A violet light-emitting diode-based gas-phase molecular absorption device for measurement of nitrate and nitrite in environmental water.

A simple and sensitive device for the detection of nitrite and nitrate in environmental waters was developed based on visible light gas-phase molecular absorption spectrometry. By integrating a detection cell (DC), semiconductor refrigeration temperature-controlling system (SRTCY), and nitrite reactor into a sequential injection analysis system, trace levels of nitrite and nitrate in complex matrices were successfully measured. A low energy-consuming light-emitting diode (violet, 400-405 nm) was coupled with a visible light-to-voltage converter (TSL257) to measure the gas-phase molecular absorption. To reduce the interference of water vapor, an SRTCY was used to condense the water vapor on-line before the gas-phase analyte entered the DC. The DC was radiatively heated by the SRTCY to avoid water vapor condensation in the light path. As a result, the obtained baseline noise reduced 3.75 times than that of without SRTCY. Under the optimized conditions, the device achieved limits of detection (3σ/k) of 0.055 and 0.36 mmol/L (0.77 and 5.04 mg N/L) for nitrite and nitrate, respectively, and the linear calibration ranges were 0.1-15 mmol/L (R2 = 0.9946) and 1-10 mmol/L (R2 = 0.9995), respectively. Precisions of 5.2 % and 9.0 % were achieved for ten successive determinations of 0.3 mmol/L nitrite and 1.0 mmol/L nitrate, and the analytical times for nitrite and nitrate determination were 5 and 13 min, respectively. This method was validated against standard methods and recovery tests, and it was applied to the measurement of nitrite and nitrate in environmental waters. Moreover, a device was designed to enable the field measurement of nitrite and nitrate in complex matrices.

Shape Control of Carbon Nanoparticles via a Simple Anion-Directed Strategy for Precise Endoplasmic Reticulum-Targeted Imaging.

Herein, small-sized fluorescent carbon nanoparticles (CNs) with tunable shapes ranging from spheres to various rods with aspect ratios (ARs) of 1.00, 1.51, 1.89, and 2.85 are prepared using a simple anion-directed strategy for the first time. Based on comprehensive morphological and structural characteristics of CNs, along with theoretical calculations of density functional theory and molecular dynamics simulations, their shape-control mechanism is attributed to interionic interactions-induced self-assembly, followed by carbonization. The endoplasmic reticulum-targeting accuracy of CNs is gradually enhanced as their shape changes from spherical to higher-AR rods, accompanied by a Pearson's correlation coefficient up to 0.90. This work presents a facile approach to control the shape of CNs and reveals the relationship between the shape and organelle-targeting abilities of CNs, thereby providing a novel idea to synthesize CNs that serve as precise organelle-targeted fluorescent probes.

Simple high-performance liquid chromatography-ultraviolet method for simultaneous separation and detection of 14 bisphenol pollutants in building materials.

A high-performance liquid chromatography-ultraviolet method was developed for rapidly and simultaneously analyzing novel and typical bisphenols in building materials, including bisphenol S, diphenolic acid, bisphenol F, bisphenol E, bisphenol A, bisphenol B, bisphenol AF, bisphenol AP, bisphenol C, bisphenol FL, bisphenol Z, bisphenol BP, bisphenol M, and bisphenol P. By using a Kromasil 100-5 C18 column, these bisphenols were completely separated in 40 min via gradually increasing the concentration of methanol in the mobile phase from 45 to 80% during the elution process. In particular, this method achieved the synchronous analysis of bisphenol S, diphenolic acid, bisphenol FL, bisphenol BP, and bisphenol M through HPLC, which were difficult to separate and had to be identified and detected through mass spectrometry. The limits of detection of the method ranged from 0.002 to 0.040 mg/L for these 14 bisphenols, with a precision of less than 4.9% (n = 7, c = 0.05 mg/L). The analytical results for five types of building materials (phenolic, epoxy, polycarbonate, polyester, and polysulfone resins) indicated that the proposed method is appropriated for the rapid measurement of bisphenols in real samples.

Retrospective analysis: The application of human menopausal gonadotropin combined with letrozole for IUI in patients undergoing artificial insemination by husband due to unexplained or mild male factors.

Objective: To compare the effects of human menopausal gonadotropin (HMG) combined with letrozole (LE) to HMG only for ovarian stimulation on pregnancy outcome of infertile patients undergoing artificial insemination by husband (AIH) due to unexplained or mild male factors. Materials and methods: Infertile patients with unexplained or mild male factors treated from July 2015 to December 2021 were selected as subjects. The patients were divided into two groups according to the ovarian stimulation schemes they received, namely HMG combined with LE or HMG only. We analyzed the laboratory examination results before drug treatment (baseline) and during ovarian stimulation and compared the pregnancy outcomes of the two groups using univariable analysis and multivariable logistic regression analysis. Results: In total, 526 cycles of 372 couples were included. The univariate analysis showed that the clinical pregnancy rate of the HMG combined with LE group was 24.8%, significantly higher than that of the HMG group (14.8%, P = 0.007). The live birth rate (19.9%) of the HMG combined with LE group were also significantly higher than those of the HMG group (11.2%, respectively). In multivariate logistic analysis, the age of males was negatively associated with the clinical pregnancy rate (OR 0.874, 95% CI 0.793~0.963, P=0.006) and live birth (OR0.875, 95% CI 0.783~0.977, P=0.018). Moreover, ovarian stimulation with HMG+LE was the only beneficial factor significantly associated with clinical pregnancy (OR 1.929, 95% CI 1.068~3.485, P=0.029) and live birth (OR 2.255, 95% CI 1.188~4.282, P=0.013). Conclusion: Ovarian stimulation using HMG combined with LE can increase the clinical outcomes (live birth and clinical pregnancy) among infertile patients undergoing AIH due to explained or mild male factors.

Determination of nitric oxide using light-emitting diode-based colorimeter with tubular porous polypropylene membrane cuvette.

On the basis of the Griess-Saltzman (GS) reaction, an optical device for nitric oxide (NO) detection in exhaled breath and atmosphere was developed by employing the light-emitting diode (LED, 560 nm) as the light source, light-to-voltage converter (LVC) as the detector, and porous polypropylene membrane tube (PPMT) as the cuvette. The PPMT was filled with GS reagents and covered with a coaxial jacket tube for gas collection and color reaction; two ends of the PPMT were connected with the LED and LVC to detect the change of light transmissivity in the wavelength range of 530 to 590 nm mainly. A gas absorber filled with GS reagents was installed prior to another absorber filled with KMnO4 solution to eliminate the interference of coexisting NO2. Under the optimized experimental conditions, the device achieved a limit of detection (3σ/k) of 4.4 ppbv for NO detection. The linearity range of this device was divided into two segments, i.e., 25 to 100 ppbv and 50 to 1000 ppbv, with both coefficients of determination > 0.99. The relative standard deviation was 2.7% (n = 9, c = 100 ppbv), and the analytical time was 5.5 min per detection. The minimum detectable quantity was decreased to 1.18 ng, which was ~ 100 times lower than the original GS method (115 ng). The present device was applied for determination of NO in exhaled breath, vehicle exhaust, and air. In addition to satisfactory spiking recoveries (i.e., 103% and 107%), the analytical results of the present device were in agreement with the results obtained by the standard method. These results assured the practicality of the developed device for NO detection in real environmental samples.

A simple, one-pot and ultrasensitive DNA sensor via Exo III-Assisted target recycling and 3D DNA walker cascade amplification.

Rapid, sensitive, and user-friendly nucleic acid detection is of growing importance in early clinical diagnosis. Here, we construct a simple, one-pot and ultrasensitive DNA sensor via exonuclease III (Exo III)-assisted target recycling amplification (ERA) combined with 3D DNA walker cascade amplification. In the presence of single-stranded DNA target, the ERA process is activated to generate numerous walker strands (WS). Thereafter, Exo III-powered WSs autonomously move along magnetic bead (MB)-based 3D track to release numerous AgNCs into the supernatant as an amplified signal output. This biosensor had a low detection limit of 18 fM and an analytical range of 40 fM to 1 pM. Furthermore, the practical application potential of this biosensor was also confirmed by the spiking experiments of p53 into human serum and urine samples.

Correction: Carbon dots with tunable dual emissions: from the mechanism to the specific imaging of endoplasmic reticulum polarity.

Correction for 'Carbon dots with tunable dual emissions: from the mechanism to the specific imaging of endoplasmic reticulum polarity' by Shuang E et al., Nanoscale, 2020, 12, 6852-6860, DOI: .

Exploiting arginine distributions for the selective and efficient depletion of arginine-rich plasma proteins.

The number and arrangement of arginine (Arg) residues in protein chains contribute greatly to the selective capturing of proteins on a designed adsorbent consisting of organic phosphate functionalized fibrous SiO2 microspheres, and the efficient depletion of high abundance Arg-rich protein species from human plasma is achieved.

Three-Dimensional DNA Nanomachine Biosensor by Integrating DNA Walker and Rolling Machine Cascade Amplification for Ultrasensitive Detection of Cancer-Related Gene.

Stochastic DNA walkers capable of traversing on three-dimensional (3D) tracks have received great deal of attention. However, DNA walker-based biosensors exhibit limited amplification efficiency because of their slow walking kinetics and low processivity. Herein, by taking advantage of the high processivity of a DNA rolling machine, a sensitive ratiometric DNA nanomachine biosensor is designed. The biosensor is constructed with hairpin-loaded Au nanoparticles (NPs) (hpDNA@AuNPs) as a DNA walker and AgNCs-decorated magnetic NPs (AgNCs@MNPs) as a DNA rolling machine. In the presence of target DNA, exonuclease III (Exo III)-powered DNA walker is activated to accomplish first-stage amplification via a burnt-bridge mechanism, generating a great deal of toehold-loaded AuNPs (Toehold@AuNPs) to hybridize with magnetic nanoparticles loaded with silver-nanoclusters-labeled DNA (AgNCs@MNPs) with the assistance of Exo III. These trigger rapid rolling of AuNPs on the AgNCs@MNPs surface and release free AgNCs, converting the biological signal into a mass spectrometric signal ratio (107Ag/197Au) with detection by ICP-MS. A linear range of 0.5-500 fmol L-1 is achieved with a detection limit of 119 amol L-1 for the p53 gene. The practical applicability of the biosensor has been demonstrated in the accurate assay of the p53 gene in the human blood.

Carbon dots with tunable dual emissions: from the mechanism to the specific imaging of endoplasmic reticulum polarity.

Regulating the fluorescence of carbon dots (CDs) is important but highly challenging. Here, carbon dots with tunable dual emissions were facilely fabricated via modulating the polymerization and carbonization processes of o-phenylenediamine (OPD) with lysine (Lys) as the co-precursor and modulator, respectively. The self-polymerization/carbonization of the OPD molecules contributed to the blue/green emission of the OPD-derived CDs. The introduction of Lys in the CD fabrication process efficiently suppressed the carbonization of the OPD polymer chains and enhanced the self-polymerization of the OPD molecules. Meanwhile, the formed OPD-Lys co-polymer chains endowed the final CD product with a new green emission center. The dual-emissive CDs were distinctly sensitive to polarity fluctuations, providing a ratiometric fluorescence response towards solution polarity. Due to their specific distribution in the endoplasmic reticulum (ER), the as-prepared dual-emissive CDs successfully distinguished the polarity variations in ER under stress, which offers a new approach for the early diagnosis of cell injury.

Improvement on the extraction efficiency of low density lipoprotein in an ionic liquid microemulsion.

A novel microemulsion is developed at room temperature with 30 µL of sodium alginate sulfate (SAS, 0.02 mol/L), 0.005 g bis (2-ethylhexyl) succinate sulfonate (AOT) and 270 µL of 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) ionic liquid as aqueous phase, surfactant and IL phase, respectively. The SAS/AOT/BmimPF6 microemulsion significantly improves the extraction efficiency for low density lipoprotein (LDL). 96% LDL in a 300 µL of PBS is selectively extracted into a same volume of microemulsion, with respect to those of 67%, 76% and 85% by BmimPF6, H2O/AOT/BmimPF6 microemulsion and sodium alginate (SA)/AOT/BmimPF6 microemulsion. LDL in the SAS/AOT/BmimPF6 microemulsion is distributed both in BmimPF6 via hydrophobic interaction and in the "pools" of the microemulsion via electrostatic interaction with AOT and specific interaction between LDL with SAS. 83% of LDL in the microemulsion can be readily back extracted into an aqueous phase with 0.8% (m/v) of sodium dodecyl sulfate (SDS) as stripping reagent. For practical applications, LDL in human serum is selectively extracted with the microemulsion, as demonstrated by enzyme linked immunosorbent assay (ELISA) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).

Polymeric Ionic Liquid-Based Fluorescent Amphiphilic Block Copolymer Micelle for Selective and Sensitive Detection of p-Phenylenediamine.

A highly sensitive and selective detection of p-phenylenediamine (PPD) is achieved by a fluorescence sensor, which is constructed by encapsulating the hydrophobic fluorescent 1-pyrenecarboxaldehyde (Py-CHO) into a polymeric ionic liquid (PIL)-based amphiphilic block copolymer (BCP) micelle. The amine-aldehyde condensation reaction between PPD and Py-CHO leads to the fluorescence quenching of Py-CHO, giving rise to the basis for the quantitative detection of PPD. The core cavity of the micelle formed by the self-assembly of PIL provides an excellent hydrophobic environment for the accommodation of fluorescent Py-CHO, offering significant improved sensitivity and selectivity for PPD detection. The amount of PIL in fabricating the amphiphilic BCP micelle, the BCP-Py-CHO micelle concentration, and the detection pH condition are investigated to obtain the best performance of this sensor. The accurate detection of PPD is achieved in the range of 0.02-10 µmol L-1 under optimal conditions, and the detection limit is 0.007 µmol L-1 (3σ/ s). The developed sensor is successfully applied to the determination of PPD contents in hair dyes, spiked water, and urine samples.

Targeted imaging of the lysosome and endoplasmic reticulum and their pH monitoring with surface regulated carbon dots.

Organelles play crucial roles in cellular activities and the functions of organelles are related greatly to the pH values, therefore, the bio-imaging of targeted organelles and their related pH sensing is of great importance in biological assays. Herein we report the fluorescence imaging of specific organelles, i.e., lysosomes and endoplasmic reticulum, and their pH sensing with surface regulated carbon dots (CDs). Carbon dots functionalized with amine groups (ACDs) are first prepared by hydrothermal treatment of citric acid and urea, and then laurylamine functionalized CDs (LCDs) are obtained via the conjugation of laurylamine with ACDs. The as-prepared ACDs and LCDs provide clear and bright imaging results for the lysosome and endoplasmic reticulum, respectively. The subcellular targeting features of the two CDs are attributed to their surface chemistries and cellular uptake pathways. Moreover, both the CDs are pH responsive within a certain pH range, i.e., 4.0-5.4 for ACDs and 6.2-7.2 for LCDs. The ACDs and LCDs are thus successfully applied to visualize the pH fluctuations of the lysosome and endoplasmic reticulum in MCF-7 cells.

Polyoxometalate-Coated Magnetic Nanospheres for Highly Selective Isolation of Immunoglobulin G.

Polyoxometalate [{a-PW11O39Zr(µ-OH)(H2O)}2]8- (POM1) is first prepared by sandwiching ZrIV among 2 mono-lacunary α-Keggin polyoxometalates, and then novel magnetic nanoparticles (NPs), Fe3O4@polyethyleneimine (PEI)@POM1, are fabricated by coating POM1 onto the surface of magnetic Fe3O4@PEI NPs under electrostatic interaction. The obtained Fe3O4@PEI@POM1 NPs are characterized by Fourier transform infrared, zeta potential, vibrating sample magnetometer, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Ascribed to the hydrogen-bonding and electrostatic interactions, the NPs exhibit high adsorption selectivity toward IgG, and the adsorption capacity is high up to 304 mg g-1 under optimal adsorption conditions. By using 0.01% cetyl trimethylammonium bromide to strip the adsorbed protein species, an elution efficiency of 95% is achieved. The feasibility of Fe3O4@PEI@POM1 NPs in real-world sample assay has been demonstrated by the selective isolation of IgG heavy chain and light chain from human serum, as confirmed by the sodium dodecyl sulfate polyacrylamide gel electrophoresis assay.

Online High Temporal Resolution Measurement of Atmospheric Sulfate and Sulfur Trioxide with a Light Emitting Diode and Liquid Core Waveguide-Based Sensor.

High temporal resolution components analysis is still a great challenge for the frontier of atmospheric aerosol research. Here, an online high time resolution method for monitoring soluble sulfate and sulfur trioxide in atmospheric aerosols was developed by integrating a membrane-based parallel plate denuder, a particle collector, and a liquid waveguide capillary cell into a flow injection analysis system. The BaCl2 solution (containing HCl, glycerin, and ethanol) was enabled to quantitatively transform sulfate into a well-distributed BaSO4 solution for turbidimetric detection. The time resolution for monitoring the soluble sulfate and sulfur trioxide was 15 h-1. The limits of detection were 86 and 7.3 µg L-1 ( S/ N = 3) with a 20 and 200 µL SO42- solution injection, respectively. Both the interday and intraday precision values (relative standard deviation) were less than 6.0%. The analytical results of the certificated reference materials (GBW(E)08026 and GNM-M07117-2013) were identical to the certified values (no significant difference at a 95% confidence level). The validity and practicability of the developed device were also evaluated during a firecracker day and a routine day, obviously revealing the continuous variance in atmospheric sulfate and sulfur trioxide in both interday and intraday studies.

Folic acid modified copper nanoclusters for fluorescent imaging of cancer cells with over-expressed folate receptor.

Water-soluble and functional copper nanoclusters (CuNCs) were prepared by using folic acid (FA) that serves both as a reducing reagent and a stabilizer. FA also acts as a functional ligand on the surface of the CuNCs, and this can be exploited to target the folate receptor which is over-expressed on the surface of HeLa cells. The FA-modified CuNCs nanoclusters have an average size of ca. 0.9 nm and are stable in aqueous medium for 30 days. Under photoexcitation at λex 270 and 350 nm, the FA-CuNCs display strong blue fluorescence with an emission peak at 440 nm. The FA-CuNCs exhibit low cytotoxicity and favorable biocompatibility as demonstrated by an MTT assay. A cell viability of >80% is found when incubating HeLa cells for 20 h with FA-CuNCs at levels of up to 200 µg mL-1. The targeting capability of the FA-CuNCs is demonstrated by live cell imaging. It is shown that HeLa cells with over-expressed folate receptor are much brighter than A549 cells where the receptor is not over-expressed. This is further corroborated by the fact that the copper content in HeLa cells (1.5 pg/cell) is 6.5-fold higher than that of A549 cells (0.23 pg/cell), both measured after the same incubation time of 3 h. If free FA is introduced into the cell culture medium, the folate receptors will be preoccupied with FA, and this results in a significant decrease in the cellular uptake of the FA-CuNCs by HeLa cells. Graphical Abstract Biocompatible copper nanoclusters (CuNCs) coated with folic acid (FA) were prepared and are shown to be viable probes for the differentiation between FR-positive HeLa cells and FR-negative A549 cells.

Pyridine boronic acid-polyoxometalate based porous hybrid for efficient depletion of high abundant glycoproteins in plasma.

A porous hybrid, namely PW12@TiO2-Si(Et)Si/Pba, is fabricated by the modification of PW12@TiO2-Si(Et)Si with pyridine boronic acid via a solvothermal method. The covalent interactions between the boronic acid group of the hybrid and the glycosylated site of proteins provide the as-prepared hybrid with favorable adsorption performance towards glycoproteins. The adsorption behaviors of glycoproteins onto the hybrid fit well with the Langmuir model, and the adsorption capacities for glycoprotein IgG and Trf are high, up to 348.5 mg g-1 and 262.6 mg g-1, respectively. Thus, a protocol for the depletion of high abundant glycoproteins from human plasma is proposed. The percentage contents of Trf, IgG, haptoglobinis and IgM are reduced from 7.38%, 5.5%, 3.01% and 1.02% to 0.951%, 4.7%, 0.126% and 0.76%, respectively. 85 low abundant proteins are identified from the raw plasma after the depletion of the high abundance proteins, demonstrating the potential of PW12@TiO2-Si(Et)Si/Pba hybrid in proteomic studies.

Discrimination and highly selective adsorption of phosphoproteins and glycoproteins with arginine-functionalized polyhedral oligomeric silsesquioxane frameworks.

The crosstalk between phosphoproteins and glycoproteins causes many difficulties in their selective isolation/enrichment from biological samples. This issue is of high significance in proteomics study, but thus far, it has not received proper attention. Herein, an arginine-functionalized polyhedral oligomeric silsesquioxane (POSS) framework, PP-x-Arg (x = 0, 1, 2, … denotes the amount of salt in preparation), was developed by combining salt-templated thermal polymerization of POSS and pyromellitic dianhydride (PMDA) with post-modification using arginine. PP-x-Arg possesses a porous nanostructure and abundant functional groups, namely, guanidine and zwitterionic groups, enabling the selective adsorption of phosphoproteins or glycoproteins via specific phosphate-guanidine affinity or hydrophilic interaction between PP-x-Arg and glycoproteins, respectively. In particular, the adsorption selectivity exhibited by PP-x-Arg can be easily regulated by adjusting the pH values of the adsorption medium. The PP-x-Arg framework was further employed for the discrimination and isolation of phosphoproteins and glycoproteins from biological samples.

Core-Corona Magnetic Nanospheres Functionalized with Zwitterionic Polymer Ionic Liquid for Highly Selective Isolation of Glycoprotein.

A novel zwitterionic polymer ionic liquid functionalized magnetic nanospheres, shortly as Fe3O4@PCL-PILs, is synthesized by grafting ionic liquid VimCOOHBr onto polymer ε-caprolactone (PCL) modified magnetic nanospheres via esterification and surface-initiated free radical polymerization. This established synthesis strategy offers the obtained magnetic nanospheres with well-defined core-corona structure, compact grafting layer, favorable zwitterionic and negative-charged surface, and high magnetic susceptibility. The as-prepared Fe3O4@PCL-PILs nanospheres exhibit typical "zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC)" behaviors toward protein binding, and selectively adsorption of glycoprotein is achieved. The adsorption capacity of the magnetic nanospheres toward Immunoglobulin G is high up to 1136.4 mg g-1, and the captured Immunoglobulin G could be efficiently recovered by using 0.5% NH3 H2O (v/v) as stripping reagent, providing a recovery of 80.5%. Fe3O4@PCL-PILs nanospheres are then employed as sorbent for the selective isolation of Immunoglobulin G from human whole blood, obtaining high-purity Immunoglobulin G as demonstrated by polyacrylamide gel electrophoresis assays.

Selective Isolation of Myosin Subfragment-1 with a DNA-Polyoxovanadate Bioconjugate.

The bioconjugation of a polyoxometalate (POMs), i.e., dodecavanadate (V12O32), to DNA strands produces a functional labeled DNA primer, V12O32-DNA. The grafting of DNA primer onto streptavidin-coated magnetic nanoparticles (SVM) produces a novel composite, V12O32-DNA@SVM. The high binding-affinity of V12O32 with the ATP binding site in myosin subfragment-1 (S1) facilitates favorable adsorption of myosin, with an efficiency of 99.4% when processing 0.1 mL myosin solution (100 µg mL-1) using 0.1 mg composite. Myosin adsorption fits the Langmuir model, corresponding to a theoretical adsorption capacity of 613.5 mg g-1. The retained myosin is readily recovered by 1% SDS (m/m), giving rise to a recovery of 58.7%. No conformational change is observed for myosin after eliminating SDS by ultrafiltration. For practical use, high-purity myosin S1 is obtained by separation of myosin from the rough protein extract from porcine left ventricle, followed by digestion with α-chymotryptic and further isolation of S1 subfragment. The purified myosin S1 is identified with matrix-assisted laser desorption/ionization time-of-flight/mass spectrometry, giving rise to a sequence coverage of 38%.