Detection of human serum albumin using a rare-earth nanosheet fluorescent probe based on intensity and lifetime signals.

Human serum albumin (HSA) is an important biomarker for early disease diagnosis. Therefore, the detection of HSA in biological samples is important. In this study, for the sensitive detection of HSA, a fluorescent probe based on Eu(III)-doped yttrium hydroxide nanosheets was designed and sensitized by α-thiophenformyl acetone trifluoride as an antenna. The morphology and structure of the as-prepared nanosheet fluorescent probe were studied by transmission electron microscopy and atomic force microscopy. A detailed investigation of the fluorescence properties of the as-obtained nanosheet probe revealed that the Eu(III) emission intensity was linearly and selectively enhanced by the consecutive addition of HSA. Furthermore, the lifetime signal of this probe was enhanced with increasing concentration. The sensitivity of the nanosheet probe to HSA is discussed based on the results of ultraviolet-visible, fluorescence, and infrared spectral analyses, the findings demonstrate that the nanosheet fluorescent probe we prepared is a highly sensitive and selective tool for detecting HSA concentration with a high intensity and a large lifetime change.

Preparation and characterization of two novel osteoinductive fishbone-derived biphasic calcium phosphate bone graft substitutes.

Many studies have reported on the conversion of natural resources into xenografts with hydroxyapatite (HA) as major component, but the extraction of biphasic calcium phosphate (HA/ß-TCP) from animal bones and transformation into bone graft substitutes are rarely reported. In this research, two kinds of fish bones were made into granular porous biphasic calcium phosphate bone graft substitutes with particle sizes between 500 to 1000 µm through a series of preparation procedures (Salmo salar calcined at 900°C named Sa900 and Anoplopoma fimbria calcined at 800°C named An800). The chemical composition was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The morphology and porous structure of the scaffolds were comparatively analyzed by scanning electron microscopy (SEM) and mercury porosimeter. The specific surface area of materials was measured by the nitrogen adsorption technique based on BET theory. Cytotoxicity and ectopic osteogenesis were also carried out to investigate the biocompatibility and osteoinductive potential of these materials. The results showed that both fishbone-derived scaffolds were composed of HA and ß-TCP with different proportions, and numerous interconnected pores with different sizes were observed at the surface of materials. An800 had higher total porosity reaching 74.8% with higher interconnectivity and micropores mostly distributed at 0.27 µm and 0.12 µm, while Sa900 had a higher specific surface area and higher intraparticle porosity with nanopores mostly distributed at 0.07 µm. CCK-8 assays and Live/dead staining demonstrated excellent biocompatibility. Material-induced osteoid formation were observed on the interface of both internal pores and periphery of materials after implantation in muscle pouch of Wistar rats for 8 weeks which indicated some extent of osteoinductive potential of materials. The possible mechanism of material-induced osteogenesis and the effects of chemical composition, surface topography, and spatial structure on osteogenesis were also discussed in this paper.

Sugar-Derived Isotropic Nanoscale Polycrystalline Graphite Capable of Considerable Plastic Deformation.

Obtaining large plastic deformation in polycrystalline van der Waals (vdW) materials is challenging. Achieving such deformation is especially difficult in graphite because it is highly anisotropic. The development of sugar-derived isotropic nanostructured polycrystalline graphite (SINPG) is discussed herein. The structure of this material preserves the high in-plane rigidity and out-of-plane flexibility of graphene layers and enables prominent plasticity by activating the rotation of nanoscale (5-10 nm) grains. Thus, micrometer-sized SINPG samples demonstrate enhanced compressive strengths of up to 3.0 GPa and plastic strains of 30-50%. These findings suggest a new pathway for enabling plastic deformation in otherwise brittle vdW materials. This new class of nanostructured carbon materials is suitable for use in a broad range of fields, from semiconductor to aerospace applications.

Gd/Y Hydroxide Nanosheets as Highly Efficient T1/T2 MRI Contrast Agents.

To develop highly efficient T1/T2 magnetic resonance imaging (MRI) contrast agents (CAs), Gd/Y hydroxide nanosheets were synthesized by a simple exfoliation method from layer compounds using sodium polyacrylate (PAA) as a dispersant and stabilizer. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) results revealed the excellent performance of monolayer nanosheets with thicknesses of up to 1.5 nm. The MRI results of the T1 and T2 relaxation times showed that all of the Gd/Y hydroxide nanosheets have high longitudinal and transverse relaxivities (r1 and r2). In particular, the 10% Gd-LRH nanosheets exhibited excellent MRI performance (r1 = 103 mM-1 s-1, r2 = 372 mM-1 s-1), which is rarely reported. Based on the relationship between the structure of 10% Gd-LRH nanosheets and their MRI performances, and the highly efficient MRI of spaced Gd atoms in the nanosheets, a special model to explain the outstanding MRI performance of the 10% Gd-LRH nanosheets is suggested. The cytotoxicity assessment of the 10% Gd-LRH nanosheets, evaluated by CCK-8 assays on HeLa cells, indicated no significant cytotoxicity. This study presents a significant advancement in 2D nanomaterial MRI CA research, with Gd-doped nanosheets positioned as highly efficient T1/T2 MRI CA candidates.

A selective and sensitive fluorescent probe for bilirubin in human serum based on europium(III) post-functionalized Zr(IV)-Based MOFs.

In the present study, a kind of Eu(III) post-functionalized Zr(IV)-based metal-organic framework (UiO-66(COOH)2, Zr-MOF: Eu3+) was synthesized and utilized as an independently luminescent probe for sensing bilirubin (BR) in human serum, a biomarker of jaundice hepatitis. It can be served as a turn-off fluorescent switch for BR because its red emission from Eu3+ can be easily quenched by BR through a fluorescent resonant energy transfer (FRET) process between BR and its ligands, and as a result, BR is recognized successfully. Particularly, Zr-MOF: Eu3+ has shown many appealing properties, such as high sensitivity, quick response (less than 1 min), broad response window (0-15 µM), and excellent selectivity. Most importantly, a kind of portable test paper based on Zr-MOF: Eu3+ probe has been developed for directly assessing the level of BR in real human serum and further diagnosing bilirubin-related diseases via visually observing the luminescent color variation.

Tb(iii)-doped nanosheets as a fluorescent probe for the detection of dipicolinic acid.

A new fluorescent probe based on terbium(iii)-doped nanosheets was designed for detecting low-levels of dipicolinic acid (DPA), a biomarker of bacterial spores. The ability to detect ultra-low concentrations of DPA is therefore of great significance. First, Tb(iii)-doped ytterbium hydroxide nanosheets were obtained by mechanical exfoliation from layered rare-earth hydroxide (LRH) materials. The morphology of the as-synthesized nanosheets was studied by transmission electron microscopy and atomic force microscopy. The Tb(iii)-doped nanosheets are demonstrated to be highly sensitive to DPA, which remarkably enhances Tb(iii) luminescence intensities at a wavelength of 544 nm. Furthermore, Tb(iii) emission increases linearly with DPA concentration. Selectivity studies were conducted by adding different competing aromatic ligands to the sensing solution; however, their fluorescence responses were observed to be negligibly small in comparison with that of DPA. Our findings provide a basis for the application of Tb(iii)-doped nanosheets for accurate, sensitive, and selective monitoring of DPA as a biomarker of anthrax.

Selective non-enzymatic total bilirubin detection in serum using europium complexes with different ß-diketone-derived ligands as luminescence probes.

Three europium(III) complexes, Eu(ectfd)3 (Hectfd = 1-(9-ethyl-9H-carbazol-7-yl)-4,4,4-trifluorobutane-1,3-dione), Eu(tta)3 (Htta = 4,4,4-trifluoro-1-(thiophen-2-yl)-butane-1,3-dione), and Eu(dbt)3 (Hdbt = 2-(4',4',4'-trifluoro-1',3'-dioxobutyl)dibenzothiophene), were synthesized and employed to detect total bilirubin (BR) in blood-serum samples. UV-visible absorption and fluorescence (FL) spectroscopies were used to evaluate the selectivity of each europium (III) fluorescence probe to BR, which was shown to remarkably reduce the luminescence intensities of the europium(III) complexes at a wavelength of 612 nm. The luminescence intensity of each complex is linearly related to BR concentration. Eu(tta)3 was shown to be the more-appropriate fluorescence probe for the sensitive and reliable detection of total BR in blood serum samples than either Eu(ectfd)3 or Eu(dbt)3. This observation can be ascribed to special σ-hole bonding between Htta and BR. In addition, the optimal pH test conditions for the detection of BR in human serum by the Eu(tta)3 probe were determined. Sensitivity was shown to be dramatically affected by the pH of the medium. The experimental results reveal that pH 7.5 is optimal for this probe, which coincides with the pH of human serum. Furthermore, BR detection using the Eu(tta)3 luminescence probe is simple, practical, and relatively free of interference from coexisting substances; it has a minimum detection limit (DL) of 68 nM and is a potential candidate for the routine assessment of total BR in serum samples. Graphical Abstract ᅟ.

Sensitive detection of free bilirubin in blood serum using ß-diketone modified europium-doped yttrium oxide nanosheets as a luminescent sensor.

Free bilirubin, when present in excess in the human body, can cause a multitude of diseases and disorders and even be fatal; hence, detecting it is of paramount importance. Herein, we report a luminescence quenching-based non-enzymatic method for the convenient, reliable, and rapid detection of free bilirubin in blood serum samples using sensing films (nanosheets/PS, nanosheets-tta/PS, and nanosheets-dbt/PS) as luminescent sensors. The luminescence intensity of the sensing films is linearly related to the free bilirubin concentration. Nanosheets-tta/PS demonstrated excellent sensing properties for the sensitive and reliable detection of free bilirubin in the range of 0.0-60.0 µM with a correlation coefficient of 0.9915, as compared to nanosheets/PS or nanosheets-dbt/PS. The limit of detection for the determination of free bilirubin was 41 nM. This method can be used to design a sensor-based test spot as a medical detection device for the visual detection of free bilirubin.

Effects of small-grit grinding and glazing on mechanical behaviors and ageing resistance of a super-translucent dental zirconia.

OBJECTIVES: The purpose of this study is to elucidate the effects of small-grit grinding on the mechanical behaviors and ageing resistance of a super-translucent dental zirconia and to investigate the necessity of glazing for the small-grit ground zirconia. METHODS: Small-grit grinding was performed using two kinds of silicon carbide abrasive papers. The control group received no grinding. The unground surfaces and the ground surfaces were glazed by an experienced dental technician. Finally, the zirconia materials were thermally aged in water at 134°C for 5h. After aforementioned treatments, we observed the surface topography and the microstructures, and measured the extent of monoclinic phase, the nano-hardness and nano-modulus of the possible transformed zone and the flexural strength. RESULTS: Small-grit grinding changed the surface topography. The zirconia microstructure did not change obviously after surface treatments and thermal ageing; however, the glaze in contact with zirconia showed cracks after thermal ageing. Small-grit grinding did not induce a phase transformation but improved the flexural strength and ageing resistance. Glazing prevented zirconia from thermal ageing but severely diminished the flexural strength. The nano-hardness and nano-modulus of the surface layer were increased by ultrafine grinding. CONCLUSIONS: The results suggest that small-grit grinding is beneficial to the strength and ageing resistance of the super-translucent dental zirconia; however, glazing is not necessary and even impairs the strength for the super-translucent dental zirconia. CLINICAL SIGNIFICANCE: This study is helpful to the researches about dental grinding tools and maybe useful for dentists to choose reasonable zirconia surface treatments.

The effect of graded glass-zirconia structure on the bond between core and veneer in layered zirconia restorations.

OBJECTIVE: The aim of this study was to test the hypothesis that a graded glass-zirconia structure can strengthen the core-veneer bond in layered zirconia materials. METHODS: A graded glass-zirconia structure was fabricated by infiltrating glass compositions developed in our laboratory into a presintered yttria tetrahedral zirconia polycrystal (Y-TZP) substrate by the action of capillary forces. The wettability of the infiltrated glass and Y-TZP substrate was investigated by the sessile drop technique. The microstructures of the graded glass-zirconia structure were examined by scanning electron microscopy (SEM). The phase structure characterization in the graded glass-zirconia structure were identified by X-ray diffraction (XRD) analysis. The elastic modulus and hardness of the graded glass-zirconia structure were evaluated from nanoindentations. Further, the shear bond strength (SBS) of the graded glass-zirconia structure and veneering porcelain was also evaluated. RESULTS: SEM images confirmed the formation of the graded glass-zirconia structure. Glass frits wet the Y-TZP substrate at 1200 °C with a contact angle of 43.2°. Only a small amount of t-m transformation was observed in as-infiltrated Y-TZP specimens. Nanoindentation studies of the glass-zirconia graded structure showed that the elastic modulus and hardness of the surface glass layer were higher than those of the dense Y-TZP layer. The mean SBS values for the graded glass-zirconia structure and veneering porcelain (24.35 ± 0.40 MPa) were statistically higher than those of zirconia and veneering porcelain (9.22 ± 0.20 MPa) (P<0.05). CONCLUSIONS: A graded glass-zirconia structure can be fabricated by the glass infiltration/densification technique, and this structure exhibits a strong core-veneer bond.

Controlled synthesis of ZnS quantum dots and ZnS quantum flakes with graphene as a template.

Novel ZnS quantum dots (QDs) and ZnS quantum flakes (QFs) were successfully prepared with graphene nanosheets (GNs) as a special template, and two unique heterostructures of ZnS/GNs were also obtained. Due to the structure-directing template effect of GNs, the as-synthesized ZnS with different morphologies, dots or flakes, were uniformly distributed on the surface of GNs by controlling nucleation and growth. The two different heterostructures of ZnS/GNs exhibited obvious photovoltaic response, and ZnS/GN QFs-on-sheet heterostructures show higher photovoltage than that of ZnS/GN QDs-on-sheet.

Self-assembly deposition and luminescence properties of TiNbO5(-) and TiTaO5(-) nanosheets.

Through a novel mechanical cleavage technology, TiNbO5(-) and TiTaO5(-) nanosheets were obtained by the exfoliation of the layered KTiTaO5 and KTiNbO5. Lamellar aggregates of the pre-prepared nanosheets accommodating Eu3+ ions have been fabricated by flocculation of colloidal nanosheet. A series of methods including X-ray diffraction (XRD), transmission electron microscopy (TEM) were used to analyze the structure of the as-obtained composites. The results indicated that the restacking nanosheets could form a uniform layered structure. Meanwhile, the Eu3+ ions could enter into the interlayer of the flocculated nanosheets. The Photoluminescence (PL) spectra were also employed to investigate the optical property of the hybrids. The characteristic emission from the composites either by exciting the nanosheet host with UV light or by directly exciting RE at a longer wavelength were studied in details.

Luminescence properties of cubic HfO2-Sc2O3:Eu3+ nano-powders.

The cubic nano-structured HfO2-Sc2O3:Eu3+ were successfully synthesized via a combustion process. Phase evolution of the synthesized powders was determined by X-ray diffraction measurements. Pure cubic phase of HfO2-Sc2O3 solid solution was obtained after being calcined at 800 degrees C for 2 h.The particle size and morphology were analyzed by TEM. The luminescence properties were also investigated. Photoluminescence spectra of Eu3+ doped HfO2-Sc2O3 nano-powders showed red emission at 613 nm which corresponds to the 5D0-7F2 transition of Eu3+ ion.

Combustion synthesis of Eu(3+)-activated Y2Hf7O17 powders.

Eu3+ doped-Y2Hf7O17 nanopowders were synthesized by the chemical self-combustion method at low temperature. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy were employed to analyze the phase composition and the characteristics of the nanopowders. The excitation and emission spectra were analyzed with a fluorescence photometer. Results show that nanoscale powders calcined at 800 degrees C have good luminescent properties. There are two peaks in the emission spectra. One is at 595 nm, and the other is at 614 nm. Analysis of X-ray diffraction and photoluminescence spectra reveals that Y2Hf7O17 is cubic phase. The sample doped with 14 mol% Eu3+ has the maximum luminescent intensity.

Surfactant-assisted growth of novel La2(MoO4)3 dendritic nanostructures via facile hydrothermal processes.

In this paper, we report for the first time the successful synthesis of novel uniform La2(MoO4)3 dendritic single-crystalline nanostructures via a surfactant-assisted hydrothermal approach. The dendritic nanostructure is composed of trunks with length of several micrometers and plenty of side branches. Both of the trunks and the branches are composed of nanoflakes with thickness of 30-50 nm. The branches are oriented nearly parallel to each other and form an angle of about 45 degrees to the trunk. The polyethylene glycol (PEG) acts as a morphology-directing agent, and by adjusting the experimental parameters, the microstructure of the processed materials could be further controlled in a certain range. The action mechanism of the surfactant has been proposed. This method is a simple and economical route for nanostructure fabrication and might provide a practical reference to the controlled synthesis of other micro-architectures. In addition, the photoluminescence properties of La2(MoO4)3:Eu dendritic nanostructures were studied.