查看更多>>摘要：Although enzyme mimics have been widely developed, limited catalytic efficiency is still a bottleneck, especially under neutral condition. Herein, we reported the bioactive quinaldic acid (QA) significantly boosted the peroxidase-like activity of Co2+ in the presence of bicarbonate (HCO3-). With 2,2 '-azino-bis-(3-ethyl-benzothiazoline-6-sulphonate) (ABTS) as the substrate, the catalytic activity of Co2+ (1 mu M) was increased by over 300 times upon adding 100 mu M QA. The formed Co2+ complex had much higher turnover number (5.52 min(-1)) than that of cobalt-based nanozymes (0.011-0.51 min(-1)) in decomposing H2O2. Based on this system, ultrasensitive colorimetric methods for the detection of Co2+, bicarbonate and urease activity were achieved with limits of detection of 4.6 nM, 40 mu M and 0.00125 U/mL, respectively. For the first time, this work established an ultrasensitive method for the detection of urease activity by activating a peroxidase-like mimic with the pro-duced HCO3-.
查看更多>>摘要：Alkaline phosphatase (ALP) exists in both normal and pathological tissues. Spatiotemporal variations in ALP levels can reveal its potential physiological functions and changes that occur during pathological conditions. However, it is still challenging to exploit fluorescent probes that can measure ALP activity under good spatial and temporal resolutions. Herein, enzyme-instructed self-assembly (EISA) was used to construct a high-performing analytical tool (MN-pY) to probe ALP activity. MN-pY alone (free state) showed negligible fluorescence but presented an almost 13-fold increase in fluorescence intensity in the presence of ALP (assembly state). Mechanism study indicated the increase in fluorescence intensity was due to hydrogelation and formation of supramolecular fibrils, mainly consisting of dephosphorylated MN-Y. The dephosphorylation and further fibrillation of MN-pY could induce the formation of a "hydrophobic pocket", leading to a further increase in fluorescence intensity. Moreover, MN-pY could selectively illuminate HeLa cells with a higher ALP expression but not LO2 cells with lower ALP levels, promising a potential application in cancer diagnosis.
查看更多>>摘要：A high-performance sensing layer based on dual-template molecularly imprinted polymer (DMIP) was fabricated and successfully applied for one-by-one detection of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) as lung cancer biomarkers. The plastic antibodies of AFP and CEA were created into the electropolymerized polypyrrole (PPy) on a fluorine-doped tin oxide (FTO) electrode. Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) tests were performed to pursue the formation and characterization of the sensing layer. Methyl orange (MO) increased the conductivity of PPy and induced the formation of MO doped PPy (PPy-MO) rectangular-shaped nanotubes. Using impedimetric detection, the rebinding of the template antigens was evaluated, the charge transfer resistance increased as the concentration of AFP and CEA increased. The linear dynamic ranges of 5-10(4) and 10-10(4) pg mL(-1) and detection limits of 1.6 and 3.3 pg mL(-1) were obtained for CEA and AFP, respectively. Given satisfactory results in the determination of AFP and CEA in the human serum samples, high sensitivity, and good stability of DMIP sensor made it a promising method for sensing of AFP and CEA in serum samples.
查看更多>>摘要：Trace disinfection by-products (DBPs) produced during the disinfection of drinking water are potentially carcinogenic, teratogenic and mutagenic, which has aroused much attention recently. In this study, a molecularly imprinted (MIP) solid -phase microextraction (SPME) fiber coating was prepared by an in-situ polymerization method using a dummy template molecule for the analysis of trace 2,6-dichloroindole-1,4-benzoquinone (2,6-DCBQ), a typical DBP. The characterization results suggested that this monolithic SPME fiber under the optimized conditions had the porous structure, large surface area and good thermal stability. Due to the strong structural recognition and molecular interaction between MIP SPME coating and target molecule, it showed good extraction selectivity and capacity to trace 2,6-DCBQ with an imprinting factor of 4.7. Then, coupling with high-performance liquid chromatography (HPLC)-ultraviolet (UV) detection, a sensitive analytical method for trace 2,6-DCBQ in water samples was successfully established with a detection limit down to 2.3 ng/mL. The recoveries of the proposed method were in range of 84.4-122% with the relative standard deviations of 1.0-13% (n = 3). The results showed that this MIP SPME-HPLC-UV method possessed high analytical selectivity and sensitivity for trace 2,6-DCBQ in water, which would benefit the improvement of the practicability of DBPs monitoring and detection methodology.
查看更多>>摘要：Since daily drinking water is one of the major source for the ingestion of radiotoxic Rn-222 and Ra-226, the demand for a simple method to determine these two radionuclides has significantly increased. In the present study, a rapid, simple sequential analysis method for determining Rn-222 and Ra-226 in drinking water using a liquid scintillation counter was developed. The method employs solvent extraction and correction equations for the effect of native Rn-222 for Ra-226 analysis. Validation and examination of applicability for drinking water analysis were conducted using Rn-222-injected water and Ra-226 standard source. Minimum required counting times for examining drinking water on Quantulus 1220 and Hidex 300SL were estimated via minimum detectable activity depending on the counting time. In addition, the correction method, including an equation for reducing analysis time by more than 10 days, was suggested based on the analytical results for different elapsed times between sampling and measurement.
查看更多>>摘要：Hemolytic triterpenoid saponins, as one of the index components of Lonicerae Flos (LF), are also the main components causing hemolytic risk of LF. In order to evaluate the quality and hemolytic risk of LF crude drugs and preparations, it was a key to establish a method for quantitative analysis of hemolytic triterpenoid saponins in LF. Here, a rapid method for quantitative determining hemolytic triterpenoid saponins had been developed via paper spray mass spectrometry (PS-MS), taking macranthoidin B (MaB), macranthoidin A (MaA) and dipsacoside B (DiB) as three target model compounds, and asperosaponin VI (ASA VI, a structural analogue) was used as internal standard. The sample solution was directly loaded and separated on chromatographic paper, sprayed and ionized by a high positive voltage, and ultimately analyzed by mass spectrometry. All analytes were detected with good linearity, precision, repeatability and accuracy. Compared with traditional high performance liquid chromatography with diode array detection (HPLC-DAD) method, PS-MS method had no significant difference in the semi-quantitative analysis of the actual samples, adding the advantages of shorter analysis time, lower reagent consumption and no-need chromatography separation process. This work provides a new strategy for fast determining hemolytic triterpenoid saponins in LF crude drugs and preparations.
查看更多>>摘要：Currently, PCR is the gold standard for the detection of hepatitis C virus (HCV). However, the PCR technique is complicated and time-consuming, which prevents its application and, clinical point-of-care testing (POCT). Herein, we report a POCT method with simplicity, high sensitivity and specificity, which consists of a catalytic hairpin assembly (CHA) signal amplification system coupled with a lateral flow immunochromatographic (LFIA) test strip for the detection of HCV. Two ingeniously designed hairpin probes were hybridized to form the H1-H2 duplex in the presence of the target DNA. The catalytic hairpin assembly which was characterized of isothermal and enzyme-free, was accomplished within 40 min and the reaction was then applied to a LFIA test strip. Only the H1-H2 duplex labeled with both digoxin and biotin could be captured by the test strip, and the fluorescence value was determined. In addition, we evaluated the application potential for the detection of clinical samples. The reported method demonstrated high sensitivity with a detectable minimum concentration at 1 fM and showed a good linear range from 10 nM to 10pM, and high specificity for various mismatched sequences. The results demonstrated that clinically positive samples could be successfully detected. In conclusion, the reported method is simple, rapid, and free of large-scale equipment. POCT is expected to be useful for HCV detection in clinic.
查看更多>>摘要：Supramolecular solvents (SUPRASs) are gaining momentum in the multi-residue analysis of liquid samples thanks to the delimited hydrophilic and hydrophobic microenvironments in their nanostructures. In this work, SUPRASs with increased hydrophilicity were synthesized with the aim of enhancing the extractability of polar compounds. For this purpose, a double-headed amphiphile, 1,2-decanediol, was self-assembled in hydro-organic media in the presence and absence of sodium chloride. The SUPRASs formed, characterized by scanning electron microscopy, consisted of sponge droplets made up of a highly convoluted three-dimensional (3D) network of amphiphile. The network contained interconnected bilayers that were intersected by similarly interconnected aqueous channels with high and nearly constant water content (similar to 30%, w/w). Both the inherently open structure of the sponge morphology and the increased hydrophilic-hydrophobic balance of the amphiphile, provided highly hydrophilic microenvironments into the aggregates that rendered in increased recovery factors for 15 perfluorinated compounds (PFCs, C-4-C-18, log P-ow values from 0.4 to 11.6) in natural waters. Extraction took 15 min without further clean-up or evaporation of extracts which were readily compatible with LC-MS/MS quantitation. Absolute recoveries for PFCs, at the level of a few ng L-1, were in the range 70-120%, except for perfluoropentanoic acid (40%) and perfluombutane sulfonic acid (51%). Detection limits for PFCs in water were in the range 0.01-0.02 ng L-1, which allowed their determination in slightly polluted waters (0.07-2.33 ng L-1). This work proves that hydrophilicity in SUPRASs can be tailored through the amphiphile and the morphology of their aggregates, and that this characteristic improves compound extractability in multi-residue analysis.
查看更多>>摘要：Both single-atom nanozymes (SAzymes) and protein-template metal nanoparticles have attracted comprehensive attention in several respects owing to their excellent catalytic performance, green facile synthesis process, and robustness. Herein, the peroxidase-like activity of single-atom copper anchored on bovine hemoglobin-template gadolinium nanoparticles (Cu,Gd@BHbFITC NPs) were successfully synthesized and two sensitive turn-on fluorescence strategies for tyrosinase (TYR) activity sensing were proposed for the first time. For strategy I, TYR sensing was carried out from 1.00 to 7.80 U/mL with the detection limit (LOD) of 0.20 U/mL based on the fluorescence resonance energy transfer (FRET) between the fluorescein isothiocyanate (FITC) and the in situ generated polydopamine dots (PDA-dots). For strategy II, The LOD of TYR was 0.05 U/mL with the linear range of 0.40-19.70 U/mL based on the elimination of inner-filter effect (IEF) between FITC and the reaction product (RC) of phenol and 4-Aminoantipyrine (AAP). The smartphone-assisted sensing platform was applied to construct the on-site detection of TYR with both strategies. The developed probe possessed good selectivity and was successfully utilized to TYR detection in serum samples.
查看更多>>摘要：Developing a sensitive portable sensor for the screening of illicit drugs is always challenging. Due to the importance of pethidine (PTD) tracking in addiction diagnosis, many demands have recently increased for a selective and real-time sensor. Herein, a simple electrochemical sensor has been developed based on conductive carbon cloth (CC) modified with carbon selenide nanofilms (CSe2NF) to provide a CSe2NF/CC electrode as a novel PTD sensing tool. Profiting from the ingenious design of doping strategy during the synthesis process, Se was doped in the carbonaceous skeleton of the CC. Thus, the active surface area of the CSe2NF (4.61 cm(2)) increased respect to the unmodified CC (0.094 cm(2)) to embed a suitable sensing interface in the fast PTD assay. By optimizing some effective experimental parameters such as pH, supporting electrolyte, Se powder amount, scan rate and accumulation time, the sensor catalyzed efficiently the oxidation reaction of PTD at 0.97 V. Based on peak current variations, the PTD was measured over a broad concentration range from 29 nM up to 181.8 mu M with a limit of detection (LOD) as low as 19.3 nM compared to the other reported PTD sensors. The developed flexible sensor recognized the spiked PTD concentrations in some biofluids, including human blood, urine and saliva. The results of PTD analysis in the non-spiked and spiked blood, urine and saliva samples as the real samples by the developed sensor were validated by HPLC analysis as the reference method using t-test statistical method at confidence level of 5%. This sensing strategy based on the binder-free electrode could be promising for designing some sizable wearable sensors at a low cost. The high sensitivity of the sensor, which is a bonus for the rapid and on-site measurement of PTD, may open up a route for noninvasive routine analysis in clinical samples.
NSTL
Elsevier