Sample Pretreatment Research Articles

Removal and detection of phenols through an SPE-HPLC method using microporous organic networks as adsorbent.

The design and development of a facile synthesis approach to construct novel materials for the rapid adsorption and removal of environmental pollutants are of significant interest. In this work, we report the rational design and facile synthesis of magnetic core-shell-based microporous organic networks, Fe3O4@MON-TBPT-TEB (TTMON, achieved by reacting 2,4,6-tris(p-bromophenyl) triazine and 1,3,5-triethynylbenzene) and Fe3O4@MON-TBPM-DEBP (TDMON, achieved by reacting tetrakis (4-bromophenyl) methane and 4-4'-diethynylbiphenyl). These MONs possessed excellent dispersity, electrostatic attraction as well as plenty of π-π and hydrophobic interaction sites enabled them to efficiently absorb targeted environmental pollutants. TTMON and TDMON exhibited excellent adsorption capacities of 440 and 510 mg g-1, respectively, at 25 °C for 2,4,6-trichlorophenol (TCP). TCP, 2,4-dichlorophenol (DCP), 2-naphthol (2-NT) and 4-nitrophenol (4-NP) from aqueous solution were treated by both MONs, followed by their analysis with high-performance liquid chromatography (HPLC). For TDMON, the proposed SPE-HPLC-UV method showed an LOD of 0.03 μg L-1, LOQ of 0.11 μg L-1, and a wide linear range of 1-1000 μg L-1 for TCP. The adsorption kinetics, thermodynamics, isotherms, effect of pH and humic acid (HA), ionic strength, regeneration, and reusability of the MONs were also studied. The results revealed that the novel-designed MONs have potential applications as efficient adsorbents in sample pretreatment.

Lactose detection and quantification in milk by gold nanoparticles-based surface-assisted laser desorption/ionization mass spectrometry technique

Lactose, or milk sugar, is one of the essential carbohydrates included in the human diet. Its most significant source is milk and other dairy products. Still, due to the ever-increasing percentage of the population with lactose intolerance, there is a need to detect and quantify it in food products. Surface-assisted laser desorption/ionization mass spectrometry (SALDI MS) method on gold nanoparticle enhanced steel target (AuNPET) was used to rapidly detect and quantify lactose with a minimum sample pretreatment including molecular weight cut-off ultrafiltration. The carbohydrate was tested directly in the concentration range from 500 µg/mL to 1 µg/mL, which corresponds to 1.46 nmol to 2.92 pmol per analyzed spot. Limit of detection (LOD) of 0.14 µg/mL or 0.42 µM is one of the best among the techniques used to determine lactose. In addition, the quantitative approach based on mass spectrometry of milk samples shown in this study made it possible to decide on lactose concentration in real samples.

Field detection of genetically modified crops: Simple DNA extraction, rapid assay and automatic output on smartphone

Rapid and accurate detection of genetically modified crops (GMC) is significant for crop supervision and genetically modified product labeling. For field detection of GMC, the rapidity and simplicity of the sample pretreatment and detection process are very important. Simplifying the extraction process of DNA in crops and speeding up the detection process are the technical problems that need to be solved. Therefore, this paper provides a field detection method for GMC. First, the selected universal LAMP primers of the chloroplast gene can be used to detect reference genes in nine crops with the most transgenic detection needs. The universal primers of reference genes can not only improve the accuracy of detection, but also omit the design and synthesis of reference gene primers in different crops. Second, a high concentration of DNA can be obtained using simple and fast DNA extraction methods within 5 min. The specific concentration of GuHCl in lysis buffer can accelerate the subsequent nucleic acid amplification reaction. Third, a new probe-LAMP method was established, with high reaction speed and specificity. Using the dual probe-LAMP for transgenic and reference genes in a handheld nucleic acid detector, the detection of GMC can be completed within 25 min. Two different fluorescence signals generated from the LAMP reaction are processed through a special logic gate, and finally three kinds of results of "Positive", "Negative" and "Invalid" are output on a smartphone. This method from sample processing to intelligent result output can achieve accurate, rapid, simple, low-cost, pollution-free field detection of GMC.

Evaluation of a Liquid Chromatography-Tandem Mass Spectrometry Method for the Analysis of Glucosylceramide and Galactosylceramide Isoforms in Cerebrospinal Fluid of Parkinson's Disease Patients.

Mutations in GBA1, encoding glucocerebrosidase beta 1 (GCase), are the most common genetic risk factor for Parkinson's disease (PD). GCase dysfunction leads to an accumulation of glucosylceramide (GluCer) substrates in different organs and fluids. Despite the challenges in quantifying GluCer isoforms in biological samples, their potential clinical interest as PD biomarkers justifies the development of robust assays. An extensively evaluated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for quantifying 14 GluCer and galactosylceramide (GalCer) isoforms in human cerebrospinal fluid (CSF) samples is presented. Sample pretreatment, HPLC, and MS/MS parameters were optimized. Evaluation was performed according to the recommendations of the Clinical and Laboratory Standards Institute and European Medicines Agency guidelines. Four 7-point calibration curves were generated, with a linearity interval from 2.5 to 200 nM (R2 ≥ 0.995). The limit of quantification was set at 5 nM. Between-run precision and accuracy were up to 12.5 and 9%, respectively. After method validation, we measured the levels of GluCer and GalCer isoforms in CSF human samples, including 6 healthy controls (HC), 22 idiopathic GBA1 wild-type PD (iPD) patients, and 5 GBA1-associated PD (PD-GBA) patients. GluCer/GalCer median ratios were found to be higher in the CSF of PD-GBA patients, particularly in severe GBA1 mutations, than those in iPD and HC. The observed trends in GluCer/GalCer ratios among groups provide novel information for the comprehensive analysis of sphingolipids as potential biomarkers of PD.

Fabrication of fluorinated magnetic microporous organic network for selective and efficient extraction of benzoylurea insecticides in tea beverages

In this work, a novel fluorinated magnetic microporous organic network (Fe3O4@FMON) was exquisitely designed and synthesized for highly efficient and selective magnetic solid phase extraction (MSPE) of fluorinated benzoylurea insecticides (BUs) from complex tea beverage samples. The Fe3O4@FMON exhibited good extraction for BUs via the pre-designed hydrophobic, π-π stacking, hydrogen bonding and specific FF interactions. A sensitive Fe3O4@FMON-based MSPE-HPLC-UV method with wide linear range (0.10–1000 μg L−1, R2 ≥ 0.996), low limits of detection (0.01–0.02 μg L−1), and large enrichment factors (85.6–98.0) for BUs from tea beverage samples was developed. By decorating F elements within MON's networks, the Fe3O4@FMON characterized good hydrophobicity and chemical stability, which could be reused at least 8 times without decrease of recoveries. This work demonstrated the great prospects of Fe3O4@FMON for enriching trace BUs from complex substrates and triggered the potential of FMON for sample pretreatment of fluorinated analytes.

Development of a Two-Dimensional Liquid Chromatography Online Deproteinization Method for Determining Paclitaxel-Related Substances in a Paclitaxel Injection (Albumin-Bound)

To determine the paclitaxel-related substances in a paclitaxel injection (albumin-bound), it is necessary to remove human blood albumin from the sample via solid-phase extraction and subsequently perform high-performance liquid chromatography analysis. The pre-processing operation is complicated, the duration of analysis is long, and much human power and material resources are needed in the sample testing process. Thus, the purpose of this study was to develop a quick two-dimensional liquid chromatography method that requires less consumables and possesses high sensitivity. Samples were directly injected into one-dimensional solid-phase extraction columns to remove human blood albumin. Paclitaxel and its related substances in the solid-phase extraction columns were then eluted into two-dimensional analytical columns through valve switching technology. The sample pretreatment step can be omitted in this method, which allows for the analysis of paclitaxel and its related substances to be completed more quickly, within only 15 min, under the developed two-dimensional elution conditions. The established method had good linearity (R2 = 0.9994), limit of detection (0.25 μg·mL−1), limit of quantification (0.5 μg·mL−1), precision (RSD = 0.5%), and accuracy (102.53–107.97%).

A candidate reference measurement procedure for quantification of glycocholic acid in human serum based on isotope dilution liquid chromatography-tandem mass spectrometry

Accurate measurement of serum glycocholic acid (GCA) is crucial for evaluating the activity of chronic hepatitis. Moreover, GCA is a novel identified biomarker for hepatocellular carcinoma. Although some laboratories have used the liquid chromatography-tandem mass spectrometry (LC–MS/MS) method to measure GCA in recent years, the problem of potential interference of GCA analogues has not been solved well yet. Neither reference measurement procedures nor reference materials for GCA have been listed in the Joint Committee for Traceability in Laboratory Medicine (JCTLM) database. For standardization of GCA, it is urgent to establish a candidate measurement procedure for GCA. In this study, a candidate reference measurement procedure for the quantification of GCA in human serum based on isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC–MS/MS) by a two-step sample pretreatment of protein precipitation and MAX solid-phase extraction was developed and validated. GCA can be completely separated from its structural analogues with gradient elution in 9 min compared with short time gradients published in previous literature by Huang’s group. Method validation indicated perfect quantitation precision with intra-day and inter-day values that were ≤1.30% and ≤1.80%, respectively. The method showed excellent linearity with high regression coefficients (R2 > 0.999) over a range of 0.92 ng/g–38.38 μg/g and perfect recoveries at three spiked levels (99.87–100.43%). No interference, matrix effect, and carryover were observed. Moreover, the cRMP was successfully applied to measure GCA in serum samples and compared with two immunoassays in a clinical laboratory. As a candidate reference method, this method can promote a GCA standardization program.Graphical

Molecularly imprinted polymer based on covalent organic framework coated steel substrate as the mass spectrometric ionization source for the direct detect of aflatoxins in complex food matrices

Ambient mass spectrometry allows direct analysis of various sample types with minimal or no pretreatment. However, due to the influence of matrix effects, there are sensitivity and issues in analyzing trace analytes in complex food samples. In this work, we developed a spray mass spectrometry platform based on SSS@TPBD-TPA@MIPs (Stainless steel substrate (SSS), terephthalaldehyde (TPA), N, N, N′, N′-tetrakis(p-aminophenyl)-p-phenylenediamine (TPBD), molecularly imprinted polymer (MIP)), for rapid, in situ, high-throughput, highly enrichment efficiency and highly selective trace analysis of aflatoxins. By simplifying the sample pretreatment and directly applying high voltage for ESI-MS, the analysis can be completed within 1 min. The established method base on SSS@TPBD-TPA@MIPs exhibited high sensitivity and accuracy when determine trace level AFs in maize and peanuts. The results demonstrated a good linear relationship within the range of 0.01–10 μg/L, with the determination coefficient (R2) ≥ 0.9956. The limits of detection (LODs) was 0.035–0.3 ng/mL and limits of quantitation (LOQs) was 0.12–0.99 ng/mL, with acceptable recovery rate of 82.09–115.66 % and good repeatability represented by the relative standard deviation (RSD) less than 17.43 %. Furthermore, SSS@TPBD-TPA@MIPs exhibited excellent reusability, with more than 8 repeated uses, and showed good adsorption performance.

Imprinted membrane-covalent organic framework platform for efficient label-free visual detection of Listeria monocytogenes and Salmonella typhimurium in food samples

BackgroundRapid and sensitive detection of foodborne pathogens in food plays a crucial role in controlling outbreaks of foodborne diseases, of which Listeria monocytogenes and Salmonella typhimurium are representative and notable pathogens. Thus, it's of great importance to achieve the effective detection of these pathogens. However, the most common detection methods (culture-based technique, Polymerase Chain Reaction and immunological methods) have disadvantages that cannot be ignored, such as time-consuming, laborious, complex sample preparation process, and the possibility of cross-reaction. Hence, it is essential to develop a facile detection method for the pathogens with high sensitivity and specificity to avoid the above-mentioned disadvantages. ResultsWe report a label-free visual platform for the simultaneous capture and detection of Listeria monocytogenes and Salmonella typhimurium. For the first time, we have prepared polydimethylsiloxane-Chromotrope 2R membrane which serves as the substrate for bacterial capture and enrichment through the formation of specific recognition sites. The positively charged Pt-covalent organic framework combines with the pathogens through surface charge interaction, thereby the label-free sandwich platform is formed. Remarkable peroxidase activity of Pt-covalent organic framework converts the conversion of bacterial quantity into amplified color signal by catalyzing 3,3′,5,5′-Tetramethylbenzidine to oxidized 3,3′,5,5′-Tetramethylbenzidine. The platform demonstrates the capability to identify two representative food-borne pathogens within a time frame of 100 min, exhibiting high sensitivity and excellent specificity without the interference from non-target bacteria. The limit of detection of the visual platform toward Listeria monocytogenes and Salmonella typhimurium was 1.61 CFU mL−1 and 1.31 CFU mL−1, respectively. And the limit of quantification toward Listeria monocytogenes and Salmonella typhimurium was 4.94 CFU mL−1 and 2.47 CFU mL−1, respectively. The relative standard derivations of the visual platform for both bacteria were lower than 4.9 %. Furthermore, our proposed platform has obtained reliable and satisfactory results on analyzing diverse food samples. SignificanceThis research expands the application of a label-free platform combined with unlabeled nanocomponents in the rapid isolation and detection of diverse of food-borne pathogens. The platform possesses the advantages of simple operation and real-time monitoring, without complicated sample pretreatment process. The whole detection process can realize the simultaneous monitoring of Listeria monocytogenes and Salmonella typhimurium within 100 min. Furthermore, it is also of reference significance for the detection of other common pathogens.

OLIVE PITS-BASED CARBON BLACK AGGLOMERATE AS AN ADSORBENT FOR PIPETTE-TIP SOLID-PHASE EXTRACTION FOR THE DETERMINATION OF CAFFEINE IN ENERGY DRINKS

Vegetal wastes are an interesting source for the synthesis of nanostructured carbon materials, which are potentially useful in various applications. Carbon black agglomerates (CBA) obtained from olive pits, synthesized in our previous research, had a low crystalline structure typical of this type of materials, with a pore size of 2.27 nm, confirming their micro/mesoporous structure, and with a high surface value of around 587 m2/g. These materials were used for the extraction of caffeine in energy drinks using a green-approach micro-sample technique called pipette-tip solid-phase extraction. This microextraction technique features reduced consumption of organic solvents, of the amount of sorbent and extraction time, thus making the whole sample pretreatment process faster and greener. In this work, we proposed an analytical method for the analysis of caffeine in commercial energy drinks, using CBA with a great extraction capacity due to its high porous surface area. The developed methodology has proven to be useful from a green chemistry point of view, using only one milligram of nanostructured sorbent, minimal solvent consumption, a reduced volume of sample, as well as easy and rapid automatization for the analysis of commercial energy drinks. For the quantification of the analyte in the energy drinks, a one-point standard addition calibration was applied to correct the matrix effect. Similar caffeine concentrations per milliliter were found in the three analyzed samples, likewise, the amounts of caffeine close to those reported by the manufacturers were established for two of the samples analyzed.

An Efficient Bio-Receptor Layer Combined with a Plasmonic Plastic Optical Fiber Probe for Cortisol Detection in Saliva.

Cortisol is a clinically validated stress biomarker that takes part in many physiological and psychological functions related to the body's response to stress factors. In particular, it has emerged as a pivotal tool for understanding stress levels and overall well-being. Usually, in clinics, cortisol levels are monitored in blood or urine, but significant changes are also registered in sweat and saliva. In this work, a surface plasmon resonance probe based on a D-shaped plastic optical fiber was functionalized with a glucocorticoid receptor exploited as a highly efficient bioreceptor specific to cortisol. The developed plastic optical fiber biosensor was tested for cortisol detection in buffer and artificial saliva. The biosensor response showed very good selectivity towards other hormones and a detection limit of about 59 fM and 96 fM in phosphate saline buffer and artificial saliva, respectively. The obtained detection limit, with a rapid detection time (about 5 min) and a low-cost sensor system, paved the way for determining the cortisol concentration in saliva samples without any extraction process or sample pretreatment via a point-of-care test.

Suspect screening of per-and polyfluoroalkyl substances in paper by selective and non-selective extraction with UHPLC-Q orbitrap MS

Non-targeted analysis and suspect screening of per- and polyfluoroalkyl substances (PFAS) in various matrices have gained traction with advancements in accurate mass analytical instruments. This study employed ultra-high performance liquid chromatography coupled to quadrupole orbitrap high-resolution mass spectrometry for PFAS suspect screening of paper grades used in the paper recycling chain. The samples were prepared using two extraction techniques; selective accelerated solvent extraction with weak anionic exchange solid-phase extraction and non-selective ultrasonic-assisted extraction. A suspect screening protocol was established to tentatively identify suspected PFAS against spectral databases using a systematic approach of peak filtering and study-specific thresholds for reporting, linked to a confidence level. The possible prevalence of previously unreported PFAS in several paper materials across the various collection sites in the paper recycling chain was inferred by the common detection of short-chain polyfluoroalkyl ketones and diketones in the paper recycling chain. The suspect screening tentatively identified 41 unique PFAS, with 3 common to both pre-treatment techniques. The detection of unique PFAS by the two sample pre-treatment techniques highlighted the significance of both selective and non-selective extraction in PFAS screening endeavours. Further, it showed the importance of understanding the acquisition mechanisms employed in mass spectrometry where data-dependent acquisition triggered fragmentation in certain identified compounds, and not in others. The tentatively identified PFAS indicated that there were several previously unreported PFAS in the paper recycling chain and that additional studies were required to investigate their abundance, possible persistence, bioaccumulation and toxicity, in relation to their functional groups and carbon chains.

High Frequency and Addressable Impedance Measurement System for On-Site Droplet Analysis in Digital Microfluidics

Digital microfluidics is a novel technique for manipulating discrete droplets with the advantages of programmability, small device size, low cost, and easy integration. The development of droplet sensing methods advances the automation control of digital microfluidics. Impedance measurement emerges as a promising technique for droplet localization and characterization due to its non-invasive nature, high sensitivity, simplicity, and cost-effectiveness. However, traditional impedance measurement approaches in digital microfluidics based on the high-voltage actuating signal are limited in sensing accuracy in practical applications. In this paper, we propose a novel droplet impedance sensing system for digital microfluidics by introducing a low-voltage and addressable measurement circuit, which enables impedance measurement over a wide frequency range. The proposed measurement system has also been used for detecting the droplet composition, size, and position in a digital microfluidic chip. The improved impedance sensing method can also promote the applications of the digital microfluidic, which requires high accuracy, real-time, and contactless sensing with automatic sample pretreatment.

An exonuclease III-driven dual-mode aptasensor based on Au-Pd@Fc nanozyme and magnetic separation pretreatment for aminoglycoside antibiotics detection

A novel dual-mode aptasensor was constructed for aminoglycoside antibiotics (AAs) detection by using a broad-spectrum aptamer as a biorecognition element, and Au-Pd@Fc functionalized by signal DNA as nanoprobes. In electrochemical mode, the target-induced cyclic amplification reaction run under the action of exonuclease-III, which increased the number of nanoprobes on the electrode surface. AAs could be quantitatively detected with LOD of 0.0355 ± 0.00613 nM. In colorimetric mode, the Au-Pd@Fc nanozyme catalyzed the color reaction of 3,3′,5,5′-tetramethylbenzidine. The blue-shifted absorbance will be observed with the change of AAs concentration, and the LOD was 0.0458 ± 0.00572 nM. Furthermore, a magnetic molecular-imprinted material capable of specific adsorption of AAs was prepared on milk sample pretreatment. The aptasensor was used to detect 10 kinds of AAs in milk and the recoveries were 97.19 ± 4.41% ∼ 98.70 ± 4.45% and 96.38 ± 3.53%-97.54 ± 4.13% in electrochemical and colorimetric methods. This work provided a theoretical basis for the application of aptamers in simultaneous detection of antibiotics.

Preparation of magnetic coconut clothing biochar for extracting neonicotinoid insecticides from environmental water samples

In this study, the magnetic coconut clothing biochar hybrid materials were successfully prepared by in-situ method. The obtained magnetic biochar was characterized in detail by using series of analytical techniques. The results showed that the magnetic hybrid materials presented alveolate network structures with abundant large pores and good magnetic separation ability with Fe3O4 nanoparticles obviously attached on the surface of biochar. The magnetic biochar hybrid materials were used as adsorbents during magnetic solid-phase extraction process for extracting neonicotinoid insecticides from environmental water samples. The adsorption and desorption parameters (adsorption time, elution condition, sample volume, sample pH) affecting magnetic solid-phase extraction efficiency were carefully investigated. Under the optimum conditions (adsorption for 15 min, 5 % formic acid-acetonitrile as elution condition, 50 mL of sample volume, 15 mg of magnetic biochar, pH at 5.0), the magnetic solid-phase extraction process based on magnetic coconut clothing biochar hybrid materials coupled with high performance liquid chromatography tandem mass spectrometry for enriching and detecting neonicotinoid insecticides in environmental water samples was established. The good linear relationship in the range of 0.5–200 ng mL−1 with correlation coefficients greater than 0.9989 and the lower limits of detection (0.0017–0.0069 ng·mL−1) were obtained. The recovery in the spiked water samples was in the range of 68.6 %-104.0 % with relative standard deviation from 0.4 % to 9.3 %. These results demonstrated that the established method was highly sensitive, convenient and repeatable for directly analyzing trace neonicotinoid insecticides in environmental water samples. More importantly, the novel biochar from coconut clothing was introduced into sample pretreatment to enrich trace organic pollutants.

Impact of copper sulphate treatment on cyanobacterial blooms and subsequent water quality risks

Control of algal blooms and associated biologically-induced water quality risks in drinking reservoirs is problematic. Copper sulphate (CuSO4) treatment is one intervention that has been utilised for >100 years. Evidence indicates a favourable short-term reduction in Cyanobacterial biomass (e.g. bloom termination), but here we indicate that it may also increase longer-term water quality risk. In 2022, we investigated the impacts of CuSO4 spraying on Cyanobacterial communities and nutrient levels within a drinking water supply reservoir using environmental DNA (eDNA) to assess community shifts, alongside monitoring nutrient fractions, orthophosphate (OP) and total phosphate (TP), post-treatment. CuSO4 application successfully reduced Cyanobacterial abundance, however elimination of Cyanobacteria resulted in a shift in bacterial dominance favouring Planctomycetota throughout the summer and a combination of Actinobacteriota and Verrucomicrobiota, throughout autumn. As Cyanobacterial abundance recovered post-treatment, Cyanobacterial genera demonstrated greater diversity compared to only three Cyanobacterial genera present across samples pre-treatment, and included taxa associated with water quality risk (e.g. taste and odour (T&O) metabolite and toxin producers). The increase in Cyanobacteria post-treatment was attributed to an increase in biologically available nutrients, primarily a significant increase in OP. Overall, findings suggest that the significant shift in biodiversity likely induces a less stable ecosystem with greater plasticity of response to changing environmental and biogeochemical variables. Legacy implications of CuSO4 spraying, in terms of shifts in ecosystem and nutrient balance over time, may have implications for drinking water quality, but importantly also for reservoir management options. As such, the effects of CuSO4 spraying should be considered carefully before consideration as a contender for in-reservoir biological control.

Versatile Solvatochromic fluorophores based on Schiff bases for colorimetric detection of metal ions

In recent years, fluorescent probes have been extensively studied as powerful tools for the effective assessment of toxic metal ions due to their high sensitivity, selectivity, capability for real-time and non-invasive monitoring, and versatility. In this paper, novel fluorescent probes based on Schiff bases, namely 2-((1E,2E)-1-(6-chlorobenzo[d]thiazol-2-ylimino)-3-(4-(dimethylamino)phenyl)allyl)phenol (1) and 2-((1E,2E)-3-(4-(dimethylamino)phenyl)-1-(4-methylbenzo[d]thiazol-2-ylimino)allyl)phenol (2), were synthesized and characterized. The optical properties of these probes were examined across a spectrum of fourteen solvents with varying polarities, revealing significant solvatochromic effects on both absorption and fluorescence spectra. The analysis delineated a discernible difference in dipole moment between electronic ground and excited states, with molecules exhibiting enhanced stabilization in singlet excited states. Subsequently, a straightforward method was devised for the selective and sensitive detection of diverse metal ions in aqueous solutions, including K+, V3+, Cr3+, Fe3+, Co2+, Ni2+, Cu2+, Se6+, Cd2+, Ba2+, and Hg2+, through naked eye observation, UV–Visible, and fluorimetric measurements. Notably, the UV–Vis spectra of probes 1 and 2 manifested a significant red shift upon the addition of metal ions, indicative of potential ligand-to-metal charge-transfer (LMCT) phenomena, with the exception of Ni2+, Cu2+, and Se6+ions. The observed alterations in optical absorption and fluorescence emission contributed to the probes' heightened selectivity and sensitivity, obviating the necessity for sample pretreatment. Competitive assays underscored the probes' preference for Cr3+ and V3+ ions over other common metal ions. Furthermore, Job's plot analysis suggested a 1:1 ligand-to-metal molar ratio binding. The investigated Schiff bases exhibited elevated binding constants (Ka), low detection limits, and limits of quantification, alongside diminished fluorescence quantum yield. Leveraging fluorescence quenching, facile paper-based sensor strips coated with Schiff bases facilitated prompt, qualitative, and quantitative in situ detection of metal ions in aqueous solutions across a broad concentration spectrum, discernible to the naked eye under UV light.

The interaction between the import carrier Hikeshi and HSP70 is modulated by heat, facilitating the nuclear import of HSP70 under heat stress conditions.

Heat stress strongly triggers the nuclear localization of the molecular chaperone HSP70. Hikeshi functions as a unique nuclear import carrier of HSP70. However, how the nuclear import of HSP70 is activated in response to heat stress remains unclear. Here, we investigated the effects of heat on the nuclear import of HSP70. In vitro transport assays revealed that pretreatment of the test samples with heat facilitated the nuclear import of HSP70. Furthermore, binding of Hikeshi to HSP70 increased when temperatures rose. These results indicated that heat is one of the factors that activates the nuclear import of HSP70. Previous studies showed that the F97A mutation in Hikeshi in an extended loop induced an opening in the hydrophobic pocket and facilitated the translocation of Hikeshi through the nuclear pore complex. We found that nuclear accumulation of HSP70 occurred at a lower temperature in cells expressing the Hikeshi-F97A mutant than in cells expressing wild-type Hikeshi. Collectively, our results show that the movement of the extended loop may play an important role in the interaction of Hikeshi with both FG (phenylalanine-glycine)-nucleoporins and HSP70 in a temperature-dependent manner, resulting in the activation of nuclear import of HSP70 in response to heat stress.

Implementing magnetic molecularly imprinted solid phase extraction to analytical method for determination of 2-phenethylamine in cocoa powder and chocolate by LC-MS/MS system

The main aim of this study was to design, develop, and apply magnetic molecularly imprinted polymer (MMIP) during sample pretreatment before liquid chromatography tandem mass spectrometry (LC-MS/MS) 2-phenylethylamine determination in cocoa powder and chocolate samples. The morphology and structure of MMIP, obtained from methacrylic acid (monomer) and trimethylolpropane trimethacrylate (cross-linker) were characterized using scanning electron microscopy, nitrogen sorption analyses, infra-red spectroscopy, X-ray diffraction measurements, vibrating-sample magnetometry, and thermogravimetry analyses. The analyte adsorption mechanism on MMIP was studied using computational simulation. The magnetic solid phase extraction procedure on MMIP was optimized, resulting in a relative matrix effect of 6.2 % for cocoa powder and 2.8 % for chocolate. The LC-MS/MS quantified the 2-phenethylamine in eighteen cocoa powder and chocolate samples, showing a concentration range between 2.4 and 8.7 μg g−1.

Fabrication of sea urchin shaped polyaniline-modified magnetic microporous organic network for efficient extraction of non-steroidal anti-inflammatory drugs from animal-derived food samples

In this work, a novel polyaniline-modified magnetic microporous organic network (MMON-PANI) composite was fabricated for effective magnetic solid phase extraction (MSPE) of five typical nonsteroidal anti-inflammatory drugs (NSAIDs) from animal-derived food samples before high performance liquid chromatography (HPLC) detection. The core-shell sea urchin shaped MMON-PANI integrates the merits of Fe3O4, MON, and PANI, exhibiting large specific surface area, rapid magnetic responsiveness, good stability, and multiple binding sites to NSAIDs. Convenient and effective extraction of trace NSAIDs from chicken, beef and pork samples is realized on MMON-PANI via the synergetic π-π, hydrogen bonding, hydrophobic, and electrostatic interactions. Under optimal conditions, the MMON-PANI-MSPE-HPLC-UV method exhibits wide linear ranges (0.2–1000 μg L−1), low limits of detection (0.07–1.7 μg L−1), good precisions (intraday and inter-day RSDs < 5.4 %, n = 3), large enrichment factors (98.6–99.9), and less adsorbent consumption (3 mg). The extraction mechanism and selectivity of MMON-PANI are also evaluated in detail. This work proves the incorporation of PANI onto MMON is an efficient way to promote NSAIDs enrichment and provides a new strategy to synthesize multifunctional MON-based composites in sample pretreatment.