Expanding Mn2+ loading capacity of BSA via mild non-thermal denaturing and cross-linking as a tool to maximize the relaxivity of water protons.

Development of nanoparticles (NPs) serving as contrast enhancing agents in MRI requires a combination of high contrasting effect with the biosafety and hemocompatibility. This work demonstrates that bovine serum albumin (BSA) molecules bound to paramagnetic Mn2+ ions are promising building blocks of such NPs. The desolvation-induced denaturation of BSA bound with Mn2+ ions followed by the glutaraldehyde-facilitated cross-linking provides the uniform in size 102.0 ± 0.7 nm BSA-based nanoparticles (BSA-NPs) loaded with Mn2+ ions, which are manifested in aqueous solutions as negatively charged spheres with high colloid stability. The optimal loading of Mn2+ ions into BSA-NPs provides maximum values of longitudinal and transverse relaxivity at 98.9 and 133.6 mM-1 s-1, respectively, which are among the best known from the literature. The spin trap EPR method indicates that Mn2+ ions bound to BSA-NPs exhibit poor catalytic activity in the Fenton-like reaction. On the contrary, the presence of BSA-NPs has an antioxidant effect by preventing the accumulation of hydroxyl radicals produced by H2O2. The NPs exhibit remarkably low hemolytic activity and hemagglutination can be avoided at concentrations lower than 110 µM. Thus, BSA-NPs bound with Mn2+ ions are promising candidates for combining high contrast effect with biosafety and hemocompatibility.

ROS-producing nanomaterial engineered from Cu(I) complexes with P2N2-ligands for cancer cells treating.

The work presents core-shell nanoparticles (NPs) built from the novel Cu(I) complexes with cyclic P2N2-ligands (1,5-diaza-3,7-diphosphacyclooctanes) that can visualize their entry into cancer and normal cells using a luminescent signal and treat cells by self-enhancing generation of reactive oxygen species (ROS). Variation of P- and N-substituents in the series of P2N2-ligands allows structure optimization of the Cu(I) complexes for the formation of the luminescent NPs with high chemical stability. The non-covalent modification of the NPs with triblock copolymer F-127 provides their high colloidal stability, followed by efficient cell internalization of the NPs visualized by their blue (⁓450 nm) luminescence. The cytotoxic effects of the NPs toward the normal and some of cancer cells are significantly lower than those of the corresponding molecular complexes, which correlates with the chemical stability of the NPs in the solutions. The ability of the NPs to self-enhanced and H2O2-induced ROS generation is demonstrated in solutions and intracellular space by means of the standard electron spin resonance (ESR) and fluorescence techniques correspondingly. The anticancer specificity of the NPs toward HuTu 80 cancer cells and the apoptotic cell death pathway correlate with the intracellular level of ROS, which agrees well with the self-enhancing ROS generation of the NPs. The enhanced level of ROS revealed in HuTu 80 cells incubated with the NPs can be associated with the significant level of their mitochondrial localization.

Carbonized Nickel Complex of Sodium Pectate as Catalyst for Proton-Exchange Membrane Fuel Cells.

Sodium pectate derivatives with 25% replacement of sodium ions with nickel ions were obtained by carbonization to temperatures of 280, 550, and 800 °C, under special protocols in an inert atmosphere by carbonization to temperatures of 280, 550, and 800 °C. The 25% substitution is the upper limit of substitution of sodium for nickel ions, above which the complexes are no longer soluble in water. It was established that the sample carburized to 550 °C is the most effective active element in the hydrogen-oxidation reaction, while the sample carbonized up to 800 °C was the most effective in the oxygen-reduction reaction. The poor performance of the catalytic system involving the pectin coordination biopolymer carbonized up to 280 °C was due to loss of proton conductivity caused by water removal and mainly by two-electron transfer in one catalytic cycle of the oxygen-reduction reaction. The improved performance of the system with coordination biopolymer carbonized up to 550 °C was due to the better access of gases to the catalytic sites and four-electron transfer in one catalytic cycle. The (Ni-NaPG)800C sample contains metallic nickel nanoparticles and loose carbon, which enhances the electrical conductivity and gas capacity of the catalytic system. In addition, almost four-electron transfer is observed in one catalytic cycle of the oxygen-reduction reaction.

Synthesis, Structure, and Electrochemical Properties of 2,3,4,5-Tetraphenyl-1-Monophosphaferrocene Derivatives.

Heteroleptic 2,3,4,5-tetraphenyl-1-monophosphaferrocene [FeCp(η5-PC4Ph4)] was obtained at a 62% yield through the reaction of lithium 2,3,4,5-tetraphenyl-1-monophosphacyclopentadienide Li(PC4Ph4) (1) with [FeCp(η6-C6H5CH3)][PF6]. The structure of 1-monophosphaferrocene 2 and its W(CO)5-complex 3 were confirmed by multinuclear NMR and single-crystal X-ray diffraction study and further supported by DFT calculations. Cyclic voltammetry demonstrated that [FeCp(η5-PC4Ph4)] 2 has a quasi-reversible oxidation wave. The comparison of the properties of phosphaferrocene 2 with those of W(CO)5-complex 3 shows the possibility of changing the coordination type during oxidation.

Specific nanoarchitecture of silica nanoparticles codoped with the oppositely charged Mn2+ and Ru2+ complexes for dual paramagnetic-luminescent contrasting effects.

The silica nanoparticles (SNs) co-doped with paramagnetic ([Mn(HL)]n-,) and luminescent ([Ru(dipy)3]2+) complexes are represented. The specific distribution of [Mn(HL)]n- within the SNs allows to achieve about ten-fold enhancing in magnetic relaxivities in comparison with those of [Mn(HL)]n- in solutions. The leaching of [Mn(HL)]n- from the shell can be minimized through the co-doping of [Ru(dipy)3]2+ into the core of the SNs. The co-doped SNs exhibit colloid stability in aqueous solutions, including those modeling a blood serum. The surface of the co-doped SNs was also decorated by amino- and carboxy-groups. The cytotoxicity, hemoagglutination and hemolytic activities of the co-doped SNs are on the levels convenient for "in vivo" studies, although the amino-decorated SNs cause more noticeable agglutination and suppression of cell viability. The co-doped SNs being intravenously injected into mice allows to reveal their biodistribution in both ex vivo and in vivo conditions through confocal microscopy and magnetic resonance imaging correspondingly.

The Phosphinate Group in the Formation of 2D Coordination Polymer with Sm(III) Nodes: X-ray Structural, Electrochemical and Mössbauer Study.

A coordination polymer has been synthesized using ferrocene-based ligand-bearing phosphinic groups of 1,1'-ferrocene-diyl-bis(H-phosphinic acid)), and samarium (III). The coordination polymer's structure was studied by both single-crystal and powder XRD, TG, IR, and Raman analyses. For the first time, the Mössbauer effect studies were performed on ferrocenyl phosphinate and the polymer based on it. Additionally, the obtained polymer was studied by the method of cyclic and differential pulse voltammetry. It is shown that it has the most positive potential known among ferrocenyl phosphinate-based coordination polymers and metal-organic frameworks. Using the values of the oxidation potential, the polymer was oxidized and the ESR method verified the oxidized Fe(III) form in the solid state. Additionally, the effect of the size of the phosphorus atom substituent of the phosphinate group on the dimension of the resulting coordination compounds is shown.

Complexes of Sodium Pectate with Nickel for Hydrogen Oxidation and Oxygen Reduction in Proton-Exchange Membrane Fuel Cells.

A number of nickel complexes of sodium pectate with varied Ni2+ content have been synthesized and characterized. The presence of the proton conductivity, the possibility of the formation of a dense spatial network of transition metals in these coordination biopolymers, and the immobilization of transition ions in the catalytic sites of this class of compounds make them promising for proton-exchange membrane fuel cells. It has been established that the catalytic system composed of a coordination biopolymer with 20% substitution of sodium ions for divalent nickel ions, Ni (20%)-NaPG, is the leading catalyst in the series of 5, 15, 20, 25, 35% substituted pectates. Among the possible reasons for the improvement in performance the larger specific surface area of this sample compared to the other studied materials and the narrowest distribution of the vertical size of metal arrays were registered. The highest activity during CV and proximity to four-electron transfer during the catalytic cycle have also been observed for this compound.

pH-Driven Intracellular Nano-to-Molecular Disassembly of Heterometallic [Au2L2]{Re6Q8} Colloids (L = PNNP Ligand; Q = S2- or Se2-).

The present work introduces a simple, electrostatically driven approach to engineered nanomaterial built from the highly cytotoxic [Au2L2]2+ complex (Au2, L = 1,5-bis(p-tolyl)-3,7-bis(pyridine-2-yl)-1,5-diaza-3,7-diphosphacyclooctane (PNNP) ligand) and the pH-sensitive red-emitting [{Re6Q8}(OH)6]4- (Re6-Q, Q = S2- or Se2-) cluster units. The protonation/deprotonation of the Re6-Q unit is a prerequisite for the pH-triggered assembly of Au2 and Re6-Q into Au2Re6-Q colloids, exhibiting disassembly in acidic (pH = 4.5) conditions modeling a lysosomal environment. The counter-ion effect of polyethylenimine causes the release of Re6-Q units from the colloids, while the binding with lysozyme restricts their protonation in acidified conditions. The enhanced luminescence response of Re6-S on the disassembly of Au2Re6-S colloids in the lysosomal environment allows us to determine their high lysosomal localization extent through the colocalization assay, while the low luminescence of Re6-Se units in the same conditions allows us to reveal the rapture of the lysosomal membrane through the use of the Acridine Orange assay. The lysosomal pathway of the colloids, followed by their endo/lysosomal escape, correlates with their cytotoxicity being on the same level as that of Au2 complexes, but the contribution of the apoptotic pathway differentiates the cytotoxic effect of the colloids from that of the Au2 complex arisen from the necrotic processes.

Molecular and Nano-Structural Optimization of Nanoparticulate Mn2+-Hexarhenium Cluster Complexes for Optimal Balance of High T1- and T2-Weighted Contrast Ability with Low Hemoagglutination and Cytotoxicity.

The present work introduces rational design of nanoparticulate Mn(II)-based contrast agents through both variation of the µ3 (inner) ligands within a series of hexarhenium cluster complexes [{Re6(µ3-Q)8}(CN)6]4- (Re6Q8, Q = S2-, Se2- or Te2-) and interfacial decoration of the nanoparticles (NPs) K4-2xMnxRe6Q8 (x = 1.3 - 1.8) by a series of pluronics (F-68, P-123, F-127). The results highlight an impact of the ligand and pluronic for the optimal colloid behavior of the NPs allowing high colloid stability in ambient conditions and efficient phase separation under the centrifugation. It has been revealed that the K4-2xMnxRe6Se8 NPs and those decorated by F-127 are optimal from the viewpoint of magnetic relaxivities r1 and r2 (8.9 and 10.9 mM-1s-1, respectively, at 0.47 T) and low hemoagglutination activity. The insignificant leaching of Mn2+ ions from the NPs correlates with their insignificant effect on the cell viability of both M-HeLa and Chang Liver cell lines. The T1- and T2-weighted contrast ability of F-127-K4-2xMnxRe6Q8 NPs was demonstrated through the measurements of phantoms at whole body 1.5 T scanner.

Data of characterization of sodium pectate complexes with iron and manganese.

Data for iron and manganese-containing sodium pectate complexes are reported. Such complexes are potentially capable of exhibiting catalytic properties to the electroreduction of small molecules. Also, the complexes are water-soluble due to their ligands. The combination of these factors makes them promising for homogeneous electrocatalysis. However, in many respects, these complexes remain poorly understood. The Fourier-transform infrared spectroscopy data for the sodium pectate complexes with manganese and iron in the range of 500-4000 cm-1 were obtained. The electron spin resonance spectra of the complexes make it possible to characterize oxidation states of the metal centers in the complexes. The cyclic voltammetry data for the complexes both in an aqueous solution saturated with argon and saturated with carbon dioxide were received. For both complexes after deposition of the complexes on graphite managed to get micrographs by the atomic force microscopy method.

A Water-Soluble Sodium Pectate Complex with Copper as an Electrochemical Catalyst for Carbon Dioxide Reduction.

A selective noble-metal-free molecular catalyst has emerged as a fruitful approach in the quest for designing efficient and stable catalytic materials for CO2 reduction. In this work, we report that a sodium pectate complex of copper (PG-NaCu) proved to be highly active in the electrocatalytic conversion of CO2 to CH4 in water. Stability and selectivity of conversion of CO2 to CH4 as a product at a glassy carbon electrode were discovered. The copper complex PG-NaCu was synthesized and characterized by physicochemical methods. The electrochemical CO2 reduction reaction (CO2RR) proceeds at -1.5 V vs. Ag/AgCl at ~10 mA/cm2 current densities in the presence of the catalyst. The current density decreases by less than 20% within 12 h of electrolysis (the main decrease occurs in the first 3 h of electrolysis in the presence of CO2). This copper pectate complex (PG-NaCu) combines the advantages of heterogeneous and homogeneous catalysts, the stability of heterogeneous solid materials and the performance (high activity and selectivity) of molecular catalysts.

Structure impact on photodynamic therapy and cellular contrasting functions of colloids constructed from dimeric Au(I) complex and hexamolybdenum clusters.

Electrostatically driven self-assembly of [Au2L2]2+ (L is cyclic PNNP ligand) with [{Mo6I8}(L')6]2- (L' = I-, CH3COO-) in aqueous solutions is introduced as facile route for combination of therapeutic and cellular contrasting functions within heterometallic colloids (Mo6-Au2). The nature of L' affects the size and aggregation behavior of crystalline Mo6-Au2 aggregates, which in turn affect the luminescence of the cluster units incorporated into Mo6-Au2 colloids. The spin trap facilitated electron spin resonance spectroscopy technique indicates that the level of ROS generated by Mo6-Au2 colloids is also affected by their size. Both (L' = I-, CH3COO-) Mo6-Au2 colloids undergo cell internalization, which is enhanced by their assembly with poly-DL-lysine (PL) for L' = CH3COO-, but remains unchanged for L' = I-. The colloids PL-Mo6-Au2 (L' = CH3COO-) are visualized as huge crystalline aggregates both outside and inside the cell cytoplasm by confocal microscopy imaging of the incubated cells, while the smaller sized (30-50 nm) PL-Mo6-Au2 (L' = I-) efficiently stain the cell nuclei. Quantitative colocalization analysis of PL-Mo6-Au2 (L' = CH3COO-) in lysosomal compartments points to the fast endo-lysosomal escape of the colloids followed by their intracellular aggregation. The cytotoxicity of PL-Mo6-Au2 differs from that of Mo6 and Au2 blocks, predominantly acting through apoptotic pathway. The photodynamic therapeutic effect of the PL-Mo6-Au2 colloids on the cancer cells correlates with their intracellular trafficking and aggregation.

Generation of a Hetero Spin Complex from Iron(II) Iodide with Redox Active Acenaphthene-1,2-Diimine.

The reaction of the redox active 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN) and iron(II) iodide in acetonitrile led to a new complex [(dpp-BIAN)FeIII2] (1). Molecular structure of 1 was determined by the single crystal X-ray diffraction analysis. The spin state of the iron cation in complex 1 at room temperature and the magnetic behavior of 1 in the temperature range of 2-300 K were studied using Mossbauer spectroscopy and magnetic susceptibility measurements, respectively. The neutral character of dpp-BIAN in 1 was confirmed by IR and UV spectroscopy. The electrochemistry of 1 was studied in solution and solid state using cyclic voltammetry. The generation of the radical anion form of the dpp-BIAN ligand upon reduction of 1 in a CH2Cl2 solution was monitored by EPR spectroscopy.

Surface modification of silica nanoparticles by hexarhenium anionic cluster complexes for pH-sensing and staining of cell nuclei.

The surface deposition of luminescent anionic cluster complex [{Re6S8}(OH)6]4- advantages to the design and synthesis of composite luminescent silica nanoparticles (SNs) for intracellular imaging and sensing, while the encapsulation of the cluster units into SNs lacks for efficient luminescence. The deposition of the Re6 clusters resulted from their assembly at the silica surface functionalized by amino-groups provides the synthetic route for the composite SNs with bright cluster-centered luminescence invariable in pH range from 4.0 to 12.0. The pH-dependent supramolecular assembly of the cluster units with polyethyleneimine (PEI) at the silica surface is an alternative route for the synthesis of the composite SNs with high cluster-centered luminescence sensitive to pH-changes within 4.0-6.0. The sensitivity derives from the pH-driven conformational changes of PEI chains resulting in the release of the clusters from the PEI-based confinement under the acidification within pH 6.0-4.0. The potential of the composite SNs in cellular contrasting has been also revealed by the cell viability and flow cytometry measurements. It has been found that the PEI-supported embedding of the cluster units facilitates cell internalization of the composite SNs as well as results in specific intracellular distribution manifested by efficient staining of the cell nuclei in the confocal images.

Synthesis, structure, and electrochemical properties of 4,5-diaryl-1,2,3-triphosphaferrocenes and the first example of multi(phosphaferrocene).

The reaction between aryl substituted sodium 1,2,3-triphospholides or disodium bis(1,2,3-triphospholide) and [Fe(η6-(C6H5CH3)Cp]+[PF6]- in boiling diglyme results in pure 1,2,3-triphosphaferrocenes 1-3 or bis(1,2,3-triphosphaferrocene) 4, respectively, in good yields. The structure of all obtained 1,2,3-triphosphaferrocenes 1-4 has been extensively studied experimentally (NMR, UV-Vis spectroscopy, and X-ray analysis for 1 and 4) and quantum chemically. The electrochemical properties of 1,2,3-triphosphaferrocenes 1-4 in the solid state were studied for the first time and a reversible one-electron oxidation (E1/2 = 0.52-0.92 V vs. Fc+/Fc) was demonstrated for 1, 3, and 4. In the case of 1,4-bis(5-phenyl-4-(1,2,3-triphospaferrocenyl))benzene 4, consecutive oxidation in the solid state is observed in contrast to other 1,2,3-triphosphaferrocenes 1-3. According to the ESR data, the g-factor of the oxidized bis(1,2,3-triphosphaferrocene), 4 (g = 2.12) is different from the g-factors of oxidized 1,2,3-triphosphaferrocenes 1-3 (g = 2.01). This is the first example of multi(ferrocenyl) systems based on the phosphaferrocene motif, which in turn opens up a new fundamental platform for the preparation of compounds with stimuli-responsive properties.

ROS-generation and cellular uptake behavior of amino-silica nanoparticles arisen from their uploading by both iron-oxides and hexamolybdenum clusters.

The present work introduces combination of superparamagnetic iron oxides (SPIONs) and hexamolybdenum cluster ([{Mo6I8}I6]2-) units within amino-decorated silica nanoparticles (SNs) as promising design of the hybrid SNs as efficient cellular contrast and therapeutic agents. The heating generated by SNs doped with SPIONs (Fe3O4@SNs) under alternating magnetic field is characterized by high specific absorption rate (SAR = 446 W/g). The cluster units deposition onto both Fe3O4@SNs and "empty" silica nanoparticles (SNs) results in Fe3O4@SNs[{Mo6I8}I6] and SNs[{Mo6I8}I6] with red cluster-centered luminescence and ability to generate reactive oxygen species (ROS) under the irradiation. The monitoring of spin-trapped ROS by ESR spectroscopy technique indicates that the ROS-generation decreases in time for SNs[{Mo6I8}I6] and [{Mo6I8}I6]2- in aqueous solutions, while it remains constant for Fe3O4@SNs[{Mo6I8}I6]. The cytotoxicity is low for both Fe3O4@SNs[{Mo6I8}I6] and SNs[{Mo6I8}I6], while the flow cytometry indicates preferable cellular uptake of the former versus the latter type of the nanoparticles. Moreover, entering into nucleus along with cytoplasm differentiates the intracellular distribution of Fe3O4@SNs[{Mo6I8}I6] from that of SNs[{Mo6I8}I6], which remain in the cell cytoplasm only. The exceptional behavior of Fe3O4@SNs[{Mo6I8}I6] is explained by residual amounts of iron ions at the silica surface.

Synthetic Tuning of CoII-Doped Silica Nanoarchitecture Towards Electrochemical Sensing Ability.

The present work introduces both synthesis of silica nanoparticles doped with CoII ions by means of differently modified microemulsion water-in-oil (w/o) and Stöber techniques and characterization of the hybrid nanoparticles (CoII@SiO2) by TEM, DLS, XRD, ICP-EOS, SAXS, UV-Vis, and UV-Vis/DR spectroscopy and electrochemical methods. The results reveal the lack of nanocrystalline dopants inside the hybrid nanoparticles, as well as no ligands, when CoII ions are added to the synthetic mixtures as CoII(bpy)3 complexes, thus pointing to coordination of CoII ions with Si-O- groups as main driving force of the doping. The UV-Vis/DR spectra of CoII@SiO2 in the range of d-d transitions indicate that Stöber synthesis in greater extent than the w/o one stabilizes tetrahedral CoII ions versus the octahedral ions. Both cobalt content and homogeneity of the CoII distribution within CoII@SiO2 are greatly influenced by the synthetic technique. The electrochemical behavior of CoII@SiO2 is manifested by one oxidation and two reduction steps, which provide the basis for electrochemical response on glyphosate and HP(O)(OEt)2 with the LOD = 0.1 µM and the linearity within 0.1-80 µM. The Stöber CoII@SiO2 are able to discriminate glyphosate from HP(O)(OEt)2, while the w/o nanoparticles are more efficient but nonselective sensors on the toxicants.

[{Re6Q8}(SO3)6]10- (Q = S or Se): Facile Synthesis and Properties of the Most Highly Charged Octahedral Cluster Complexes and High Magnetic Relaxivity of Their Colloids with Gd3+ Ions.

New octahedral rhenium cluster complexes [{Re6Q8}(SO3)6]10- (Q = S or Se) were synthesized starting from [{Re6Q8}(H2O)4(OH)2]·12H2O. The complexes were crystallized as sodium salts and characterized by X-ray single-crystal diffraction and elemental analyses, IR, UV/vis and luminescence spectroscopies. Magnetic relaxation data demonstrate the complex formation of the cluster units with gadolinium ions. The analysis of the magnetic relaxation rates measured at various Gd:cluster ratios and different concentrations revealed the conversion of the aggregates (Gdx[{Re6Se8}(SO3)6]y)n- into a nanoparticulate form even at x = 1 and y ≥ 1. Thus, the self-assembly of the cluster units into the nanoparticles is greatly facilitated by counterion binding with sodium cations. The concentration conditions were optimized for the formation and hydrophilization of NaxGdy[{Re6Q8}(SO3)6]-based colloids with the magnetic relaxivity values of r1(2) = 21.0(24.1) and r1(2) = 25.9(29.8) mM-1 s-1 for the {Re6S8}2+ and {Re6Se8}2+ derivatives, respectively.

Fluorescent magnetic nanoparticles for modulating the level of intracellular Ca2+ in motoneurons.

This report introduces both synthesis and in vitro biological behaviour of dual magnetic-fluorescent silica nanoparticles. The amino group-decoration of 78 nm sized silica nanoparticles enables their efficient internalization into motoneurons, which is visualized by the red fluorescence arising from [Ru(dipy)3]2+ complexes encapsulated into a silica matrix. The internalized nanoparticles are predominantly located in the cell cytoplasm as revealed by confocal microscopy imaging. The magnetic function of the nanoparticles resulted from the incorporation of 17 nm sized superparamagnetic iron oxide cores into the silica matrix, enabling their responsivity to magnetic fields. Fluorescence analysis revealed the "on-off" switching of Ca2+ influx under the application and further removal of the permanent magnetic field. This result for the first time highlights the movement of the nanoparticles within the cell cytoplasm in the permanent magnetic field as a promising tool to enhance the neuronal activity of motoneurons.