An AIEE polyelectrolyte as a light-up fluorescent probe for heparin sensing in full detection range

Polyelectrolyte PTPEPyH, containing tetraphenylethene (TPE) and pyridinium, was synthesized. Its optical properties were investigated with spectroscopies and the results showed that there were two emission-enhanced stages in the interaction between positive-charged PTPEPyH and negative-charged biomacromolecule heparin. The mechanism was very different due to the reduced non-radiative energy loss and the change of surroundings. The polyelectrolyte PTPEPyH, compared with ChS and HA, also showed high selectivity for heparin in the buffer solution and could be used as a potential bio-probe for heparin quantification in the clinical full range.     

A differential ICT based molecular probe for multi-ions and multifunction logic circuits

This paper presents anthraquinone and benzimidazole based hybrid molecular architect as the state of the art for multifunctional molecular logic circuits. The moleculator exhibits differential output behavior towards F(-), Zn(2+) and Cu(2+) ions to provide opportunities for elaboration of XOR, INHIBIT, XNOR, AND, OR, NOR, logic functions and their integrated logic functions half-adder, half-subtractor and comparator within a single molecule. These integral logic functions can be reprogrammed by self-annihilation or by another additional input in the same cell. This single molecule behaves uniquely where different logic functions can be operated and reset by using different inputs and outputs.     

脱氢枞酸基芳胺荧光探针探测金属离子的应用

通过脱氢枞酸基芳胺荧光探针a,b,c对不同金属离子(Ca2+、K+、Mg2+、Mn2+、Na+、Ni2+、Pb2+、Fe3+、Cu2+)的识别性、对其他金属离子的抗干扰性、以及金属离子对探针的荧光滴定试验,研究了它们作为金属离子荧光探针的应用。结果表明,a和b对Fe3+、c对Cu2+具有良好识别性,其识别性能受其他金属离子的干扰性不明显;Fe3+浓度分别在1.0×10-7~6.0×10-6mol·L-1和2.0×10-7~7.0×10-6mol·L-1范围内,a和b的荧光强度与Fe3+浓度有较好的线性关系,Cu2+浓度在6.0×10-6~3.0×10-5mol·L-1范围内,c的荧光强度与Cu2+浓度有较好的线性关系,可以定量检测中性水溶液中Fe3+和Cu2+含量。     

Multivalent ions and biomolecules: Attempting a comprehensive perspective

Ions are ubiquitous in nature. They play a key role for many biological processes on the molecular scale, from molecular interactions, to mechanical properties, to folding, to self-organisation and assembly, to reaction equilibria, to signalling, to energy and material transport, to recognition etc. Going beyond monovalent ions to multivalent ions, the effects of the ions are frequently not only stronger (due to the obviously higher charge), but qualitatively different. A typical example is the process of binding of multivalent ions, such as Ca²⁺, to a macromolecule and the consequences of this ion binding such as compaction, collapse, potential charge inversion and precipitation of the macromolecule. Here we review these effects and phenomena induced by multivalent ions for biological (macro)molecules, from the “atomistic/molecular” local picture of (potentially specific) interactions to the more global picture of phase behaviour including, e. g., crystallisation, phase separation, oligomerisation etc. Rather than attempting an encyclopedic list of systems, we rather aim for an embracing discussion using typical case studies. We try to cover predominantly three main classes: proteins, nucleic acids, and amphiphilic molecules including interface effects. We do not cover in detail, but make some comparisons to, ion channels, colloidal systems, and synthetic polymers. While there are obvious differences in the behaviour of, and the relevance of multivalent ions for, the three main classes of systems, we also point out analogies. Our attempt of a comprehensive discussion is guided by the idea that there are not only important differences and specific phenomena with regard to the effects of multivalent ions on the main systems, but also important similarities. We hope to bridge physico-chemical mechanisms, concepts of soft matter, and biological observations and connect the different communities further.     

Crystal violet as a fluorescent switch-on probe for i-motif: label-free DNA-based logic gate

The first application of crystal violet as a selective fluorescent switch-on probe for i-motif DNA has been reported. This interaction has been exploited to develop a label-free DNA-based "OR" logic gate for potassium and hydrogen ions.     

Heteroelemental diatomic secondary ions as a probe for molecular states

Summary The complete chemical characterization of environmental particles requires a depth resolved analysis of the chemical state of the elements. Using dynamic SIMS, a depth-resolved determination of the chemical state of chromium was derived from measurements of ten different chromium salts and oxides. The evaluation is based on the signals of Cr ₂ ⁺ , CrO⁺ and Cr₂O⁺ which are the most intense molecular ions. The valence state of chromium can be determined for concentrations far less than 1 atom %. The transferability of this kind of analysis is shown for manganese compounds. Additionally binary mixed metal clusters are shown to indicate binding partners of compounds in mixtures.     

Click synthesized dianthryl-TTFV: an efficient fluorescent turn-on probe for transition metal ions

Tetrathiafulvalene vinylogue (TTFV) was functionalized with two anthryl fluorophores via Cu(I)-catalyzed alkyne-azide [3 + 2] cycloaddition, forming a dianthryl-TTFV hybrid to show fluorescent turn-on sensing behaviour for Cu(2+), Fe(2+), and Cd(2+) ions in THF with remarkably low detection limit down to the sub-ppm level.     

Interface composition of multiple emulsions: rheology as a probe

We have investigated the dynamic rheological properties of concentrated multiple emulsions to characterize their amphiphile composition at interfaces. Multiple emulsions (W1/O/W2) consist of water droplets (W1) dispersed into oil globules (O), which are redispersed in an external aqueous phase (W2). A small-molecule surfactant and an amphiphilic polymer were used to stabilize the inverse emulsion (W1 in oil globules) and the inverse emulsion (oil globules in W2), respectively. Rheological and interfacial tension measurements show that the polymeric surfactant adsorbed at the globule interface does not migrate to the droplet interfaces through the oil phase. This explains, at least partly, the stability improvement of multiple emulsions as polymeric surfactants are used instead of small-molecule surfactants.     

Cruciforms as functional fluorophores: response to protons and selected metal ions

The photophysics of dialkylamino- and/or pyridine-containing functional chromophores, 1,4-distyryl-2,5-bis(ethynylaryl)benzenes (cruciforms) was investigated; their fluorescence quantum yields and emissive lifetimes were determined. Depending upon their substituents, the frontier molecular orbitals (FMOs) of these cruciforms are either congruent, i.e., HOMO and LUMO occupy the same real space, or disjoint, i.e., the HOMO is located on one branch of the cruciform while the LUMO is located on the second one. Donor-acceptor substitution leads to a disjoint FMO pattern, while the parent 1,4-distyryl-2,5-bis(phenylethynyl)benzene shows congruent FMOs. The photophysics of the cruciforms was investigated upon addition of either an excess of trifluoroacetic acid or an excess of selected metal (Mg(2+), Ca(2+), Mn(2+), Zn(2+)) trifluoromethanesulfonate salts. Addition of either metal ions or protons led to analogous but not identical changes in the spectroscopic properties of the investigated cruciforms. The collected data suggest that the metals bind preferentially at the aniline nitrogen and not at the electron-rich arene. The spatially separated FMOs permit the independent manipulation of the HOMO and the LUMO of such cruciforms. If the branches contain metal-complexing moieties, metal binding leads to either a hypsochromic or a bathochromic shift in emission via interaction of the metal cations with either the HOMO or the LUMO.     

Sorption properties of a composite material based on titanium phosphate in relation to nonferrous metal ions

Sorption of nonferrous metal ions under static conditions by a composite sorbent based on titanium phosphate was studied. The distribution coefficients and exchange constants for Cu(II), Ni(II), and Co(II) were calculated from the experimental data. The kinetics of the sorption of multiply charged ions from dilute hydrochloric acid solutions was studied, and the diffusion coefficients of exchanging ions were determined.     

Atomic XAFS as a tool to probe the reactivity of metal oxide catalysts: quantifying metal oxide support effects

The potential of atomic XAFS (AXAFS) to directly probe the catalytic performances of a set of supported metal oxide catalysts has been explored for the first time. For this purpose, a series of 1 wt % supported vanadium oxide catalysts have been prepared differing in their oxidic support material (SiO2, Al2O3, Nb2O5, and ZrO2). Previous characterization results have shown that these catalysts contain the same molecular structure on all supports, i.e., a monomeric VO4 species. It was found that the catalytic activity for the selective oxidation of methanol to formaldehyde and the oxidative dehydrogenation of propane to propene increases in the order SiO2 < Al2O3 < Nb2O5 < ZrO2. The opposite trend was observed for the dehydrogenation of propane to propene in the absence of oxygen. Interestingly, the intensity of the Fourier transform AXAFS peak decreases in the same order. This can be interpreted by an increase in the binding energy of the vanadium valence orbitals when the ionicity of the support (increasing electron charge on the support oxygen atoms) increases. Moreover, detailed EXAFS analysis shows a systematic decrease of the V-Ob(-M(support)) and an increase of a the V-O(H) bond length, when going from SiO2 to ZrO2. This implies a more reactive OH group for ZrO2, in line with the catalytic data. These results show that the electronic structure and consequently the catalytic behavior of the VO4 cluster depend on the ionicity of the support oxide. These results demonstrate that AXAFS spectroscopy can be used to understand and predict the catalytic performances of supported metal oxide catalysts. Furthermore, it enables the user to gather quantitative insight in metal oxide support interactions.     

Use of immobilized metal ions as a negative adsorbent for purification of enzymes: application to phosphoglycerate mutase from chicken muscle extract and horseradish peroxidase.

Two enzymes, phosphoglycerate mutase and peroxidase, were purified by using an immobilized metal ion adsorbent for the removal of unwanted proteins. The mutase was obtained pure from a single column, whereas the purification of peroxidase required the use of a thiophilic adsorbent in a tandem. The capacity was 2.5 mg pure peroxidase per mL gel.     

The ATCUN domain as a probe of intermolecular interactions: application to calmodulin-peptide complexes

The utility of a three-residue Cu2+ binding motif (ATCUN domain) for studying intermolecular interactions is demonstrated. By comparing a set of 1H-15N correlation spectra recorded on complexes of calmodulin (CaM) and peptides with the ATCUN tag in the presence and absence of Cu2+ the two possible canonical binding orientations of the peptide can be rapidly distinguished. The methodology is confirmed with studies of complexes of CaM and peptides from myosin light chain kinase and CaM kinase kinase, for which high-resolution structures are available, and then applied to a complex with CaM kinase I for which structural data has not been obtained. The orientation of the CaM kinase I and myosin light chain kinase peptides are shown to be identical. In the case of a complex of CaM with a peptide for which structural information is not available, the present methodology, in combination with 1H-15N residual dipolar couplings measured on CaM, and the database of existing CaM-peptide structures, allows a homology model to be built rapidly and with confidence.     

EPR spectroscopy as a probe of metal centres in biological systems

Molecular paramagnetism pervades the bioinorganic chemistry of V, Mn, Fe, Co, Ni, Cu, Mo, W, and of a number of non-biological transition elements. To date we can look back at half a century of fruitful EPR studies on metalloproteins, and against this background evaluate the significance of modern EPR spectroscopy from the perspective of a biochemist, making a distinction between conventional continuous wave X-band spectroscopy as a reliable work horse with broad, established applicability even on crude preparations, vs. a diffuse set of "advanced EPR" technologies whose practical application typically calls for narrowly focused research hypotheses and very high quality samples. The type of knowledge on metalloproteins that is readily obtainable with EPR spectroscopy, is explained with illustrative examples, as is the relation between experimental complexity and the spin value of the system.     

Fluorescence enhancement of a signaling system in the simultaneous presence of transition and alkali metal ions: a potential AND logic gate

Attachment of a laterally non-symmetric cryptand and a macrocycle at the 9- and 10-positions of anthracene leads to a fluorescent signaling system L1 which gives fluorescence enhancement in the simultaneous presence of alkali and transition metal ions.     

Precipitation of metal ions by organic acids as a mean for metal recovery and decontamination of wastewater

The dicarboxylic and oxycarboxylic acids known as complexing agents for metal ions under the conditions when the amount of metal ions exceeds that in metal complexes, act as precipitants for metal ions. The completeness of precipitation, depends on the kind of metal and organic acid, pH and the concentrations of substances. The abundance of metals in metal finishing industry enables to use such precipitation for regeneration and decontamination of the complexing agents containing solutions.     

59Co solid-state NMR as a new probe for elucidating metal binding in polynucleotides

Although magnesium fulfills several essential biochemical roles, direct studies on this ion are complicated by its unfavorable spectroscopic characteristics. This contribution explores the possibility of monitoring magnesium-nucleic acid binding via a combination of [Co(NH3)6]3+ as surrogate for [Mg(H2O)6]2+, and of high-resolution solid-state 59Co NMR as a spectroscopic probe. Such strategy quenches fast cationic exchanges between bound and free states, while exploiting the superior NMR properties of the 59Co spin. Experiments on relatively small amounts of tRNA can then discern resonances corresponding to different metal binding environments. These characterizations were assisted by studies on model compounds and by multinuclear 31P-59Co recoupling experiments.     

Chemically bonded multiwalled carbon nanotubes as efficient material for solid phase extraction of some metal ions in food samples

Multiwalled carbon nanotubes chemically functionalized with 2-((3-silylpropylimino) methyl) phenol (SPIMP-MWCNT) and successfully applied for the solid phase extraction (SPE) of some metal ions in food samples. The influences of the analytical parameters including pH, amounts of solid phase, eluent conditions (type, volume and concentrations), sample volume and interference of some metal ions on the recoveries of ions Cu²⁺, Pb²⁺, Fe²⁺, Ni²⁺ and Zn²⁺ ion were investigated. The metal ions retained on SPIMP-MWCNT was eluted using 6?mL of 4?mol?L^?1 HNO₃ solution and their content was determined by flame atomic absorption spectrometry (FAAS) with recoveries more than 95% and relative standard deviations (n?=?5) between 2.4–3.4% for both reproducibility and repeatability. The detection limit of this metal ions was between 1.0–2.6?ng?mL^?1 (3S _b , n?=?10) and their preconcentration factor was 100, while their loading capacity was above 32.9?mg?g^?1 of SPIMP-MWCNT. The proposed method was successfully applied for the preconcentration and determination of analytes in different samples.