Ascorbic acid-sensitized Au nanorods-functionalized nanostructured TiO2 transparent electrodes for photoelectrochemical genosensing

Au nanorods (NRs) modified nanostructured TiO2/ITO electrodes have been fabricated and characterized in order to develop a biosensing platform for the photoelectrochemical determination of microRNAs. The proposed method is based on the use of thiolated DNA capture-probes (CPs) immobilized onto Au NR surface. The Au NRs are chemically bound at the surface of TiO2/ITO electrodes by means of the mercaptosuccinic acid linker. Subsequently, the DNA CPs are bound to the Au NR surface through the thiolate group, and reacted with the target RNA sequence. Finally, the obtained biosensing platform is incubated with alkaline phosphatase and l-ascorbic acid 2-phosphate (AAP) enzymatic substrate, for the in situ generation of ascorbic acid (AA). Such AA molecule, coordinating to surface Ti atoms, generates a charge transfer complex, that results in a shift of the UV absorption threshold toward the visible spectral region of the nanostructured TiO2 forming the electrode and, hence, in the occurrence of an absorption band centered at 450\u202fnm. The photoelectrochemical monitoring of the formation of the AA-TiO2 complex, under the visible light of a commercial LED light source, allows the selective and quantitative detection of the target microRNA strands

Preliminary dendroecological survey on pedunculate oak (Quercus robur L) stands in Tuscany (Italy)

This paper studies the influence of climate on pedunculate oak radial growth in some stands of central Mediterranean Italy. Three populations growing along the course of the River Arno were selected. Core samples were measured, and their growth curves standardized and modellized, in order to isolate the climate signal. The response functions were calculated by orthogonal regression of the variables of the tree ring (dependent variables) and the climate (explicative variables). This paper provides an eco-physiological analysis of the results This study helps us understand how the ecotype of the pedunculate oak has adapted to a Mediterranean climate where water supply is a strong limiting factor.Observations dendroécologiques préliminaires sur des peuplements de chênes pédonculés en Toscane (Italie). Le travail concerne l'étude de l'influence du climat sur la croissance radiale du chêne pédonculé dans l'Italie centrale. On a choisi et échantillonné 3 peuplements le long de l'Arno. Les échantillons ont été mesurés et les courbes d'accroissement ont été standardisées et modélisées dans le but d'isoler le signal climatique. Les fonctions de réponse ont été calculées par régression orthogonalisée entre la variable cerne (variable dépendante) et les variables climatiques (variable explicative). Les résultats sont discutés du point de vue écophysiologique. Cette étude aide à comprendre comment des écotypes de chêne pédonculé se sont adaptés au climat méditerranéen où la disponibilité de l'eau est le facteur limitant le plus important