Fukushima Daiichi Nuclear Power Plant Accident: Understanding Formation Mechanism of Radioactive Particles through Sr and Pu Quantities.

The Fukushima Daiichi Nuclear Power Plant accident released considerable radionuclides into the environment. Radioactive particles, composed mainly of SiO2, emerged as distinctive features, revealing insights into the accident's dynamics. While studies extensively focused on high-volatile radionuclides like Cs, investigations into low-volatile nuclides such as 90Sr and Pu remain limited. Understanding their abundance in radioactive particles is crucial for deciphering the accident's details, including reactor temperatures and injection processes. Here, we aimed to determine 90Sr and Pu amounts in radioactive particles and provide essential data for understanding the formation processes and conditions within the reactor during the accident. We employed radiochemical analysis on nine radioactive particles and determined the amounts of 90Sr and Pu in these particles. 90Sr and Pu quantification in radioactive particles showed that the 90Sr/137Cs radioactivity ratio (corrected to March 11, 2011) aligned with core temperature expectations. However, the 239+240Pu/137Cs activity ratio indicated nonvolatile Pu introduction, possibly through fuel fragments. Analyzing 90Sr and Pu enhances our understanding of the Fukushima Daiichi accident. Deviations in 239+240Pu/137Cs activity ratios underscore nonvolatile processes, emphasizing the accident's complexity. Future research should expand this data set for a more comprehensive understanding of the accident's nuances.

Hydration Structure of 102No2+: A Density Functional Theory-Molecular Dynamics Study.

The hydration structure of No2+, the divalent cation of nobelium in water, was investigated by ab initio molecular dynamics (MD) simulations. First, a series of benchmark calculations were performed to validate the density functional theory (DFT) calculation methods for a molecule containing a No atom. The DFT-MD simulation of the hydration structure of No2+ was conducted after the MD method was validated by simulating the hydration structures of Ca2+ and Sr2+, whose behavior was previously reported to be similar to that of No2+. The model cluster containing M2+ (M = Ca, Sr, or No) and 32 water molecules was used for DFT-MD simulation. The results showed that the hydration distance of No2+ was intermediate between those of Ca2+ and Sr2+. This trend in the hydration distance is in good agreement with the elution position trend obtained in a previous radiochemical experiment. The calculated No-O bond lengths in the optimized structure of [No(H2O)8]2+ was 2.59 Å, while the average No-O bond length of [No(H2O)8]2+ in water by DFT-MD was 2.55 Å. This difference implies the importance of dynamic solvent effects, considering the second (and further) coordination sphere in the theoretical calculation of solution chemistry for superheavy elements.

Fibroblast activation protein targeted therapy using [177Lu]FAPI-46 compared with [225Ac]FAPI-46 in a pancreatic cancer model.

PURPOSE: Fibroblast activation protein (FAP), which has high expression in cancer-associated fibroblasts of epithelial cancers, can be used as a theranostic target. Our previous study used 64Cu and 225Ac-labelled FAP inhibitors (FAPI-04) for a FAP-expressing pancreatic cancer xenograft imaging and therapy. However, the optimal therapeutic radionuclide for FAPI needs to be investigated further. In this study, we evaluated the therapeutic effects of beta-emitter (177Lu)-labelled FAPI-46 and alpha-emitter (225Ac)-labelled FAPI-46 in pancreatic cancer models. METHODS: PET scans (1 h post injection) were acquired in PANC-1 xenograft mice (n = 9) after the administration of [18F]FAPI-74 (12.4 ± 1.7 MBq) for the companion imaging. The biodistribution of [177Lu]FAPI-46 and [225Ac]FAPI-46 were evaluated in the xenograft model (total n = 12). For the determination of treatment effects, [177Lu]FAPI-46 and [225Ac]FAPI-46 were injected into PANC-1 xenograft mice at different doses: 3 MBq (n = 6), 10 MBq (n = 6), 30 MBq (n = 6), control (n = 4) for [177Lu]FAPI-46, and 3 kBq (n = 3), 10 kBq (n = 2), 30 kBq (n = 6), control (n = 7) for [225Ac]FAPI-46. Tumour sizes and body weights were followed. RESULTS: [18F]FAPI-74 showed rapid clearance by the kidneys and high accumulation in the tumour and intestine 1 h after administration. [177Lu]FAPI-46 and [225Ac]FAPI-46 also showed rapid clearance by the kidneys and relatively high accumulation in the tumour at 3 h. Both [177Lu]FAPI-46 and [225Ac]FAPI-46 showed tumour-suppressive effects, with a mild decrease in body weight. The treatment effects of [177Lu]FAPI-46 were relatively slow but lasted longer than those of [225Ac]FAPI-46. CONCLUSION: This study suggested the possible application of FAPI radioligand therapy in FAP-expressing pancreatic cancer. Further evaluation is necessary to find the best radionuclide with shorter half-life, as well as the combination with therapies targeting tumour cells directly.

Comparison of the Therapeutic Effects of [211At]NaAt and [131I]NaI in an NIS-Expressing Thyroid Cancer Mouse Model.

Astatine (211At) is an alpha-emitter with a better treatment efficacy against differentiated thyroid cancer compared with iodine (131I), a conventional beta-emitter. However, its therapeutic comparison has not been fully evaluated. In this study, we compared the therapeutic effect between [211At]NaAt and [131I]NaI. In vitro analysis of a double-stranded DNA break (DSB) and colony formation assay were performed using K1-NIS cells. The therapeutic effect was compared using K1-NIS xenograft mice administered with [211At]NaAt (0.4 MBq (n = 7), 0.8 MBq (n = 9), and 1.2 MBq (n = 4)), and [131I]NaI (1 MBq (n = 4), 3 MBq (n = 4), and 8 MBq (n = 4)). The [211At]NaAt induced higher numbers of DSBs and had a more reduced colony formation than [131I]NaI. In K1-NIS mice, dose-dependent therapeutic effects were observed in both [211At]NaAt and [131I]NaI. In [211At]NaAt, a stronger tumour-growth suppression was observed, while tumour regrowth was not observed until 18, 25, and 46 days after injection of 0.4, 0.8, and 1.2 MBq of [211At]NaAt, respectively. While in [131I]NaI, this was observed within 12 days after injection (1, 3, and 8 MBq). The superior therapeutic effect of [211At]NaAt suggests the promising clinical applicability of targeted alpha therapy using [211At]NaAt in patients with differentiated thyroid cancer refractory to standard [131I]NaI treatment.

α-Emitting cancer therapy using 211 At-AAMT targeting LAT1.

α-Methyl-l-tyrosine (AMT) has a high affinity for the cancer-specific l-type amino acid transporter 1 (LAT1). Therefore, we established an anti-cancer therapy, with 211 At-labeled α-methyl-l-tyrosine (211 At-AAMT) as a carrier of 211 At into tumors. 211 At-AAMT had high affinity for LAT1, inhibited tumor cell growth, and induced DNA double-stranded breaks in vitro. We evaluated the accumulation of 211 At-AAMT in vivo and the role of LAT1. Treatment with 0.4 MBq/mouse 211 At-AAMT inhibited tumor growth in the PANC-1 tumor model and 1 MBq/mouse 211 At-AAMT inhibited metastasis in the lung of the B16F10 metastasis model. Our results suggested that 211 At would be useful for anti-cancer therapy and that LAT1 is suitable as a target for radionuclide therapy.

Intratumoral administration of astatine-211-labeled gold nanoparticle for alpha therapy.

BACKGROUND: 211At is a high-energy α-ray emitter with a relatively short half-life and a high cytotoxicity for cancer cells. Its dispersion can be imaged using clinical scanners, and it can be produced in cyclotrons without the use of nuclear fuel material. This study investigated the biodistribution and the antitumor effect of 211At-labeled gold nanoparticles (211At-AuNP) administered intratumorally. RESULTS: AuNP with a diameter of 5, 13, 30, or 120 nm that had been modified with poly (ethylene glycol) methyl ether (mPEG) thiol and labeled with 211At (211At-AuNP-S-mPEG) were incubated with tumor cells, or intratumorally administered to C6 glioma or PANC-1 pancreatic cancers subcutaneously transplanted into rodent models. Systemic and intratumoral distributions of the particles in the rodents were then evaluated using scintigraphy and autoradiography, and the changes in tumor volumes were followed for about 40 days. 211At-AuNP-S-mPEG was cytotoxic when it was internalized by the tumor cells. After intratumoral administration, 211At-AuNP-S-mPEG became localized in the tumor and did not spread to systemic organs during a time period equivalent to 6 half-lives of 211At. Tumor growth was strongly suppressed for both C6 and PANC-1 by 211At-AuNP-S-mPEG. In the C6 glioma model, the strongest antitumor effect was observed in the group treated with 211At-AuNP-S-mPEG with a diameter of 5 nm. CONCLUSIONS: The intratumoral single administration of a simple nanoparticle, 211At-AuNP-S-mPEG, was shown to suppress the growth of tumor tissue strongly in a particle size-dependent manner without radiation exposure to other organs caused by systemic spread of the radionuclide.

Activity of 90Sr in Fallout Particles Collected in the Difficult-to-Return Zone around the Fukushima Daiichi Nuclear Power Plant.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released abundant radioactive particles into the surrounding environment. Herein, we analyzed the activity of 90Sr in these particles to estimate the contribution of this radionuclide to the overall radiation exposure and shed light on the processes that occurred during the accident. Seven radioactive particles were isolated from the dust and soil samples collected from areas surrounding the FDNPP, and the minimum/maximum 137Cs activities were determined as 224/4,100 Bq. Based on the size, specific activity, and 134Cs/137Cs activity ratios, we concluded that six of the seven radioactive particles were released from the Unit 1 reactor, while one particle was released from the Unit 3 reactor by a hydrogen explosion. Strontium-90 was detected in all radioactive particles, and the minimal/maximal 90Sr activities were determined as 0.046/1.4 Bq. 137Cs/90Sr activity ratios above 1000 were observed for all seven particles, that is, compared to 137Cs, 90Sr had negligible contribution to the overall radiation exposure. The 137Cs/90Sr activity ratios of the radioactive particles were similar to those of terrestrial environmental samples and were higher for particles released from the Unit 1 reactor than for samples collected from the Unit 1 reactor building, which indicates possibility of additional 90Sr-rich contamination after release of the particles.

Atmospheric Activity Concentration of 90Sr and 137Cs after the Fukushima Daiichi Nuclear Accident.

On March 11, 2011, the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident occurred and large amounts of radionuclides were discharged into the atmosphere. We have operated continuous aerosol samplings at four locations in Japan from the accident until the end of 2011. The activities of 90Sr and 137Cs in the aerosol samples were measured using low background liquid scintillation counters and high-purity germanium detectors, respectively. The atmospheric 90Sr and 137Cs concentrations decreased exponentially during 2011. The time variation of the 90Sr/137Cs ratio was obtained, and we found that the ratio rose from 1.2 × 10-3 in March to 1.3 × 10-1 in August 2011. One reason for the increase in the 90Sr/137Cs ratio could be the change in the primary emission source of activity at the FDNPP, which occurred near June 2011.

Nondestructive elemental depth-profiling analysis by muonic X-ray measurement.

Elemental analysis of materials is fundamentally important to science and technology. Many elemental analysis methods have been developed, but three-dimensional nondestructive elemental analysis of bulk materials has remained elusive. Recently, our project team, dreamX (damageless and regioselective elemental analysis with muonic X-rays), developed a nondestructive depth-profiling elemental analysis method after a decade of research. This new method utilizes a new type of probe; a negative muon particle and high-energy muonic X-rays emitted after the muon stops in a material. We performed elemental depth profiling on an old Japanese gold coin (Tempo-Koban) using a low-momentum negative muon beam and successfully determined that the Au concentration in the coin gradually decreased with depth over a micrometer length scale. We believe that this method will be a promising tool for the elemental analysis of valuable samples, such as archeological artifacts.

Feasibility studies towards future self-sufficient supply of the (99)Mo-(99m)Tc isotopes with Japanese accelerators.

In order to establish a self-sufficient supply of (99m)Tc, we studied feasibilities to produce its parent nucleus, (99)Mo, using Japanese accelerators. The daughter nucleus, (99m)Tc, is indispensable for medical diagnosis. (99)Mo has so far been imported from abroad, which is separated from fission products generated in nuclear reactors using enriched (235)U fuel. We investigated (99m)Tc production possibilities based on the following three scenarios: (1) (99)Mo production by the (n, 2n) reaction by spallation neutrons at the J-PARC injector, LINAC; (2) (99)Mo production by the (p, pn) reaction at Ep = 50-80 MeV proton at the RCNP cyclotron; (3) (99m)Tc direct production with a 20 MeV proton beam from the PET cyclotron. Among these three scenarios, scenario (1) is for a scheme on a global scale, scenario (2) works in a local area, and both cases take a long time for negotiations. Scenario (3) is attractive because we can use nearly 50 PET cyclotrons in Japan for (99m)Tc production. We here consider both the advantages and disadvantages among the three scenarios by taking account of the Japanese accelerator situation.

Excited-state characteristics of tetracyanidonitridorhenium(V) and -technetium(V) complexes with N-heteroaromatic ligands.

Six-coordinate tetracyanidonitridorhenium(V) and -technetium(V) with axial N-heteroaromatic ligands, (PPh4)2[MN(CN)4L] [M = Re, L = 4-(dimethylamino)pyridine (dmap), 3,5-lutidine (lut), 4-picoline (pic), 4-phenylpyridine (ppy), pyridine (py), 3-benzoylpyridine (3bzpy), 4,4'-bipyridine (bpy), pyrazine (pz), 4-cyanopyridine (cpy), or 4-benzoylpyridine (4bzpy); M = Tc, L = dmap, lut, pic, py, pz, or cpy] were synthesized and characterized. The crystal structures of 11 complexes were determined by single-crystal X-ray analysis. All of the complexes showed photoluminescence in the crystalline phase at room temperature. The emission maximum wavelengths (λ(em)) of the rhenium complexes with dmap, lut, pic, ppy, or py were similar to one another with a quite high emission quantum yield (Φ(em)): λ(em) = 539-545 nm, Φ(em) = 0.39-0.93, and emission lifetime (τ(em)) = 10-45 µs at 296 K. The emission spectra at 77 K exhibited vibronic progressions, and the emissive excited state is characterized as (3)[(d(xy))(1)(dπ*)(1)] (dπ* = d(xz), d(yz)). On the other hand, the emission maximum wavelength of the rhenium complex with 3bzpy, bpy, pz, cpy, or 4bzpy was significantly dependent on the nature of the axial ligand in the crystalline phase: λ(em) = 564-669 nm, Φ(em) ≤ 0.01-0.36, and τ(em) = 0.03-13.3 µs at 296 K. The emission spectra at 77 K in the crystalline phase did not show vibronic progressions. The emissive excited state of the rhenium complex with bpy, pz, cpy, or 4bzpy is assignable to originate from the metal-to-N-heteroaromatic ligand charge-transfer (MLCT)-type emission with a spin-triplet type. The change in the excited-state characteristics of rhenium complexes by the N-heteroaromatic ligand is a result of stabilization of the π* orbital of the N- heteroaromatic ligand to a lower energy level than the dπ* orbitals. The emission spectral shapes of technetium complexes were almost independent of the nature of the N-heteroaromatic ligand with λ(em) = 574-581 nm at room temperature. The different emission characteristics between the pz and cpy coordinate rhenium complexes and the technetium analogues would be due to stabilization of technetium-centered orbitals compared with the rhenium ones in energy.

Measurement of the Md3+/Md2+ reduction potential studied with flow electrolytic chromatography.

The reduction behavior of mendelevium (Md) was studied using a flow electrolytic chromatography apparatus. By application of the appropriate potentials on the chromatography column, the more stable Md(3+) is reduced to Md(2+). The reduction potential of the Md(3+) + e(-) → Md(2+) couple was determined to be -0.16 ± 0.05 V versus a normal hydrogen electrode.

Second primary squamous cell carcinoma arising in a skin flap: a case report and literature review on etiologic factors and treatment strategy.

The number of reports describing malignant tumors arising in flaps has been increasing recently. This report describes the case of a patient who had a second squamous cell carcinoma (SCC) in the center of the skin island of a forearm flap raised approximately 6 years previously. Histopathologic examination suggested human papillomavirus infection and "mucosalization" of the flap. In addition, the authors review previous cases, with special attention to etiologic factors and surgical strategies. There might be a causal relation between second primary SCC in the flap and the carcinogenic effect (chronic inflammation) induced by the environment surrounding the squamous epithelium of the flap. If environmental factors have greatly contributed to the occurrence of a tumor, there is a potential for tumor occurrence in the remaining flap. There also might be a potential for generating second primary SCC in these foci. The results suggested that total resection of the flap might be recommended in the surgical resection of second primary SCC arising in a flap.

Photoluminescence switching with changes in the coordination number and coordinating volatile organic compounds in tetracyanidonitridorhenium(V) and -technetium(V) complexes.

Six-coordinate distorted octahedral tetracyanidonitridorhenium(V) and -technetium(V) complexes with a volatile organic compound (VOC) coordinating at the trans position of a nitrido ligand, (PPh4)2[MN(CN)4L] (M = Re, L = MeOH, EtOH, acetone, or MeCN; M = Tc, L = MeOH), and five-coordinate square-pyramidal tetracyanidonitrido complexes without an axial ligand, (PPh4)2[MN(CN)4] (M = Re or Tc), were synthesized and characterized. Single-crystal X-ray structural analysis was carried out for (PPh4)2[MN(CN)4L] (M = Re, L = MeOH, EtOH, or acetone; M = Tc, L = MeOH) and (PPh4)2[ReN(CN)4]. All complexes studied showed photoluminescence in the solid state at room temperature. Reversible luminescence switching between six- and five-coordinate rhenium(V) complexes and between the relevant six-coordinate rhenium(V) complexes except that between the MeCN and acetone complexes was achieved by exposing them to VOC vapor in the solid state at room temperature. Luminescence changes were observed from the five-coordinate technetium(V) complexes in a MeOH vapor atmosphere in the solid state. In contrast, no vapochromic luminescence was observed from the five- and six-coordinate complexes in an acetone vapor atmosphere.

Minimally invasive endoscopic osteosynthesis for frontozygomatic fracture: a new approach.

Miniplate fixation on the lateral face of the orbital rim using existing endoscopic methods for frontozygomatic fracture still has some disadvantages, such as cosmetic disturbance from the lateral brow incision for the trocar, and abnormal palpability of the miniplate. We applied a new method of endoscopic osteosynthesis by access through temporal incisions alone and miniplate fixation on the lateral temporal face of the frontozygoma. Postoperative courses were uneventful in all four cases treated, and we achieved cosmetic improvement (minimizing incision and scars) as well as decreased palpability of the miniplate.

Tuning the Ground- and Excited-State Redox Potentials of Octahedral Hexanuclear Rhenium(III) Complexes by the Combination of Terminal Halide and N-Heteroaromatic Ligands.

The present study reports that the ground- and excited-state Re6(23e)/Re6(24e) redox potentials of an octahedral hexanuclear rhenium(III) complex can be controlled by systematically changing the number and type of the N-heteroaromatic ligand (L) and the number of chloride ions at the six terminal positions. Photoirradiation of [Re6(µ3-S)8Cl6]4- with an excess amount of L afforded a mono-L-substituted hexanuclear rhenium(III) complex, [Re6(µ3-S)8Cl5(L)]3- (L = 4-dimethylaminopyridine (dmap), 3,5-lutidine (lut), 4-methylpyridine (mpy), pyridine (py), 4,4'-bipyridine (bpy), 4-cyanopyridine (cpy), and pyrazine (pz)). The bis- and tris-lut-substituted complexes, trans- and cis-[Re6(µ3-S)8Cl4(lut)2]2- and mer-[Re6(µ3-S)8Cl3(lut)3]-, were synthesized by the reaction of [Re6(µ3-S)8Cl6]3- with an excess amount of lut in refluxed N,N-dimethylformamide. The mono-L-substituted complexes showed one-electron redox processes assignable to E 1/2[Re6(23e)/Re6(24e)] = 0.49-0.58 V versus Ag/AgCl. The ground-state oxidation potentials were linearly correlated with the pK a of the N-heteroaromatic ligand [pK a(L)], the 1H NMR chemical shift of the ortho proton on the coordinating ligand, and the Hammett constant (σ) of the pyridyl-ligand substituent. The series of [Re6(µ3-S)8X6-n (L) n ] n-4 complexes (n = 0, X = Cl, Br, I, or NCS; n = 1-3, X = Cl) showed a linear correlation with the sum of the Lever electrochemical parameters at the six terminal ligands (ΣE L). The cyclic voltammograms of the mono-L-substituted complexes (L = bpy, cpy, and pz) showed one-electron redox waves assignable to E 1/2(L0/L-) = -1.28 to -1.48 V versus Ag/AgCl. Two types of photoluminescences were observed for the complexes, originating from the cluster core-centered excited triplet state (3CC) for L = dmap, lut, mpy, and py and from the metal-to-ligand charge-transfer excited triplet state (3MLCT) for L = bpy, cpy, and pz. The complexes with the 3CC character exhibited emission features and photophysical properties similar to those of ordinary hexanuclear rhenium complexes. The emission maximum wavelength of the complexes with 3MLCT shifted to the longer wavelength in the order L = 4-phenylpyridine (ppy), bpy, pz, and cpy, which agreed with the difference between E 1/2[Re6(23e)/Re6(24e)] and E 1/2(L0/L-). The calculated oxidation potential of the excited hexanuclear rhenium complex with the 3CC character was linearly correlated with pK a(L), σ, and ΣE L. The ground- and excited-state oxidation potentials were finely tuned by the combination of halide and L ligands at the terminal positions.

Coprecipitation with samarium hydroxide using multitracer produced through neutron-induced fission of 235U toward chemical study of heavy elements.

For new chemical studies on heavy elements, we previously investigated the coprecipitation behaviors with samarium hydroxide for various elements. Herein, we report the coprecipitation experiment using multitracer produced by neutron-induced fission of 235U. The coprecipitation behaviors of 10 elements were investigated: new data were obtained for Sr, Ru, I, Pm, and Np. The present results support the previously obtained conclusion that the hydroxide precipitation properties of various elements can be qualitatively investigated through their coprecipitation behaviors.

Non-destructive 3D imaging method using muonic X-rays and a CdTe double-sided strip detector.

Elemental analysis based on muonic X-rays resulting from muon irradiation provides information about bulk material composition without causing damage, which is essential in the case of precious or otherwise unreachable samples, such as in archeology and planetary science. We developed a three-dimensional (3D) elemental analysis technique by combining the elemental analysis method based on negative muons with an imaging cadmium telluride double-sided strip detector (CdTe-DSD) designed for the hard X-ray and soft [Formula: see text]-ray observation. A muon irradiation experiment using spherical plastic samples was conducted at the Japan Proton Accelerator Research Complex (J-PARC); a set of projection images was taken by the CdTe-DSD, equipped with a pinhole collimator, for different sample rotation angles. The projection images measured by the CdTe-DSD were utilized to obtain a 3D volumetric phantom by using the maximum likelihood expectation maximization algorithm. The reconstructed phantom successfully revealed the 3D distribution of carbon in the bulk samples and the stopping depth of the muons. This result demonstrated the feasibility of the proposed non-destructive 3D elemental analysis method for bulk material analysis based on muonic X-rays.

Astatine-211-Labeled Gold Nanoparticles for Targeted Alpha-Particle Therapy via Intravenous Injection.

Alpha-particle radiotherapy has gained considerable attention owing to its potent anti-cancer effect. 211At, with a relatively short half-life of 7.2 h, emits an alpha particle within a few cell diameters with high kinetic energy, which damages cancer cells with high biological effectiveness. In this study, we investigated the intravenous injection of 211At-labeled gold nanoparticles (AuNPs) for targeted alpha-particle therapy (TAT). Different kinds of surface-modified gold nanoparticles can be labeled with 211At in high radiochemical yield in 5 min, and no purification is necessary. The in vivo biodistribution results showed the accumulation of 5 nm 211At-AuNPs@mPEG at 2.25% injection dose per gram (% ID/g) in tumors within 3 h via the enhanced permeability and retention (EPR) effect. Additionally, we observed a long retention time in tumor tissues within 24 h. This is the first study to demonstrate the anti-tumor efficacy of 5 nm 211At-AuNPs@mPEG that can significantly suppress tumor growth in a pancreatic cancer model via intravenous administration. AuNPs are satisfactory carriers for 211At delivery, due to simple and efficient synthesis processes and high stability. The intravenous administration of 5 nm 211At-AuNPs@mPEG has a significant anti-tumor effect. This study provides a new framework for designing nanoparticles suitable for targeted alpha-particle therapy via intravenous injection.

Design and synthesis of new fluorescent probe for rapid and highly sensitive detection of proteins via electrophoretic gel stain.

A new fluorescent molecular probe, 2,2'-(1E,1'E)-2,2'-(4-(dicyanomethylene)-4H-pyrane-2,6-diyl)bis(ethene-2,1-diyl)bis(sodium benzenesulfonate) salt (1), possessing the cyanopyranyl moieties and two benzene sulfonic acid groups was designed and synthesized to detect proteins in solution and for high-throughput SDS-PAGE. Compound 1 exhibited no fluorescence in the absence of proteins; however, it exhibited strong fluorescence on the addition of bovine serum albumin as a result of intramolecular charge transfer. Compared with the conventional protocols for in-gel protein staining, such as SYPRO Ruby and silver staining, 1 achieves higher sensitivity, even though it offers a simplified, higher throughput protocol. In fact, the total time required for protein staining was 60-90 min under optimum conditions much shorter than that required by the less-sensitive silver staining or SYPRO Ruby staining protocols. Moreover, 1 was successfully applied to protein identification by mass spectrometry via in-gel tryptic digestion, Western blotting, and native PAGE together with protein staining by 1, which is a modified protocol of blue native PAGE (BN-PAGE). Thus, 1 may facilitate high-sensitivity protein detection, and it may be widely applicable as a convenient tool in various scientific and medical fields.