Although generally ascribed to the presence of defects, an ultimate assignment of the different contributions to the emission spectrum in terms of surface states and deep levels in ZnO nanostructures is still lacking. In this work we unambiguously give first evidence that zinc vacancies at the (1010) nonpolar surfaces are responsible for the green luminescence of ZnO nanostructures. The result is obtained by performing an exhaustive comparison between spatially resolved cathodoluminescence spectroscopy and imaging and ab initio simulations. Our findings are crucial to control undesired recombinations in nanostructured devices.

Selective detection of bioanalytes in physiological fluids, such as blood, sweat or saliva, by means of lowcost and non-invasive devices, is of crucial importance to improve diagnosis and prevention in healthcare.To be really useful in everyday life a sensing system needs to be handy, non-invasive, easy to read and possibly wearable. Only a sensor that satisfies these requirements could be eligible for applications in healthcare and physiological condition monitoring. Herein an organic electrochemical transistor has been investigated as a simple, low-cost and e-textile biosensor, fully integrated on a single cotton yarn.The biosensor has been used for real-time detection of adrenaline, selectively compared to the saline content in human physiological fluids. The sensing mechanism is based on the oxidation of adrenaline at the Pt-gate electrode surface, with the formation of adrenaline-quinone and adrenochrome. Two independent organic electrochemical transistors, characterized by different gate-electrode materials, detect saline and adrenaline concentrations, respectively, in real human sweat. Measurements performed in real-time mode show the complete independence of adrenaline detection from NaCl and, hence, guarantee the simultaneous monitoring of both concentrations. The oxidation of adrenaline has been studied by means of absorption spectroscopy in air, with either silver or platinum working electrodes.Our results confirm that the oxidation reaction driven by the Pt-electrode leads to the formation of adrenochrome, while with the Ag-electrode the oxidation is similar to the spontaneous one occurring in air. The cotton-based biosensor shows the possibility of monitoring human performances (hydration and stress) in situ and using a non-invasive approach, opening new unexplored opportunities in healthcare, fitness and work safety.

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Cadmium sulfide quantum dots (CdS QDs) are used in the manufacture of a number of electronics products. Their small size allows their ready entry into living cells, but as yet no attempt has been made to assess their toxicity. Our aim was to exploit two Ds transposition-induced mutant lines of Arabidopsis thaliana which tolerated exposure to CdS QDs to identify the genetic basis of their tolerance. Both a genome-wide top-down (from mutant to genes) and a bottom-up (from gene expression to phenotype) approach were applied. The differential responses of the mutants compared to the wild type showed that sensitivity to CdS QDs was unrelated to sensitivity to Cd(2+) ions. A transcriptomic analysis identified a number of genes whose transcript abundance was correlated with the tolerance. The phenotype of one of the mutants was correlated with the overexpression of ELM2, an MYB containing gene visited by a Ds transposon. Segregation analysis showed that the genetic basis of CdS QDs tolerance in both mutants was monogenic. The phenotype of the other mutant could be explained by the mutation of HCF101, a gene involved in photosynthesis.