Stabilized Lipid Films in Electrochemical Biosensors

Lipid membrane based electrochemical biosensors have been exploited for the last 40 years. However, a major obstacle that limited their applications and commercialization was their fragility. Recent advances in stabilization of lipid membranes have tremendously increased the number of publications in the last 5 years. The objective of the present article is to present procedures for the stabilization of lipid film biosensors and recent advances in their analytical uses. These novel devices are used as chemo‐ and biosensors for the quantification of environmental contaminants and food toxicants. Recent research is directed to the construction of a portable mini electrochemical device that will be commercialized and readily be used by non‐skilled personnel for in the field measurements.     

Practical issues in laser cleaning of stone and painted artefacts: optimisation procedures and side effects

In the last twenty years lasers have acquired an important role in the study and the preservation of Cultural Heritage (CH) objects and Monuments, as they have effectively illuminated a number of complex diagnostic and restoration problems. Their unique properties have enabled their use in a wide range of conservation applications, since they ensure interventions with precise control, material selectivity and immediate feedback.     

The use of model probes for assessing in depth modifications induced during laser cleaning of modern paintings

The cleaning of over-paint layers is a usual requirement to be met in the conservation of modern paintings. In most cases, acrylics or other related compounds must be removed without affecting the original painting. The elucidation of the extent of any photochemical or structural modification induced to the substrate following laser irradiation is a crucial challenge for the broader implementation of such laser cleaning strategies into the conservation practice. To achieve this, a methodology based on the use of a sensitive photochemical and photomechanical model system is introduced. A probe consisting of a polymeric material (e.g., Paraloid B72) doped with aromatic photo-sensitizers (e.g., POPOP) of known photochemistry and coated with uniform acrylic layer effectively simulates the real case scenario. Following laser irradiation, a variety of spectroscopic techniques including single or multiphoton laser-induced fluorescence and third-harmonic generation are employed for the assessment of any photochemical and structural modification induced in the bulk material. Practical issues related to the laser parameters employed will be presented, and the potential for a more general applicability of this methodology in the laser cleaning of modern paintings will be discussed.     

The Development of Highly Sensitive and Selective Immunosensor Based on Antibody Immobilized ZnO Nanorods for the Detection of D‐Dimer

ZnO nanorods were grown on gold coated glass substrate by low temperature aqueous chemical growth method. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) techniques were used for the characterization of ZnO nanorods. ZnO nanorods are highly dense, uniform, well aligned and perpendicular‐oriented to the substrate. ZnO nanorods exhibited good crystal quality. The well aligned ZnO nanorods were potentially used for the development of selective and sensitive immunosensor for the detection of D‐dimer by immobilizing antibody on stabilized lipid films. The ZnO nanorods based immunosensor responded to a wide range of D‐dimer concentrations with fast response time of ca. 20 s.     

A Selective Immunosensor for D‐dimer Based on Antibody Immobilized on a Graphene Electrode with Incorporated Lipid Films

The present article describes a miniaturized potentiometric D‐dimer biosensor on graphene nanosheets with incorporated lipid films. The graphene electrode was used for the development of a very selective and sensitive immunosensor for the detection of D‐dimer by immobilizing the mouse anti human D‐dimer antibody on stabilized lipid films. The immunosensor responded for the wide range of D‐dimer concentrations with fast response time of ca. 15 s. The presented potentiometric D‐dimer biosensor is easy to construct and exhibits good reproducibility, reusability, selectivity, rapid response times, long shelf life and high sensitivity of ca. 59 mV/decade over the D‐dimer logarithmic concentration range from 10^?6 μg/L to 10^?3 μg/L.     

Freeze-Dried Saccharomyces cerevisiae Cells Immobilized on Potato Pieces for Low-Temperature Winemaking

A biocatalyst was prepared by immobilization of Saccharomyces cerevisiae AXAZ-1 yeast cells on potato pieces. This biocatalyst was subjected to freeze-drying, and the effect of several protective agents and storage at 5 °C, up to 9 months, on viability and fermentative activity of yeasts cells were studied. From several protective agents tested, sodium glutamate preserved the viability of immobilized yeast cells at high levels even after 9-month storage. The freeze-drying biocatalyst was used for repeated batch fermentations of grape must at low temperatures until 5 °C. The produced wines analyzed for volatile byproducts by GC and GC/MS and the results showed that the freeze-dried biocatalysts, with sodium glutamate as protectant, produced wines with higher formation of esters than free cells and having at least similar aromatic profile to those produced by wet biocatalysts.     

Development of a Potentiometric Chemical Sensor for the Rapid Detection of Carbofuran Based on Air Stable Lipid Films with Incorporated Calix[4]arene Phosphoryl Receptor Using Graphene Electrodes

The present article describes a miniaturized potentiometric carbofuran chemical sensor on graphene nanosheets with incorporated lipid films. The graphene electrode was used for the development of a very selective and sensitive chemical sensor for the detection of carbofuran by immobilizing an artificial selective receptor on stabilized lipid films. The artificial receptor was synthesized by transformation of the hydroxyl groups of resorcin[4]arene receptor into phosphoryl groups. This chemical sensor responded for the wide range of carbofuran concentrations with fast response time of ca. 20 s. The presented potentiometric carbofuran chemical sensor is easy to construct and exhibits good reproducibility, reusability, selectivity, rapid response times, long shelf life and high sensitivity of ca. 59 mV/decade over the carbofuran logarithmic concentration range from 10^?6 to 10^?3 M.     

Well‐defined complex macromolecular architectures by anionic polymerization of styrenic single and double homo/miktoarm star‐tailed macromonomers

Styrenic single and double star‐tailed macromonomers were synthesized by selective reaction of living homo/miktoarm stars with the chlorosilane groups of 4‐(chlorodimethylsilyl)‐ and 4‐(dichloromethylsilyl)styrene, respectively. The in situ anionic homopolymerization of macromonomers with sec‐BuLi and copolymerization with butadiene and styrene, led to single/double homo/miktoarm star‐tailed molecular brushes and combs, as well as a block copolymer consisting of a linear polystyrene chain and a double miktoarm (PBd/PS) star‐tailed brush‐like block. Molecular characterization by size exclusion chromatography, size exclusion chromatography/two‐angle laser light scattering, and NMR spectroscopy, revealed the high molecular/compositional homogeneity of all intermediate and final products. These are only a few examples of the plethora of complex architectures possible using the above macromonomers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1826–1842, 2008     

Low-valent ene-amido iron complexes for the asymmetric transfer hydrogenation of acetophenone without base

Examination of the role of base in the activation of our previously reported iron(II) complexes having the general formula [Fe(CO)(Br)(PNNP)][BPh(4)] revealed a five-coordinate iron(II) complex in which the tetradentate PNNP ligand had been doubly deprotonated. The new iron(II) complexes were used in the transfer hydrogenation of acetophenone in isopropanol in the absence of added base, and certain analogues showed catalytic activity.     

The origin of chemoselectivity in the hydrocarbonylation of alkenes catalysed by trialkylphosphine complexes of rhodium

The formation of monophosphine acyl intermediates explains why PPr(i)(3) and PBu(i)(3) generate aldehydes in alkene hydrocarbonylation reactions carried out in protic solvents, whilst PEt(3), for which the acyl complex contains two phosphines, produces alcohols.