An indole-based near-infrared fluorescent "Turn-On" probe for H2O2: Selective detection and ultrasensitive imaging of zebrafish gallbladder

Fluorescent probes play essential roles in medical imaging, where the researchers can select one of many molecules to use to help monitor the status of living systems under investigation. To date, a few scaffolds that allow the in vivo detection of H2O2 are available only. Herein, we provide a highly sensitive and selective near-infrared fluorescent probe that detects H2O2 based on the ICT sensing mechanism. We report the first indole-incorporated fluorescent probe Indo-H2O2 that allows H2O2 detection with a LOD of 25.2 nM featuring a boronate group conjugated to an indole scaffold; the boronate cleaves upon reaction with H2O2. A 5-membered malononitrile derivative was incorporated; Indo-H2O2 has near-infrared (NIR) properties and the reaction time is low (∼25 min) compared to other related probes. Indo-H2O2 was successfully employed in both endogenous and exogenous imaging trials of H2O2 in living cells. Indo-H2O2 also allows the real-time monitoring of H2O2in vivo. It preferentially accesses the gallbladder of zebrafish. Our findings support Indo-H2O2 as a highly sensitive fluorescent NIR probe for detecting H2O2, and an idea to incorporate a central indole unit in future fluorescent probe designs.

Highly sensitive and rapid detection of hypochlorous acid in aqueous media and its bioimaging in live cells and zebrafish using an ESIPT-driven mycophenolic acid-based fluorescent probe

Excessive production of potent biological oxidants such as HOCl has been implicated in numerous diseases. Thus, it is crucial to develop highly specific and precise methods to detect HOCl in living systems, preferably with molecules that can show a distinct therapeutic effect. Our study introduces the synthesis and application of a highly sensitive fluorescence "turn-on" probe, Myco-OCl, based on the mycophenolic acid scaffold with exceptional water solubility. The ESIPT-driven mechanism enables Myco-OCl to specifically and rapidly detect (<5 s) HOCl with an impressive Stokes shift of 105 nm (λex = 417 nm, λem = 522 nm) and a sub-nanomolar (97.3 nM) detection limit with the detection range of 0 to 50 μM. The potential of Myco-OCl as an excellent biosensor is evident from its successful application for live cell imaging of exogenous and endogenous HOCl. In addition, Myco-OCl enabled us to detect HOCl in a zebrafish inflammatory animal model. These underscore the great potential of Myco-OCl for detecting HOCl in diverse physiological systems. Our findings thus offer a highly promising tool for detecting HOCl in living organisms.

"Lighting up" fluoride: cellular imaging and zebrafish model interrogations using a simple ESIPT-based mycophenolic acid precursor-based probe

The discovery and implementation of media that derive from bioinspired designs and bear optical readouts featuring large Stokes shifts are of continued interest to a wide variety of researchers and clinicians. Myco-F, a novel mycophenolic acid precursor-based probe features a cleavable tert-butyldimethylsiloxy group to allow for fluoride detection. Myco-F exhibits high selectivity and specificity towards F^- (Stokes shift = 120 nm). All measurements were performed in complete aqueous media (LOD=0.38 μM). Myco-F enables detection of fluoride ions in living HEK293 cells and localizes in the eye region (among other regions) of the zebrafish. DFT calculations support the proposed ESIPT working photomechanism.

Theoretical model study of adsorbed antimalarial-graphene dimers: doping effects, photophysical parameters, intermolecular interactions, edge adsorption, and SERS

Future diagnostics and therapy applications are in part riding on the discovery and implementation of new optical techniques and strategies (which often derive from dyads) for example, prediction of features in surface-enhanced Raman spectroscopy requires the study of chromophore-chromophore interactions involve intermolecular forces, drug delivery, and photo mechanisms which are of great interest. New matches between chromophore systems (i.e. FRET), and π-delocalized surfaces are important to study. We explore low-molecular weight drug molecules and their interaction with the reporter material/surface of graphene. Bonding, charge transfer and orbital interactions for 2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole (megazol or AMIT) on graphene were carried out. The graphene model substrate was monotonically/monatomically substituted (doped) with one neutral heteroatom (N/O/S/B) in place of one carbon center; chemical adsorption of AMIT is due to charge transfer from doped graphene to AMIT (DFT). Our AMIT-nanocluster studies show that the nanoclusters will act as a sensor component for the detection of drugs due to SERS. Our findings identified that the greater the energy of the charge transfer, the stronger the calculated chemical adsorption. Additionally, charge transfer is highest for the N-doped systems and least for pristine graphene, resulting in a stronger adsorption energy for N-doped graphene. Mulliken charge analysis of structures confirms enhancement found in QD-AMIT systems.Communicated by Ramaswamy H. Sarma.

A foundational theoreticalAl12E12(E = N, P) adsorption and quinolone docking study: cage–quinolone pairs, optics and possible therapeutic and diagnostic applications

This combined Al₁₂E₁₂ (E = N, P) surface adsorption and docking study describes the new possibility of prospective potential probing(photophysical/optical) and therapy(medicinal/biochemical) with these adsorbent conjugates. DFT investigations were undertaken herein to help generate geometrical models and better understand the possible favorable adsorption energetics. We attempt to explain their adsorption behaviors and docking involving SARS-CoV-2 viruses (PDB)to assess their possible pharmaceutical potential against the pandemic virus (COVID-19). The adsorption behavior of 8-hydroxy-2-methylquinoline (MQ) and its halogenated derivatives, 5,7-diiodo-8-hydroxy-2-methylquinoline (MQI), 5,7-dichloro-8-hydroxy-2-methylquinoline (MQCl), and 5,7-dibromo-8-hydroxy-2-methylquinoline (MQBr), with aluminum-nitrogen (AlN), and aluminum-phosphorous (AlP) fullerene-like nanocages is reported. A decrease in the hardness of the nanoclusters when adsorbed with drug molecules resulted in an incrementally improved chemical softness (see e.g., Hard-Soft Acid Base theory) indicating that reactivity of the drug molecule in the resulting complex increases upon cluster chemical adsorption. The energy gap is found to be maximized for AlN-MQ and minimized for AlP-MQI; the reduced density gradient (RDG) iso-surfaces and AIM studies also corroborated this. Therefore, these two were found, respectively, to be the least and most electrically conductive of the species under study. We selected a simple medicinal building block (chelator)in addition to selecting the cluster based on previous literature reports. Important parameters such as gap energies and global indices were determined. We assessed NLO properties. The SARS-CoV-2 virus PDB docking data for 6VW1, 6VYO, 6WKQ, 7AD1, 7AOL, 7B3C, were enlisted as ligand targets for studies of docking (PatchDock Server) using the requisite PDB geometries (For the structure of 6VW1, kindly see reference, 2020; For the structure of 6VYO kindly see reference, 2020; For the structure of 6WKQ kindly see reference, 2020; For the structure of 7AD1 kindly see reference, 2021; For the structure of 7AOL kindly see reference, 2021; For the structure of 7B3C kindly see reference, 2021). Such findings indicate that the AlN-drug conjugation have inhibitory effect against these selected receptors.Communicated by Ramaswamy H. Sarma.

Phosphinate-benzoindocyanin fluorescent probe for endogenous mitochondrial peroxynitrite detection in living cells and gallbladder access in inflammatory zebrafish animal models

Potent oxidants such as peroxynitrite (ONOO^-) play important roles in the regulation of different physiopathological processes; their overproduction is thought to potentially cause several diseases in living organisms. Hence, the precise and selective monitoring of ONOO^- is imperative for elucidating its interplay and roles in pathological and physiological processes. Herein, we present a novel diphenyl phosphinate-masked benzoindocyanin "turn-on" fluorogenic probe to help detect mitochondrial ONOO^- in living cells and zebrafish models. A pale yellow color solution of BICBzDP turns rose-red upon the addition of ONOO^-_, selectively, contrary to that of other competitive bioactive molecules. BICBzDP displays an ultra-sensitivity detection limit (47.8 nM) with outstanding selectivity and sensitivity towards mitochondrial ONOO^- and possesses a notable 68-fold fluorescence enhancement involving a large redshift of 91 nm. Importantly, further biological experimental investigations with BICBzDP indicate specific sensitivity and reliability of the probe to track the ONOO^- level, not only in live cells, but also demonstrates dynamic fluctuations in the inflammatory zebrafish animal models. Thus, BICBzDP could be employed as a future potential biological tool for exploiting the role of ONOO^- in a variety of different physiological systems.

Bisphenol-based cyanide sensing: Selectivity, reversibility, facile synthesis, bilateral "OFF-ON" fluorescence, C2ν structural and conformational analysis

A structurally characterized novel dual-pocketed tetra-conjugated bisphenol-based chromophore (fluorescence = 652 nm) was synthesized in gram scale in ~90% yield from its tetraaldehyde. Highly selective, naked-eye detection of CN^- (DMSO/H₂O) was confirmed by interferent testing. A detection limit of 0.38 µM, within the permissible limit of CN^- concentration in drinking water was achieved as mandated by WHO. The "reversibility" study shows potential applicability and reusability of Sen. Moreover, cost-effective and on-site interfaces, application tools such as fabricated cotton swabs, plastic Petri dishes, and filter papers further demonstrated the specific selectivity of Sen for the toxic CN^-. In addition, an easily available and handy smartphone-assisted "Color Picker" app was utilized to help estimate the concentration of CN^- ion present. A dual phenol deprotonation mechanism is active and supported by ¹H NMR spectroscopic data and DFT calculation results.

Discussions of Fluorescence in Selenium Chemistry: Recently Reported Probes, Particles, and a Clearer Biological Knowledge

In this review from literature appearing over about the past 5 years, we focus on selected selenide reports and related chemistry; we aimed for a digestible, relevant, review intended to be usefully interconnected within the realm of fluorescence and selenium chemistry. Tellurium is mentioned where relevant. Topics include selenium in physics and surfaces, nanoscience, sensing and fluorescence, quantum dots and nanoparticles, Au and oxide nanoparticles quantum dot based, coatings and catalyst poisons, thin film, and aspects of solar energy conversion. Chemosensing is covered, whether small molecule or nanoparticle based, relating to metal ion analytes, H2S, as well as analyte sulfane (biothiols-including glutathione). We cover recent reports of probing and fluorescence when they deal with redox biology aspects. Selenium in therapeutics, medicinal chemistry and skeleton cores is covered. Selenium serves as a constituent for some small molecule sensors and probes. Typically, the selenium is part of the reactive, or active site of the probe; in other cases, it is featured as the analyte, either as a reduced or oxidized form of selenium. Free radicals and ROS are also mentioned; aggregation strategies are treated in some places. Also, the relationship between reduced selenium and oxidized selenium is developed.