene unit (the spider body) fully substituted with 5-(2,2'-bithiophen)yl pendants (the spider legs). Absorption and electrochemical data are in good agreement and point to a high pi-conjugation level, comparable to those displayed by much larger assemblies. Electrode potential cycling in proximity of the first oxidation peak affords fast and reproducible formation of conducting, highly stable [TXn]m films, mainly consisting of dimers (m=2). Electrooxidation kinetic experiments on deuterium-labelled T9 5, coupled to laser-desorption-ionization mass spectroscopy on the resulting dimer demonstrated that the coupling process is extremely regioselective in the alpha positions of the more conjugated pentathiophene chain. The optical and the electrochemical properties of the films are reported and discussed. A peculiar feature is their impressive charge-trapping ability. Spider-like oligothiophenes are promising materials for applications as active layers in multifunctional organic devices.

Nanoscale carbon materials (i.e., fullerenes and nanotubes) are an attractive platform for applications in biotransformations and biosensors. The interesting properties displayed by nanoparticles demand new strategies for the manipulation of these materials on the nanoscale. Controlled modification of their surface with biomolecules is required to fully realize their potential in bionanotechnology. In this work, immobilization of a fullerene derivative with a mutant subtilisin is demonstrated, and the effect of the fullerene on the protein activity is determined. The fullerene-conjugated enzyme had improved catalytic properties in comparison to subtilisin immobilized on nonporous silica. Further, the pH profile of free and fullerene-conjugated subtilisin were almost identical.

An increase in bone resorption is one of the main symptoms of osteoporosis, a disease that affects more and more individuals every day. Bisphosphonates are known to inhibit bone resorption and thus are being used as a treatment for osteoporosis. Aminobisphosphonates present a functionality that can be easily used for conjugation to other molecules, such as peptides, proteins, and ligands for protein recognition. In this study, an aminobisphosphonate conjugated with biotin was used as a model linker for protein attachment to bone. With this system, the interaction of biotinylated aminobisphosphonate with hydroxyapatite, a major mineral component of bone, was investigated. Quantification of the binding of aminobisphosphonate to hydroxyapatite was performed using a fluorescently labeled antibody for biotin. Additionally, the interaction of the biotinylated aminobisphosphonate with multiple treatments of cortical bone from the midshaft of a cow femur was studied. It was demonstrated that modified aminobisphosphonate reagents can bind hydroxyapatite and bone at high levels, while the biotin functionality is free to be recognized by the fluorescently labeled antibiotin antibody, suggesting that modified aminobisphosphonates could be used to link other peptides or proteins to the bone surface.

A novel biotinylated fullerene has been synthesized to facilitate the attachment of biotin-conjugated proteins to C 60 through the use of streptavidin as a molecular adapter. The strong biotin-streptavidin interaction enables the attachment of fullerenes to streptavidin and, because of the availability of four biotin-binding sites on streptavidin, to biotinylated biomolecules. The feasibility of this approach is demonstrated by using biotinylated alkaline phosphatase. Due to the insolubility of fullerenes in aqueous media, the immobilized enzyme can be eventually recovered by simple centrifugation with no significant loss in activity.

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