Given its pivotal role in modulating various pathological processes, precise measurement of nitric oxide (●NO) levels in physiological solutions is imperative. The key techniques include the ...ozone-based chemiluminescence (CL) reactions, amperometric ●NO sensing, and Griess assay, each with its advantages and drawbacks. In this study, a hemin/H2O2/luminol CL reaction was employed for accurately detecting ●NO in diverse solutions. We investigated how the luminescence kinetics was influenced by ●NO from two donors, nitrite and peroxynitrite, while also assessing the impact of culture medium components and reactive species quenchers. Furthermore, we experimentally and theoretically explored the mechanism of hemin oxidation responsible for the initiation of light generation. Although both hemin and ●NO enhanced the H2O2/luminol-based luminescence reactions with distinct kinetics, hemin’s interference with ●NO/peroxynitrite– modulated their individual effects. Leveraging the propagated signal due to hemin, the ●NO levels in solution were estimated, observing parallel changes to those detected via amperometric detection in response to varying concentrations of the ●NO-donor. The examined reactions aid in comprehending the mechanism of ●NO/hemin/H2O2/luminol interactions and how these can be used for detecting ●NO in solution with minimal sample size demands. Moreover, the selectivity across different solutions can be improved by incorporating certain quenchers for reactive species into the reaction.
Nitric oxide (•NO) is one of the prominent free radicals, playing a pivotal role in breast cancer progression. Hyaluronic acid (HA) plays an essential role in neutralizing free radicals in tumor ...tissues. However, its interactions with nitric oxide have not been thoroughly investigated. Hence, this study attempts to understand the mechanism of these interactions and the different effects on the intracellular •NO levels and migration of breast cancer cells. The affinity of HA to scavenge •NO was investigated alongside the accompanying changes in specific physico-chemical properties and the further effects on the •NO-induced attachment and migration of the breast cancer cell lines, MDA-MB-231 and HCC1806. The reaction of the nitrogen dioxide radical, formed via •NO/O2 interactions, with HA initiated a series of oxidative reactions, which, in the presence of •NO, induce the fragmentation of the polymeric chains. Furthermore, these interactions were found to hinder the NO-induced migration of cancer cells. However, the NO-induced HA modification/fragmentation was inhibited in the presence of hemin, a NO-scavenging compound. Collectively, these results help toward understanding the involvement of HA in the •NO-induced cell migration and suggest the possible modification of HA, used as one of the main materials in different biomedical applications.
Decarbonisation of the economy has become a priority at the global level, and the resulting legislative pressure is pushing the chemical and energy industries away from fossil fuels. Microbial ...electrosynthesis (MES) has emerged as a promising technology to promote this transition, which will further benefit from the decreasing cost of renewable energy. However, several technological challenges need to be addressed before the MES technology can reach its maturity. The aim of this review is to critically discuss the bottlenecks hampering the industrial adoption of MES, considering the whole production process (from the CO2 source to the marketable products), and indicate future directions. A flexible stack design, with flat or tubular MES modules and direct CO2 supply, is required for site-specific decentralised applications. The experience gained for scaling-up electrochemical cells (e.g. electrolysers) can serve as a guideline for realising pilot MES stacks to be technologically and economically evaluated in industrially relevant conditions. Maximising CO2 abatement rate by targeting high-rate production of acetate can promote adoption of MES technology in the short term. However, the development of a replicable and robust strategy for production and in-line extraction of higher-value products (e.g. caproic acid and hexanol) at the cathode, and meaningful exploitation of the currently overlooked anodic reactions, can further boost MES cost-effectiveness. Furthermore, the use of energy storage and smart electronics can alleviate the fluctuations of renewable energy supply. Despite the unresolved challenges, the flexible MES technology can be applied to decarbonise flue gas from different sources, to upgrade industrial and wastewater treatment plants, and to produce a wide array of green and sustainable chemicals. The combination of these benefits can support the industrial adoption of MES over competing technologies.
•MES is a resilient technology for recycling CO2 into various marketable products•Increase production rates and minimise costs and footprint are required for scaling-up MES•MES can upgrade existing treatment plants to comply with future legislation on CO2 emissions•In-line product extraction is cost-effective and avoids product inhibition•Membranes with selectivity and anti-fouling properties will reduce extraction costs•Renewable energy sources pave the ground towards sustainable MES
With photovoltaics becoming a mature, commercially feasible technology, society is willing to allocate resources for developing and deploying new technologies based on using solar light. Analysis of ...projects supported by the European Commission in the past decade indicates exponential growth of funding to photocatalytic (PC) and photoelectrocatalytic (PEC) technologies that aim either at technology readiness levels (TRLs) TRL 1–3 or TRL > 3, with more than 75 Mio€ allocated from the year 2019 onward. This review provides a summary of PC and PEC processes for the synthesis of bulk commodities such as solvents and fuels, as well as chemicals for niche applications. An overview of photoreactors for photocatalysis on a larger scale is provided. The review rounds off with the summary of reactions performed at lab scale under natural outdoor solar light to illustrate conceptual opportunities offered by solar-driven chemistry beyond the reduction of CO2 and water splitting. The authors offer their vision of the impact of this area of research on society and the economy.
Sandwiched: The cobaltabisdicarbollide (mono‐)anion (3,3′‐Co(1,2‐C2B9H11)2−, COSAN−) forms monolayer vesicles at low concentrations in water (see picture). An increase in concentration leads to a ...Coulomb explosion of the closely packed vesicles into small micelles, which results in the coexistence of both aggregation states at higher concentrations.
The alkyne azide “click” reaction was successfully used to prepare new Bodipy-functionalized triazoles and triazolium salts. The Bodipy functionality was compatible with cyclometalation conditions as ...well as with transmetalation procedures involving a triazolyldene silver intermediate, as demonstrated by the successful formation of a metallacyclic palladium dimer and an iridium chelate. Both complexes were characterized by X-ray diffraction, and spectroscopic studies demonstrate unperturbed photoluminescence of the Bodipy chromophore (emission around 545 nm, quantum yields in the 0.35–0.7 range, and excited-state lifetimes between 3 and 7 ns). The palladium dimer 4 was cleaved using N,N-dimethylaminopyridine (dmap) and acridine to afford monomeric triazolylidene palladium complexes 5 and 6. While dmap is a classical spectator ligand, acridine acts as photoluminescence quencher and quenching constants were determined as K SV = 0.86 and 1.6 × 104 M–1 for complexes 4 and 5, respectively. This dual reactivity of acridine as ligand and quencher was utilized for a ligand displacement assay that allowed modification of the organometallic site of the hybrid complex to be monitored by emission spectroscopy.
Graphitic carbon nitride (g‐CN) is a transition metal free semiconductor that mediates a variety of photocatalytic reactions. Although photoinduced electron transfer is often postulated in the ...mechanism, proton‐coupled electron transfer (PCET) is a more favorable pathway for substrates possessing X−H bonds. Upon excitation of an (sp2)N‐rich structure of g‐CN with visible light, it behaves as a photobase—it undergoes reductive quenching accompanied by ion of a proton from a substrate. The results of modeling allowed us to identify active sites for PCET—the ‘triangular pockets’ on the edge facets of g‐CN. We employ excited state PCET from the substrate to g‐CN to selectively cleavethe endo‐(sp3)C−H bond in oxazolidine‐2‐ones followed by trapping the radical with O2. This reaction affords 1,3‐oxazolidine‐2,4‐diones. Measurement of the apparent pKa value and modeling suggest that g‐CN excited state can cleave X−H bonds that are characterized by bond dissociation free energy (BDFE) ≈100 kcal mol−1.
Transformation of oxazolidinones to corresponding oxazolidine‐2,4‐diones is enabled by mpg‐CN, a carbon nitride photocatalyst, using oxygen gas as an oxidant. The reaction proceeds via proton‐coupled electron transfer. The mechanism of this transformation is established by photocatalytic experiments, transient absorption spectroscopy and DFT calculations.
Multiplex optical detection in live cells is challenging due to overlapping signals and poor signal‐to‐noise associated with some chemical reporters. To address this, the application of spectral ...phasor analysis to stimulated Raman scattering (SRS) microscopy for unmixing three bioorthogonal Raman probes within cells is reported. Triplex detection of a metallacarborane using the B−H stretch at 2480–2650 cm−1, together with a bis‐alkyne and deuterated fatty acid can be achieved within the cell‐silent region of the Raman spectrum. When coupled to imaging in the high‐wavenumber region of the cellular Raman spectrum, nine discrete regions of interest can be spectrally unmixed from the hyperspectral SRS dataset, demonstrating a new capability in the toolkit of multiplexed Raman imaging of live cells.
Hyperspectral stimulated Raman scattering (SRS) microscopy with spectral phasor analysis enables the multiplex detection of bioorthogonal Raman groups in cells. Unmixing of the overlapping alkyne and deuterium signals together with the detection of metallacarboranes is reported within the cell‐silent region of the Raman spectrum.
The enhanced expression of nitric oxide (•NO) synthase predicts triple-negative breast cancer outcome and its resistance to different therapeutics. Our earlier work demonstrated the efficiency of ...hemin to scavenge the intra- and extracellular •NO, proposing its potency as a therapeutic agent for inhibiting cancer cell migration. In continuation, the present work evaluates the effects of •NO on the migration of MDA-MB-231 cells and how hemin modulates the accompanied cellular behavior, focusing on the corresponding expression of cellular glycoproteins, migration-associated markers, and mitochondrial functions. We demonstrated for the first time that while •NO induced cell migration, hemin contradicted that by •NO-scavenging. This was in combination with modulation of the •NO-enhanced glycosylation patterns of cellular proteins with inhibition of the expression of specific proteins involved in the epithelial–mesenchymal transition. These effects were in conjunction with changes in the mitochondrial functions related to both •NO, hemin, and its nitrosylated product. Together, these results suggest that hemin can be employed as a potential anti-migrating agent targeting •NO-scavenging and regulating the expression of migration-associated proteins.
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