Electroanalysis of the interaction between (-)-epigallocatechin-3-gallate (EGCG) and amyloid-ß in the presence of copper.

The misfolding of amyloid-beta (Aß) peptide is one of the pathological hallmarks of Alzheimer's disease (AD). Polyphenols are strong antioxidants and metal chelators, with characteristics that are of beneficial therapeutic values for their development as candidates targeting neurodegenerative and metal-induced diseases. We have demonstrated here the electrochemical properties of a green tea component, (-)-epigallocatechin-3-gallate (EGCG), and its potent activity on Aß peptides. Characterization of early interactions (≤48 h) between EGCG and Aß was conducted using square wave voltammetry (SWV). The interaction of Cu(ii) ions with the Tyr-10 residue of Aß was shown to be affected by surrounding His residues. Morphological changes due to the binding of EGCG and Cu(II) were also elucidated using transmission electron microscopy (TEM). Electroanalytical techniques are promising for facilitating the investigation of metals and flavonoids in drug screening studies.

Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring.

This article presents the fabrication and characterization of novel tattoo-based solid-contact ion-selective electrodes (ISEs) for non-invasive potentiometric monitoring of epidermal pH levels. The new fabrication approach combines commercially available temporary transfer tattoo paper with conventional screen printing and solid-contact polymer ISE methodologies. The resulting tattoo-based potentiometric sensors exhibit rapid and sensitive response to a wide range of pH changes with no carry-over effects. Furthermore, the tattoo ISE sensors endure repetitive mechanical deformation, which is a key requirement of wearable and epidermal sensors. The flexible and conformal nature of the tattoo sensors enable them to be mounted on nearly any exposed skin surface for real-time pH monitoring of the human perspiration, as illustrated from the response during a strenuous physical activity. The resulting tattoo-based ISE sensors offer considerable promise as wearable potentiometric sensors suitable for diverse applications.

Disposable immunochips for the detection of Legionella pneumophila using electrochemical impedance spectroscopy.

The rapid diagnosis of Legionellosis is crucial for the effective treatment of this disease. Currently, most clinical laboratories utilize rapid immunoassays that are sufficient for the detection of Legionella serogroup 1, but not other clinically relevant serogroups. In this report, the development of a disposable immunochip system is described in connection with electrochemical impedance spectroscopy and fluorescence microscopy. The immunochips were prepared by covalently immobilizing fluorophore-conjugated L. pneumophilaantibodies on Au chips. The analytical performance of the immunochips was optimized as a prescreening tool for L. pneumophila. The versatile immunochips described here can be easily adapted for the monitoring of all Legionella serogroups in clinical and environmental samples.