A Phenanthrenequinone-Based Ratiometric Fluorescent Probe for Rapid Detection of Peroxynitrite with Imaging in Osteoblast Precursor Cells.

In the current situation, peroxynitrite (ONOO-) is drawing the increasing attention of researchers for its pivotal role in diverse pathological and physiological processes on grounds of robust oxidation and nitrification. Herein, we have successfully designed and synthesized a phenanthrenequinone benzyl borate-based chemosensor for fast and selective detection of ONOO-. The probe PTDP itself had an orange fluorescence, which was changed to strong blue fluorescence upon the addition of ONOO-, indicating the ratiometric response of the probe. This is so because of the cleavage of the benzyl boronate-protecting group of PTDP upon the addition of ONOO- with simultaneous releasing of pyridinyl-based chemosensor PPI. The PTDP showed outstanding performance in the various photophysical studies such as good selectivity, excellent sensitivity with a very low detection limit of 2.74 nM, and a very fast response time (<15 s). Furthermore, for practical applicability, it was successfully applied in the ratiometric detection of ONOO- in osteoblast precursor cells.

A chemodosimetric chemosensor for the ratiometric detection of nerve agent-mimic DCP in solution and vapor phases.

Nerve agents are among the most deadly and lethal chemical warfare agents (CWAs). Rapid identification is crucial for specialized individuals to take action against dangerous drugs. This paper describes the synthesis and characterisation of a probe (MNFZ) based on the methoxy naphthalene-furoic hydrazide group. The probe rapidly (100 s) detects and quantifies the nerve-agent simulant diethyl chlorophosphate (DCP) in both solution and vapor phases. This sensor uses a new recognition center, furoic hydrazide, where the nitrogen atom of the imine group (CN) attacks the electrophilic core phosphorus atom of DCP, followed by the hydrolysis of the imine group in the acetonitrile (ACN) solution to produce the corresponding aldehyde MNPA. The development of ICT character resulted in a distinct red-shifted ratiometric fluorescence response to DCP, with a very low limit of detection (12.2 nM). The probe is an efficient chemosensor due to its high selectivity over other organophosphorus compounds as well as its chemical stability across a wide pH range. DFT calculations, 1H NMR and HRMS were performed to finalize the sensing mechanism. Lastly, the as-designed sensor was successfully used to build a highly sensitive portable kit in test strips and a cotton biopolymer for simple and safe real-time monitoring of DCP.

A ratiometric small-molecule fluorescent probe for the selective detection of hypochlorite by an oxidative cyclization reaction: application to commercial disinfectants and live cells.

A highly selective thiophene-thioimidazole hydrazine-based ratiometric chemodosimeter (TPBN) was designed and synthesized to detect hypochlorite (ClO-). The probe showed yellow fluorescence and exhibited ultra sensitivity towards hypochlorite (detection limit 8.74 nM) through the oxidative intramolecular cyclization process to give a blue fluorescent triazole product (TPBN-P). Additionally, the as-designed sensor displayed a fast response (80 s) to hypochlorite with excellent selectivity over other competing analytes. DFT calculations, ESI-MS, and 1H NMR titration experiments supported the detection mechanism. The probe was a valuable and practical ratiometric sensor for test strips, commercial disinfectants, and water samples. The probe was successfully used in the bio-imaging of hypochlorite in human breast cancer cells due to its noteworthy photophysical characteristics and good cell permeability.

A turn-on fluorescent probe for selective detection of H2S in environmental samples and bio-imaging in human breast cancer cells.

A triphenylamine-benzothaizole-based turn-on fluorescent probe TPB-NO2 was designed and synthesized for tracking H2S in both environmental and biological samples depending upon the sensing strategy of thiolysis of 2,4-dinitrophenyl (DNP) ether. Due to PET (photoinduced electron transfer), occurring from donor triphenylamine moiety to acceptor DNP moiety, the probe TPB-NO2 itself is very weakly fluorescent and colorless in DMSO/H2O solution (1 : 1, v/v; 10 mM HEPES buffer, pH 7.4). But the addition of H2S leads to thiolysis of 2,4-dinitrophenyl ether to block the initial PET process and hence it exhibits naked eye detectable turn-on response with bright cyan fluorescence and intense brown color. Not only that, the probe exhibits excellent selectivity over other bio-thiols like Cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), fast response time (<2 min), and high sensitivity with a detection limit of 9.81 nM. Moreover, to explore the practical applicability of our probe we employed it to monitor H2S successfully in environmental water samples, solid-state TLC strip study, Quantitative determination of H2S in eggs, and in the bioimaging of human breast cancer cells (MDA-MB 231).

A small-molecule fluorogenic probe for the detection of hypochlorite and its application in the bio-imaging of human breast cancer cells.

A certain amount of hypochlorite can help to regulate the body's defense system while excessive hypochlorite has some complex influence on health. Herein, a thiophene-derived biocompatible turn-on fluorescent probe (TPHZ) was synthesized and characterized for the detection of hypochlorite (ClO-). The fluorescence and colorimetric sensing of the probe followed an ICT OFF strategy. The experimental results showed a remarkable turn on fluorescence enhancement from colorless to bright blue after the addition of ClO- within 130 s in a solvent system having 80% water with high selectivity and a low detection limit of 53.8 nM. The sensing mechanism was attributed to ClO- mediated electrophilic addition to the imine bond which was justified by DFT calculations, and ESI-MS and 1H-NMR titration experiments. The probe was used in an application to visualize ClO- in human breast cancer cells which can be helpful for investigating the functions of hypochlorite in living cells. Finally, by virtue of fine photophysical properties, good sensing performance, good water solubility and low limit of detection, the probe TPHZ was successfully applied to TLC test strips, and commercial bleach and water samples.

Switching to a 'turn-on' fluorescent probe for rapid detection of hydrazine in human breast cancer cells using a test-strip.

A fluorescent probe TPSBT was developed to monitor hydrazine detection with a "turn on" response, converting from a "non-responsive" probe by a simple structural modification. The probe shows very weak fluorescence due to the strong ICT process and upon treatment with hydrazine, green fluorescence appears due to the blocking of this ICT by the formation of a hydrazone. The probe TPSBT can detect hydrazine with a very low detection limit (1.22 × 10-7 M) and within a very short time period of 50 s. Additionally, the probe is able to give a response in live cell imaging (MDA-MB 231) and also in the solid phase.

An ICT-guided ratiometric naphthalene-benzothiazole-based probe for the detection of cyanide with real-time applications in human breast cancer cells.

A methoxynaphthalene benzothiazole conjugate (MNBTZ) armed with CC vinylic double bonds was synthesized and utilized for the selective detection of CN- ions. The probe showed yellow fluorescence due to ICT from the methoxynaphthalene moiety to benzothiazole, which instantly changed to light purple upon the nucleophilic addition of CN- to the vinylic double bond, inhibiting ICT due to the break-in conjugation. The effectiveness of the probe was proved by this brilliant ratiometric fluorescence change, which was achieved selectively as observed by experiments with competing anions. 1H NMR titrations and DFT calculations support this mechanism. A low detection limit of 2.1(±0.0022) × 10-8 M along with good fluorescence color change on solid TLC plates and human breast cancer cells makes it amenable to CN- sensing.

Systematic Review on Treatment Trials of Tocilizumab: A Repurposing Drug against COVID-19.

BACKGROUND: Coronavirus disease (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has become a global issue today. There exists an ongoing health crisis all over the world, and efficacious drugs against COVID-19 are not available yet. Therefore, on an urgent basis, scientists are looking for safe and efficacious drugs against SARSCoV- 2. METHODS: The reported individual patient data and clinical outcomes, including the rate of recovery and mortality, patients' characteristics, and complications, are reviewed. Randomized controlled trials, single-center cohort studies, and different case studies are provided, and the PICO model is used to illustrate the outcomes. RESULTS: There exist several FDA (U.S Food and Drug Administration) approved anti coronavirus drugs that sometimes are unsuccessful in curing COVID-19 critical conditions. It has been observed that a humanized monoclonal antibody, Tocilizumab (licensed for the treatment of rheumatoid arthritis), targeting the interleukin-6 (IL-6) receptor, has an integral role in the treatment of COVID-19. CONCLUSION: The cause behind the mortality of COVID-19 patients was found to be the Cytokine Release Syndrome (CRS). Therefore, besides other antiviral drugs, the utilization of tocilizumab should also be considered as it can effectively block IL-6 and reduce the inflammatory signal.