In-situ IR spectra of polypyrrole layers on gold electrodes

Electrochemically modulated infrared spectroscopy (EMIRS) has been used to study the changes occurring in polypyrrole films during electrochemical oxidation and reduction. Films containing perchlorate, tetrafluoroborate and ferrocyanide counterions have been studied in both aqueous and nonaqueous electrolytes. With the EMIRS technique it has been possible to detect electrochemically produced changes in the polymer backbone, in the counterion species and in incorporated solvent.     

A non-oxide sol-gel route to synthesise silicon imidonitride monolithic gels and high surface area aerogels

Monolithic gels have been produced by reaction of Si(NHMe)(4) with ammonia in THF solution and converted to high surface area aerogels by critical point drying with ammonia saturated diethylamine solvent.     

An in situ amperometric biosensor for the detection of vapours from explosive compounds

An amperometric biosensor based on genetically-modified enzymes was used for the in situ detection of trace vapours from a number of explosive compounds. The vapour samples that were generated from a purpose-built vapour generator were collected and pre-concentrated using a trap able to concentrate samples at a rate of 60-fold per minute of sampling. The amperometric biosensor achieved a remarkably low vapour detection limit of 6 parts per trillion from a room temperature sample. The specific activity of the reported enzyme toward a number of explosive compounds was also confirmed using absorbance measurements.     

In situ Ellipsometric Study of Redox Induced Orientation of a Short Chained Ferrocenylalkylthiol Monolayer Self-Assembled on Gold

The structural modifications accompanying the redox switching of a short ferrocene derivative [(C₅H₅)Fe(C₅H₄)CO(CH₂)₅SH] monolayer self-assembled on gold are investigated using ellipsometry. Average values for the complex refractive index and thickness of the monolayer are estimated from ex situ and in situ experiments. The changes in the optical parameters are monitored during potential cycling and between two potential values, where the ferrocene is in its either reduced or oxidized form. The optical changes point to an increase of 1 to 2 Å in the monolayer thickness as the ferrocene is oxidized to the ferricinium cation. The thickness variation is in very good agreement with the rotation of the ferrocene rings towards a more perpendicular position relative to the electrode surface. The changes in orientation are reversible when the potential is cycled. However, instability of the monolayer is observed when the modified electrode is polarized for a few minutes at potentials where the monolayer is oxidized and then returned to the reduced form. This instability is associated with the ferrocene moiety, since a loss of electroactivity is simultaneously detected by cyclic voltammetry.     

Colloidal gold modified with a genetically engineered nitroreductase: toward a novel enzyme delivery system for cancer prodrug therapy

Directed enzyme prodrug therapy is an extensive area of research in cancer chemotherapy. Although very promising, the current directed approaches are still hampered by inefficient enzyme expression and tumor targeting. This work investigates the viability of using metal nanoparticles as a novel delivery vehicle for prodrug-activating enzymes. Using genetically incorporated amino acid sequences, a nitroreductase from E. coli was directly immobilized onto a 50 nm gold colloid, as confirmed by gel electrophoresis, DLS, and UV-vis spectroscopy. The resulting conjugates showed excellent stability in changing proton and sodium chloride environments, including PBS at 37 °C. Remarkably, the immobilized nitroreductase retained more than 99% activity to the CB1954 prodrug without the need for stabilizers. This work provides the foundation for attaching prodrug-activating enzymes to metal nanoparticles for future use in directed enzyme prodrug therapy.     

Synthesis and photoreactivity of 4,5-dithienyl[1,3]dithiol-2-ones

Whereas irradiation of 4,5-dithiophen-2-yl[1,3]dithiol-2-one leads to the expected 2,3,5,6-tetrathiophen-2-yl-1,4-dithiine product, similar reaction of thiophen-3-yl-substituted [1,3]dithiol-2-ones leads to thieno[3,4-c]dithiines via a unique ring cleavage reaction.     

Preparation,chemical modification and absorption properties of various phthalocyanines

A series of phthalocyanines were prepared from phthalodinitrile and corresponding metal salts by means of the ‘solvent’ methods. Some experiments were also conducted in the absence of a solvent in a ‘solvent-free’ process from phthalanhydride, urea and metal chlorides. All of the prepared phthalocyanines were modified by the incorporation of desirable functional groups in order to transform the virtually insoluble phthalocyanine skeleton into more soluble forms. Derivatives soluble in polar media were prepared by means of sulphonation, while those soluble in non-polar media were produced by chlorosulphonation with the subsequent condensation of prepared sulphochlorides with primary alkyl amines.     

Photo-induced catalytic partial oxidation of citronellol with assistance of phthalocyanines

Attention was paid to the role of sulfonated phthalocyanines as efficient photocatalysts in the photo-induced partial oxidation of citronellol. Performance of the singlet oxygen species inducing the formation of citronellol hydroperoxides was studied in detail. The involved reactions may be of great importance in the catalytic production of rose oxide — a highly appreciated component of many synthetic fragrances.