title: Piezoelectric sensor functionalised by a self-assembled bipyridinium derivative: characterisation and preliminary applications in the detection of heavy metal ions.
abstract: The synthesis of a molecule, 1-(11-dodecylsulfanyl-undecyl)-[4,4']bipyridinium bromide (1), suitable at the same time to form a covalent bond with gold electrodes of a piezoelectric quartz crystal and to interact with heavy metal ions in aqueous solutions, has been successfully accomplished. A commercial quartz crystal microbalance instrument has been modified in order to perform a Flow-Injection Analysis. The behaviour of the system follows the Kanazawa-Gordon equation as demonstrated by measurements with glucose solutions. The self-assembled layer of 1 onto a gold electrode has been characterised by Atomic Force Microscopy before and after the sensing tests. The sensing performances of the modified gold electrode were investigated by monitoring the frequency variation induced by the presence of heavy metal ions, such as lead, cadmium and mercury, in aqueous media. The explored concentrations ranged between 10(-4) and 10(-2) M and the corresponding frequency variations ranged between 10 and 50 Hz. All responses observed were fast, reproducible and reversible. In particular, the response to mercury appears significantly higher in comparison with the other analytes. To the best of our knowledge, this contribution represents the first example of sensing layer based on bipyridinium receptor showing reversible and, at some extent, differentiated response towards heavy metal ions.
authors.affiliation: Dipartimento di Ingegneria dell'Innovazione, Università degli Studi di Lecce, Via Monteroni, Edificio "La Stecca", I-73100 Lecce, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Casilli
authors.forename: Cosimino
authors.initials: C
authors.lastname: Malitesta
authors.forename: Sabrina
authors.initials: S
authors.lastname: Conoci
authors.forename: Salvatore
authors.initials: S
authors.lastname: Petralia
authors.forename: Salvatore
authors.initials: S
authors.lastname: Sortino
authors.forename: Ludovico
authors.initials: L
authors.lastname: Valli
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003460:Crystallization / Q000379:methods; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D007477:Ions; D008422:Materials Testing; D019216:Metals, Heavy / Q000032:analysis* / Q000737:chemistry*; D011726:Pyridinium Compounds / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties; D014159:Transducers; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D020099:Coated Materials, Biocompatible; D007477:Ions; D019216:Metals, Heavy; D011726:Pyridinium Compounds; D012996:Solutions; D014874:Water Pollutants, Chemical; D014867:Water