Molecular sensors confined on SiOx substrates

The sensing of ions, ion-pairs, gases, toxic materials, biomolecules, and explosives represents an important issue of high practical relevance. Consequently, significant efforts are currently underway to develop sufficiently reliable and sensitive and yet possibly simple methods for this purpose. In this context, molecular sensing is particularly important, presenting itself as a useful tool for alleviating global security concerns, tackling environmental issues, and contributing to biomedical analysis and other associated areas. Innovatively designed molecules and metallo-organic moieties having a specifically tailored receptor site, a clearly defined reporter group, and a signal processing unit are the basic components of a working molecular sensor. However, solution-based molecular sensors, although of great standing, suffer frequently from relatively long response time as well as from poor solubility and recyclability of the sensing material. In contrast, surface-confined sensors permit easier manoeuvrability in different media and are characterized by a shorter response time, better signal amplification, as well as by regeneration and recyclability of the sensor through chemical or physical post-treatments. Additionally, depending on the structural, redox, or optical behavior of the analyte and the sensing material, a suitable transduction technique or a combination of several such techniques may be employed for analyzing surface attributes and studying analyte-host interaction. In this regard, SiOx substrates and molecular assembles thereon offer distinct advantages over other common supports such as metals, polymers, membranes, etc. in terms of cost, durability, stability, and scope. In this context, this review deals with the most recent developments in design and fabrication of molecular sensors confined on SiOx substrates. Here we provide representative and relevant examples of molecular sensors on these substrates, arranged with respect to the entities under analysis, viz. ions, specific gases, biomolecules, explosives, and warfare agents, paying also some attention to the general aspects of such sensor design. (C) 2016 Elsevier B.V. All rights reserved.