A highly sensitive and selective fluoride sensor based on a riboswitch-regulated transcription coupled with CRISPR-Cas13a tandem reaction

A fluoride sensor based on riboswitch-regulated transcription coupled with Cas13a sensor can detect fluoride in water with a portable fluorometer. This sensor expands nuclei acid sensors to an anion, with high sensitivity and selectivity against other common anions.

Fluorescence Fluoride Ion Sensor Utilizing Desilylation of N-Silylated 9- Aminoanthracene

N,N-Bis(trimethylsilyl)-9-aminoanthracene (Si9AA) was synthesized by deprotonation of 9-aminoanthracne (9AA) with n-BuLi followed by the addition of trimethylsilyl chloride (TMSCl). Under ultraviolet, Si9AA showed blue fluorescence originated from the anthracene skeleton due to orthogonal relation between anthracene skeleton and bis(trimethylsilyl)amino group, which was determined by X-ray crystallographic analysis, while 9AA, in which conjugation exists between the anthracene and the amino group, showed green fluorescence. In a THF solution, Si9AA was converted to 9AA by desilylation of bis(trimethylsilyl)amino group with fluoride ion, which was contained in tetrabutylammonium fluoride (TBAF) or KF-18-crown-6 complex, resulting in fluorescence color change from blue to green. Si9AA was found to utilize as a sensor to detect fluoride ion in THF solution or on a thin layer chromatography (TLC) via the fluorescence color change without any metals, regarding a metal free fluorescence fluoride sensor in green chemistry.

Experimental Study of Sidewall Pressure Induced by Ferroparticles in Fluid under a Pulsating Magnetic Field

For several decades, magnetic nano- and microparticles have been used in various applications, as they can be attracted and controlled using external magnetic fields. Recently, carbonyl iron microparticles were used in a feasibility study of a new cardiac pacing application. The particles were inserted into a heart, attracted to its sidewall using a pulsating magnetic field, and applied pulsating pressure on its sidewall. The magnitude of the sidewall pressure is a critical parameter for the success and safety of the application, and it was evaluated analytically using a simplified model. In the present study, the behaviour of carbonyl iron microparticles in a water chamber was studied experimentally. Several masses of these particles were attracted to the sidewall of the chamber using an external pulsating magnetic field; the behaviours of the masses of particles, the particle–particle interaction, and the influence of fluid dynamics on them were examined during different periods of pulses. The sidewall pressure during their attraction was measured using an in-house piezoelectric polyvinylidene fluoride sensor. The relations between the measured sidewall pressure and the mass of the particles, their sizes, and the magnetic field exposure time were investigated. The obtained results suggest an asymptotic sidewall pressure value for the specified magnetic field. The measurements of the sidewall pressure are compared with evaluated results from the analytical model, showing that the model over-predicts the sidewall pressure.