Cheng-Kuan Su

Three-dimensional printed sample load/inject valves enabling online monitoring of extracellular calcium and zinc ions in living rat brains.

We have developed a simple and low-cost flow injection system coupled to a quadruple ICP-MS for the direct and continuous determination of multi-element in microdialysates. To interface microdialysis sampling to an inductively coupled plasma mass spectrometer (ICP-MS), we employed 3D printing to manufacture an as-designed sample load/inject valve featuring an in-valve sample loop for precise handling of microliter samples with a dissolved solids content of 0.9% NaCl (w/v). To demonstrate the practicality of our developed on-line system, we applied the 3D printed valve equipped a 5-μL sample loop to minimize the occurrence of salt matrix effects and facilitate an online dynamic monitoring of extracellular calcium and zinc ions in living rat brains. Under the practical condition (temporal resolution: 10h(-1)), dynamic profiling of these two metal ions in living rat brain extracellular fluid after probe implantation (the basal values for Ca and Zn were 12.11±0.10mg L(-1) and 1.87±0.05μg L(-1), respectively) and real-time monitoring of the physiological response to excitotoxic stress elicited upon perfusing a solution of 2.5mM N-methyl-d-aspartate were performed.

Fully 3D-Printed Preconcentrator for Selective Extraction of Trace Elements in Seawater.

In this study, we used a stereolithographic 3D printing technique and polyacrylate polymers to manufacture a solid phase extraction preconcentrator for the selective extraction of trace elements and the removal of unwanted salt matrices, enabling accurate and rapid analyses of trace elements in seawater samples when combined with a quadrupole-based inductively coupled plasma mass spectrometer. To maximize the extraction efficiency, we evaluated the effect of filling the extraction channel with ordered cuboids to improve liquid mixing. Upon automation of the system and optimization of the method, the device allowed highly sensitive and interference-free determination of Mn, Ni, Zn, Cu, Cd, and Pb, with detection limits comparable with those of most conventional methods. The systems analytical reliability was further confirmed through analyses of reference materials and spike analyses of real seawater samples. This study suggests that 3D printing can be a powerful tool for building multilayer fluidic manipulation devices, simplifying the construction of complex experimental components, and facilitating the operation of sophisticated analytical procedures for most sample pretreatment applications.

Quantitatively profiling the dissolution and redistribution of silver nanoparticles in living rats using a knotted reactor-based differentiation scheme.

Whether silver nanoparticles (AgNPs) degrade and release silver ions (Ag(+)) in vivo has remained an unresolved issue. To evaluate the biodistribution and dissolution behavior of intravenously administered AgNPs in living rats, we employed a knotted reactor (KR) device to construct a differentiation scheme for quantitative assessment of residual AgNPs and their released Ag(+) ions in complicated animal tissues; to do so, we adjusted the operating parameters of the KR, namely, the presence/absence of a rinse solution and the sample acidity. After optimization, our proposed differentiation system was confirmed to be tolerant to rat tissue and organ matrix and provide superior reliability of differentiating AgNPs/Ag(+) than the conventional centrifugal filtration method. We then applied this differentiation strategy to investigate the biodistribution and dissolution of AgNPs in rats 1, 3, and 5 days postadministration, and it was found that the administered AgNPs accumulated predominantly in the liver and spleen, then dissolved and released Ag(+) ions that were gradually excreted, resulting in almost all of the Ag(+) ions becoming deposited in the kidney, lung, and brain. Histopathological data also indicated that toxic responses were specifically located in the AgNP-rich liver, not in the Ag(+)-dominated tissues and organs. Thus, the full-scale chemical fate of AgNPs in vivo should be integrated into future assessments of the environmental health effects and utilization of AgNP-containing products.

Simultaneous in vivo monitoring of multiple brain metals using an online microdialysis-in-loop solid phase extraction-inductively coupled plasma mass spectrometry system

Using a non-functionalized small-bore polytetrafluoroethylene (PTFE) sample loop as a preconcentrator, a novel hyphenated system—comprising microdialysis sampling, online automatic in-loop solid phase extraction (SPE), and inductively coupled plasma mass spectrometry (ICP-MS)—for monitoring the levels of trace metal ions in living rat brains was developed. Taking advantage of the selective polymer–ion interaction to online separate metal ions from highly saline operating in the in-loop PTFE SPE system, it could online remove the salt matrix selectively from the microdialysate of rat brain extracellular fluid after slightly adjusting the pH; the next analytical cycle could be performed without the need for a pre-conditioning procedure after the prior elution with HNO3. Owing to the simplicity and convenience of the developed operation sequence, this method combines extremely low blank level and detection limits (0.003–0.5 μg L−1) and acceptable spike recoveries (90–98%) with the ability to analyze multiple elements. To demonstrate analytical reliability and compatibility, the analysis of standard reference material NIST 1643e (trace elements in water) and 2670a (trace elements in human urine) as well as continuous long-term monitoring of the variations of multiple trace metal ions in rat brain were performed in this work. According to the analytical results, it showed that the developed hyphenation system had the ability to analyze the SRM samples accurately, and the basal values of Ni (0.36 ± 0.16 μg L−1), Zn (3.09 ± 0.31 μg L−1), and Mn (1.31 ± 0.06 μg L−1) in rat brain extracellular fluid could also be measured.

In vivo measurement of extravasation of silver nanoparticles into liver extracellular space by push–pull-based continuous monitoring system

With the increasing prevalence of silver nanoparticles (AgNPs) in various products, whether such AgNPs will introduce new injury mechanisms from new pathologies remains to be determined. From the toxicokinetic viewpoint, it is vital to have in-depth knowledge of their in vivo transport kinetics and extravasation phenomenon. By combining push-pull perfusion sampling, in-tube solid phase extraction, and inductively coupled plasma mass spectrometry, we used an in vivo push-pull-based continuous monitoring system to investigate in vivo transport kinetics of extracellular AgNPs in living rat liver with a detection limit and temporal resolution of 0.64μgL(-1) and 10min, respectively. Before administration into living rats, the pre-incubation in DMEM with 10% FBS for 8h was adopted as the optimized exposure condition for the used AgNPs. After repeated-dose treatments, we observed a higher concentration of AgNPs in the liver extracellular space, suggesting that AgNP clearance by the reticuloendothelial system (RES) may be blocked by a prior administration of AgNPs. Future studies on AgNP distribution in different liver compartments (blood stream, extracellular space and Kupffer cells/hepatocytes) are necessary for defining the risks and benefits of AgNP applications.

Considerations of inductively coupled plasma mass spectrometry techniques for characterizing the dissolution of metal-based nanomaterials in biological tissues

Dissolution of metal-based nanomaterials (MNMs) leads to the release of metal ion species; this phenomenon is a major concern affecting the widespread application of MNMs because it can affect their subsequent biodistribution patterns and toxic responses toward living biological systems. It is crucial that we thoroughly understand the dissolution behavior and chemical fate—and associated health effects—of MNMs when assessing their safety considerations. To date, however, quantitative characterization of the transformations of MNMs within living animal bodies has remained a methodological challenge. In this review, we address the technical issues, the state of the art, and the limitations of currently available sample preparation procedures, as well as the various differentiation schemes coupled with inductively coupled plasma mass spectrometry (ICP-MS) techniques for analysis, that have been employed to reveal MNM dissolution in complicated biological tissue samples. In addition, we highlight the importance of developing new analytical strategies for ICP-MS to facilitate unbiased investigations into the dissolution behavior of MNMs with respect to their long-term biological effects and nanotoxicological properties.

Online solid phase extraction using a PVC-packed minicolumn coupled with ICP-MS for determination of trace multielements in complicated matrices

We have developed a simple and clean online-packed minicolumn solid phase extraction (SPE) device coupled with inductively coupled plasma-mass spectrometry (ICP-MS) for the determination of trace elements in seawater and urine samples. In the preconcentration step, the extraction efficiency was optimal when the pH of the sample was adjusted to 7.0 using phosphate buffer solution. After extraction onto the PVC beads, the adsorbed analytes were eluted with 0.5% HNO3 prior to online ICP-MS measurement. Noteworthily, because surface chemical pre- and post-conditioning of PVC beads is not necessary, a relatively unsophisticated and clean procedure was attained and extremely low detection limits in the range of 0.67 to 7.0 ng L−1 were thus obtained for the analysis of Cu, Co, Zn, Cd and Pb in 100 μL seawater and urine samples. We confirmed the analytical reliability of this method through the analysis of the certified reference material NASS-2 (open ocean seawater), SLEW-3 (estuarine water) and 2670a (human urine) and demonstrated its applicability through simultaneous determination of Cu, Co, Zn, Cd and Pb in complicated aqueous matrices.

In vivo monitoring of distributional transport kinetics and extravasation of quantum dots in living rat liver.

Although the unique optical properties of surface-modified quantum dots (QDs) have attracted wide interest in molecular biology and bioengineering, there are very few reports of their in vivo biodistribution, due to a lack of analytical techniques for characterizing the dynamic variation of QDs in living animals. In this study, we used an in vivo online monitoring system and a batch-wise elemental analytical method to investigate the biodistribution/extravasation of various surface-modified CdTeSe/ZnS (QDs) in rat liver. It is found that the surface modification dictated not only the blood retention profile but also the degree of extravasation and the clearance of extracellular QDs, making it an important variable for regulating the transfer and exchange process of QDs among three physiological compartments-bloodstream, extracellular space and Kupffer cells/hepatocytes.

Selective chemical vaporization of exogenous tellurium for characterizing the time-dependent biodistribution and dissolution of quantum dots in living rats

Quantum dots (QDs) are generally toxic as a result of their heavy metal content. However, direct characterization of their dissolution behavior in living systems remains complicated because of the lack of differentiation methods suitable for analyzing the released components and residual nanostructures. To investigate the degree of dissolution of QDs in living rats, we used a chemical vapor generation scheme as a novel strategy to selectively vaporize the chalcogen (Te) species released from CdSeTe–ZnS core–shell QDs (QD705) in organ/tissue samples from rats. Under optimized conditions, we established a chemical differentiation method that had a better performance and applicability than the commonly used filtration method. We used Solvable tissue solubilizer to dissolve the tissues harvested from rats that had been administered with QD705 intravenously. Our experimental results showed differences in the Te- and Cd-based biodistribution patterns of QD705. In addition, we found that the ratio of the concentrations of the Te species released from the dissolution of QD705 to the total Te species (Ter/Tetotal) increased in the blood, liver, and spleen of the rats, but decreased in their kidneys from 2 to 16 weeks post-administration. Therefore the QD705 administered in living rats must have dissolved and redistributed progressively during the time course of the experiment, suggesting that the long-term chemical fate of nanosized materials in vivo should be considered in future nanotoxicological research.

Online open-tubular fractionation scheme coupled with push-pull perfusion sampling for profiling extravasation of gold nanoparticles in a mouse tumor model.

The extravasation of administered nano-drug carriers is a critical process for determining their distributions in target and non-target organs, as well as their pharmaceutical efficacies and side effects. To evaluate the extravasation behavior of gold nanoparticles (AuNPs), currently the most popular drug delivery system, in a mouse tumor model, in this study we employed push-pull perfusion (PPP) as a means of continuously sampling tumor extracellular AuNPs. To facilitate quantification of the extravasated AuNPs through inductively coupled plasma mass spectrometry, we also developed a novel online open-tubular fractionation scheme to allow interference-free determination of the sampled extracellular AuNPs from the coexisting biological matrix. After optimizing the flow-through volume and flow rate of this proposed fractionation scheme, we found that (i) the systems temporal resolution was 7.5h(-1), (ii) the stability presented by the coefficient of variation was less than 10% (6-h continuous measurement), and (iii) the detection limits for the administered AuNPs were in the range 0.057-0.068μgL(-1). Following an intravenous dosage of AuNPs (0.3mgkg(-1) body weight), in vivo acquired profiles indicated that the pegylated AuNPs (PEG-AuNPs) had greater tendency toward extravasating into the tumor extracellular space. We also observed that the accumulation of nanoparticles in the whole tumor tissues was higher for PEG-AuNPs than for non-pegylated ones. Overall, pegylation appears to promote the extravasation and accumulation of AuNPs for nano-drug delivery applications.