Liquid–liquid extraction for the removal of pertechnetate (⁹⁹TcO₄⁻) and perrhenate (ReO₄⁻) is reported based on using the tripodal extractant N,N,N′,N′,N″,N″-hexa-n-octylnitrilotriacetamide (HONTA) composed of three amide groups and a tertiary amine. The extraction behaviors were compared with those using alkyldiamideamines (ADAAM(Oct) and ADAAM(EH)), and the commercial amine-type extractant, trioctylamine (TOA). HONTA quantitatively extracted ⁹⁹TcO₄⁻ and ReO₄⁻ in the pH range from 1.0 to 2.5 by the co-extraction of protons. The extraction performance of the extractants was improved in the order of HONTA > ADAAM(Oct) > ADAAM(EH) > TOA. ⁹⁹TcO₄⁻ and ReO₄⁻ in the extracting phase were successfully stripped using neutral aqueous solutions as the receiving phase, and the extraction ability of HONTA was maintained after five repeated uses.

An efficient methodology has been developed to determine the tricyclazole residue in matrix based on surface-enhanced Raman scattering (SERS) coupled with dispersible matrix solid-phase extraction. After pretreatment and test conditions optimization, peaks at 1373 and 1317 cm⁻¹ in the SERS spectrum were respectively selected as quantitative peaks for rice and Brassica campestris L. ssp. chinensis var. utilis Tsen, respectively. The matrix standard curve-external standard method was used to quantitatively conduct a statistical analysis. The correlation between the quantitative peak response and tricyclazole concentration showed a significant linear relationship with a correlation coefficient of R² > 0.99. The lowest spiked concentration was determined to be the quantitative limit that was below the maximum residue limits of tricyclazole. This study provides a sensitive, stable and rapid approach for the analysis of tricyclazole in above matrix via SERS, and it will be a useful complement to the quantitative analysis of tricyclazole in a complex matrix.

We report on a simple, cost-effective, instrument-free, and portable distance-based paper device coupled with NFs for the determination of glucose. The analysis reaction is based upon the oxidative etching reaction of silver nanoparticles (AgNPs) in the presence of H₂O₂ that is produced from glucose after a glucose oxidase (GOx) catalytic reaction leading to a morphological transformation of AgNPs. A color band length of AgNPs is coated on to a detection channel and then etched by H₂O₂, and these were changed from a purple color to colorless as a correlate of the glucose concentration. To improve the performance of the enzyme immobilization, NFs, which are biocompatible without compromising their structure and biological activity, were then placed onto the sample zone. The naked-eye detection limit was 0.1 mM for 40 min of analysis time. The recoveries of glucose spiked in the artificial urine samples and control urine samples were then verified by our device and were in the acceptable range of 96 – 100%.

Traditional methods for the analysis of trace heavy metals in the atmosphere require collecting atmospheric particles on filter substrates, such as cellulose, quartz fiber member, etc. In this paper, we report on a different filter to capture trace heavy metals in atmospheric particulates. Four kinds of electrospun nanofiber filters, polystyrene (PS), polystyrene-dithizone (PS-DZ), acrylic acid (AR), and acrylic acid-dithizone (AR-DZ) were produced by electrospinning, and used as filters to trap heavy metals in atmospheric particles. Based on these nanofiber filters, the digestion method and eluent were optimized. Under the optimal conditions (oscillation extraction with acetic acid–potassium acetate (HAC–KAC) buffer solution (0.1 mol L⁻¹, pH = 4.5)), the developed method was successfully applied to determine the four particulate metal elements (As, Cd, Hg, and Pb) in air in two urban areas of Suzhou, China. Furthermore, a correlation between heavy metals in air and breast milk was observed. The results confirmed that an electrospun nanofiber mat could be a potential candidate for the sampling of heavy metals in atmospheric particles with higher efficiency.

Enzyme-linked immunosorbent assay (ELISA) is a widespread analytical biochemistry assay. In this work, a direct ELISA method using a metallic nanoparticle (NP)-immobilized 96-well plate was developed for high-throughput, highly sensitive fluorescence analysis. Immobilization of metallic NPs on a 96-well plate effectively amplified fluorescence signals of the assay. The silver (Ag) NP-immobilized plate showed the best fluorescence enhancement effect of all the metal-immobilized plates tested. We used the Ag NP-immobilized plate to detect biomolecules and bacteria and found that both the fluorescence intensity and the limit of detection (LOD) were strongly enhanced by more than 100 times compared with those of the unmodified 96-well plates. Quantitative and qualitative considerations for target bacteria regarding the impact of autofluorescence on detection were successfully obtained for several strains. Our results demonstrate the potential of applying Ag NPs for enhancing the efficiency of direct and indirect ELISA assays.

Heparin is an anticoagulant medication that is usually injected subcutaneously. The quality of a set of commercial heparin injections from different producers was examined by NMR, IR, UV-Vis spectroscopies and potentiometric multisensor system. The type of raw material regarding heparin animal origin and producer, heparin molecular weight and activity values were derived based on the non-targeted analysis of ¹H NMR fingerprints. DOSY NMR spectroscopy was additionally used to study homogeneity and additives profile. UV-Vis and IR, being cheaper than NMR, combined with multivariate statistics were successfully applied to study excipients composition as well as semi-estimation of activity values. Potentiometric multisensor measurements were found to be an important additional source of information about inorganic composition of finished heparin formulations. All investigated instrumental techniques are useful for finished heparin injections and should be selected according to availability as well as the information and confidence required for a specific sample.

Barium (Ba) stable isotopes in carbonate rock have great potential to provide valuable information on environmental change and the biogeochemical cycles of oceans in the past. Ba in carbonate rock can exist in various phases, such as adsorbable and silicate-bound Ba. However, only the carbonate-bound phase is considered to record the Ba isotopic compositions of ambient seaweater. Here, we designed a two-step leaching experiment to obtain the carbonate-bound Ba in two typical carbonate rocks: limestone and cap dolostone. The results showed that after leaching by 1 mol L⁻¹ ammonium acetate, the carbonate-bound Ba extracted by mixed solution of 1.5 mol L⁻¹ acetic acid and 1 mol L⁻¹ ammonium acetate in each studied sample have indistinguishable isotope ratios in leaching time conditions between 12 and 72 h. More importantly, the carbonate-bound Ba isotope ratios were quite different from those of the residue (up to 10 times of analytic uncertainty, 2SD ≤ ±0.04‰) after leaching in three out of four leaching experiments, indicating that noncarbonated fraction could overprint a primary seawater signal. Our sequential leaching techniques could improve targeting of carbonate-bound Ba isotope signatures in various carbonate rocks to trace the Ba cycling in the oceans.

Nephrotoxicity, the most important toxicity in high-dose methotrexate (MTX) therapy, is partly caused by the formation of crystal deposits in the kidney due to poor water solubility of MTX and its metabolites 7-hydroxy methotrexate (7-OH MTX), deoxyaminopteroic acid (DAMPA) and 7-hydroxy deoxyaminopteroic acid (7-OH DAMPA). Plasma MTX level-guided urine alkalinization, leucovorin rescue and glucarpidase detoxification are common strategies to overcome MTX-related nephrotoxicity. However, overestimation is a problem for MTX analysis by immunoassays due to the cross-reactivity of MTX metabolites (7-OH MTX and DAMPA). An UHPLC-MS/MS method for the simultaneous determination of MTX, 7-OH MTX, DAMPA and 7-OH DAMPA in human urine was developed, validated and applied in clinical practice. Samples were treated by one-step protein precipitation and analyzed within 3 min. The calibration range was 0.02 to 4 μmol/L for MTX and DAMPA, and 0.1 to 20 μmol/L for 7-OH MTX and 7-OH DAMPA. For all analytes, the intra-day and inter-day bias and imprecision were –8.0 to 7.6 and <9.0%, the internal standard normalized recovery and matrix factor were 92.34 to 109.49 and <20.68%. The plasma MTX and 7-OH MTX levels increased with the urine drug levels, age, serum creatinine and alanine transaminase, but urine could not replace blood for MTX monitoring due to their poor correlation (R², 0.16 to 0.51). Dose-normalized urine and plasma MTX and 7-OH MTX levels were similar between different patient groups (urine pH <7 or ≥7). Due to the large inter-individual variance of the analytes levels in both plasma and urine, these findings should be treated with caution.

Since the elasticity of biological tissues is related to their pathological states, the development of new methods allowing for non-invasive measurements of the elasticity has been desired in the medical field. We present a characterization of the elasticity of objects buried in media from the temporal waveforms of photoacoustic signals. As the increment in Young’s moduli of the objects, the frequency corresponding to the gravitational center of the power spectra obtained by the Fourier-transformation of the waveforms is increased. In our experiment configuration, the elasticity of buried objects is able to be identified up to about 1 MPa of Young’s modulus from the frequency. These results suggest that measurements on the temporal waveforms of photoacoustic signals and the resultant power spectra would provide a useful method for evaluating the elasticity of deeply-situated microscopic pathological lesions, such as stage 0 or 1 mammary gland cancer, which is difficult by conventional ultrasound elastography.

Several scientific works have reported the use of colloidal gold nanoparticle (AuNP) solutions as a colorimetric probe for creatinine detection. Nonetheless, urinary protein is one of the primary chemical components that can interfere with creatinine detection. In this work, we developed a colorimetric probe using AuNP colloidal solution to detect creatinine in the urine of proteinuria patients. A microchamber array was prepared to minimize the sample volume and was used to simultaneously perform spectral recording and image acquisition of several samples. The analyzed volume for each sample was 15 μL. A camera coupled with liquid crystal tunable filters was used to record hyperspectral images, and the signals were then converted to localized surface plasmon resonance (LSPR) spectra. Color changes in the AuNP colloidal solution in the presence of varying concentrations of creatinine and human serum albumin (HSA) indicated different features and could be detected by a hyperspectral imaging technique. The relevant concentration ranges of creatinine and HSA were 5 – 200 and 50 – 250 mg dL⁻¹, respectively. Furthermore, a smartphone camera was adopted to record a color mapping image of the AuNP colloidal solution in the presence of creatinine and HSA at these concentration ranges. Contour plots of red and blue chromaticity levels from color mappings were produced, and 2D fitting equations obtained from these contour plots were adopted to determine the creatinine concentration in the urine of proteinuria patients. This practical technique can be used for screening and can be further developed as a household biosensing device for urinalysis.

Sensitivity amplification strategies in label-free electrochemical immunosensors are mainly limited by redox molecules leaking and degradation of electrical conductivity caused by layers of decoration. Herein, a relatively stable and sensitive label-free electrochemical immunosensor based on a hierarchically flower-like gold microstructures/polyaniline/reduced graphene oxide/prussian blue (HFG/PANI/rGO/PB) composite modified electrode was stepwise fabricated for determination of α-fetoprotein (AFP). In this process, the effect of PANI and rGO on the proposed immunosensor was studied. In detail, PANI/rGO due to the unique electrochemical properties can effectively prevent PB leakage and form a stable sensing platform, which causes sensitive responsiveness and thus a more satisfied detection limit. Meanwhile, the HFG with good biological compatibility can effectively immobilize plenty of antibodies. Under optimal conditions, the HFG/PANI/rGO/PB modified immunosensor exhibited an excellent linearity (0.01 – 30 ng/mL) and a low detection limit (0.003 ng/mL) (S/N = 3), suitable specificity as well as stability and reproducibility towards AFP. The present work offered a promising platform for clinical hepatocellular carcinoma diagnostics.

The photocurrent (sample current) of insulating 0.7-μm thick polyethylene terephthalate (PET) films on conductive substrates (C, Au, Cu) was clearly measured through the substrates during soft X-ray irradiation on the PET films. X-ray absorption measurements of the PET/conductive-substrates using the total-electron-yield (TEY) method by measuring sample current easily provide the X-ray absorption spectra (XAS) of PET films, which are independent of the substrates. From additional X-ray absorption measurements using self-standing PET/Au and Au/PET-films, I–V measurements, and thickness-dependent sample current measurements, it can be confirmed that electrically conductive paths form in the insulating PET film in thickness direction along the soft X-ray beam trajectory. Such phenomena enable easy and simple TEY-XAS measurements of insulating μm-order-thick samples.

Artisanal small gold mining (ASGM) is responsible for approximately 40% of the total Hg emissions into the atmosphere worldwide. In developing countries, many people are engaged in ASGM activities. We developed a small, simple Hg measuring device, which detects Hg in the air based on the change of the oscillation frequency of an Au electrode on a quartz crystal microbalance (QCM). This device is called QCM-Hg. We tested the viability of the QCM-Hg in various work settings including a gold mining area and gold shops. In working environments with an airborne Hg concentration of several μg m⁻³, the changing rate of the oscillation frequency for either 2 or 3 min corresponded with the Hg concentrations measured using the conventional method of gold amalgamation and cold vapor atomic absorption spectrometer (CVAAS). The results revealed that the QCM-Hg is a useful device for real-time Hg monitoring in actual working environments related to ASGM activities and Hg treatment facilities.

Renal cell carcinoma is a very aggressive and often fatal disease for which there are no specific biomarkers found to date. The purpose of this work was to find features that differentiate urine metabolic profiles of healthy people and cancer patients. Laser desorption/ionization mass spectrometry on gold nanostructures-based techniques were used for the metabolic analysis of urine of 50 patients with kidney cancer. Comparison with data from 50 healthy volunteers led to the discovery of several compounds that may be considered potential renal cell carcinoma (RCC) biomarkers. Statistical analysis of data allowed for the discovery of m/z values that had the greatest impact on group differentiation. A database search enabled the assignment of signals for the most promising 15 features among them: serine, heptanol, 3-methylene-indolenine, 2-methyl-3-hydroxy-5-formylpyridine-4-carboxylate, phosphodimethylethanolamine, 4-methoxyphenylacetic acid, N-acetylglutamine, 3,5-dihydroxyphenylvaleric acid, hydroxyhexanoylglycine, valyl-leucine, leucyl-histidine, oleamide, 9,12,13-trihydroxyoctadecenoic acid, stearidonyl carnitine and squalene. Differences of metabolite profiles of human urine could be identified by gold nanoparticle-enhanced target (AuNPET) LDI MS method and used for the detection of renal cancer.

Monitoring the changes in the level of KRAS point mutation (the concentration fraction of the KRAS point mutated DNA to the total DNA) in clinical treatment progress can guide and greatly improve the personalized therapy and therapeutic evaluation of patients with cancer. In this work, based on FRET fluorescence quenching and apyrimidinic site-induced guanine/pterin specific binding, we developed a pterin-FAM-TAMRA tri-color fluorescence sensing system to assess the level of KRAS point mutation in one step. The responses from TAMRA displayed good and similar linear correlations in the range from 60 nM to 2 μM for all four types of DNA, resulting in a common linear equation related to the T-DNA concentration (N_ΔFTAMRA = 2.908c_T-DNA + 0.364). Meanwhile, the responses from pterin showed excellent selectivity to W-DNA and an excellent linear correlation to the W-DNA in the concentration range from 60 nM to 1 μM (N_ΔFpterin = –0.364c_gDNA-G + 0.034). This biosensor has an effective concentration range for detecting KRAS point mutations. Especially, because the apyrimidinic site-induced guanine/pterin binding is selective for the detection of wild-type DNA, the sensing system can be applied for clinical mutation level detection of all kinds of KRAS point mutations (G → A, G → C and G → T) in blood samples, which is crucial for the personalized therapy and therapeutic evaluation of patients with most KRAS-related cancer types.

A new bifunctional chemosensor HBP ((E)-2-(2-((5-bromopyridin-2-yl)methylene)hydrazinyl) quinoline) based on heterocyclic compounds was designed and studied. The HBP showed successful detecting ability toward cobalt ion with a UV-visible red-shift and a color change of colorless to pink. Moreover, toward zinc ion, the HBP showed an obvious fluorescence turn-on response. The binding ratio of the HBP to cobalt and zinc was a 2 to 1 for both ions. The detection limits were found to be 10 nM for Co²⁺ and 18 nM for Zn²⁺. Based on UV-vis and fluorescent spectral variations, Job plots, ESI-MS, FT-IR and calculations, the binding mechanisms of the HBP toward cobalt and zinc ions were proposed.

The adsorption behaviors of a silica-based hybrid donor adsorbent (TAMIA-EH+1-dodecanol)/SiO₂–P towards Pd(II) were investigated under the effect of the contact time, temperature etc. in simulated high-level liquid waste. The adsorption rates of Pd(II) and Re(VII) were fairly fast and could reach the equilibrium state in only 1 h compared with other co-existing metal ions. The adsorption kinetics of Pd(II) was found to fit well with the pseudo-first order model. Even though with increasing the concentration of HNO₃ above 1 M, the adsorption performance of (TAMIA-EH+1-dodecanol)/SiO₂–P decreased gradually; it still exhibited a better selectivity towards Pd(II) when [HNO₃] > 0.5 M. The adsorption isotherms of Pd(II) and Re(VII) were well-described by the Langmuir isotherm model, while the Freundlich isotherm model was considered to be more suitable for the adsorption of Ru(III), Zr(IV) and Mo(VI). A high temperature of an aqueous solution was not good for the effective recovery of Pd(II). The calculated thermodynamic parameters revealed that the adsorption of Pd(II) was exothermic in nature.

A novel modified glassy carbon electrode with platinum (Pt)-electrodecorated and nitrogen-containing functional groups was prepared by stepwise electrolysis. The prepared electrode exhibited electrocatalytic activity towards sulfite oxidation that was better than that of a bare glassy carbon electrode. The electrocatalytic activity of sulfite oxidation has been applied to an amperometric sulfite sensor. A favorable linear relationship between the current response (ΔI) and the sulfite concentration up to 500 μM was exhibited. The detection limit was estimated to be 3 μM based on the criterion of a signal-to-noise (S/N) ratio of 3 under optimized conditions. In regards to the reproducibility, the RSD (n = 10) was 8.9% for 80 μM sulfite.

¹H/³¹P NMR techniques were applied to analyze the binding mode of guanosine 2′-monophosphate (2′-GMP) to histone. To date, no structures of the complex comprising 2′-GMP and histone have been deposited in Protein Data Bank. Because the ³¹P nucleus can be a selective marker of phosphorylated compounds, the combined use of ¹H and ³¹P NMR spectroscopy has been applied to investigate these molecular interactions. The complex formation was initially confirmed by ³¹P-diffusion ordered spectroscopy and ³¹P-T₁ measurements. In ¹H{¹H} saturation transfer difference experiments, H2′ and H3′ signals of 2′-GMP were significantly attenuated, while the rest of the unexchangeable protons were observed, indicating that the contribution of H2′ and H3′ to the binding epitopes was low. The WaterLOGSY-type experiment with ³¹P detection also indicated that a phosphorylated group located close to H2′ and H3′ had little access to histone.

A method involving cloud point–salting out extraction (CPSOE) coupled with UHPLC-MS/MS was developed for the determination of eleven sulfonamides in milk. In this study, the type and concentration of the surfactant, de-emulsification condition, pH value, volume of n-butanol, equilibration temperature and time were optimized. For this developed method, the linear range of SAs was from 0.05 to 50 μg L⁻¹, and the correlation coefficients were higher than 0.997. The average recoveries for SAs were from 61.32 to 91.67%, and the LOQs were less than 0.06 μg kg⁻¹.

A molecularly imprinted polymer-modified potentiometric histamine (HIS) sensor was prepared and used for quantitative determination of HIS in bovine serum. The calibration curve using the potential responses measured in 1 × 10⁻³ mol L⁻¹ phosphate buffer (pH 7.4) showed good linearity in the HIS concentration range of 3 × 10⁻⁴ to 1 × 10⁻² mol L⁻¹ (r = 0.92), with a detection limit of 1.6 × 10⁻⁴ mol L⁻¹. In bovine serum samples, the HIS sensor showed good recovery values of 91 – 104%. Therefore, this HIS sensor successfully determined the HIS concentration in bovine serum samples.

An on-line H₂O₂ analyzer was developed for application to the ultrapure water production process, using a gasometric method. The analyzer consists of a dissolved oxygen (DO) sensor and analyzer, a catalyst that converts H₂O₂ to O₂, and a computer that stores the DO data. H₂O₂ concentrations were calculated by measuring the change in DO concentration before and after the catalyst and using the calculation formula presented in this study. In order to accurately analyze a sub-ppb level of H₂O₂, a DO meter which can correctly measure the DO concentration at the ppb level was applied. An ion exchange resin with Pd, was selected as an appropriate catalyst since it could decompose 99% of H₂O₂ to O₂ at a space velocity of 120/h. The minimum analysis time was 20 min, and the detection limit was observed to be 0.27 ppb. When the DO concentration of the sample was 1.5 ppb or lower, an H₂O₂ concentration of 1 ppb or lower was successfully measured. Good correlation, with an R² value of 0.99, was observed between the measured and calculated H₂O₂ concentrations.