https://zenodo.org/record/1258475/files/article.pdf

Electron transfers in chemistry and biology

Detection of chemical and biological agents plays a fundamental role in biomedical, forensic and environmental sciences1–4 as well as in anti bioterrorism applications.5–7 The development of highly sensitive, cost effective, miniature sensors is therefore in high demand which requires advanced technology coupled with fundamental knowledge in chemistry, biology and material sciences.8–13

In general, sensors feature two functional components: a recognition element to provide selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two essential components for the recognition process in terms of response time, signal to noise (S/N) ratio, selectivity and limits of detection (LOD).14,15 Therefore, designing sensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors15–27 as well as improving the S/N ratio by miniaturization of the sensor elements.28

Gold nanoparticles (AuNPs) possess distinct physical and chemical attributes that make them excellent scaffolds for the fabrication of novel chemical and biological sensors (Figure 1).29–36 First, AuNPs can be synthesized in a straightforward manner and can be made highly stable. Second, they possess unique optoelectronic properties. Third, they provide high surface-to-volume ratio with excellent biocompatibility using appropriate ligands.30 Fourth, these properties of AuNPs can be readily tuned varying their size, shape and the surrounding chemical environment. For example, the binding event between recognition element and the analyte can alter physicochemical properties of transducer AuNPs, such as plasmon resonance absorption, conductivity, redox behavior, etc. that in turn can generate a detectable response signal. Finally, AuNPs offer a suitable platform for multi-functionalization with a wide range of organic or biological ligands for the selective binding and detection of small molecules and biological targets.30–32,36 Each of these attributes of AuNPs has allowed researchers to develop novel sensing strategies with improved sensitivity, stability and selectivity. In the last decade of research, the advent of AuNP as a sensory element provided us a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.37



Figure 1

Physical properties of AuNPs and schematic illustration of an AuNP-based detection system.



In this current review, we have highlighted the several synthetic routes and properties of AuNPs that make them excellent probes for different sensing strategies. Furthermore, we will discuss various sensing strategies and major advances in the last two decades of research utilizing AuNPs in the detection of variety of target analytes including metal ions, organic molecules, proteins, nucleic acids, and microorganisms.

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Gold nanoparticles in chemical and biological sensing.

The science of the total environment

Recent developments in polysaccharide-based materials used as adsorbents in wastewater treatment

Direct And Mediated Anodic Oxidation of Organic Pollutants

Mesoporous silica-based materials have been synthesized and studied for applications in the environmental field. Haloacetic acids have been chosen as test compounds since they are byproducts of disinfection processes of water for human consumption. For this purpose mesoporous materials have been synthesized in acid, basic or neutral conditions. The effect of composition and synthesis conditions of mesoporous materials on their retention properties have been studied. The retention mechanism has also been elucidated in term of electrostatic interactions and as a function of the residual surfactant content in the materials.

Mesoporous materials for the retention and separation of haloacetic acids

The kinetics of oxidation of formic acid by silver(II) in acidic perchlorat emedia (1.00 ⩽[HClO4]⩽ 4.00M) at 14.0, 22.0, and 30.0 °C have been investigated by means of a stopped-flow spectrophotometric technique. The experimental rate law, at constant [H+] and with formic acid in excess, is –d[AgII]/dt=kI0[AgII][HCO2H]+kII0[AgII]2+[HCO2H][AgI]–1. The [H+] dependence of the terms is explained by taking into account the presence of the hydrolyzed species [Ag(OH)]+ and [Ag(OH)]2+: the corresponding hydrolysis equilibrium constants have been evaluated. The mechanism of the reaction is discussed in terms of different paths and reacting species. Comparison is made with previous findings concerning formic acid oxidation with other metal ions and oxidations with AgII.

Edoardo Mentasti

Papers

Mesoporous materials for the retention and separation of haloacetic acids

Kinetics of oxidation of formic acid by silver(II) in aqueous perchloric acid solution

Comparison of ligands for the recovery of trace aluminium(III) by anion-exchange

Optical fibres: atomic spectroscopic methods for the determination of fluoride glasses composition

Kinetic determination of binary mixtures of phenols with a stopped-flow technique