Perfluorocarbon Emulsion Contrast Agents: A Mini Review

Perfluorocarbon emulsions offer a variety of applications in medical imaging. The substances can be useful for most radiological imaging modalities; including, magnetic resonance imaging, ultrasonography, computed tomography, and positron emission tomography. Recently, the substance has gained much interest for theranostics, with both imaging and therapeutic potential. As MRI sequences improve and more widespread access to 19F-MRI coils become available, perfluorocarbon emulsions have great potential for new commercial imaging agents, due to high fluorine content and previous regulatory approval as antihypoxants and blood substitutes. This mini review aims to discuss the chemistry and physics of these contrast agents, in addition to highlighting some of the past, recent, and potential applications.

Thermodynamics and Kinetics Research of the Fluorination Process of the Concentrate Rutile

The growth in the production of titanium metal and its compounds leads to an increase in the amount of toxic waste. As a result, at the legislative level, emissions of such wastes are limited, which leads to a drop in the production of titanium-containing products and a shortage of titanium in the international market. This paper presents the results of the process of fluorination of rutile concentrate from the Tarsky deposit (Russia, Omsk region) with elemental fluorine using a laboratory setup of a special design. For fluorination, samples of rutile concentrate weighing 0.1–1.0 g were used. The particle size distribution of particles varied from 2 × 10−6 to 2 × 10−5 m. To determine the possibility of carrying out the process, the calculation of the change in the logarithm of the equilibrium constant versus temperature was performed. The influence of the following operating parameters on the fluorination process has been studied: various concentrations of F2 in a fluorinating mixture of fluorine with nitrogen; process time from 0 to 9 min; different ratios of the initial solid phase to fluorine (10 and 50% excess of fluorine and 10 and 50% of its deficiency); fluorination temperature in the range of 300–1800 K. A kinetic equation is selected that most accurately describes the fluorination process. The values of the activation energy and the preexponential factor in the kinetic equation are determined. The obtained results show that with an increase in the fluorine content in the fluorinating gas mixture and the temperature of the process, the fluorination rate increases. Optimal conditions for fluorination: temperature—680 K; time—5 min excess fluorine in the fluorinating mixture—20–25%. The obtained results allow to propose and consider the conditions of process execution on industrial equipment.

FLUORIDE LEVELS IN SALIVA AFTER CHEWING BLACK TEA CANDY (CAMELLIA SINENSIS) IN CHILDREN

ABSTRACTBackground: Black tea has been shown to affect reducing dental plaque and increasing fluoride levels in saliva. The practice of consuming black tea in the form of candy for dental health purposes is not familiar yet. A study on the effectiveness of chewing black tea candy added with sorbitol sugar for a month on salivary fluoride levels in children aged 7-8 years can be an innovation in the prevention of dental caries. This study aims to investigate the difference in fluoride levels in saliva before and after chewing black tea candy for one month in children aged 7-8 years.Method: This is a field experimental study with double-blind and randomization. Subjects involved in this study were 44 children divided into control and intervention groups using simple random sampling. Measurement of salivary fluorine levels using the TECAN Infinite M200 Pro® UV – VIS Spectrophotometer for 3 times.Result: The results of the independent T-test showed that there were significant differences in the fluorine content in the intervention group using black tea candy on 26 November 2019, 29 November 2019, and 16 December 2019 (p<0.05).Conclusion: Chewing black tea candy is effective in increasing the amount of fluoride in saliva. Thus, it can be an alternative to anti-cariogenic agents.

Au(I) Catalyzed HF Transfer: Tandem Alkyne Hydrofluorination and Perfluoroarene Functionalisation

HF transfer reactions between organic substrates are an incredibly rare class of transformation. Such reactions require the development of new catalytic systems that can promote both defluorination and fluorination steps in a single reaction sequence. Herein, we report a novel catalytic protocol in which an equivalent of HF is generated from a perfluoroarene | nucleophile pair and transferred directly to an alkyne. The reaction is catalysed by [Au(IPr)NiPr2] (IPr = N,N’-1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and is 100 % atom efficient. HF transfer generates two useful products in the form of functionalised fluoroarenes and fluoroalkenes. Mechanistic studies (rate laws, KIEs, DFT calculations, competition experiments) are consistent with the Au(I) catalyst facilitating a catalytic network involving both concerted SNAr and hydrofluorination steps. The nature of the nucleophile impacts the turnover-limiting step. The cSNAr step is turnover-limiting for phenol-based nucleophiles while proteodeauration likely becomes turnover-limiting for aniline-based nucleophiles. The new approach removes the need for direct handling of HF reagents in hydrofluorination and offers new possibilities to manipulate the fluorine content of organic molecules through catalysis.

PAI Materials Synthesized by 4,4′-Diaminodiphenyl Ether/2,2′-Bis (Trifluoromethyl)-4,4′-Diaminophenyl Ether and their Properties

In this paper,4,4′-diaminodiphenyl ether and 2,2′-bis (trifluoromethyl)-4,4′-diaminophenyl ether are selected for molecular structure design, and PAI materials are synthesized by acyl chloride method. 2,2′-bis (trifluoromethyl)-4,4′-diaminophenyl ether has the same main chain structure as 4,4′-diaminodiphenyl ether, but the side chain contains two trifluoromethyl groups, which has high fluorine content. PAI terpolymerswere prepared by compounding two diamine monomers, and the effects of trifluoromethyl on heat resistance, friction and wear properties, hydrophobic properties and mechanical properties of PAI materials were studied. The results showed that with the increase of trifluoromethyl content, the Tg of PAI material first increased and then changed little, and the Td5% would decrease and the tensile properties would also decrease. The wear mechanism of PAI varied with the content of trifluoromethyl. With the increase of the amount of fluorinated diamine monomer, the adhesive wear degree of PAI materials gradually increased, and reached the maximum when the molar ratio of the two monomers was 5:5, and then decreased gradually. Different trifluoromethyl content had little effect on friction coefficient, and the friction coefficient increased slightly when the molar ratio of 4,4′-diaminodiphenyl ether to 2,2′-bis (trifluoromethyl)-4,4′-diaminophenyl ether is 1:9. With the increase of trifluoromethyl content, the wear of PAI material would increase. With the increase of the amount of trifluoromethyl, the water absorption of PAI material decreased and the water contact angle increased, which indicated that the hydrophobic property of PAI material was improved. To sum up, the results of this study showed that the introduction of trifluoromethyl into the side chain provided an effective way to prepare PAI materials with low water absorption. Considering the comprehensive properties such as heat resistance, friction and wear, tensile properties, etc., the appropriate addition amount is 10–30%.

Non-invasive in Vivo Assessment of 11β-hydroxysteroid Dehydrogenase type 1 Activity by 19 F-magnetic Resonance Spectroscopy

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) amplifies tissue glucocorticoid levels and is a pharmaceutical target in diabetes and cognitive decline. Clinical translation of inhibitors is hampered by lack of in vivo pharmacodynamic biomarkers. Our goal was to monitor substrates and products of 11β-HSD1 non-invasively in liver via 19 Fluorine magnetic resonance spectroscopy (19 F-MRS). Interconversion of mono/poly-fluorinated substrate/product pairs was studied in Wistar rats (male, n=6) and healthy men (n=3) using 7 T and 3 T MRI scanners, respectively. Here we show that the limit of detection, as absolute fluorine content, was 0.625 μmol in blood. Mono-fluorinated steroids, dexamethasone and 11-dehydrodexamethasone, were detected in phantoms but not in vivo in human liver following oral dosing. A non-steroidal polyfluorinated tracer, 2-(phenylsulfonyl)-1-(4-(trifluoromethyl)phenyl)ethanone and its metabolic product were detected in vivo in rat liver after oral administration of the keto-substrate, giving a readout of reductase activity. Administration of a selective 11β-HSD1 inhibitor in vivo in rats altered total liver 19 F-MRS signal. We conclude that there is insufficient sensitivity to measure mono-fluorinated tracers in vivo in man with current dosage regimens and clinical scanners. However use of a poly-fluorinated tracer allowed detection of hepatic reductase activity in rats and could be developed for translation to man.

A Novel Phosphorescent Iridium(III) Complex Bearing Formamide for Quantitative Fluorine Anion Detection

Fluorine anion plays a critical role for human health, especially for the teeth and the skeletal system, and a deficiency or excess of fluorine anion will result in various diseases. Thus, the accurate and timely detection of fluorine content is of great importance. Herein, a novel and sensitive fluorine probe based on ionic iridium(III) complex using 5-formamide phenanthroline as an ancillary ligand was designed and synthesized rationally. The probe exhibited excellent performance for F− detection in organic solvents. H-bonding between the fluoride and the amide proton was formed, thus changing the photophysical properties of the probe and leading to significant phosphorescence quenching. Nuclear magnetic resonance titration and theoretical calculations were carried out to understand the mechanism in detail. This is the first report of an iridium(III) complex probe for F− detection based on the interaction between formamide and fluorine anion.

Fluorine Depth Profiling Based on the 19F(p,p’g)19F Excitation Function

Ion beam analysis of fluorine has applications in research on teeth and bones, materials science, geochemistry and archaeometry. A novel PIGE (Particle Induced Gamma-ray Emission) standard free methodology for fluorine content determination for in-depth heterogeneous samples based on the excitation function of the 19F(p,p’γ)19F nuclear reaction is presented. New precise cross section measurements of this reaction in the proton energy range 2.1 to 4.1 MeV have been performed. In addition, the ERYA-Profiling code, a computer program specially developed for PIGE analysis of in-depth heterogeneous samples, employed this new excitation function in a case study where different fluorine simulated depth profiles probed the capability of insight into fluorine distributions in a given sample, showing the potential of PIGE analysis.

STUDY OF THE FLUORINE CONTENT IN THE HOUSEHOLD AND DRINKING WATER IN THE TURSUNZADE SETTLEMENTS

Analysis of fluorine content in the household and drinking water in the Tursunzade settlements, depending on the wind directions and the season.