查看更多>>摘要：This paper describes a new strategy using oxygen plasma treatment to tune the localized surface plasmon resonance (LSPR) of gold nanorods coated with a mesoporous silica shell (AuNRs@mSiO2) exposed to mercury (Hg) solution. Dark-field (DF) microscopy and spectroscopy were used to reveal the effects of oxygen plasma treatment on the structural and LSPR spectral changes of single amalgamated AuNRs@mSiO2. Due to the structural stability provided by the mesoporous silica shell, the amalgamated AuNRs@mSiO2 exposed to oxygen plasma treatment showed no morphological transformation. Furthermore, real-time monitoring of single AuNRs@mSiO2 showed slow Hg inward diffusion into AuNR cores in air over a long timeframe (24 h), as revealed by the redshift and linewidth narrowing of the LSPR peak. However, the oxygen plasma treatment resulted in faster inward diffusion of Hg into AuNR cores within 20 min, almost 60 times faster than the amalgamated AuNRs@mSiO2 untreated with oxygen plasma. Thus, oxygen plasma treatment was further presented as a new effective approach to control the LSPR properties by promoting the inward Hg diffusion in amalgamated AuNRs@mSiO2 without structural deformation.
查看更多>>摘要：Traditional Chinese herbal medicines are subject to heavy metal contamination. Standard detection methods are too complicated, time-consuming, and expensive for routine analysis, so low-cost methods are in high demand for rapid on-site screening. This study reports a high-sensitivity X-ray fluorescence (HS-XRF) method to determine As, Pb, and Cd residues simultaneously in herbal medicines. It couples monochromatic excitation energy dispersive X-ray fluorescence spectrometry and the fast fundamental parameters method. Each test takes only 10–30 min and costs 1/10th to 1/5th of the standard method. The detection limits, precision and accuracy were evaluated using different approaches, and application notes in practice are also proposed. This study is the first attempt to establish and evaluate HS-XRF in analyzing multiple heavy metals in herbal medicines. This rapid screening method would promote the testing efficiency and thus improve the monitoring of heavy metal contamination in herbal medicines.
查看更多>>摘要：We aimed to develop an amino acid sequence-dependent analytical method using near-infrared (NIR) spectroscopy. The detailed analysis of the NIR spectra of eight different amino acid aqueous solutions (glycine, alanine, serine, glutamine, lysine, phenylalanine, tyrosine, and proline) revealed different spectral patterns characteristic of different amino acid residues in the 6200–5700 and 5000–4200 cm?1 regions, and the amino acids were identified based on the patterns. The spectra in the region of 5000–4500 cm?1 for tripeptide organic solutions that were composed of the aforementioned eight amino acids clearly showed the spectral differences depending on the amino acid species and amino acid sequences. Namely, tripeptide species were clearly differentiated from each other based on the spectral pattern of NIR bands due to the combinations of N–H stretching and amide II/III modes and those derived from the first overtones of amide II and amide I. The quantitative evaluation of changes in the concentrations of dipeptides and tripeptides composed of two different amino acids, glycine and proline was performed using partial least squares regression (PLSR) analysis and a combination of bands for amide modes. The calibration and validation results with high determination coefficients (R2 ≥ 0.99) were successfully obtained based on the amino acid sequences. The results not only revealed the usefulness of NIR spectroscopy as a process analytical technology (PAT) tool for synthesizing peptides in a micro flow reactor but also proposed a general method for quantitatively analyzing NIR spectra obtained in the course of chemical synthesis.
查看更多>>摘要：Chlorine is used as a powerful disinfectant in several water-related industries and in the food industry to remove bacteria and other harmful contaminants. In this paper, we present a solution-based fabrication process for biodegradable free chlorine sensors using asparagine that is functionalized onto graphene oxide (GO). An ink solution of asparagine, NaOH, and GO was mixed at room temperature for 24 h before being centrifuged and washed with deionized (DI) water and ethanol, then stored in a solution of equal parts DI water and ethanol. The formulated ink was drop-casted onto a screen-printed carbon electrode (SPCE), spin-coated to achieve a uniform film, and then dried. The sensor showed high sensitivity of 0.30 μA ppm?1 in a linear range of 0 to 8 ppm with a hysteresis-limited resolution of 0.2 ppm, very high selectivity in the presence of commonly interfering ions, and an operating voltage well below the reduction potential of dissolved oxygen. The sensor response time to achieve a steady state was 50 s, and it showed little change in its drift response over 16 h and over a temperature range of 10 to 45 °C.
查看更多>>摘要：The flexible surface-enhanced Raman scattering (SERS) platform has ceaselessly propelled the development of point-of-care testing (POCT) in diverse fields. Herein, we report a facile strategy for the SERS-chemometric analysis of four β-blockers (bisoprolol, metoprolol, acebutolol and esmolol) based on a super-sticky mussel-inspired hydrogel SERS tape. The surface morphology and mechanical properties of the hydrogel tape can be easily controlled by adjusting the compositional ratio. The optimized tape with excellent toughness and adhesiveness allows efficient collection of analytes through a simple “paste and peel off” approach, further by spraying with silver nanoparticles using a household sprayer to instantly assemble a flexible SERS substrate, the analytes can then detected by a portable Raman spectrometer. This POCT strategy enables the identification and discrimination of four similar β-blockers with high sensitivity and accuracy in combination with the statistical algorithms. The developed SERS tape is finally utilized for the recognition of β-blockers in simulated urine solution, which realizes a limit of detection of 1.0 ng mL?1, revealing a promising potential of this SERS-based POCT for the clinical detection of doping abuse.
查看更多>>摘要：The development of orthogonal acceleration time-of-flight (oa-tof) technology is driven forward due to higher mass accuracy and resolving power than conventional linear/reflectron tof instruments. This is achieved with a more accurate definition of starting energies and coordinates of ions by spatial separation of ion generation and orthogonal ion extraction. Consequently, the ability to cover the whole mass spectral range without scanning is not given anymore. Therefore, continuous ion sources are favored for ensuring high duty cycles and thus high temporal resolution. For pulsed ion sources, high repetition rates are mandatory for covering large m/z ranges without losing their high temporal resolution. We have combined an oa-tof with deuterium lamp single-photon ionization (SPI) as a continuous ion source together with a pulsed 2000 Hz excimer (KrF) laser for resonance enhanced multi-photon ionization (REMPI). These two ionization techniques can be used simultaneously. To the best of our knowledge, this system is the first of its kind in combining a vacuum pulsed ionization source with an oa-tof instrument without any other ion storage hardware. The combination of a soft broadband ionization for organics (SPI) in combination with a very sensitive and selective soft ionization (REMPI) can be used for covering the whole mass range or in targeted on-line monitoring cases one or several smaller mass ranges. To demonstrate the simultaneous SPI/REMPI-oa-tof technique, two applicative areas are explored: on-line monitoring of coffee roast gas emissions and e-cigarette vapor. The complementary information from SPI and REMPI signals are combined in a way to exploit the advantages of both ionization types. In a further development step, a second data acquisition card is built into the system. This modification allows the independent storage of data from both ionization methods without mixing. For demonstration, a third example with a GC measurement is provided. The last example shows the possibility of modified sensitivities for different mass regions in REMPI data acquisition without affecting the SPI channel. The newly developed system shows high robustness in terms of measurements in real industrial environments. The simultaneous measurement technique provides a higher density of information in a single measurement, saving time and resources.
查看更多>>摘要：Studies have shown that homocysteine (Hcy) levels are closely related to cardiovascular and cerebrovascular diseases. In this work, we have developed and synthesized three copper complexes, F542-Cu2+, F508-Cu2+, and F465-Cu2+ for Hcy detection. The different binding constants (Ks) of the copper complexes endow them with dramatic reactivity toward biothiols. The pyridine-containing tetraazacycle was employed in the construction of F542-Cu2+, which renders the medium Ks value for the copper complex compared with cyclen and TACN and effectively prevented the disintegration of the complexes. Pyridine-containing tetraazacycle provided the basis and possibility for the hypothesis for the reduction of Cu2+ by biothiols to shape into a stable six-membered ring structure. The obtained results verified that F542-Cu2+ could be utilized to specifically probe Hcy in a switched-on fluorescence mode. F542-Cu2+ exhibited excellent environmental stability, superior sensitivity, and outstanding selectivity toward Hcy under physiological conditions. The mechanism of Hcy specificity was confirmed to be related to the generation of Hcy-induced six-membered ring by fluorescence imaging, time-dependent fluorescence spectra, ESI-MS, and electron paramagnetic resonance (EPR) analyses. Furthermore, we exploited the application of F542-Cu2+ and developed a strategy for evaluating the activity of S-adenosylhomocysteine hydrolase (AHCY) in vitro by fluorescence analysis. More importantly, real-time in vivo evaluation of the enzymatic activity of AHCY was realized and assisted by our probe, providing the possibility of opening up a new avenue for enzymatic reaction assessment.
查看更多>>摘要：Residues of flumetralin, a dinitroaniline herbicide, in foods pose a health risk to humans. In this study, we produced a sensitive monoclonal antibody (mAb) against flumetralin and developed a gold nanoparticle-based lateral flow immunoassay (LFIA) strip for screening flumetralin in orange. The subtype of mAb 3F5 was IgG1 and had a half-maximal inhibitory concentration of 9.43 ng mL?1. The cross-reactivity assay indicated that mAb had good specificity. The LFIA strip had a visual limit of detection of 200 ng g?1 in orange. We obtained results with the naked eye within 15 min. The calculated LOD of the strip in orange was 33.26 ng g?1, with a linear detection of 80.72–1672.10 ng g?1. The strip had recovery rates ranging from 98.4% to 110.1%. Therefore, our developed method is an effective and reliable tool for the rapid detection of flumetralin in orange.
查看更多>>摘要：Silica nanoparticles (SiNPs) are used in consumer products, engineering and medical technologies. Attractive properties of SiNPs (e.g. size/surface-modification) enhance usage and thus the likelihood of environmental/human exposures. The assessment of health risks associated with exposures to SiNPs requires information on their relative potencies and toxicity mechanisms. In this work, phagocytic J774 cells were exposed to amorphous pristine (15, 30, 75 nm) and surface-modified (–NH2, –C3COOH, –C11COOH, –PEG) SiNP variants, and internalization was assessed by transmission electron microscopy (TEM), while cellular ATP was measured as a cytotoxicity endpoint. Furthermore, mitochondrial fractions from J774 cells were exposed to these SiNP variants (5, 15 μg mL?1), as well as two reference particles (SiNP 12 nm and TiO2), and proteomic changes were analyzed by mass spectrometry. Ingenuity Pathway Analysis was used to identify toxicity pathways. TEM analyses showed SiNP internalization and distribution along with some changes in mitochondrial structure. SiNP size- and surface-modification and chemical composition-related changes in mitochondrial proteins, including key proteins of the respiratory complex and oxidative stress, were evident based on high content mass spectrometry data. In addition, the dose-related decrease in cellular ATP levels in SiNP-exposed cells was consistent with related mitochondrial protein profiles. These findings suggest that physicochemical properties can be determinants of SiNP exposure-related mitochondrial effects, and mitochondrial exposures combined with proteomic analysis can be valuable as a new approach methodology in the toxicity screening of SiNPs for risk assessment, with added insight into related toxicity mechanisms.
NSTL
Royal Soc Chemistry