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Magnetotactic bacteria (MTB) are ubiquitous aquatic microorganisms that mineralize dissolved iron into intracellular magnetic crystals. After cell death, these crystals are trapped into sediments that remove iron from the soluble pool. MTB may significantly impact the iron biogeochemical cycle, especially in the ocean where dissolved iron limits nitrogen fixation and primary productivity. A thorough assessment of their impact has been hampered by a lack of methodology to measure the amount of, and variability in, their intracellular iron content. We quantified the iron mass contained in single MTB cells of Magnetospirillum magneticum strain AMB-1 using a time-resolved inductively coupled plasma-mass spectrometry methodology. Bacterial iron content depends on the external iron concentration, and reaches a maximum value of ~10-6 ng of iron per cell. From these results, we calculated the flux of dissolved iron incorporation into environmental MTB populations and conclude that MTB may mineralize a significant fraction of dissolved iron into crystals.

In this study, mono-, bi-, and tri-metallic engineered nanoparticles (ENPs) are first analysed using an ICP-ToF-MS in single particle mode. The method is also used to characterize natural NPs (NNPs) (i.e. oxide and clay minerals). We provide here the elemental composition and mass distribution of these different NPs. For the first-time using spICP-ToF-MS, the presence of Ti- and Si-NPs as well as that of a second population with a distinct Si–Al ratio is highlighted in kaolinite. Finally, for mixtures of the different original NPs, an automated post-processing approach based on hierarchical agglomerative clustering (HAC) is applied. The elemental signature of the different clusters is in agreement with the results of previous characterizations. This illustrates the applicability of coupling spICP-ToF-MS with HAC to determine elemental fingerprints of NPs and to differentiate one from the other when mixed. The described methodology could be a starting point to simplify the analysis and make reliable interpretations of unknown NP populations and thereby more accurately understand NP populations in natural systems. However, as illustrated, thorough evaluation of the data must be performed in order to avoid misclassification of the NPs in future studies. [ABSTRACT FROM AUTHOR]

Capitalising on the previous identification of a distyryl coordinated Ru(II) polypyridine complex as a promising photosensitizer for photodynamic therapy, eight new complexes were synthesized by modifications of the ligands or by changing the metal coordinated. We report in this work the effects of these modifications on the physical, spectroscopic, and biological properties of the synthesized complexes. Subtle structural modifications of the distyryl ligand only had a moderate effect on the corresponding complexes' visible light absorption and singlet oxygen quantum yield. These modifications however had a significant effect on the lipophilicity, the cellular uptake and the phototoxicity of the complexes. Although the lipophilicity of the complexes had a somewhat expected effect on their cellular uptake, this last parameter could not be directly correlated to their phototoxicity, revealing other underlying phenomena. Overall, this work allowed identification of two promising ruthenium complexes as photosensitisers for photodynamic therapy and provides some guidance on how to design better photosensitizers. [ABSTRACT FROM AUTHOR]

PtII complexes are commonly used to treat cancer. To reduce their side effects and improve their pharmacological properties, PtIV complexes are being developed as prodrug candidates that are activated by reduction in cancer cells. Concomitantly, RuII polypyridine complexes have gained much attention as photosensitizers for use in photodynamic therapy due to their attractive characteristics. In this article, a novel PtIV–RuII conjugate, which combines cancer activated chemotherapy with PDT, is presented. Upon entering the cancer cell, the PtIV centre is reduced to PtII and the axial ligands including the RuII complex and phenylbutyrate are released. As each component has its individual targets, the conjugate exerts a multi‐target and multi‐action effect with (photo‐)cytotoxicity values upon irradiation up to 595 nm in the low nanomolar range in various (drug resistant) 2D monolayer cancer cells and 3D multicellular tumour spheroids. [ABSTRACT FROM AUTHOR]

Cancer is one of the main causes of death worldwide. Chemotherapy, despite its severe side effects, is to date one of the leading strategies against cancer. Metal‐based drugs present several potential advantages when compared to organic compounds and they have gained trust from the scientific community after the approval on the market of the drug cisplatin. Recently, we reported the ruthenium complex ([Ru(DIP)2(sq)](PF6) (where DIP is 4,7‐diphenyl‐1,10‐phenantroline and sq is semiquinonate) with a remarkable potential as chemotherapeutic agent against cancer, both in vitro and in vivo. In this work, we analyse a structurally similar compound, namely [Ru(DIP)2(mal)](PF6), carrying the flavour‐enhancing agent approved by the FDA, maltol (mal). To possess an FDA approved ligand is crucial for a complex, whose mechanism of action might include ligand exchange. Herein, we describe the synthesis and characterisation of [Ru(DIP)2(mal)](PF6), its stability in solutions and under conditions that resemble the physiological ones, and its in‐depth biological investigation. Cytotoxicity tests on different cell lines in 2D model and on HeLa MultiCellular Tumour Spheroids (MCTS) demonstrated that our compound has higher activity than cisplatin, inspiring further tests. [Ru(DIP)2(mal)](PF6) was efficiently internalised by HeLa cells through a passive transport mechanism and severely affected the mitochondrial metabolism. [ABSTRACT FROM AUTHOR]

The μ-dDIHEN allows direct nebulization of small samples into the plasma at a flow rate down to 5 μL min−1. It is composed of a demountable direct injection high efficiency nebulizer (d-DIHEN), a flow injection analysis (FIA) valve and a gas displacement pump (GDP) connected to a μ-mass-flow meter delivering very stable liquid flow. The system was successfully tested with sample loops of 10 and 50 μL and for liquid flow rates between 5 and 50 μL min−1 on two different inductively coupled plasma mass spectrometry (ICP-MS) instruments, a sector-field-ICP-MS (SF-ICP-MS) and a multi-collector-ICP-MS (MC-ICP-MS), and for three different applications: boron isotopic ratio measurement of geological samples, multi-element analyses of natural water samples and gold nanoparticle characterization by single particle ICPMS (spICP-MS). Signal sensitivity was increasing with the liquid uptake rate of the μ-dDIHEN (and the GDP gas flow rate), but stopped increasing above 30 μL min−1, due to bad spray quality and poor ionization under extra-wet conditions. We successfully measured boron isotopic ratios (δ11B) for reference material solutions with B concentrations between 10 and 200 μg L−1; the reproducibility of the measurements depending on both the B concentration of the sample and the uptake rate: 10B signals below 20–30 mV (with 1011 ohms amplifiers) gave 2SD reproducibility ≥0.5‰ (n = 5). The best measurement conditions were not necessarily with the lowest uptake rate but rather at 25 μL min−1, allowing for higher signals. We also tested transient versus continuous measurement modes for a series of natural samples (with 10 and 50 μL sample loops). The two modes gave fully comparable results but the transient mode allows triplicate δ11B measurements and is recommended for very small samples (≤100 μL and B content of a few ng). For multi-element analyses by SF-ICP-MS, the limits of quantification (LOQs) of the majority of the trace and ultra-trace elements were lower (up to 15 times) with the μ-dDIHEN than with a concentric nebulizer and spray chamber, due to the much lower sample volume needed. Lastly, the μ-dDIHEN is highly promising for nanoparticle (NP) characterization by spICPMS. The first measurements for gold NPs of 40 nm certified size led to a transport efficiency of 85%. [ABSTRACT FROM AUTHOR]

High Ca concentrations in complex matrices such as river waters often hamper the detection of titanium nanomaterials (TiO2 NPs) by single particle inductively coupled plasma mass spectrometry (spICPMS), because of isobaric interference of 48Ca on the most abundant Ti isotope (48Ti). Several approaches were used to reduce this interference while measuring TiO2 in solutions with different Ca concentrations up to 100 mg L−1. ICP-MS/MS was used with ammonia as the reaction cell gas and high resolution (HR) ICP-MS was used under different resolution settings. These approaches were compared by measuring different Ti isotopes (47Ti and 49Ti). spICPMS data were then treated with a deconvolution method to filter out dissolved signals and identify the best approach to detect the lowest possible corresponding spherical size of TiO2 NPs (Dmin). ICP-MS/MS allowed for an important decrease of the theoretical Dmin compared to standard quadrupole ICP-MS, down to 64 nm in ultrapure water; however the sensitivity was reduced by the reaction gas and increasing Ca concentrations also increased the Dmin. The comparably higher sensitivity of HR-ICP-MS allowed for theoretically measuring a Dmin of 10 nm in ultrapure water. Combined with the deconvolution analysis, the highest resolution mode in HR-ICP-MS leads to the lowest Dmin at high Ca concentrations, even though significant broadening of the measured mass distributions occurred for TiO2 NPs at Ca concentrations up to 100 mg L−1. [ABSTRACT FROM AUTHOR]

Core-shell nanogels are attractive stabilizers and supports for catalytically active metallic nanoparticles. Herein, we present the synthesis and the characterization of a nanostructured well-defined core-shell nanogel with the ability to stabilize Pd0 nanoparticles in its core. This hybrid nanogel displays a remarkable stability in both the solid state and in solution. This feature allowed its successful application as a catalyst for the Mizoroki-Heck reaction between n-butyl acrylate and a series of bromo- and iodoarenes. The yields spanned from good to excellent, and catalyst recycling could be achieved up to three times without a significant activity loss. Three-phase tests indicated that the hybrid nanogel acts as a Pd0 nanoreservoir. The catalysis proceeds in a quasihomogeneous fashion as part of the catalytic activity occurs outside the nanogel, which explains the observed limited recyclability. [ABSTRACT FROM AUTHOR]

Copyright of Geostandards & Geoanalytical Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geostandards & Geoanalytical Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Maleimide-containing prodrugs can quickly and selectively react with circulating serum albumin following their injection in the bloodstream. The drug-albumin complex then benefits from longer blood circulation times and better tumor accumulation. Herein, we have applied this strategy to a previously reported highly phototoxic Ru polypyridyl complex-based photosensitizer to increase its accumulation at the tumor, reduce off-target cytotoxicity, and therefore improve its pharmacological profile. Specifically, two complexes were synthesized bearing a maleimide group: one complex with the maleimide directly incorporated into the bipyridyl ligand, and the other has a hydrophilic linker between the ligand and the maleimide group. Their interaction with albumin was studied in-depth, revealing their ability to efficiently bind both covalently and noncovalently to the plasma protein. A crucial finding is that the maleimide-functionalized complexes exhibited significantly lower cytotoxicity in noncancerous cells under dark conditions compared to the nonfunctionalized complex, which is a highly desirable property for a photosensitizer. The binding to albumin also led to a decrease in the phototoxicity of the Ru bioconjugates in comparison to the nonfunctionalized complex, probably due to a decreased cellular uptake. Unfortunately, this decrease in phototoxicity was not compensated by a dramatic increase in tumor accumulation, as was demonstrated in a tumor-bearing mouse model using inductively coupled plasma mass spectrometry (ICP-MS) studies. Consequently, this study provides valuable insight into the future design of in situ albumin-binding complexes for photodynamic therapy in order to maximize their effectiveness and realize their full potential.

The currently used photodynamic therapy (PDT) photosensitizers (PSs) are generally associated with a poor cancer cell selectivity, which is responsible for some undesirable side effects. To overcome these problems, there is an urgent need for a selective drug delivery system for PDT PSs. Herein, the encapsulation of a promising Ru(II) polypyridine complex in a polymer with terminal folate groups to form nanoparticles is presented. While the Ru(II) complex itself has a cytotoxic effect in the dark, the encapsulation is able to overcome this drawback. Upon light exposure, the nanoparticles were found to be highly phototoxic in 2D monolayer cells as well as 3D multicellular tumor spheroids upon 480 or 595 nm irradiation. Importantly, the nanoparticles demonstrated a high selectivity for cancerous cells over noncancerous cells and were found to be active in drug resistant cancer cells lines, indicating that they are able to overcome drug resistances.

Chemotherapy remains one of the dominant treatments to cure cancer. However, due to the many inherent drawbacks, there is a search for new chemotherapeutic drugs. Many classes of compounds have been investigated over the years to discover new targets and synergistic mechanisms of action including multicellular targets. In this work, we designed a new chemotherapeutic drug candidate against cancer, namely, [Ru(DIP) 2 (sq)](PF 6 ) ( Ru-sq ) (DIP = 4,7-diphenyl-1,10-phenanthroline; sq = semiquinonate ligand). The aim was to combine the great potential expressed by Ru(II) polypyridyl complexes and the singular redox and biological properties associated with the catecholate moiety. Experimental evidence ( e.g ., X-ray crystallography, electron paramagnetic resonance, electrochemistry) demonstrates that the semiquinonate is the preferred oxidation state of the dioxo ligand in this complex. The biological activity of Ru-sq was then scrutinized in vitro and in vivo , and the results highlight the promising potential of this complex as a chemotherapeutic agent against cancer.

The utilization of photodynamic therapy (PDT) for the treatment of various types of cancer has gained increasing attention over the last decades. Despite the clinical success of approved photosensitizers (PSs), their application is sometimes limited due to poor water solubility, aggregation, photodegradation, and slow clearance from the body. To overcome these drawbacks, research efforts are devoted toward the development of metal complexes and especially Ru(II) polypyridine complexes based on their attractive photophysical and biological properties. Despite the recent research developments, the vast majority of complexes utilize blue or UV-A light to obtain a PDT effect, limiting the penetration depth inside tissues and, therefore, the possibility to treat deep-seated or large tumors. To circumvent these drawbacks, we present the first example of a DFT guided search for efficient PDT PSs with a substantial spectral red shift toward the biological spectral window. Thanks to this design, we have unveiled a Ru(II) polypyridine complex that causes phototoxicity in the very low micromolar to nanomolar range at clinically relevant 595 nm, in monolayer cells as well as in 3D multicellular tumor spheroids.

Four novel monocationic Ru(II) polypyridyl complexes were synthesized with the general formula [Ru(DIP) 2 flv]X, where DIP is 4,7-diphenyl-1,10-phenanthroline, flv stands for the flavonoid ligand (5-hydroxyflavone in [Ru(DIP) 2 (5-OHF)](PF 6 ), genistein in [Ru(DIP) 2 (gen)](PF 6 ), chrysin in [Ru(DIP) 2 (chr)](OTf), and morin in [Ru(DIP) 2 (mor)](OTf)), and X is the counterion, PF 6 - , and OTf ̅ (triflate, CF 3 SO 3 ̅), respectively. Following the chemical characterization of the complexes by 1 H and 13 C NMR, mass spectrometry, and elemental analysis, their cytotoxicity was tested against several cancer cell lines. The most promising complex, [Ru(DIP) 2 (gen)](PF 6 ), was further investigated for its biological activity. Metabolic studies revealed that this complex severely impaired mitochondrial respiration and glycolysis processes, contrary to its precursor, Ru(DIP) 2 Cl 2 , which showed a prominent effect only on the mitochondrial respiration. In addition, its preferential accumulation in MDA-MB-435S cells (a human melanoma cell line previously described as mammary gland/breast; derived from metastatic site: pleural effusion), which are used for the study of metastasis, explained the better activity in this cell line compared to MCF-7 (human, ductal carcinoma).

Due to the great potential expressed by an anticancer drug candidate previously reported by our group, namely, Ru-sq ([Ru(DIP) 2 (sq)](PF 6 ) (DIP, 4,7-diphenyl-1,10-phenanthroline; sq, semiquinonate ligand), we describe in this work a structure-activity relationship (SAR) study that involves a broader range of derivatives resulting from the coordination of different catecholate-type dioxo ligands to the same Ru(DIP) 2 core. In more detail, we chose catechols carrying either an electron-donating group (EDG) or an electron-withdrawing group (EWG) and investigated the physicochemical and biological properties of their complexes. Several pieces of experimental evidences demonstrated that the coordination of catechols bearing EDGs led to deep-red positively charged complexes 1 - 4 in which the preferred oxidation state of the dioxo ligand is the uninegatively charged semiquinonate. Complexes 5 and 6 , on the other hand, are blue/violet neutral complexes, which carry an EWG-substituted dinegatively charged catecholate ligand. The biological investigation of complexes 1 - 6 led to the conclusion that the difference in their physicochemical properties has a strong impact on their biological activity. Thus, complexes 1 - 4 expressed much higher cytotoxicities than complexes 5 and 6 . Complex 1 constitutes the most promising compound in the series and was selected for a more in depth biological investigation. Apart from its remarkably high cytotoxicity (IC 50 = 0.07-0.7 μM in different cancerous cell lines), complex 1 was taken up by HeLa cells very efficiently by a passive transportation mechanism. Moreover, its moderate accumulation in several cellular compartments (i.e., nucleus, lysosomes, mitochondria, and cytoplasm) is extremely advantageous in the search for a potential drug with multiple modes of action. Further DNA metalation and metabolic studies pointed to the direct interaction of complex 1 with DNA and to the severe impairment of the mitochondrial function. Multiple targets, together with its outstanding cytotoxicity, make complex 1 a valuable candidate in the field of chemotherapy research. It is noteworthy that a preliminary biodistribution study on healthy mice demonstrated the suitability of complex 1 for further in vivo studies.