Study on cellular uptake of a hydrophobic near-infrared-absorbing diradical-platinum(II) complex solubilized by albumin using hyperspectral imaging, spectrophotometry, and spectrofluorimetry.

Owing to its biopenetrability and minimal invasiveness, near-infrared (NIR) light in the region between 700-1100 nm has attracted attention in cancer diagnosis and therapy. Our group previously reported that the hydrophobic diradical-platinum(II) complex PtL is a promising agent for cancer photothermal therapy (L = 3,5-dibromo-1,2-diiminobenzosemiquinonate radical). Because PtL does not fluoresce, its intercellular uptake of PtL cannot be observed with a fluorescence microscope.

Kinetic aspects of iron(III)-chelation therapy with deferasirox (DFX) revealed by the solvolytic dissociation rate of the Fe(III)-DFX complex estimated with capillary electrophoretic reactor.

Capillary electrophoresis was used to estimate the solvolytic dissociation rate (k) of metal complexes of deferasirox (DFX, HL), a drug used to treat iron overload. Inert CoL did not dissociate. The estimated k value for FeL was (2.

MRI Contrasting Agent Based on Mn-MOF-74 Nanoparticles with Coordinatively Unsaturated Sites.

Purpose: The development of magnetic resonance imaging (MRI) contrasting agents (CAs) that are safer and have a higher relaxivity than Gd(III)-based agents is a significant research topic. Herein, we propose the use of a Mn-based metal organic framework (MOF), Mn-MOF-74, characterized by a safe paramagnetic center, a coordinatively unsaturated site (CUS) for aquation, and a long rotational correlation time, endowing high relaxivity. Furthermore, biocompatibility and delivery to the tumor are generally expected for MOFs that are obtainable in the nanometer size range.

Selective crystallization of dysprosium complex from neodymium/dysprosium mixture enabled by cooperation of coordination and crystallization.

Designing a molecular-level Ln separation system remains a challenge for developing next-generation separation methodologies. Herein, we report crystallization-based Nd/Dy separation using a tripodal Schiff base ligand. Highly selective crystallization of the Dy complex was enabled by cooperation between the coordination and crystallization processes.

Photostable near-infrared-absorbing diradical-platinum(ii) complex solubilized by albumin toward a cancer photothermal therapy agent.

A hydrophobic diradical-platinum(ii) complex was solubilized in aqueous solutions by using bovine serum albumin and exhibited photothermal conversion under near-infrared (NIR) light irradiation. The complex was introduced into cancer cells and induced cell death upon absorption of NIR. These results imply that the complex can function as a photothermal therapeutic agent.

Capillary electrophoretic reactor for estimation of spontaneous dissociation rate of Trypsin-Aprotinin complex.

A capillary electrophoretic reactor was used to analyze the dissociation kinetics of an enzyme-inhibitor complex in a homogeneous solution without immobilization. The complex consisting of trypsin (Try) and aprotinin (Apr) was used as the model. Capillary electrophoresis provided a reaction field for Try-Apr complex to dissociate through the steady removal of free Try and Apr from the Try-Apr zone.

Multi-coloration of Calixarene-coated Silver Nanoparticles for the Visual Discrimination of Metal Elements.

Upon mixing with metal ions such as Cd, Tb, Cu, Ni, Pb, Zn, and Co at pH 10.0, solutions of silver nanoparticles (AgNPs) coated with calix[4]arene-p-tetrasulfonate (CAS-AgNP) exhibited multi-coloration from yellow to orange, violet, and green, depending on the metal elements present, which allowed for visual discrimination of the ions. This is contrary to the AgNP sensors exhibiting a uniform color change from yellow to red upon binding of a receptor molecules at the surface of AgNPs to an analyte.

High kinetic stability of Zn(II) coordinated by the tris(histidine) unit of carbonic anhydrase towards solvolytic dissociation studied by affinity capillary electrophoresis.

Solvolytic dissociation rate constants (kd) of bovine carbonic anhydrase II (CA) and its metallovariants (M-CAs, M=Co(II), Ni(II), Cu(II), Zn(II), and Cd(II)) were estimated by a ligand substitution reaction, which was monitored by affinity capillary electrophoresis to selectively detect the undissociated CAs in the reaction mixture. Using EDTA as the competing ligand for Zn-CA, the dissociation followed the unimolecular nucleophilic substitution (SN1) mechanism with kd=1.0×10(-7)s(-1) (pH7.

Gd3TCAS2: An Aquated Gd(3+)-Thiacalix[4]arene Sandwich Cluster with Extremely Slow Ligand Substitution Kinetics.

In aqueous solution, Gd(3+) and thiacalix[4]arene-p-tetrasulfonate (TCAS) form the complex [Gd3TCAS2](7-), in which a trinuclear Gd(3+) core is sandwiched by two TCAS ligands. Acid-catalyzed dissociation reactions, as well as transmetalation and ligand exchange with physiological concentrations of Zn(2+) and phosphate, showed [Gd3TCAS2](7-) to be extremely inert compared to other Gd complexes. Luminescence lifetime measurements of the Tb analogue Tb3TCAS2 allowed estimation of the mean hydration number q to be 2.

Thiacalixarene assembled heterotrinuclear lanthanide clusters comprising Tb(III) and Yb(III) enable f-f communication to enhance Yb(III)-centred luminescence.

A mixture of heterotrinuclear lanthanide cluster complexes, Tb3-xYbxTCAS2 (x = 1, 2), was obtained by mixing thiacalix[4]arene-p-tetrasulfonate (TCAS), Tb(III), and Yb(III), which shows enhanced Yb(III)-centred luminescence and shortened lifetime for Tb(III)-centred luminescence as compared to Yb3TCAS2 and Tb3TCAS2, indicating f-f communication, i.e., energy transfer from Tb(III) to Yb(III).

Thermodynamics of binding of a sulfonamide inhibitor to metal-mutated carbonic anhydrase as studied by affinity capillary electrophoresis.

By affinity capillary electrophoresis (ACE), the thermodynamic binding constants of a sulfonamide (SA) inhibitor to bovine carbonic anhydrase II (CA) and metal mutated variants (M-CAs) were evaluated. 1-(4-Aminosulfonylphenylazo)-2-naphthol-6,8-disulfonate was used as the SA in the electrophoretic buffer for ACE. The Scatchard analysis of the dependence of the electrophoretic mobility of native CA on the SA concentration provided the binding constant to be Kb=(2.

Dissociation kinetic analysis of Ce(III) complex with Quin2 by microchip capillary electrophoretic reactor.

Dissociation kinetic analysis of a complex of Ce(3+) with a polyaminocarboxylic ligand, 8-amino-2-[(2-amino-5-methylphenoxyl)methyl]-6-methoxyquinoline-N,N,N',N',-tetraacetic acid (Quin2), was studied by microchip capillary electrophoretic reactor. Dissociation rate constants, k(d), of Ce(3+)-Quin2 complex in alkaline conditions at pH 8.3 - 9.

A molecular probe for recognizing the size of hydrophobic cavities based on near-infrared absorbing diradical-Pt(II) complexes.

A diradical-platinum(II) complex was able to recognize the subtle difference in cavity size between β- and γ-cyclodextrin with on-off switching of intense near-infrared absorption. This provides a new probe for identifying the size of hydrophobic cavities, which has been successfully applied here to differentiate human serum albumin from α-chymotrypsin.

Highly efficient near-infrared-emitting lanthanide(III) complexes formed by heterogeneous self-assembly of Ag(I), Ln(III), and thiacalix[4]arene-p-tetrasulfonate in aqueous solution (Ln(III) = Nd(III), Yb(III)).

Heterogeneous self-assembly of thiacalix[4]arene-p-tetrasulfonate (TCAS), Ag(I), and Ln(III) (= Nd(III), Yb(III)) in aqueous solutions conveniently afforded ternary complexes emitting Ln(III)-centered luminescence in the near-infrared (NIR) region. A solution-state study revealed that the Ag(I)-Nd(III)-TCAS system gave a complex Ag(I)(4)·Nd(III)·TCAS(2) in a wide pH range of 6-12. In contrast, the Ag(I)-Yb(III)-TCAS system gave Ag(I)(2)·Yb(III)(2)·TCAS(2) at a pH of around 6 and Ag(I)(2)·Yb(III)·TCAS(2) at a pH of approximately 9.

Detection of cationic guest molecules by quenching of luminescence of a self-assembled host molecule consisting of terbium(III) and calix[4]arene-p-tetrasulfonates.

By self-assembly in aqueous solution, calix- (CAS) and thiacalix[4]arene-p-tetrasulfonate (TCAS) formed luminescent complexes Tb(III).(CAS)2 and Tb(III).TCAS, respectively, which were utilized as a host for cationic guests.

Ligand-substitution mode capillary electrophoretic reactor: extending capillary electrophoretic reactor toward measurement of slow dissociation kinetics with a half-life of hours.

A method employing capillary electrophoresis (CE) was developed to determine the rate constant of the very slow spontaneous dissociation of a complex species. The method uses a CE reactor (CER) to electrophoretically separate components from a complex zone and, thus, spontaneously dissociate a complex. The dissociation is accelerated by ligand substitution (LS) involving a competing ligand added to the electrophoretic buffer.

Expanding the scope of CE reactor to ssDNA-binding protein-ssDNA complexes as exemplified for a tool for direct measurement of dissociation kinetics of biomolecular complexes.

CE reactor (CER), which was developed as a tool for direct measurement of the dissociation kinetics of metal complexes, was successfully applied to the complexes of Escherichia coli ssDNA-binding protein (SSB) with ssDNA. The basic concept of CER is the application of CE separation process as a dissociation kinetic reactor for the complex, and the observation of the on-capillary dissociation reaction profile of the complex as the decrease of the peak height of the complex with increase of the migration time. The peak height of [SSB-ssDNA] decreases as the migration time increases since the degree of the decrease of [SSB-ssDNA] through the on-capillary dissociation reaction is proportional to the degree of the decrease of the peak height of [SSB-ssDNA].

Sulfonylcalix[4]arenetetrasulfonate as pre-column chelating reagent for selective determination of aluminum(III), iron(III), and titanium(IV) by ion-pair reversed-phase high-performance liquid chromatography with spectrophotometric detection.

Sulfonylcalix[4]arenetetrasulfonate (SO(2)CAS) has been examined as a pre-column chelating reagent for ultratrace determination of metal ions by ion-pair reversed-phase high-performance liquid chromatography with spectrophotometric detection. Metal ions were converted into the SO(2)CAS chelates in an acetic buffer solution (pH 4.7).

Exceptionally long-lived luminescence emitted from Tb(III) ion caged in an Ag(I)-Tb(III)-thiacalix[4]arene supramolecular complex in water.

The compositions and photophysical properties of luminescent ternary complexes of thiacalix[4]arene-p-sulfonate (TCAS), Tb(III), and Ag(I) ions were determined. At pH 6, Ag(I) (2)Tb(III) (2)TCAS(2) formed. Moreover, at pH 10, in the presence of a 20-fold excess of Ag(I) and a 50-fold excess of TCAS with respect to Tb(III), Ag(I) (2)Tb(III)TCAS(2) formed as the main luminescent species.

A dodecalanthanide wheel supported by p-tert-butylsulfonylcalix[4]arene.

A dodecaholmium wheel of [Ho12(L)6(mal)4(AcO)4(H2O)14] (1; mal = malonate) was synthesized by using p-tert-butylsulfonylcalix[4]arene (H4L) as a cluster-forming ligand. The wheel consists of three fragments of mononuclear A3- ([Ho(L)(mal)(H2O)]3-), trinuclear B3- ([Ho(H2O)2(mal)(Ho(L)(AcO))2]3-), and C3+ ([Ho(H2O)2]3+), and an alternate arrangement of these fragments (A(3-)-C(3+)-B(3-)-C(3+)-A(3-)-C(3+)-B(3-)-C(3+)-) results in a wheel structure. The longest and shortest diameters of the core were estimated to be 17.