Performance of a gaseous detector based energy dispersive X-ray fluorescence imaging system: Analysis of human teeth treated with dental amalgam

Energy dispersive X-ray fluorescence (EDXRF) imaging systems are of great interest in many applications of different areas, once they allow us to get images of the spatial elemental distribution in the samples. The detector system used in this study is based on a micro patterned gas detector, named Micro-Hole and Strip Plate. The full field of view system, with an active area of 28 × 28 mm² presents some important features for EDXRF imaging applications, such as a position resolution below 125 μm, an intrinsic energy resolution of about 14% full width at half maximum for 5.9 keV X-rays, and a counting rate capability of 0.5 MHz. In this work, analysis of human teeth treated by dental amalgam was performed by using the EDXRF imaging system mentioned above. The goal of the analysis is to evaluate the system capabilities in the biomedical field by measuring the drift of the major constituents of a dental amalgam, Zn and Hg, throughout the tooth structures. The elemental distribution pattern of these elements obtained during the analysis suggests diffusion of these elements from the amalgam to teeth tissues.     

Performance of triple coincidence imaging as an addition to dedicated PET

In this work, we investigate the performance of semiconductor detectors imaging capabilities in three-photon annihilation processes in order to combine this novel imaging modality with conventional positron emission tomography. The spatial resolution is studied as a function of detector positions and selected energy window. This was measured from different experimental arrangements and found to be in the range between 3.3–3.9 cm with a mean of 3.5±0.1 cm. Scatter and random events, coincidence timing resolution and count rate performance are discussed.     

A new X-ray pinhole camera for energy dispersive X-ray fluorescence imaging with high-energy and high-spatial resolution

A new X-ray pinhole camera for the Energy Dispersive X-ray Fluorescence (ED-XRF) imaging of materials with high-energy and high-spatial resolution, was designed and developed. It consists of a back-illuminated and deep depleted CCD detector (composed of 1024 × 1024 pixels with a lateral size of 13 μm) coupled to a 70 μm laser-drilled pinhole-collimator, positioned between the sample under analysis and the CCD. The X-ray pinhole camera works in a coaxial geometry allowing a wide range of magnification values.The characteristic X-ray fluorescence is induced on the samples by irradiation with an external X-ray tube working at a maximum power of 100 W (50 kV and 2 mA operating conditions).The spectroscopic capabilities of the X-ray pinhole camera were accurately investigated. Energy response and energy calibration of the CCD detector were determined by irradiating pure target-materials emitting characteristic X-rays in the energy working-domain of the system (between 3 keV and 30 keV).Measurements were performed by using a multi-frame acquisition in single-photon counting. The characteristic X-ray spectra were obtained by an automated processing of the acquired images. The energy resolution measured at the Fe–Kα line is 157 eV.The use of the X-ray pinhole camera for the 2D resolved elemental analysis was investigated by using reference-patterns of different materials and geometries. The possibility of the elemental mapping of samples up to an area of 3 × 3 cm² was demonstrated.Finally, the spatial resolution of the pinhole camera was measured by analyzing the profile function of a sharp-edge. The spatial resolution determined at the magnification values of 3.2 × and 0.8 × (used as testing values) is about 90 μm and 190 μm respectively.     

Wavelength dispersive X-ray fluorescence imaging using a high-sensitivity imaging sensor

A new wavelength-dispersive X-ray fluorescence (WD-XRF) imaging spectrometer equipped with a high-sensitivity imaging sensor was developed in our laboratory. In this instrument, a straight polycapillary optic was applied instead of a Soller slit as well as a 2D imaging X-ray detector instead of X-ray counters, which are used in conventional WD-XRF spectrometers. Therefore, images of elemental distribution were available after a short exposure time. Ni Kα images and Cu Kα images were clearly obtained at corresponding diffraction angles for a short exposure time of 10 s. By optimizing the spectrometer, the time required for imaging is reduced, leading to XRF image movies. It is difficult to distinguish two peaks (Ti Kα (4.508 keV) and Ba Lα (4.465 keV)) due to the poor energy resolution of EDXRS. However, Ti and Ba images could be successfully observed by the WD-XRF imaging spectrometer. The energy resolution of the developed spectrometer was 25 eV at the Ti Kα peak.     

Automated apparatus for the rapid determination of liquid–liquid and solid–liquid phase transitions

An automated apparatus developed for the determination of liquid–liquid and solid–liquid equilibrium temperatures with a resolution of 1 mK and a traceable accuracy of 0.01 K is described. The amount of light transmitted through six sample cells placed in a computer controlled thermostat is recorded at heating or cooling rates from 0.075 to 15 K h⁻¹. The construction does not require expensive optic equipment like lasers, glass fibre optics or photomultipliers, but is based on light emitting diodes (LED) as light sources and light dependent resistors (LDR) or photodiodes as detectors. As shown by the discussed examples, the instrument has a wide range of possible applications from the investigation of simple one-component and binary systems to the study of the complicated phase behavior of surfactant solutions.     

In vivo monitoring of the distribution of a monoclonal antibody fragment

This study demonstrates the potential of in vivo, whole body fluorescence imaging for pharmacokinetic studies. The distribution of a novel human anti-tumour antibody fragment, NovoMab-G2-scFv, labelled with a fluorescent dye (Cy5.5.18) was monitored in vivo. The NovoMab-G2-scFv–Cy5 complex was injected via the tail vein into nude mice bearing subcutaneous human melanoma tumour cells. The distribution of fluorescence NovoMab-G2-scFv–Cy5 was imaged non-invasively using a charge-coupled device (CCD) camera. Whole body fluorescence images were acquired 2, 6, 12, 24, 48 and 72 h post-injection. Fluorescence was detected at the tumour site following injection of NovoMab-G2-scFv–Cy5 but not following injection of a labelled irrelevant antibody fragment, demonstrating specific binding of the antibody–dye complex to the tumour. Fluorescence from the tumour site peaked 2 h post-injection and gradually declined, reaching a minimum 72 h post-injection. Fitting an exponential decay to fluorescence data extracted from images allowed the half-time of the antibody at the tumour site to be calculated, and a value of 7.7 h was obtained.Fluorescence was also apparent in the kidneys, indicating clearance of the NovoMab-G2-scFv through the kidneys. Again, fluorescence intensity decreased with time, reaching a minimum 72 h post-injection. Imaging of isolated organs (ex vivo) confirmed the presence of the antibody–dye complex in the tumours, kidneys and liver. No fluorescence was observed in the brain, heart, lungs or spleen, suggesting that these organs do not accumulate the NovoMab-G2-scFv–dye complex.     

Binary mixing of micelles using Pluronics for a nano-sized drug delivery system

Pluronics with different structural compositions and properties are used for several applications, including drug delivery systems. We developed a binary mixing system with two Pluronics, L121/P123, as a nano-sized drug delivery carrier. The lamellar-forming Pluronic L121 (0.1 wt%) was incorporated with Pluronic P123 to produce nano-sized dispersions (in case of 0.1 and 0.5 wt% P123) with high stability due to Pluronic P123 and high solubilization capacity due to Pluronic L121. The binary systems were spherical and less than 200-nm diameter, with high thermodynamic stability (at least 2 weeks) in aqueous solution. The CMC of the binary system was located in the middle of the CMC of each polymer. In particular, the solubilization capacity of the binary system (0.1/0.1 wt%) was higher than mono-systems of P123. The main advantage of binary systems is overcoming limitations of mono systems to allow tailored mixing of block copolymers with different physicochemical characteristics. These nano-sized systems may have potential as anticancer drug delivery systems with simple preparation method, high stability, and high loading capacity.     

Photochromic fluorescence switching from diarylethenes and its applications

The review describes the photochromic and fluorescent characteristics of various diarylethene (DAET) derivatives, and presents recent research into their applications. This comprises a discussion of the optical characteristics of some DAET-based molecules exhibiting red, green, or blue (RGB) colors or fluorescence. Molecular calculations of the optical properties of DAET interpret intriguing experimental observations and predict photochemical or photophysical properties. In particular, stabilization of HOMO in the BTFOn (n = 1, 2, 3, 4) increases the energy difference between the HOMO and the LUMO, which leads to the blue-shift of absorption and emission bands as the number of oxygen attached to sulfur (n) increases. Various devices and application studies have been designed as photon-mode systems based on photochemical control of the fluorescence energy. The photochromic DAET materials have shown promise as optical data storage, switching devices, and biological applications such as the development of biomaterial sensors, analysis of biological dynamics, and live cell imaging.     

A combined laser-induced breakdown and Raman spectroscopy Echelle system for elemental and molecular microanalysis

Raman and laser-induced breakdown spectroscopy is integrated into a single system for molecular and elemental microanalyses. Both analyses are performed on the same ~ 0.002 mm² sample spot allowing the assessment of sample heterogeneity on a micrometric scale through mapping and scanning. The core of the spectrometer system is a novel high resolution dual arm Echelle spectrograph utilized for both techniques. In contrast to scanning Raman spectroscopy systems, the Echelle–Raman spectrograph provides a high resolution spectrum in a broad spectral range of 200–6000 cm^? 1 without moving the dispersive element. The system displays comparable or better sensitivity and spectral resolution in comparison to a state-of-the-art scanning Raman microscope and allows short analysis times for both Raman and laser induced breakdown spectroscopy. The laser-induced breakdown spectroscopy performance of the system is characterized by ppm detection limits, high spectral resolving power (15,000), and broad spectral range (290–945 nm). The capability of the system is demonstrated with the mapping of heterogeneous mineral samples and layer by layer analysis of pigments revealing the advantages of combining the techniques in a single unified set-up.     

In vitro evaluation of Radachlorin® sensitizer for photodynamic therapy

This paper reports the evaluation of a new photosensitizer, Radachlorin® in comparison with one of its well known components but used solely, Chlorin e₆. The photodynamic properties and cell uptake and localisation of the two drugs were compared. In vitro studies were conducted on human adenocarcinoma cells (HT29) and lung carcinoma cell line (A549). Both dyes showed an absorption maximum between 640 and 650 nm, but those absorption peaks are enhanced by interactions with serum, with a shifted maximum at 661 and 664 nm, and much higher absorbance. As Radachlorin® is constituted of different products and as photoreactivity is dependent on absorbed light energy, we chose to adapt concentrations so that both drugs had the same absorption at the irradiation wavelength (664 nm) for photoreactivity tests, and express concentrations in optical density at 664 nm. The capacity of the two drugs to generate Reactive Oxygen Species was identical, but on HT29 cells, Radachlorin® reaches its optimal LD50 sooner than Chlorin e₆. Radachlorin® LD50 on HT29 cells was 0.0251 OD_664nm after 2 h and 0.0672 OD_664nm for Chlorin e₆ for a 20 J cm^?2 irradiation. Radachlorin® gave very similar results on A549 cells, LD50 being 0.05 for 5 J irradiation, and 0.026 for 10 and 20 J cm^?2. Pharmacokinetics using fluorescence showed that, even if Radachlorin® quickly crossed HT29 (a human colonic cancer line) cell membrane, cellular distribution evolved from a diffuse cytoplasmic repartition 1 hour after Radachlorin® addition to a delimited localisation into organelles all around the nucleus. Radachlorin® intracellular fluorescence decreased after 4 h, whereas we did not observe a decrease of Chlorin e₆ intracellular fluorescence for times up to 24 h. In both case, a quick decline was observed as soon as the culture medium was replaced with a drug-free one. Radachlorin® appears to be an excellent photosensitizer, with similar phototoxicity to Chlorin e₆ on cell cultures, but with quicker kinetics, which could be an improvement if confirmed on further in vivo studies.     

Novel luminescent nanoparticles for DNA detection

Highly luminescent LaF₃:Ce³⁺/Tb³⁺ nanocrystals were successfully prepared and surface functionalized via Layer-by-Layer technology. These as-prepared nanocrystals are highly resistant to photobleaching and pretty dispersible in aqueous solution. Due to the efficient luminescence quenching of the nanocrystals by nucleic acids, a facile fluorescence quenching method was developed for the detection of trace amount of nucleic acids. Under optimal conditions, the fluorescence intensity was proportional to the DNA concentration over the range of 0.60–25.0 μg mL^?1 for calf thymus DNA (ct-DNA) and 0.60–30.0 μg mL^?1 for herring sperm DNA (hs-DNA), respectively. The corresponding detection limit is 0.21 μg mL^?1 for ct-DNA and 0.31 μg mL^?1 for hs-DNA, respectively. The results indicated that the reported method is simple and rapid with wide linear range. Also, the recovery and relative standard deviation of this method are reasonable and satisfactory.     

Direct visualization of chirality in two dimensions

Surface science techniques have been used to investigate 2D chirality induced by molecular adsorption at the Cu(1 1 0) surface. Particular emphasis has been devoted to presenting molecular resolution scanning tunnelling microscope images which provide direct, real-space access to chiral behaviour at the nanoscale. The systems chosen demonstrate the gamut of chiral organization: conglomerates, racemates and solid solutions. They show the creation of chirality from achiral adsorbates, and the enantiospecific hosting of an intrinsic chiral guest. In short, chirality at surfaces manifests its full range of behaviours, and STM provides the means by which that behaviour can be captured.     

Application of non-aggressive sample preparation and electrothermal atomic absorption spectrometry to quantify platinum in biological matrices after cisplatin nanoparticle administration

A reproducible, simple, rapid and sensitive electrothermal atomic absorption spectrometry (ETAAS) method using low volume of sample (< 50 μL) was described for the quantitative analysis of cis-diamminedichloroplatinum (II) (cisplatin) in several biological matrices after PLGA [Poly (d,l-lactic-co-glycolic acid)] cisplatin nanoparticles (NP) administration to tumor-bearing mice. The validation parameters such as specificity, linearity, accuracy and precision obtained in this method were according to FDA guidelines and are presented in the text, as well as the limit of detection and quantification. Two applications were carried out with this method. In-vitro application was used to measure the loading efficacy of cisplatin in the formulation, and to characterize the drug kinetic release in culture cell medium. For in-vivo application, three groups of nu/nu mice injected with tumor cells were treated with 5 mg kg^? 1 dose of free cisplatin by intravenous and intraperitoneal routes, respectively, and with NP by intraperitoneal route. Blood samples were collected at different times, to measure cisplatin plasma concentrations, and at the end of the study, different organs were removed from each animal to quantify drug distribution. Additionally, the relationship between cisplatin levels and its apoptotic activity in each tumor sample, could be also characterized. This simple and sensitive method without aggressive manipulation allowed the quantification of cisplatin in different biological matrices with independence of the formulation used. Therefore, these pre-clinical results show the possibility to include this method for clinical applications.     

An efficient material via meta-position connection as thermally activated delayed fluorescence emitter for organic light-emitting diodes

A novel compound was designed and synthesized by connecting a dicyanobenzene acceptor and two 9,9-dimethyl-9,10-dihydroacridine donors to the 1,3,5-position of a phenyl ring by meta-position connection. This compound, which is a novel emitter for OLED devices, exhibits preferable heat stability. Moreover, the energy gap between its singlet and triplet states is as small as 0.04 eV, resulting in this molecule possesses thermally activated delayed fluorescence. Therefore, the corresponding device showed efficient electroluminescent performances. The maximum external quantum efficiency, maximum current efficiency, maximum power efficiency and maximum luminance were 16.5%, 40.8 cd A^?1, 45.8 lm W^?1 and 5120 cd m^?2, respectively. In addition, the CIE_x,y only changed from (0.22, 0.38) to (0.22, 0.39) over the entire operating voltage range, which confirms that the device possesses highly stable chromaticity with respect to the current density. Based on these experimental results, meta-connected type structures may provide a new approach for developing high-performance TADF emitters for OLED applications.     

A lysosomal targeting fluorescent probe and its zinc imaging in SH-SY5Y human neuroblastoma cells

A fluorescent probe based PET mechanism was designed, and the probe could image endogenous release of Zn²⁺ upon H₂O₂ stimulation in SH-SY5Y cells.     

Binding of the bioflavonoid robinetin with model membranes and hemoglobin: Inhibition of lipid peroxidation and protein glycosylation

Recent years have witnessed burgeoning interest in plant flavonoids as novel therapeutic drugs targeting cellular membranes and proteins. Motivated by this scenario, we explored the binding of robinetin (3,7,3′,4′,5′-pentahydroxyflavone, a bioflavonoid with remarkable ‘two color’ intrinsic fluorescence properties), with egg yolk phosphatidylcholine (EYPC) liposomes and normal human hemoglobin (HbA), using steady state and time resolved fluorescence spectroscopy. Distinctive fluorescence signatures obtained for robinetin indicate its partitioning (K_p = 8.65 × 10⁴) into the hydrophobic core of the membrane lipid bilayer. HbA–robinetin interaction was examined using both robinetin fluorescence and flavonoid-induced quenching of the protein tryptophan fluorescence. Specific interaction with HbA was confirmed from three lines of evidence: (a) bimolecular quenching constant K_q ? diffusion controlled limit; (b) closely matched values of Stern–Volmer quenching constant and binding constant; (c) τ₀/τ = 1 (where τ₀ and τ are the unquenched and quenched tryptophan fluorescence lifetimes, respectively). Absorption spectrophotometric assays reveal that robinetin inhibits EYPC membrane lipid peroxidation and HbA glycosylation with high efficiency.     

Emerging applications of near-infrared fluorescent metal nanoclusters for biological imaging

Recent advances in the development of near-infrared fluorescent metal nanoclusters for bioimaging applications have been thoroughly overviewed.     

Study on the enhanced fluorescent spectrum of ciprofloxacin + Al(III) + La(III) + cetyltrimethylammonium bromide system and its application

The fluorescence of ciprofloxacin (CIP) in HAc–NaAc buffer solution and the presence of cetyltrimethylammonium bromide (CTMAB) enhanced visibly with adding Al(III) and La(III). This enhanced fluorescence spectra were studied, and a new co-luminescence system of CIP + Al(III) + La(III) + CTMAB was discovered. There was a linear relationship between the enhanced fluorescence intensity and the concentration of CIP in the range of 0.50–80.2 μg l^?1 under the optimized condition. A novel enhanced fluorescence method for the determination of trace CIP was established by using this co-luminescence system. The detection limit of the proposed method was 0.17 μg l^?1 for CIP. This method is simple, rapid and sensitive. The CIP in milk samples were analyzed by the proposed method with satisfactory results. The relative standard deviation and the recovery were in ranges of 3.21–4.34% and 97.1–100.1%, respectively. The mechanism of the co-luminescence reaction and the reasons for fluorescence enhancement has been discussed.     

Isobaric specific heat capacity of typical lithium chloride liquid desiccants using scanning calorimetry

Three kinds of lithium chloride desiccants were selected, which are considered to be potential and interesting working fluids for a desiccant/dehumidification or absorption refrigeration system, and their isobaric specific heat capacities were determined in this context. Experiments were conducted at a high accuracy twin-cell scanning calorimeter. The temperature accuracy and heat flux resolution of the calorimeter are ±0.05 K and 0.1 μW respectively. The data of lithium chloride + water and lithium chloride + triethylene glycol (TEG)/propylene glycol (PG) + water systems were achieved at temperatures from 308.15 K to 343.15 K and atmospheric pressure. The mass fraction of LiCl ranged from 15% to 45% in the LiCl + H₂O system, and the mass fraction of LiCl and glycol ranged from 10% to 23.3% and 20% to 46.7% in the ternary systems respectively. Based on the experimental heat capacity data, a universal empirical formula was correlated as a function of temperature and solute mass fraction. In the experimental mass fractions and temperatures range, the average absolute deviation (AAD) between experiment results and calculated values is no more than 0.15%, and maximum absolute deviation (MAD) is within 0.38%. These thermodynamic data of lithium chloride solutions can be effectively used for analysis and design of desiccant/dehumidification systems and absorption refrigeration systems in both refrigeration and chemical industry.     

Electrokinetic pumping system based on nanochannel membrane for liquid delivery

Nonmechanical pumping of liquids is of key importance for applications from the biomedical microfluidic chip to drug delivery systems. In this paper, a new electrokinetic pump (EOP) system with polycarbonate nanochannel membrane sandwiched between two membrane holders was constructed. The pump was tested with water and phosphate buffer at 1-6 V applied voltage, the maximum pressure and flow rate are 0.32 MPa (3.2 atm) and 4.2 mL/min for phosphate buffer, respectively. This proof-of-concept pump shows its potential use for drugs or chemical agents delivery by the usage of different membrane materials.