Single-step batch fabrication of microfluidic paper-based analytical devices with a 3D printer and their applications in nanoenzyme-enhanced visual detection of dopamine

Wax printing is the most widely used method for fabricating microfluidic paper-based analytical devices (μPADs), but it still suffers from disadvantages like discontinuation of wax printers and need for additional equipment for heating treatment. To address these issues, this work initially describes a new class of wax printing approach for high-precision, batch fabrication of μPADs using a household 3D printer. It only involves a one patterning step of printing polyethylene wax into rice paper body. Under optimized parameters, a fabrication resolution, namely the minimum hydrophilic channel width, down to ~189 ± 30 μm could be achieved. In addition, the analytical applicability of such polyethylene wax-patterned μPADs was demonstrated well with enhanced colorimetric detection of dopamine as a model analyte by combining metal-organic framework (MOF) based nanoenzymes (ZIF-67) with a smartphone (for portable quantitative readout). The developed nanosensor could linearly detect dopamine over a concentration range from 10 to 1000 μM, with a detection limit of ca. 2.75 μM (3σ). The recovery results for analyzing several real samples (i.e., pig feed, chicken feed, pork and human serum) were between 91.82 and 102.79%, further validating its good detection accuracy for potential practical applications in food safety and medical diagnosis.

Insight into the interaction and binding mechanism of a natural nonnutritive sweetener mogroside V with soybean protein isolates based on multi-spectroscopic techniques and computational simulations

As a natural low-calorie sweetener, Mogroside V (Mog-V) has gradually become one of the alternatives to sucrose with superior health attributes. However, Mog-V will bring unpleasant aftertastes when exceeding a threshold concentration. To investigate the possibility of soy protein isolates (SPIs), namely β-conglycinin (7S), and glycinin (11S) as flavor-improving agents of Mog-V, the binding mechanism between Mog-V and SPIs was explored through multi-spectroscopy, particle size, zeta potential, and computational simulation. The results of the multi-spectroscopic experiments indicated that Mog-V enhanced the fluorescence of 7S/11S protein in a static mode. The binding affinity of 7S-Mog-V was greater compared with 11S-Mog-V. Particle size and zeta potential analysis revealed that the interaction could promote aggregation of 7S/11S protein with different stability. Furthermore, computational simulations further confirmed that Mog-V could interact with the 7S/11S protein in different ways. This research provides a theoretical foundation for the development and application of SPI to improve the flavor of Mog-V, opening a new avenue for further expanding the market demand for Mog-V.

A colorimetric sensor for rapid discrimination of tea polyphenols and tea authentication based on Rh-decorated Pd nanocubes with high peroxidase-like activity

The rapid development of nanozymes has offered substantial opportunities for the fields of biomedicine, chemical sensing, and food safety. Among these applications, multichannel sensors, with the capability of simultaneously detecting multiple target analytes, hold promise for the practical application of nanozymes in chemical sensing with high detection efficiency. In this study, Rh-decorated Pd nanocubes (Pd-Rh nanocubes) with significantly enhanced peroxidase-like activity are synthesized through the mediation of underpotential deposition (UPD) and subsequently employed to develop a multichannel colorimetric sensor for discriminating tea polyphenols (TPs) and tea authentication. Based on a single reactive unit of efficient catalytic oxidation of 3,3',5,5'-tetramethylbenzidine dihydrochloride (TMB), the nanozyme-based multichannel colorimetric sensor responds to each analyte in as short as 1 min. With the aid of principal component analysis (PCA) and hierarchical cluster analysis (HCA), various TPs and types of tea can be accurately identified. This work not only provides a new type of simply structured and highly active nanozymes but also develops a concise and rapid multichannel sensor for practical application in tea authentication and quality inspection.

Wildfire particulate exposure and risks of preterm birth and low birth weight in the Southwestern United States

OBJECTIVES

Wildfire air pollution is a growing concern on human health. The study aims to assess the associations between wildfire air pollution and pregnancy outcomes in the Southwestern United States.

STUDY DESIGN

This was a retrospective cohort study.

METHODS

Birth records of 627,404 singleton deliveries in 2018 were obtained in eight states of the Southwestern United States and were linked to wildfire-sourced fine particulate matter (PM2.5) and their constituents (black carbon [BC] and organic carbon [OC]) during the entire gestational period. A double-robust logistic regression model was used to assess the associations of wildfire-sourced PM2.5 exposures and preterm birth and term low birth weight, adjusting for non-fire-sourced PM2.5 exposure and individual- and area-level confounder variables.

RESULTS

Wildfire-sourced PM2.5 contributed on average 15% of the ambient total PM2.5 concentrations. For preterm birth, the strongest association was observed in the second trimester (odds ratio [OR]: 1.06, 95% confidence interval [CI]: 1.05-1.07 for PM2.5; 1.06, 95% CI: 1.05-1.07 for BC; 1.04, 95% CI: 1.03-1.05 for OC, per interquartile range increment of exposure), with higher risks identified among non-smokers or those with low socio-economic status. For term low birth weight, the associations with wildfire-sourced PM2.5 exposures were consistently elevated for all trimesters except for the exposure averaged over the entire gestational period. Overall, the associations between wildfire-sourced PM2.5 and pregnancy outcomes were stronger than those with total PM2.5.

CONCLUSIONS

Wildfire-sourced PM2.5 and its constituents are linked to higher risks of preterm birth and term low birth weight among a significant US population than the effects of ambient total PM2.5.

LC-QTOF/MS-based non-targeted metabolomics to explore the toxic effects of di(2-ethylhexyl) phthalate (DEHP) on Brassica chinensis L

Di(2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer known to pose health risks to humans upon exposure. Recognizing the toxic nature of DEHP, our study aimed to elucidate the response mechanisms in Brassica chinensis L. (Shanghai Qing) when subjected to varying concentrations of DEHP (2 mg kg-1, 20 mg kg-1, and 50 mg kg-1), particularly under tissue stress. The findings underscored the substantial impact of DEHP treatment on the growth of Brassica chinensis L., with increased DEHP concentration leading to a notable decrease in chlorophyll levels and alterations in the content of antioxidant enzyme activities, particularly superoxide dismutase (SOD) and peroxidase (POD). Moreover, elevated DEHP concentrations correlated with increased malondialdehyde (MDA) levels. Our analysis detected a total of 507 metabolites in Brassica chinensis L., with 331 in shoots and 176 in roots, following DEHP exposure. There was a significant difference in the number of metabolites in shoots and roots, with 79 and 64 identified, respectively (VIP > 1, p < 0.05). Metabolic pathway enrichment in Brassica chinensis L. shoots revealed significant perturbations in valine, leucine, and isoleucine biosynthesis and degradation, aminoacyl-tRNA, and glucosinolate biosynthesis. In the roots of Brassica chinensis L., varying DEHP levels exerted a substantial impact on the biosynthesis of zeatin, ubiquinone terpenoids, propane, piperidine, and pyridine alkaloids, as well as glutathione metabolic pathways. Notably, DEHP's influence was more pronounced in the roots than in the shoots, with higher DEHP concentrations affecting a greater number of metabolic pathways. This experimental study provides valuable insights into the molecular mechanisms underlying DEHP-induced stress in Brassica chinensis L., with potential implications for human health and food safety.

Simple, sensitive, colorimetric detection of pyrophosphate via the analyte-triggered decomposition of metal-organic frameworks regulating their adaptive multi-color Tyndall effect

This paper describes initially the application of the Tyndall effect (TE) of metal-organic framework (MOF) materials as a colorimetric signaling strategy for the sensitive detection of pyrophosphate ion (PPi). The used MOF NH2-MIL-101(Fe) was prepared with Fe3+ ions and fluorescent ligands of 2-amino terephthalic acid (NH2-BDC). The fluorescence of NH2-BDC in MOF is quenched due to the ligand-to-metal charge transfer effect, while the NH2-MIL-101(Fe) suspension shows a strong TE. In the presence of PPi analyte, the MOFs will undergo decomposition because of the competitive binding of Fe3+ by PPi over NH2-BDC, resulting in a significant decrease in the TE signal and fluorescence restoration from the released ligands. The results demonstrate that the new method only requires a laser pointer pen (for TE creation) and a smartphone (for portable quantitative readout) to detect PPi in a linear concentration range of 1.25-800 μM, with a detection limit of ~210 nM (3σ) which is ~38 times lower than that obtained from traditional fluorescence with a spectrophotometer (linear concentration range, 50-800 µM; detection limit, 8.15 µM). Moreover, the acceptable recovery of PPi in several real samples (i.e., pond water, black tea, and human serum and urine) ranges from 97.66 to 119.15%.

Pretreatment synthetic MRI features for triple-negative breast cancer

AIM

To evaluate the quantitative parameters derived from synthetic magnetic resonance imaging (SyMRI) for predicting triple-negative breast cancer (TNBC).

MATERIALS AND METHODS

This prospective study enrolled participants with invasive ductal breast carcinoma (IDBC) and separated them into a TNBC group and a Non-TNBC group. Preoperative breast MRI included both the SyMRI and conventional MRI sequences. The quantitative parameters derived from the SyMRI included T1 and T2 relaxation times, proton density (PD), and their standard deviations (SD). Clinicopathological characteristics, conventional MRI findings, and quantitative synthetic parameters were assessed for all participants. Multivariable logistic regression analysis was performed to determine the potential independent imaging predictors for TNBC preoperatively. Receiver operating characteristic (ROC) curve analysis was used to evaluate the performance of these parameters.

RESULTS

A total of 231 participants with histopathological proven IDBC were included in this study (n=46 in the TNBC group and n=185 in the Non-TNBC group). The TNBC group had significantly larger tumour size (p=0.011) and more frequent intratumoural cystic or necrotic lesions (p<0.001) as compared to the Non-TNBC group. The univariate analysis showed that the TNBC tumours had significantly higher T1 (p=0.006) and T2 (p<0.001) values than Non-TNBC tumours. Subsequent multivariable analysis indicated that T2 values and the presence of cystic or necrotic lesions were the independent predictors for TNBC.

CONCLUSION

The T2 from synthetic imaging and the presence of cystic degeneration or necrosis within the breast cancer may serve as potential imaging biomarkers for preoperative differentiation of TNBC from Non-TNBC.

Impact of storage time on non-volatile metabolites and fungal communities in Liupao tea using LC-MS based non-targeted metabolomics and high-throughput sequencing

Long-term storage of Liupao tea (LPT) is usually believed to enhance its quality and commercial value. The non-volatile metabolites variations and the fungal succession play a key role for organoleptic qualities during the storage procedure. To gain in-depth understanding the impact of storage time on the quality of LPT, two different brands of LPT with different storage time, including Maosheng LPTs (MS) with 0, 5, 10 and 15 years and Tianyu LPTs (TY) with 0, 3, 5, 8 and 10 years, were resorted to investigate the changes of non-volatile metabolites and fungi as well as their correlation by multi-omics. A total of 154 and 119 differential metabolites were identified in these two different brands of MS and TY, respectively, with the aid of high-performance liquid chromatography with quadrupole-time-of-flight mass spectrometry. In both categories of LPTs, the transformation of differential metabolites in the various stages referred to the formation of alkaloids, increase of organic acids, biosynthesis of terpenoids as well as glycosylation and methylation of flavonoids. Thereinto, glycosylation and methylation of flavonoids were the critical stages for distinguishing MS and TY, which were discovered in MS and TY stored for about 10 and 8 years, respectively. Moreover, the results of high-throughput sequencing showed that the key fungal genera in the storage of LPTs consisted of Eurotium, Aspergillus, Blastobotrys, Talaromyces, Thermomyces and Trichomonascus. It was confirmed on the basis of multivariate analysis that the specific fungal genera promoted the transformation of metabolites, affecting the tea quality to some extent. Therefore, this study provided a theoretical basis for the process optimization of LPT storage.

Varietal Authenticity Assessment of QTMJ Tea Using Non-Targeted Metabolomics and Multi-Elemental Analysis with Chemometrics

In this paper, a combination of non-targeted metabolomics and multi-element analysis was used to investigate the impact of five different cultivars on the sensory quality of QTMJ tea and identify candidate markers for varietal authenticity assessment. With chemometric analysis, a total of 54 differential metabolites were screened, with the abundances significantly varied in the tea cultivars. By contrast, the QTMJ tea from the Yaoshan Xiulv (XL) monovariety presents a much better sensory quality as result of the relatively more abundant anthocyanin glycosides and the lower levels of 2'-o-methyladenosine, denudatine, kynurenic acid and L-pipecolic acid. In addition, multi-elemental analysis found 14 significantly differential elements among the cultivars (VIP > 1 and p < 0.05). The differences and correlations of metabolites and elemental signatures of QTMJ tea between five cultivars were discussed using a Pearson correlation analysis. Element characteristics can be used as the best discriminant index for different cultivars of QTMJT, with a predictive accuracy of 100%.

Prevalence and influencing factors of anaemia among pregnant women in rural areas of Northwestern China

OBJECTIVES

Anaemia during pregnancy is a significant public health problem that adversely impacts both the mother and foetus. However, the factors influencing maternal anaemia in deprived areas of Northwestern China have not yet been thoroughly investigated. This study aimed to describe the prevalence and potential influencing factors of anaemia among expectant mothers in rural areas of Northwestern China.

STUDY DESIGN

This was a cross-sectional survey.

METHODS

A cross-sectional survey of 586 expectant mothers was conducted to investigate the prevalence of anaemia, prenatal healthcare coverage, dietary diversity and nutrient supplementation intake. The study population was selected from the sample areas using a random sampling method. Data were collected through a questionnaire, and haemoglobin concentrations were measured by a capillary blood test.

RESULTS

The results show that 34.8% of the study population were anaemic, with 13% having moderate-to-severe anaemia. The results of the regression analysis showed that diet was not significantly associated with haemoglobin concentrations or the prevalence of anaemia. However, regular prenatal healthcare attendance was found to be an important influencing factor for both haemoglobin concentration (β = 3.67, P = 0.002) and the prevalence of anaemia (odds ratio = 0.59, P = 0.011).

CONCLUSIONS

Pregnant women receiving regular prenatal care were less likely to be anaemic; thus, it is essential to implement strategies to improve attendance at maternal public health services to reduce the prevalence of maternal anaemia.

Quantitative colorimetric sensing of heavy metal ions via analyte-promoted growth of Au nanoparticles with timer or smartphone readout

This work describes two new colorimetric nanosensors for label-free, equipment-free quantitative detection of nanomolar copper (II) (Cu²⁺) and mercury (II) (Hg²⁺) ions. Both are based on the analyte-promoted growth of Au nanoparticles (AuNPs) from the reduction of chloroauric acid by 4-morpholineethanesulfonic acid. For the Cu²⁺ nanosensor, the analyte can accelerate such a redox system to rapidly form a red solution containing dispersed, uniform, spherical AuNPs that is related to these particles' surface plasmon resonance property. For the Hg²⁺ nanosensor, on the other hand, a blue mixture consisting of aggregated, ill-defined AuNPs with various sizes can be created, showing a significantly enhanced Tyndall effect (TE) signal (in comparison with that produced in the red solution of AuNPs). By using a timer and a smartphone to quantitatively measure the time of producing the red solution and the TE intensity (i.e., the average gray value of the corresponding image) of the blue mixture, respectively, the developed nanosensors are well demonstrated to achieve linear ranges of 6.4 nM to 100 μM and 6.1 nM to 1.56 μM for Cu²⁺ and Hg²⁺, respectively, with detection limits down to 3.5 and 0.1 nM, respectively. The acceptable recovery results obtained from the analysis of the two analytes in the complex real water samples including drinking water, tap water, and pond water ranged from 90.43 to 111.56%.

Investigation of the binding behavior of bioactive 7-methoxyflavone to human serum albumin by coupling multi-spectroscopic with computational approaches

The natural flavonoids with bioactivity as secondary plant metabolites are mostly found in fruits, vegetables, tea and herbs, the distribution and bioavailability of which in vivo depends on the interaction and successive binding with carrier proteins in the systemic circulation. In this paper, the binding behavior of bioactive 7-methoxyflavone (7-MF) with human serum albumin (HSA) was studied with the aid of the combination of multi-spectroscopic methods, molecular docking and molecular dynamic simulation. The results of multi-spectroscopic experiments revealed that 7-MF interacted with HSA predominantly via fluorescence static quenching and the microenvironment around the fluorophore Trp residues in HSA became more hydrophilicity with the binding of 7-MF. Thermodynamic analysis demonstrated that hydrogen bonds and van der Waals forces played a dominant role in stabilizing the HSA-7-MF complex. Moreover, the docking experiment and molecular dynamic simulation further confirmed that 7-MF could enter the active cavity of HSA and caused more stable conformation and change of secondary structure of HSA through forming hydrogen bond. The exploration of the mechanism of 7-MF binding to HSA lights a new avenue to understand the stability, transport and distribution of 7-MF and 7-MF may hold great potential to be extended as a promising alternative of dietary supplements or pharmaceutical agents.

Correlation between primary family caregiver identity and maternal depression risk in poor rural China

INTRODUCTION

Prenatal and postpartum depression are important public health challenges because of their long-term adverse impacts on maternal and neonatal health. This study investigated the risk of maternal depression among pregnant and postpartum women in poor rural China, along with the correlation between primary family caregiver identity and maternal depression risk.

METHODS

Pregnant women and new mothers were randomly selected from poor rural villages in the Qinba Mountains area in Shaanxi. Basic demographic information was collected regarding the women and their primary family caregivers. The Edinburgh Postnatal Depression Scale was used to identify women at risk of depression, and the Perceived Social Support Scale was used to evaluate perceived family support.

RESULTS

This study included 220 pregnant women and 473 new mothers. The mean proportions of women at risk of prenatal and postpartum depression were 19.5% and 18.6%, respectively. Regression analysis showed that identification of the baby's grandmother as the primary family caregiver was negatively correlated with maternal depression risk (β=-0.979, 95% confidence interval [CI]=-1.946 to -0.012, P=0.047). However, the husband's involvement in that role was not significantly correlated with maternal depression risk (β=-0.499, 95% CI=-1.579 to 0.581, P=0.363). Identification of the baby's grandmother as the primary family caregiver was positively correlated with family support score (β=0.967, 95% CI=-0.062 to 1.996, P=0.065).

CONCLUSION

Prenatal and postpartum depression are prevalent in poor rural China. The involvement of the baby's grandmother as the primary family caregiver may reduce maternal depression risk, but the husband's involvement in that role has no effect.

Utilisation of village clinics in Southwest China: evidence from Yunnan Province

INTRODUCTION

Primary healthcare in rural China is underutilised, especially in village clinics in Southwest China. The aim of this study was to explore any relationships among the ethnicity of the healthcare provider, the clinical competence of the healthcare provider, and the utilisation of village clinics in Southwest China.

METHODS

This cross-sectional survey study involved 330 village healthcare providers from three prefectures in Yunnan Province in 2017. Multiple logistic regressions were adopted to investigate the utilisation of primary healthcare among different ethnic healthcare providers.

RESULTS

Primary healthcare utilisation was higher in village clinics where healthcare providers were Han Chinese than those where healthcare providers were ethnic minority (151 vs 101, P=0.008). The logistic regression analysis showed that clinical competence was positively associated with the utilisation of primary healthcare (odds ratio [OR]=1.49, 95% confidence interval [CI]=1.12-2.00; P=0.007) and that inadequate clinical competence of ethnic minority health workers may lead to a lag in the utilisation of primary healthcare (OR=0.45, 95% CI=0.23-0.89; P=0.022).

CONCLUSION

Our results confirm differences in the utilisation of primary healthcare in rural Yunnan Province among healthcare providers of different ethnicities. Appropriate enhancements of clinical competence could be conducive to improving the utilisation of primary healthcare, especially among ethnic minority healthcare providers.

Anthropometric measures and breast cancer risk among Hispanic women in Puerto Rico

INTRODUCTION

Increased risk of postmenopausal breast cancer associated with anthropometric measures including Body Mass Index (BMI), adult weight gain, and waist circumference has been observed in North American and European populations, but little evidence is available for Hispanic women. Breast cancer is the leading type of cancer, and leading cause of cancer-related deaths among Hispanic women in Puerto Rico (PR). However, compared with the United States, breast cancer incidence rates are lower but increasing more rapidly.

PURPOSE

To examine associations between anthropometric characteristics and breast cancer risk in Hispanic women in PR.

METHODS

Data from a population-based case-control study in the San Juan metropolitan region (cases = 315; controls = 348) were used to examine associations between anthropometric measures and breast cancer risk, also considering menopausal status and hormone therapy (HT).

RESULTS

Among premenopausal participants, there was a significant trend for lower odds of breast cancer with higher BMI and borderline significant with higher waist to height ratio (WHtR). For postmenopausal participants, a significant trend for lower odds of breast cancer was observed with higher WHtR, and waist to hip ratio (WHR), borderline significant with higher BMI, and higher odds with height. Among postmenopausal participants using HT, a significant trend for lower odds of breast cancer was observed with higher waist circumference, WHtR, WHR, and body shape index.

CONCLUSION

Our study provides evidence of anthropometric differences in relation to breast cancer risk in PR compared to previous studies. Future studies should include analyses of fat and lean mass distribution, and hormone receptor status to further understand anthropometry and breast cancer risk among Hispanic women.

Effects of chlorpyrifos on the metabolic profiling of Bacillus megaterium strain RRB

Many microorganisms have been reported to degrade organic pollutants in the environment and plants, however, the specific information about the effect of organic pollutants on the metabolism of microorganisms is poorly investigated. In the present study, the effect of the pesticide chlorpyrifos on the metabolic profiling of Bacillus megaterium strain RRB was investigated using metabolomics. Our data show that chlorpyrifos acting as an energy source was readily concentrated in the strain RRB from the culture medium. During early cultivation, the shift in energy sources from tryptic soy broth to chlorpyrifos may temporarily cause the strain RRB to enter the starvation stage, where some synthesis-related amino acids and intermediates in the pathways of TCA cycle and pyridoxine metabolism were decreased. The increase of nucleotides and lysine may help the strain RRB cope with the starvation stage. During later cultivation, many metabolites including organic acids, nucleosides and sugar phosphates were gradually accumulated, which indicates that chlorpyrifos could be utilized by the stain RRB to generate metabolites bacteria needed. In addition, arginine acting as a nitrogen-storage amino acid was gradually decreased with later cultivation, suggesting that chlorpyrifos could not provide enough nitrogen for bacteria.

[Association between tea consumption and all-cause mortality in Chinese adults]

Objective: To investigate the association between tea consumption and the risk of all-cause and cause-specific mortality among Chinese adults. Methods: This study was based on China Kadoorie Biobank (CKB). Tea consumption information was self-reported by participants at baseline. Death was mainly identified by linkage to the death registry system. Cox proportional hazard regression models estimated HR and 95%CI. Results: With a median follow-up of 11.1 years, there were 34 661 deaths in 438 443 participants. Compared with those who never drink tea, all-cause mortality HR(95%CI) were 0.89(0.86-0.91) and 0.92(0.88-0.95) for non-daily tea drinkers and daily tea drinkers, respectively. A statistically significant difference was found in the association of tea consumption and the risk of all-cause mortality between men and women(interaction P<0.05). The protective effect was mainly seen in men. Compared with those who never drink tea, daily tea drinkers had a reduced risk of death from ischemic heart disease, ischemic stroke, hemorrhagic stroke, cancer, respiration diseases and other causes of death, and the corresponding HR(95%CI) were 0.83(0.76-0.92), 0.82(0.69-0.97), 0.86(0.78-0.94), 1.03(0.97-1.09), 1.00(0.87-1.16), 0.84(0.78-0.90). Among never smokers and non-excessive drinkers, there was no statistically significant association between daily tea drinking and the risk of death from cancer. While smokers and excessive drinkers had an increased risk of death from cancer (interaction P<0.001). Conclusions: Tea consumers had reduced risks of all-cause mortality and partial cause-specific mortality, but not for the risk of death from cancer. On the contrary, daily tea drinkers with smoking habits and excessive alcohol drinking had an increased risk of death from cancer.

Tyndall-Effect-inspired assay with gold nanoparticles for the colorimetric discrimination and quantification of mercury ions and glutathione

This work initially reports a new nanosening method for simple, sensitive, specific, visual detection of mercury (II) (Hg²⁺) and glutathione (GSH) using the Tyndall Effect (TE) of the same colloidal gold nanoparticle (GNP) probes for efficient colorimetric signaling amplification. For the TE-inspired assay (TEA) method, arginine (Arg) molecules are pre-modified on the GNPs' surfaces (Arg-GNPs). Upon the Hg²⁺ introduction, it can be specifically coordinated with the terminal -NH₂ and -COOH groups of the Arg molecules to make the Arg-GNPs aggregate, producing a significantly-enhanced TE signal in the reaction solution after its irradiation by a 635-nm red laser pointer pen. On the other hand, the introduction of the GSH results in the production of the original Arg-GNPs' weak TE response, as it is able to bind such metal ion via mercury-thiol reactions to inhibit the above aggregation. Under the optimal conditions, the utility of the new TEA method is well demonstrated to quantitatively detect the Hg²⁺ and GSH with the aid of a smartphone as a portable TE reader during the linear concentration ranges of 50-3000 and 10-3000 nM, respectively. The detection limits for the Hg²⁺ and GSH are estimated to be as low as ∼3.5 and ∼0.3 nM, respectively. The recovery results obtained from the detection of Hg²⁺ in the complex tap and pond water samples and the assay of GSH in real human serum and urine samples are also satisfactory.

Relations of Variety and Quantity of Dietary Proteins Intake from Different Sources with Mortality Risk: A Nationwide Population-Based Cohort

OBJECTIVES

The relations of variety and quantity of dietary proteins intake from different sources with mortality risk were still controversial. We aimed to examine the associations of variety and quantity of different sourced proteins with all-cause mortality risk in adults and older adults.

MATERIALS AND METHODS

17,310 participants (mean age was 44.0 [SD: 15.9] years and 51.0% were females) with utilizable data from the China Health and Nutrition Survey were included. Dietary intake was collected using three consecutive 24-h dietary recalls combined with a household food inventory. The variety score of protein sources was defined as the number of proteins consumed at the appropriate level, accounting for both types and quantity of proteins. The primary outcome was all-cause mortality.

RESULTS

Over a median follow-up of 9.0 years, 1324 (7.6%) death cases were reported. There were reversed J-shaped relationships of percentages energy from total protein, and protein from legume with all-cause mortality; U-shaped relationships of proteins from unprocessed red meat, processed red meat, poultry and whole grain with all-cause mortality; L-shaped relationships of proteins from egg and fish with all-cause mortality; and a reversed L-shaped relationship of protein from refined grain with all-cause mortality (all P values for nonlinearity < 0.001). Moreover, there was a significant inverse association between the variety score of protein sources with overall mortality risk (per score increment, HR, 0.69; 95%CI, 0.66-0.72).

CONCLUSIONS

Greater variety of proteins with appropriate quantity from different food sources was associated with significantly lower risk of mortality in Chinese adults and older adults.

Tyndall-effect-based colorimetric assay with colloidal silver nanoparticles for quantitative point-of-care detection of creatinine using a laser pointer pen and a smartphone

Herein, this paper initially reports a new colorimetric Tyndall effect-inspired assay (TEA) for simple, low-cost, sensitive, specific, and point-of-care detection of creatinine (an important small biomolecule) by making use of silver nanoparticles (AgNPs) as model colloidal nanoprobes for visual light scattering signaling. The naked-eye TEA method adopts negatively-charged citrate-capped AgNPs (Cit-AgNPs) prepared by sodium citrate reduction. In the presence of alkaline conditions, the creatinine analyte can form carbanion/oxoanion amino tautomers which in turn crosslink with carboxylate groups on the Cit-AgNPs via a hydrogen bonding network to mediate the aggregation of such colloidal nanoprobes showing a significantly-enhanced TE signal that was created and quantified by a hand-held laser pointer pen and a smartphone, respectively. The results demonstrate that the resulting equipment-free method with the TE readout could enable the portable quantification of creatinine with a detection limit of ∼55 nM, which was ∼90–2334 times lower than that obtained from AgNP-based colorimetric approaches with the most common localized surface plasma resonance signaling. Moreover, it shows a larger analytical sensitivity up to ∼580.8227 signal per nM, offering ∼2.4–232-fold improvement in comparison with many of the recent instrumental creatinine nanosensors. The accuracy and practicality of the developed nanosensing system was additionally confirmed with satisfactory recovery results ranging from ca. 98.52 to 100.36% when analyzing a set of real complex human urine samples.

This work describes a new nanosensor for one-step ultrasensitive naked-eye detection of creatinine based on the target-triggered aggregation of silver nanoparticles showing dramatically enhanced Tyndall effect.

Single-cell transcriptomics reveals the heterogeneity of the decidual endothelial cells that participate in labor onset

OBJECTIVE

To investigate the heterogeneity of decidual endothelial cells and their changes during delivery.

PATIENTS AND METHODS

Single-cell RNA sequencing was used to characterize the transcriptomes of decidual endothelial cells before and after the onset of labor.

RESULTS

Decidual endothelial cells (9748 cells) were divided into five subgroups with different functions according to differences in the transcriptome. The functions of cluster 5 were enriched in vascular development and response to growth factors. After the onset of labor, the activities of each cluster were different, including the interleukin 17 pathway and regulation of ERK1 and ERK2 cascade. The downregulated genes were related to scavenger receptor (cluster 5), which may reflect the process of endothelial activation. In terms of genetic changes, cluster 5 may be more actively involved in labor than the other clusters.

CONCLUSIONS

Peripartum decidual endothelial cells are heterogeneous and participate in labor to varying degrees. One of the five subtypes of endothelial cells may be more actively involved in labor onset. Our findings may enable the assessment of decidual endothelial cells and labor onset.

Effect of neonicotinoid dinotefuran on root exudates of Brassica rapa var. chinensis

Root exudates are released by plant roots and are important carrier substances for material exchange and information transmission among plants and the rhizosphere. In the present study, the effect of dinotefuran on root exudates of Chinese cabbage (Brassica rapa var. chinensis) was investigated. The physiological activities revealed that dinotefuran uptake caused oxidative stress in vegetable tissues even at low dinotefuran exposure levels. The metabolic profile of plant root exudates acquired by LC-QTOF/MS was clearly changed by dinotefuran, where the numbers of both up- and down-regulated MS peaks increased with increasing dinotefuran concentration. Under dinotefuran stress, some osmotic adjustment substances (proline and betaine) and defence-related metabolites (spermidine, phenylalanine and some phenolic acids) were significantly upregulated, which may help plants adapt to adverse environmental conditions. Specifically, the contents of some phenylalanine-derived secondary metabolites increased with increasing dinotefuran concentration, which may increase the external detoxification ability of plants. Moreover, respiration metabolism was significantly affected, where some intermediates in the TCA cycle (succinic acid and malic acid) were upregulated with low-level dinotefuran exposure; however, anaerobic respiration products (lactic acid and 3-phenyllactic acid) were accumulated at high exposure levels. In addition, the release of glucosinolates was significantly inhibited in both dinotefuran treatment groups.

Ultrasensitive visual detection of Hg2+ ions via the Tyndall effect of gold nanoparticles

This work describes a new nanosensor for one-step ultrasensitive naked-eye detection of Hg²⁺ ions based on the target-triggered aggregation of gold nanoparticles showing a dramatically enhanced Tyndall effect.

A novel strategy for sensitive and rapid detection of ascorbic acid via the Tyndall effect of cobalt hydroxide nanoflakes

Cobalt oxyhydroxide (CoOOH) nanoflakes, as nanoenzymes and fluorescence quenchers, have been widely used in colorimetric and fluorescent analysis. However, their promising light scattering property—the Tyndall effect (TE)—has never been applied in biosensors and biological analysis to date. Herein, we report for the first time a novel strategy for point-of-care detection of ascorbic acid (AA) with the TE of CoOOH nanoflakes providing colorimetric signaling. In this detection system, CoOOH nanoflakes exhibit a strong red TE signal under the illumination of a hand-held 635 nm laser pointer pen. However, the introduction of AA could induce a significant decrease of the TE because it could reduce CoOOH into Co²⁺ and results in the degradation of the CoOOH nanoflakes. The changes in the TE intensity could be read-out using a smartphone for the portable quantitative analysis of AA. The results showed that this CoOOH nanoflake-based TE-inspired assay (TEA) exhibited a good linear range from 0.25 μM to 40 μM for AA, with a detection limit of 12 nM. It also showed high selectivity toward AA over common potential interfering species. Importantly, this method possessed the advantages of simple operation, low consumption of time and equipment-free analysis and was successfully applied to the detection of AA in vitamin C tablets.

A novel colorimetric nanosensor was initially developed for the equipment-free sensitive detection of ascorbic acid based on the Tyndall effect of cobalt hydroxide nanoflakes.

Enzymatic dephosphorylation-triggered self-assembly of DNA amphiphiles

In this work, phosphorylated lipid-conjugated oligonucleotide (DNA-lipid-P) has been synthesized to develop an enzyme-responsive self-assembly of DNA amphiphiles based on dephosphorylation-induced increase of hydrophobicity. Since elevated ALP level is a critical index in some diseases, ALP-triggered self-assembly of DNA amphiphiles shows promise in disease diagnosis and cancer treatment.

Enzymatic dephosphorylation-triggered self-assembly of DNA amphiphiles is developed by integrating enzymatic dephosphorylation-induced increase of hydrophobicity and intermolecular aggregation of lipid-conjugated oligonucleotides.

On-site, rapid and visual method for nanomolar Hg2+ detection based on the thymine–Hg2+–thymine triggered “double” aggregation of Au nanoparticles enhancing the Tyndall effect

This work describes a new nanosensor for the simple, rapid, portable, colorimetric analysis of mercury(ii) (Hg²⁺) ions by combining the sensitive Tyndall effect (TE) of colloidal Au nanoparticles (AuNPs) with specific thymine–Hg²⁺–thymine (T–Hg²⁺–T) coordination chemistry for the first time. For the TE-inspired assay (TEA), in the presence of Hg²⁺ in a sample, the analyte can selectively mediate the hybridization of three types of flexible single-stranded DNAs (ssDNAs) to form stable rigid double-stranded DNAs (dsDNAs) via the T–Hg²⁺–T ligand interaction. Subsequent self-assembly of the dsDNAs with terminal thiol groups on the AuNPs' surfaces led to their “double” aggregation in addition to the lack of sufficient ssDNAs as the stabilizing molecules in a high-salt solution, resulting in a remarkably enhanced TE signal that positively relied on the Hg²⁺ level. The results demonstrated that such a TEA method enabled rapid naked-eye qualitative analysis of 625 nM Hg²⁺ within 10 min with an inexpensive laser pointer pen as an inexpensive handheld light source to generate the TE response. Making use of a smartphone for portable TE readout could further quantitatively detect the Hg²⁺ ions in a linear concentration range from 156 to 2500 nM with a limit of detection as low as 25 nM. Moreover, the developed equipment-free nanosensor was also used to analyze the Hg²⁺ ions in real samples including tap water, drinking water, and pond water, the obtained recoveries were within the range of 93.68 to 108.71%. To the best of our knowledge, this is the first report of using the AuNPs and functional nucleic acids to design a TE-based biosensor for the analysis of highly toxic heavy metal ions.

A new equipment-free colorimetric nanosensor was initially developed for quantitative point-of-need detection of nanomolar Hg²⁺ ions based on the enhancement in Tyndall effect of Au nanoparticles via their target-triggered “double” aggregation.

Transforming glucose into fluorescent graphene quantum dots via microwave radiation for sensitive detection of Al3+ ions based on aggregation-induced enhanced emission

This paper initially describes a nanosensor for fluorescence detection of Al3+ ions by using graphene quantum dots (GQDs) that are synthesized via microwave-assisted single-step ring-closure condensation of glucose molecules. The one-pot synthesis strategy based on the microwave radiation could be finished in several minutes and no post-modification of the GQDs was required. In particular, the GQD nanoprobes showed a sensitive and specific fluorescence enhancement response to Al3+. The involved mechanism might be the Al3+-mediated aggregation of the GQDs leading to aggregation-induced enhanced emission (AIEE). Under optimal conditions, this new fluorescent nanosensor was able to quantitatively detect Al3+ in a linear concentration range of 0.4-500 μM. The limit of detection was estimated to be ∼59.8 nM according to the 3σ rule, which made it be among the most sensitive systems currently available for sensing the target ion. Moreover, satisfactory recovery results (ranging from 96.8 to 109.7%) of analyzing a set of real water examples additionally validated its accuracy for practical applications. Considering its simplicity, high sensitivity and specificity, low cost, and good reliability, the developed fluorescent nanosensing system for Al3+ holds great promise for broad uses in water safety, environmental monitoring, and waste management.

Communication skills of providers at primary healthcare facilities in rural China

INTRODUCTION

Effective provider-patient communication has been confirmed to improve diagnosis, treatment planning, health outcomes, patient satisfaction, and treatment compliance. Few studies have measured the effectiveness of communication between patients and rural providers in China. To fill this gap in the literature, the present study describes the communication skills of providers at primary healthcare facilities in rural China and investigates the provider- and facility-level factors underlying these communication skills.

METHODS

The standardised patients successfully completed 504 interactions across two tiers of China's rural health system and engaged with providers at village clinics and township health centres. We assessed providers' communication skills based on recorded interactions between the providers and the standardised patients using the SEGUE Framework, which contains the following five dimensions: 'Set the stage', 'Elicit information', 'Give information', 'Understand the patient's perspective', and 'End the encounter'.

RESULTS

The providers' overall average score was 50.6% on the SEGUE communication tasks. They did well in 'Set the stage' (54.4%) and 'Elicit information' (56.2%) but performed poorly in 'End the encounter' (24.5%) and 'Understand the patient's perspective' (44.0%). Female and younger providers scored 0.75 (P<0.05) and 0.04 (P<0.01) points higher than their male and older counterparts on total SEGUE score, respectively.

CONCLUSION

Providers in rural China had relatively poor communication skills overall, especially in terms of their demonstration of care for patients and inviting them to participate in the interaction. Gender and age were significantly associated with providers' level of communication skills in rural China.

Enhanced functional DNA biosensor for distance-based read-by-eye quantification of various analytes based on starch-hydrolysis-adjusted wettability change in paper devices

Low-cost, equipment-free and quantitative detection of a wide range of analytes of interest at home and in the field holds the potential to revolutionize disease diagnosis, environmental pollution monitoring, and food safety analysis. Herein, we describe a functional DNA biosensor for the first time that integrates analyte-directed assembly of enzyme-coated microbead probes for robust yet efficient signal amplification with a simple quantitative detection motif of distance measurement on portable paper devices based on starch-hydrolysis-adjusted wettability change of paper. Its utility is well demonstrated with highly sensitive and specific detection of model analytes ranging from adenosine (an important small biomolecule; 1.6 μM detection limit) to interferon-γ (a protein marker; 0.3 nM detection limit) and Pb²⁺ (a highly toxic metal ion; 0.5 nM detection limit) by simply using an inexpensive, ubiquitous ruler. The developed general method with the distance-measuring readout should be easily tailored for the portable, read-by-eye, quantitative detection of many other types of analytical targets by taking advantage of their specific functional DNA partners like aptamers and DNAzymes.

A functional DNA sensor was initially developed for the distance-measuring quantification of various analytes based on the starch-hydrolysis-adjusted wettability change of paper.

Clostridium butyricum promotes intestinal motility by regulation of TLR2 in interstitial cells of Cajal

OBJECTIVE

Clostridium butyricum (C. butyricum) as a probiotic has been reported to have an important role in the pathogenesis of gastrointestinal diseases. However, the effects of C. butyricum on regulation of intestinal motility of ulcerative colitis (UC) remain unclear. Our study aimed to explore the cross-regulation effect of C. butyricum and toll-like receptor 2 (TLR-2) on UC.

MATERIALS AND METHODS

Interstitial cells of Cajal (ICCs) were treated by C. butyricum for 2 h, the mRNA and protein levels of TLR-2, IL-6, and IL-8 were detected by RT-qPCR and Western blot. Then, TLR2-specific small interfering RNA (si-TLR2) was transfected into ICCs, and the relative expressions of IL-6 and IL-8, SCF, cell viability, ghrelin, SP, and ET were measured by RT-qPCR, Western blot, CCK-8, and ELISA. Besides, the signal pathways of NF-κB and JNK were determined by Western blot.

RESULTS

C. butyricum significantly increased TLR2, IL-6, and IL-8 expressions in ICCs. However, TLR2 silence alleviated C. butyricum-induced IL-6 and IL-8 expressions. Moreover, TLR2 silence significantly inhibited C. butyricum-induced cell viability in ICCs. Additionally, C. butyricum significantly increased SCF expression and promoted the secretion of ghrelin and SP. However, a significant reduction in the levels of SCF, ghrelin, and SP was evident in the silence of TLR2 expression. Besides, TLR2 silence reduced C. butyricum-activation NF-κB and JNK signal pathways in ICCs.

CONCLUSIONS

These findings revealed that C. butyricum promoted intestinal motility by regulation of TLR2 in ICCs, which contributed to understand the molecular mechanisms of C. butyricum on UC.

Quercetin reduces atherosclerotic lesions by altering the gut microbiota and reducing atherogenic lipid metabolites

AIMS

Epidemiological studies have correlated cardiovascular disease and atherosclerosis with lifestyle factors such as sedentary behaviour and a high-calorie diet. Recent studies of pathogenesis have highlighted the significance of the intestinal microbiota and chronic inflammation with respect to both the onset and development of atherosclerosis. This study examined the hypothesis that the oral administration of quercetin to low-density lipoprotein receptor-null (Ldlr^-/- ) mice would improve gut health by altering the gut microbiota and controlling the levels of atherogenic lipid metabolites and proinflammatory mediators in the intestine and serum.

METHODS AND RESULTS

Mice were maintained on a high-fat diet with or without oral quercetin administration for 12 weeks. Quercetin treatment suppressed body weight gains and reduced the extent of atherosclerotic lesions in the aortic sinus. Reduced malondialdehyde and increased interleukin 6 levels further indicated the protective effect of quercetin against immune/inflammatory responses and oxidative stress. Furthermore, quercetin led to decreased intestinal levels of cholesterol, lysophosphatidic acids and atherogenic lysophosphatidylcholine (LPC 18:1) and an increased level of coprostanol. A phylum-level microbial analysis revealed that quercetin treatment reduced the abundance of Verrocomicrobia and increased microbiome diversity and the abundances of Actinobacteria, Cyanobacteria and Firmicutes. A Spearman analysis revealed negative correlations of Actinobacteria with intestinal and plasma LPC 18:1 and caecal cholesterol levels and of Firmicutes and Cyanobacteria with the plasma LPC 18:1 level.

CONCLUSIONS

This study demonstrated the ability of quercetin treatment to reduce lipid levels, as well as the areas of atherosclerotic lesions and sizes of plaques. This treatment also altered the composition of the gut microbiota and decreased the levels of atherogenic lipid metabolites.

SIGNIFICANCE AND IMPACT OF THE STUDY

Oral quercetin treatment may represent a new approach to mitigating the onset and development of atherosclerosis.

P2637Hypertension as a risk factor for all-cause and cardiovascular mortality in women compared with men: a systematic review and meta-analysis of prospective cohort studies

Background

What is more, some recent meta-analysis have demonstrated the sex difference between smoking, diabetes, and atrial fibrillation, and the risk of CVD mortality. Whether and to what extent the excess risk of cause-specific mortality from CVD death conferred by hypertension differs among women and men remain unclear.

Objective

A systematic review with meta-analysis was performed to explore whether and to what extent the excess risk of cause-specific mortality from CVD death conferred by hypertension differs among women and men.

Methods

PubMed and EMBASE was systematically searched for prospective cohort studies published from inception to 7 October 2017. Eligible studies reported sex-specific relative risk (RR) estimates for mortality of all-cause, CVD, coronary heart disease (CHD) and stroke associated with hypertension. The data were pooled using random effects models with inverse variance weighting, and estimates of the women-to-men ratio of RRs (RRR) for each outcomes were derived.

Results

Twenty-four studies with 2,939,659 participants were included in this meta-analysis. The RR for CHD mortality associated with hypertension compared with no hypertension was 2.24 (95% CI 2.03–2.46) in women and 1. 72 (1.61–1.84) in men. The multiple-adjusted RRR for CHD mortality was 22% greater in women with hypertension than in men with hypertension (RRR 1.22, 95% CI 1.03–1.44) with no significant heterogencity between studies (I2=45%, P=0.11, Figure 1). No evidence was observed sex difference in the relationship between hypertension and the mortality from all-cause, CVD and stroke. Furthermore, the subgroup analyses showed that the pooled RRR for all-cause mortality, CVD and stroke mortality were not significantly associated with cohort region, the duration of follow-up, mean age of participants and the publication year of studies.

Conclusions

Hypertension is a major risk factor for all-cause, CVD, CHD and stroke among women and men. Moreover, women with hypertension have more than a 22% higher risk of CHD mortality compared with men with hypertension. Further studies need to identify the biological and/or lifestyle mechanisms involved in sex differences driving these associations.

P5495Sex differences in marital status and risk of cardiovascular disease, cancer, and all-cause mortality: a systematic review and meta-analysis of 7,881,040 individuals

Background

Marital status has been identified as an important social factor associated with mortality. In current epidemiologic research, being unmarried was observed to be a suboptimal health status in the global population. The growing number of unmarried people has health implications, in light of evidence suggesting that it is associated with an increase in the incidence of various diseases and high mortality. Few attempts have been made to produce an overall estimate and sufficiently clarified of the sex difference between unmarried status and mortality risks, this is still a matter of debate.

Purpose

To ascertain whether sex differences exist in the relationship between marital status and cardiovascular disease (CVD), cancer, all-cause mortality in the general population and to explore the potential effect of age, location, the duration of follow-up and publication years on these outcomes.

Methods

A systematic search was performed in PubMed and EMBASE from inception through to April 2018 and review of references. We used the sex-specific RRs (relative risk) to derive the women-to-men ratio of RRs (RRR) and 95% CIs from each study. Subsequently, the RRR for each outcome was pooled with random effects meta-analysis weighted by the inverse of the variances of the log RRRs.

Results

Twenty-one studies with 7,881,040 individuals were included for meta-analysis. Compared with married individuals, being unmarried was significantly associated with all-cause mortality, cancer mortality, CVD mortality and coronary heart disease (CHD) mortality, especially for singles, for both sexes (Figure 1). However, the association with death from all-cause and CVD was significantly stronger in men. Compared with women who were divorced/separated, divorced/separated men had significantly higher risk of all-cause mortality, cancer mortality and CVD mortality. Moreover, never married men had 31% and 9% higher excess risk of stroke mortality and all-cause mortality, respectively, compared with never married women. No sex differences were observed concerning the impact of any unmarried status on CHD mortality.

Conclusions

Being unmarried (widowed, divorced/separated or never married) conferred higher excess risk of stroke mortality and all-cause mortality for men than women. Moreover, divorced/separated men had significantly higher risk of cancer mortality and CVD mortality. Further studies are warranted to clarify the biological, behavioral, and/or social mechanisms involved in sex differences driving these associations.

[Determination of seven urinary metabolites of benzene, toluene and xylene by ultra-high performance liquid chromatography-triple quadrupole mass spectrometry]

Objective: To develop a method using ultra-high performance liquid chromatography-triple quadrupole mass spectrometry to determine the urinary metabolites of benzene, toluene and xylene. The selected metabolites are S-phenylmercapturic acid (S-PMA) , trans, trans-muconic acid (t, t-MA) , 8-hydroxy-2 deoxyguanosine (8-OHdG) , hippuric acid (HA) , 2-methylhippuric acid (2-MHA) , 3-methylhippuric acid (3-MHA) and 4-methylhippuric acid (4-MHA) . Methods: The urine sample was pretreated using methanol to precipitate the proteins. HSS T3 chromatographic column was used to separate the metabolites. The mass spectrometric acquisition was carried out using multiple reaction monitoring (MRM) after ionization with ESI source. External standard method was used for quantification. Results: All the standard curves showed good linear relation, and r of the seven metabolites was all above 0.999. The detection limits and quantitative limits of the seven metabolites were 0.01-500 ng/ml and 0.02-1 000 ng/ml (based on the actual dilution ratio) , respectively. The average spiked recoveries of four loadings ranged from 85.8% to 109.9%. The intra-day and inter-day precisions were 0.2%-4.5% and 0.6%-9.5%, respectively. The samples can be kept for at least 14 days at both 4 ℃ and -20 ℃. Conclusion: This method is simple, rapid and highly sensitive with low cost, and its accuracy, precision and stability can meet the daily test requirements. It can be applied for the determination of urinary S-PMA, t, t-MA, 8-OHdG, HA, 2-MHA, 3-MHA and 4-MHA for the occupational population exposed to benzene, toluene and xylene.

Preparation and application of molecularly imprinted polymer solid-phase microextraction fiber for the selective analysis of auxins in tobacco

As signal molecules, auxins play an important role in mediating plant growth. Due to serious interfering substances in plants, it is difficult to accurately detect auxins with traditional solid-phase extraction methods. To improve the selectivity of sample pretreatment, a novel molecularly imprinted polymer -coated solid-phase microextraction fiber, which could be coupled directly to high-performance liquid chromatography, was prepared with indole acetic acid as template molecule for the selective extraction of auxins. The factors influencing the polymer formation, such as polymerization solvent, cross-linker, and polymerization time, were investigated in detail to enhance the performance of indole acetic acid-molecularly imprinted polymer coating. The morphological and chemical stability of this molecularly imprinted polymer-coated fiber was characterized by scanning electron microscopy, infrared spectrometry, and thermal analysis. The extraction capacity of the molecularly imprinted polymer-coated solid-phase microextraction fiber was evaluated for the selective extraction of indole acetic acid and indole-3-pyruvic acid followed by high-performance liquid chromatography analysis. The linear range for indole acetic acid and indole-3-pyruvic acid was 1-100 µg/L and their detection limit was 0.5 µg/L. The method was applied to the simultaneous determination of two auxins in two kinds of tobacco (Nicotiana tabacum L and Nicotiana rustica L) samples, with recoveries range from 82.1 to 120.6%.

Enhanced 3D paper-based devices with a personal glucose meter for highly sensitive and portable biosensing of silver ion

A variety of routine methods are available for the detection of silver (I) (Ag⁺) ions, but most of them rely on expensive, sophisticated and desktop instruments. Herein, a low-cost, instrument-free and portable Ag⁺ biosensor was described by initially designing a new class of 3D origami microfluidic paper-based analytical devices (μPADs) into each of which one piece of reagent-loaded nanoporous membrane was integrated. It combines analyte-triggered self-growing of silver nanoparticles to block the membrane's pores in situ for rapid yet efficient signal amplification with a handheld personal glucose meter for a portable and sensitive quantitative readout based on the biocatalytic reactions between the glucose oxidase and glucose. Its utility is well demonstrated with the specific detection of the analyte with a limit of detection as low as ∼58.1 pM (3σ), which makes this new biosensing method one of the most sensitive Ag⁺ assays in comparison with many other typical methods recently reported. Moreover, the satisfactory recovery of analyzing several types of real water examples, i.e., tap water, drinking water, pond water and soil water, additionally validates its feasibility for practical applications.