Yi-Kong Hsieh

Lead determination in whole blood by laser ablation coupled with inductively coupled plasma mass spectrometry

This work describes a simple procedure for blood lead level determination. The proposed method requires little sample pretreatment and subsequent direct analysis of a dried blood spot on a filter membrane using laser ablation coupled with inductively coupled plasma mass spectrometry (LA-ICP-MS). In general, LA-ICP-MS studies are somewhat limited by the lack of matrix-matched standards for calibration purposes. Here we describe aqueous standard calibration and matrix-matched calibration methods. This method was validated by analysis of the reference materials. With the matrix-matched calibration method, the recovery ranged from 97.8% to 112.8%, while the aqueous standard calibration method ranged 90.4% to 122.4%. The lower detection limit was estimated as 0.1 ng mL(-1). The determination precision, expressed as the relative standard deviation (RSD), was not worse than 10% for all results. A sample throughput of approximately 5 min per sample made it possible to rapidly screen a large number of samples.

Using dried-droplet laser ablation inductively coupled plasma mass spectrometry to quantify multiple elements in whole blood

This paper describes a simple procedure for the direct analysis and determination of multiple elements in dried blood samples on a filter membrane using laser ablation coupled with inductively coupled plasma mass spectrometry (LA-ICP-MS). With this technique, we simultaneously quantified 13 elements in whole blood: Be, Mn, Co, Ni, Tl, Bi, Sb, Pb, Cu, Zn, Ba, Mg, and Cd. The measured accuracies was in agreement with the Seronorm CRM certified values, except for Mn, Zn, Ba and Cd, which presented absolute differences higher than the expanded uncertainty for these elements. The within-run precision was less than 5.7% (relative standard deviation, RSD), except for the analyses of Be, and Mn (8.6% and 11.1%, respectively). The reproducibility (between-run precision) was calculated in terms of the RSD obtained for 12 analyses (i.e., four replicates of each sample in three analytical runs). Apart from Be, Mn, and Zn, the reproducibilities of all the elements listed above ranged between 4.0% and 8.5%. In contrast, for Cd, the concentration obtained was significantly different from the certified value; analyses of this element exhibited low reproducibility. Applying the matrix-matched calibration method, the accuracy for Cd measured was in agreement with both SRM966 and BCR 635; thus, matrix-matched calibration is a practical means of overcoming matrix-enhancement effects for the quantification of Cd. Sample throughput (ca. 5 min per sample) made it possible to rapidly screen a larger number of samples relative to other techniques that require time-consuming sample preparation steps (e.g., removal of a portion of the solid sample or digestion).

The in vivo biodistribution and fate of CdSe quantum dots in the murine model: a laser ablation inductively coupled plasma mass spectrometry study

Understanding the cytotoxicity of quantum dots strongly relies upon the development of new analytical techniques to gather information about various aspects of the system. In this study, we demonstrate the in vivo biodistribution and fate of CdSe quantum dots in the murine model by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). By comparing the hot zones of each element acquired from LA-ICP-MS with those in fluorescence images, together with hematoxylin and eosin-stained images, we are able to perceive the fate and in vivo interactions between quantum dots and rat tissues. One hour after intravenous injection, we found that all of the quantum dots had been concentrated inside the spleen, liver and kidneys, while no quantum dots were found in other tissues (i.e., muscle, brain, lung, etc.). In the spleen, cadmium-114 signals always appeared in conjunction with iron signals, indicating that the quantum dots had been filtered from main vessels and then accumulated inside splenic red pulp. In the liver, the overlapped hot zones of quantum dots and those of phosphorus, copper, and zinc showed that these quantum dots have been retained inside hepatic cells. Importantly, it was noted that in the kidneys, quantum dots went into the cortical areas of adrenal glands. At the same time, hot zones of copper appeared in proximal tubules of the cortex. This could be a sign that the uptake of quantum dots initiates certain immune responses. Interestingly, the intensity of the selenium signals was not proportional to that of cadmium in all tissues. This could be the result of the decomposition of the quantum dots or matrix interference. In conclusion, the advantage in spatial resolution of LA-ICP-MS is one of the most powerful tools to probe the fate, interactions and biodistribution of quantum dots in vivo.

Influence of sodium halides (NaF, NaCl, NaBr, NaI) on the photocatalytic performance of hydrothermally synthesized hematite photoanodes.

It has been suggested that a high concentration of Fe(3+) in solution, a low pH, and noncomplexing ions of high ionic strength are all essential for developing a high-quality hematite array. Our curiosity was piqued regarding the role of the electrolyte ions in the hydrothermal synthesis of hematite photoanodes. In this study, we prepared hematite photoanodes hydrothermally from precursor solutions of 0.1 M FeCl3 at pH 1.55 with a background electrolyte of 1.0 M sodium halide (NaF, NaCl, NaBr, or NaI). We compared the structures and properties of the as-obtained hematite photoanodes with those of the material prepared in 1.0 M NaNO3, the most widely adopted electrolyte in previous studies. Among our studied systems, we found that the hematite photoanode prepared in NaCl solution was the only one possessing properties similar to those of the sample obtained from the NaNO3 solution-most importantly in terms of photoelectrochemical performance (ca. 0.2 mA/cm(2) with +0.4 V vs SCE). The hematites obtained from the NaF, NaBr, and NaI solutions exhibited much lower (by approximately 2 orders of magnitude) photocurrent densities under the same conditions, possibly because of their relatively less ordered crystallinity and the absence of rodlike morphologies. Because the synthetic protocol was identical in each case, we believe that these two distinct features reflect the environments in which these hematite photoanodes were formed. Consistent with the latest studies reported in the literature of the X-ray photoelectron spectra of fast-frozen hematite colloids in aqueous solutions, it appears that the degree of surface ion loading at the electrolyte-hematite interface (Stern layer) is critical during the development of hematite photoanodes. We suspect that a lower ion surface loading benefits the hematite developing relatively higher-order and a rodlike texture, thereby improving the photoelectrochemical activity.

Using laser ablation/inductively coupled plasma mass spectrometry to bioimage multiple elements in mouse tumors after hyperthermia

AbstractIn this study, we employed laser ablation/inductively coupled plasma mass spectrometry (LA-ICP-MS) to map the spatial distribution of Gd-doped iron oxide nanoparticles (IONPs) in one tumor slice that had been subjected to magnetic fluid hyperthermia (MFH). The mapping results revealed the high resolution of the elemental analysis, with the distribution of Gd atoms highly correlated with that of the Fe atoms. The spatial distributions of C, P, S, and Zn atoms revealed that the effect of MFH treatment was significantly dependent on the diffusion of the magnetic fluid in the tissue. An observed enrichment of Cu atoms after MFH treatment was probably due to inflammation in the tumor. The abnormal distribution of Ni atoms suggests a probable biochemical reaction in the tumor. Therefore, this LA-ICP-MS mapping technique can provide novel information regarding the spatial distribution of elements in tumors after cancer therapy. FigureMapping and ion intensities of a56Fe and b158Gd atoms. The red line indicates the path taken during the time-resolved analyses of Fe and Gd atoms

CO2 uptake performance and life cycle assessment of CaO-based sorbents prepared from waste oyster shells blended with PMMA nanosphere scaffolds

In this paper, we demonstrate a means of simultaneously solving two serious environmental issues by reutilization of calcinated mixture of pulverized waste oyster shells blending with poly(methyl methacrylate) (PMMA) nanospheres to prepare CaO-based sorbents for CO2 capture. After 10 cycles of isothermal carbonation/calcination at 750°C, the greatest CO2 uptake (0.19 g CO2/g sorbent) was that for the sorbent featuring 70 wt% of PMMA, which was almost three times higher than that (0.07 g CO2/g sorbent) of untreated waste oyster shell. The greater CO2 uptake was likely a result of particle size reduction and afterwards surface basicity enhancement and an increase in the volume of mesopores and macropores. Following simplified life cycle assessment, whose all input values were collected from our experimental results, suggested that a significant CO2 emission reduction along with lesser human health and ecosystems impacts would be achieved immediately once waste is reutilized. Most importantly, the CO2 uptake efficiency must be greater than 20% or sorbents prepared from limestone mining would eventually produce a net positive CO2 emission.

Using laser ablation inductively coupled plasma mass spectrometry to characterize the biointeractions of inhaled CdSe quantum dots in the mouse lungs

Quantum dots (QDs) show great promise for use as drug delivery carriers and fluorescent markers, with potential applications in, for example, pulmonary drug delivery and lung imaging, respectively. Nevertheless, few adequate analytical techniques are available for mapping or determining QDs in tissue samples. In this study, we employed laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to map the spatial distribution of inhaled CdSe QDs in mouse lung slices. Mapping of control and QD-inhaled samples revealed a distribution of Cd atoms in the lungs arising from QDs accumulated in the bronchiolar area, as confirmed through fluorescence spectroscopy imaging. We also simultaneously monitored other selected elements, namely 13C, 31P, 34S, 56Fe, 57Fe, 63Cu, 66Zn, 82Se, 125Te, 111Cd, 112Cd, and 114Cd. The high correlation between the spatial distributions of 114Cd and 82Se suggested that the QDs underwent no obvious degradation during a span of 17 days, providing insight into the potential cytotoxicity of the QDs. The LA-ICP-MS data coupled with hematoxylin and eosin (H&E)-stained images revealed that the inhaled QDs appeared in the same locations as the lymphocytes accumulated in the lungs. These results, in conjunction with the observed distribution of Cu atoms, suggest that the lymphocytic system was involved in inflammation triggered by the inhaled QDs. The observed enrichment of Cu atoms in the sample was probably due to certain immune responses induced by the inhaled QDs. Finally, spiking with standard solutions allowed us to quantify the QDs in the tissue slices.

Accurate technetium-99 determination using the combination of TEVA resin pretreatment and ICP-MS measurement and its influence on the Tc-99/Cs-137 scaling factor calculation

Accurate determination of technetium-99 (Tc-99) is very important because any overestimation will cause the examined radioactive wastes to be categorized into super C class, which dramatically increases the cost of waste management. Herein, we demonstrated that by adopting the analytical method comprising TEVA resin pretreatment and ICP-MS measurement, the determined Tc-99 concentrations in representative waste stream samples from the Lan-Yu low-level radioactive waste temporary storage site in Taiwan were approximately two orders of magnitude lower than those determined from the beta radiation measurement using a low background liquid scintillation counter. Two important concerns emerged from our results. First, severe interferences from other nuclides residing in the matrix considerably affect the determination of Tc-99, even when a low background liquid scintillation counter was used. Second, the currently used Tc-99/Cs-137 scaling factor should be carefully revised, or it might lead to a considerable overestimation of the Tc-99 concentration.

Direct Micromachining of Microfluidic Channels on Biodegradable Materials Using Laser Ablation

Laser patterning on polymeric materials is considered a green and rapid manufacturing process with low material selection barrier and high adjustability. Unlike microelectromechanical systems (MEMS), it is a highly flexible processing method, especially useful for prototyping. This study focuses on the development of polymer surface modification method using a 193 nm excimer laser system for the design and fabrication of a microfluidic system similar to that of natural vasculatures. Besides from poly(dimethyl siloxane) (PDMS), laser ablation on biodegradable polymeric material, poly(glycerol sebacate) (PGS) and poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate) (APS) are investigated. Parameters of laser ablation and fabrication techniques to create microchannels are discussed. The results show that nano/micro-sized fractures and cracks are generally observed across PDMS surface after laser ablation, but not on PGS and APS surfaces. The widths of channels are more precise on PGS and APS than those on PDMS. Laser beam size and channel depth are high correlation with a linear relationship. Repeated laser ablations on the same position of scaffolds reveal that the ablation efficiencies and edge quality on PGS and APS are higher than on PDMS, suggesting the high applicability of direct laser machining to PGS and APS. To ensure stable ablation efficiency, effects of defocus distance into polymer surfaces toward laser ablation stability are investigated. The depth of channel is related to the ratio of firing frequency and ablation progression speed. The hydrodynamic simulation of channels suggests that natural blood vessel is similar to the laser patterned U-shaped channels, and the resulting micro-patterns are highly applicable in the field of micro-fabrication and biomedical engineering.

Interfacial phenomena in hematite photoanodes fabricated by directly associating iron oxide suspensions with FTO substrates using a dipping-annealing method

The fabrication of solid semiconductor nanoparticles on conductive substrates while retaining their high photocatalytic activity as they were in the dispersed form remains a challenge. In this study, we adopted the idea of used a dipping–annealing (DA) method to associate solid iron oxide nanoparticles directly onto an FTO substrate. We focused on the interfacial phenomenon of the as-fabricated hematite photoanodes to evaluate factors that may affect their photocatalytic performance. A significant sintering effect occurs during calcination; this process converts the iron (hydro)oxide precursor into a hematite structure and removes binder molecules. This sintering effect is more severe for the nanocubes than the nanospheres. However, the sintering effect would induce a size effect, further compromising the photocatalytic performance of the prepared photoanodes. Based on EIS analyses, the deteriorated photocatalytic performance arises from the deactivation that occurs at the exposed facet, increasing the open circuit potential and the resistance of hematite bulk, as well as decreasing the capacitance at the hematite–electrolyte interface.