Low-toxic Mn-doped ZnSe@ZnS quantum dots conjugated with nano-hydroxyapatite for cell imaging

Fluorescent bio-imaging has received significant attention in a myriad of research disciplines, and QDs are playing an increasingly important role in these areas. Doped QDs, an important alternative to conventional heavy metal-containing QDs are employed for biomedical applications. However, since QDs are exogenous substances to the biological environment, the biocompatibility of QDs is expected to be challenging in some cases. Herein, nano fluorine-doped hydroxyapatite (FAp, a well-known biocompatible material) was introduced to endow biocompatibility to Cd-free Mn-doped ZnSe@ZnS QDs. Thus, a nano-FAp-QD conjugate was developed and the biocompatibility, as well as potential cell imaging application, was investigated. To construct the proposed conjugate, Cd-free highly luminescent Mn-doped ZnSe@ZnS QDs and monodispersed nano-FAp were first prepared in high-temperature organic media. For facilitating the conjugation, hydrophobic nano-FAp was made water soluble via o-phosphoethanolamine (PEA) coating, which further provides conjugating sites for QDs to anchor. Cytotoxicity studies indicated the developed conjugate indeed possesses good compatibility and low toxicity to cells. The nano-FAp-QDs conjugate was successfully employed for cancer cell staining for at least 24 h, demonstrating the potential usefulness of this material in future biomedical research.

Inductively coupled plasma mass spectrometry-based immunoassay: a review

The last 10 years witnessed the emerging and growing up of inductively coupled plasma mass spectrometry (ICPMS)-based immunoassay. Its high sensitivity and multiplex potential have made ICPMS a revolutionary technique for bioanalyte quantification after element-tagged immunoassay. This review focuses on the major developments and the applications of ICPMS-based immunoassay, with emphasis on methodological innovations. The ICPMS-based immunoassay with elemental tags of metal ions, nanoparticles, and metal containing polymers was discussed in detail. The recent development of multiplex assay, mass cytometry, suspension array, and surface analysis demonstrated the versatility and great potential of this technique. ICPMS-based immunoassay has become one of the key methods in bioanalysis.

Analytical method for the determination of trace toxic elements in milk based on combining Fe3O4 nanoparticles accelerated UV fenton-like digestion and solid phase extraction

A UV Fenton-like digestion method was developed first time for a complete digestion of milk samples by using 1.6 g L(-1) Fe3O4 magnetic nanoparticles, 0.2% (v/v) nitric acid, and 6% (w/w) H2O2. During the digestion, the liberated As-, Sb-, and Bi-containing species were preconcentrated onto the surface of Fe3O4 magnetic nanoparticles, which were conveniently separated with a hand-held magnet and subsequently dissolved in hydrochloric acid prior to hydride generation atomic fluorescence spectrometric detection. Owing to the integration of UV Fenton-like digestion, solid phase extraction, and magnetic separation into a single step, the developed method significantly simplifies sample preparation steps and reduces chemical consumption and hazardous waste. Limits of detection of 0.0015, 0.0022, and 0.0025 μg L(-1) were obtained for As, Sb, and Bi, respectively, using a 50 mL milk sample. The method was applied to the determination of these elements in a Certified Reference Material and milk samples.

Graphical user interface for yield and dose estimations for cyclotron-produced technetium

The cyclotron-based (100)Mo(p,2n)(99m)Tc reaction has been proposed as an alternative method for solving the shortage of (99m)Tc. With this production method, however, even if highly enriched molybdenum is used, various radioactive and stable isotopes will be produced simultaneously with (99m)Tc. In order to optimize reaction parameters and estimate potential patient doses from radiotracers labeled with cyclotron produced (99m)Tc, the yields for all reaction products must be estimated. Such calculations, however, are extremely complex and time consuming. Therefore, the objective of this study was to design a graphical user interface (GUI) that would automate these calculations, facilitate analysis of the experimental data, and predict dosimetry. The resulting GUI, named Cyclotron production Yields and Dosimetry (CYD), is based on Matlab®. It has three parts providing (a) reaction yield calculations, (b) predictions of gamma emissions and (c) dosimetry estimations. The paper presents the outline of the GUI, lists the parameters that must be provided by the user, discusses the details of calculations and provides examples of the results. Our initial experience shows that the proposed GUI allows the user to very efficiently calculate the yields of reaction products and analyze gamma spectroscopy data. However, it is expected that the main advantage of this GUI will be at the later clinical stage when entering reaction parameters will allow the user to predict production yields and estimate radiation doses to patients for each particular cyclotron run.

Antiemesis effect and brain fMRI response of gastric electrical stimulation with different parameters in dogs

BACKGROUND

The aims of this study were to investigate the effect of gastric electrical stimulation (GES) with different parameters on emesis induced by apomorphine, and possible center mechanisms by brain functional magnetic resonance imaging (fMRI).

METHODS

Six dogs implanted with electrodes on gastric serosa were used in this study. Part 1: Apomorphine was injected in the control session and GES sessions. GESs with different parameters were applied in GES session. Gastric slow waves and emesis and behaviors suggestive of nausea were recorded in each session. Part 2: Each dog was anesthetized and given GESs with different parameters or sham stimulation for 15 min after baseline (5 min), respectively. The location of cerebral activation induced by GES was investigated by fMRI.

KEY RESULTS

Apomorphine induced emesis and behaviors suggestive of nausea, and gastric dysrhythmia. The emesis frequency in control session was 5.5 ± 0.99, and symptoms score was 22.17 ± 1.01. GES with short pulse and long pulse could not improve emesis and symptoms induced by apomorphine. The emesis frequency (4.5 ± 0.76 in short pulse and 6.33 ± 1.05 in long pulse) and symptoms scores had no significant difference compared to control session (each p > 0.05). GES with trains of short pulse reduced emesis time frequency (3.83 ± 0.7, p = 0.042 vs control) and symptoms score (p = 0.037 vs control) obviously. Brain fMRI showed that GES with short pulse and long pulse activated brain stem region, and trains of short pulse made amygdala and occipital lobe activation.

CONCLUSIONS & INFERENCES

Apomorphine induced emesis and gastric dysrhythmia. GES with trains of short pulses relieves emetic responses through activation of amygdala region.

Electrothermal vaporization for universal liquid sample introduction to dielectric barrier discharge microplasma for portable atomic emission spectrometry

Direct introduction of liquid sample into a microplasma for analytical atomic spectrometry can be a problem for its lowered atomization/excitation capability or can even extinguish it. The low power dielectric barrier discharge (DBD) microplasma has been widely used in optical spectrometry, but the number of detectable elements by atomic emission spectrometry (AES) is very limited, partially for the same reason. Here we use electrothermally vaporized analyte-containing species for sample introduction into a DBD microplasma, together with simple heating of the DBD, to enhance its atomization/excitation capability for AES. A compact tungsten coil electrothermal vaporizer (W-coil ETV) was used in this work, onto which a tiny volume of liquid sample was pipetted. Through administrating the heating program for the W-coil, sample solvent and matrix were removed first and subsequently atomized/vaporized analyte with extra energy provided by the W-coil was swept directly into the DBD microplasma for further atomization/excitation. These significantly contribute the stability of the DBD microplasma and save its power for reatomization/excitation of analyte thus improving the detectability. Under optimized experimental conditions, limits of detection of 0.8 μg L(-1) (0.008 ng) for cadmium and 24 μg L(-1) (0.24 ng) for zinc were obtained, with relative standard deviation (RSD) of 3.2% for 5 μg L(-1) Cd and 3.7% for 100 μg L(-1) Zn. Its potential application was also demonstrated by successfully analyzing several Certified Reference Materials. Its characteristics including compactness, low power consumption, cost effectiveness, tiny sample requirement, and easy operation make it very promising for field analytical chemistry.

Schistosoma japonicum: susceptibility of neonate mice born to infected and noninfected mothers following subsequent challenge

This study was to investigate the differences between neonate mice born to Schistosoma japonicum-infected mothers and those born to noninfected mothers in subsequent challenge. The intensity of infection (evidenced by worm burden and liver egg burden) and liver immunopathology (number and size of liver granulomas) were significantly reduced in neonates from infected mothers (I.M.) compared with neonates from noninfected mothers (N.M.). Anti-soluble worm antigen of S. japonicum (SWA) IgG could be detected in sera of neonates from I.M. (N.N./I.M.) at 1 week after delivery, remained a plateau for 2 weeks and gradually decreased until 8 weeks of age. Parasite-specific IgM was not detected in sera from N.N./I.M. at any time after delivery. At 6 weeks after infection, the level of anti-SWA IgG in infected neonates from I.M. (I.N./I.M.) was significantly higher than that of infected neonates from N.M. (I.N./N.M.). In addition, production of IFN-γ, IL-12 and TGF-β by cultured splenocytes from I.N./I.M. was significantly increased, while the level of IL-4 was significantly decreased when compared to those from I.N./N.M.. These data demonstrate that congenital exposure to schistosomiasis japonica may render neonatal mice born to I.M. less susceptible to subsequent challenge and result in down-regulation of both infection intensity and immunopathology.

Inferred cosmic-ray spectrum from Fermi large area telescope γ-ray observations of Earth's limb

Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range ∼90  GeV-6  TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above ∼200  GeV, respectively.

Semicondutor quantum dots-based metal ion probes

Semiconductor quantum dots (QDs) exhibit unique optical and photophysical properties that offer significant advantages over organic dyes as optical labels for chemo/bio-sensing. This review addresses the methods for metal ion detection with QDs, including photoluminescent, electrochemiluminescent, photoelectrochemical, and electrochemical approaches. The main mechanisms of direct interaction between QDs and metal ions which lead to photoluminescence being either off or on, are discussed in detail. These direct interactions provide great opportunities for developing simple yet effect metal ion probes. Different methods to design the chemically-modified QD hybrid structures through anchoring metal ion-specific groups onto the surface of QDs are summarized. Due to the spatial separation of the luminescence center and analyte recognition sites, these chemically-modified QDs offer greatly improved sensitivity and selectivity for metal ions. Several interesting applications of QD-based metal ion probes are presented, with specific emphasis on cellular probes, coding probes and sensing with logic gate operations.

Dual-mode chemical vapor generation for simultaneous determination of hydride-forming and non-hydride-forming elements by atomic fluorescence spectrometry

A dual-mode chemical vapor generation system was developed for simultaneous multi-element analysis of hydride-forming and non-hydride-forming elements.