No abstract

The Nicholson×s treatment for the evaluation of the heterogeneous standard rate constant k 0 of electron transfer from cyclic voltammetric (CV) data is combined with the Klingler and Kochi method suitable to totally irreversible systems in order to use very large DE p x n values, where n is the number of electrons involved in a simple electron-transfer process O n e À > R. An empirical relationship between the dimensionless parameter Y k 0 [pDnvF/(RT)] À1/2 and DE p x n which practically replaces the Nicholson×s working curve up to about 200 mV is reported.

The growing demand for increased fresh food shelf life as well as the need of protection\ud against foodborne diseases urged the development of antimicrobial food packaging. Among the\ud most efficient methods, the combination of organic–inorganic, packaging, i.e. polymer embedded\ud metal nanoparticles proved to be highly effective. Silver nanoparticles (AgNPs), in particular, have\ud antimicrobial, anti-fungi, anti-yeasts and anti-viral activities and can be combined with both nondegradable\ud and edible polymers for active food packaging. The actual application of AgNPs in food\ud packaging is regulated by EU and USA food safety authorities in a prudent way, due to the inability\ud to make conclusive statements on their toxicity. Therefore, their use is evaluated in terms of Ag+\ud migration into the packed food.\ud In this mini review, the most recent studies are reported on protection of meat, fruit and dairy\ud products against the most common food pathogens by AgNPs-doped non-degradable and edible\ud polymers and oils are reported

Here we report the first mediated microneedles-based biosensor for minimally invasive continuous sensing of lactate in the dermal interstitial fluid (ISF). To further demonstrate the capability of microneedle arrays as second generation biosensors we have functionalized gold microneedles with nanocarbons at which mediated electron transfer of lactate oxidase takes place. In particular the gold surface of the microneedles electrode has been modified in 3 subsequent steps: i) electrodeposition of Au-multiwalled carbon nanotubes (MWCNTs); ii) electropolymerization of the mediator, methylene blue (MB); iii) immobilization of the enzyme lactate oxidase (LOX) by drop-casting procedure. The resulting microneedle-based LOX biosensor displays an interference-free lactate detection without compromising its sensitivity, stability, selectivity and response time. The performance of the microneedle array, second generation biosensor for lactate detection was assessed in artificial interstitial fluid and in human serum, both spiked with lactate. The results reveal that the new microneedles lactate sensor holds interesting promise for the development of a real-time monitoring device to be used in sport medicine and clinical care.

Electrical wiring of different types of pyranose oxidase (P2O) (fungal wild type, recombinant wild type with a hexahistidine tag, mutant form E542K with a hexa-histidine tag) from Trametes multicolor, and recombinant P2O from Coriolus sp. overexpressed in Escherichia coli as well as of pyranose dehydrogenase (PDH) from Agaricus meleagris and Agaricus xanthoderma with an osmium redox polymer (poly(1-vinylimidazole) 12 -[Os(4,4'-dimethyl-2,2'-dipyridyl) 2 -Cl 2 ] 2þ/þ ) on graphite electrodes was carried out. After optimization studies using glucose as substrate, the biosensors, which showed the best characteristics in terms of linear range, detection limit and sensitivity were selected, viz. wild type P2O from T. multicolor and PDH from A. meleagris. These two enzymes were used and investigated for their selectivity for a number of different sugars.