A Portable Array Visualization Device Integrating Sample Preparation and Detection All-in-One for the On-Site Analysis of Complex Samples.

A gas membrane separation/array fluorescence visualization (GMS/AFV) device is developed by integrating hydrazine-based carbonized copolymer dots (PD-N2H4) for visual on-site analysis. The novel PD-N2H4 was synthesized using a "polymer template" approach, exhibiting strong blue fluorescence capable of visual sensing. The GMS/AFV device integrates sample preparation and detection all-in-one, consisting of a smartphone, a sample pretreatment system, and an optical system. In the detection procedure, the samples will be treated in the sample pretreatment system to create volatile gases. Therefore, any gas samples as well as solid and liquid samples that potentially produce volatile gases can be visually detected on-site by the device. H2S was utilized as a model analyte to test the practicality of the GMS/AFV device. The entire analysis can be finished in 3 min, and the limit of detection of H2S is as low as 3.4 µg/L. Surprisingly, the device is also capable of high-throughput sample detection, which can process 48 samples simultaneously in about 20 min. The device offers a quick, easy, cheap, and environmentally friendly way to analyze volatile gases, and it creates new opportunities for on-site detection of complex samples.

The Effect of Aerobic Exercise on Cognitive Function in Patients with Type 2 Diabetes Mellitus: A Meta-Analysis.

Background: Diabetes, a chronic disease metabolic disorder, commonly affects people. It is well-documented that aerobic exercise significantly reduces blood glucose in diabetic conditions. This study aimed to demonstrate the role of aerobic exercise on T2DM patients and cognitive impairment. Methods: We selected studies that published random controlled trials (RCTs) on the effects of aerobic exercise on cognitive function in patients with T2DM. However, the animal trials were we excluded in this study. We retrieved the data of random controlled trials from 8 databases based on the influences of aerobic exercise on cognitive function in patients with type 2 diabetes mellitus (T2DM). We utilized RevMan 5.3 software to analyze the data after evaluating the literature. Results: We selected 685 studies based on the information in the abstract and title after deleting the duplicate references. Then, we investigated the full text of 15. After full-text evaluation,we selected 10 random controlled trials to perform this comprehensive meta-analysis. We found that 10 studies derived the information of cognitive function between the test and the control groups and the cognitive function is significantly higher in the experimental group (SMD: 1.88; 95% Cl: 0.91,2.84; P < .01) than the control group. Moreover, the experimental group showed significantly higher minimum mental state examination (MMSE) (SMD: 2.06; 95% Cl: 0.96,3.14; P < .01) and Montreal Cognitive Assessment (MoCA) (SMD:1.62; 95% Cl: 0.54, 2.69; P < .01) than the normal group. Conclusion: Our findings demonstrated that aerobic exercise is crucially potent in T2DM patients and cognitive impairment, as evidenced by total cognitive function, MMSE, and MoCA. The above results should be warranted to verify with sophisticated clinical trials. In the future, aerobic exercise is suggested to guide patients'srecovery.

Recent Progress on Microfluidics Integrated with Fiber-Optic Sensors for On-Site Detection.

This review introduces a micro-integrated device of microfluidics and fiber-optic sensors for on-site detection, which can detect certain or several specific components or their amounts in different samples within a relatively short time. Fiber-optics with micron core diameters can be easily coated and functionalized, thus allowing sensors to be integrated with microfluidics to separate, enrich, and measure samples in a micro-device. Compared to traditional laboratory equipment, this integrated device exhibits natural advantages in size, speed, cost, portability, and operability, making it more suitable for on-site detection. In this review, the various optical detection methods used in this integrated device are introduced, including Raman, ultraviolet-visible, fluorescence, and surface plasmon resonance detections. It also provides a detailed overview of the on-site detection applications of this integrated device for biological analysis, food safety, and environmental monitoring. Lastly, this review addresses the prospects for the future development of microfluidics integrated with fiber-optic sensors.

Ag/Poly(N-isopropylacrylamide)-laponite Hydrogel Surface-Enhanced Raman Membrane Substrate for Rapid Separation, Concentration and Detection of Hydrophilic Compounds in Complex Sample All-in-One.

In this work, Ag nanoparticles (AgNPs) were embedded into a poly(N-isopropylacrylamide)-laponite (Ag/PNIP-LAP) hydrogel membrane for highly sensitive surface-enhancement Raman scattering (SERS) detection. In situ polymerization was initiated by UV light to encapsulate AgNPs in a PNIP-LAP hydrogel to prepare a highly active SERS membrane with a three-dimensional structure. Due to the surface plasmon resonance and high swelling/shrinkage ratio of the Ag/PNIP-LAP hydrogel SERS membrane, its network structure has a "sieving" effect, which makes it easier for hydrophilic small-molecule targets to enter the sterically confined hydrogel, and the AgNPs are close to each other to form a Raman "hot spot" through the shrinkage of the hydrogel, at the same time, the analyte is enriched in the confined space and close to the AgNPs to form a stronger SERS signal. The characterization of the SERS activity of the Ag/PNIP-LAP hydrogel showed that the prepared three-dimensional membrane had high detection sensitivity for urotropine, 2,5-dimethylpyrazine, pyrazinamide, and pyrazine; the detection limits (S/N = 3) were 17.4, 31.0, 53.1, and 1.11 µg/L, and the analytical time was 35 min. Due to the hydrophilicity of the Ag/PNIP-LAP hydrogel membrane, the small molecules can easily enter the SERS membrane, and the hydrophobic macromolecules are blocked outside the SERS membrane. The SERS method has good selectivity, stability, and reproducibility. The SERS method was applied to the detection of urotropine in dried bean curd sticks, 2,5-dimethylpyrazine in nuts and potato chips, and pyrazinamide in human plasma with recoveries of 81.8-116.8% and the relative standard deviation within 4.9-9.9%. The results matched well with that found by the corresponding chromatographic methods. The proposed method has the advantages of simple sample pretreatment, speediness, high sensitivity, and good selectivity to hydrophilic compounds and has potential application in the rapid on-site detection.

Chiral-Controlled Cyclic Chemiluminescence Reactions for the Analysis of Enantiomer Amino Acids.

The similarity and complexity of chiral amino acids (AAs) in complex samples remain a significant challenge in their analysis. In this work, the chiral metal-organic framework (MOF)-controlled cyclic chemiluminescence (CCL) reaction is developed and utilized in the analysis of enantiomer AAs. The chiral MOF of d-Co0.75Zn0.25-MOF-74 is designed and prepared by modifying the Co0.75Zn0.25-MOF-74 with d-tartaric acid. The developed chiral bimetallic MOF can not only offer the chiral recognize sites but also act as the catalyst in the cyclic luminol-H2O2 reaction. Moreover, a distinguishable CCL signal can be obtained on enantiomer AAs via the luminol-H2O2 reaction with the control of d-Co0.75Zn0.25-MOF-74. The amplified difference of enantiomer AAs can be quantified by the decay coefficient (k-values) which are calculated from the exponential decay fitting of their obtained CCL signals. According to simulation results, the selective recognition of 19 pairs of AAs is controlled by the pore size of the MOF-74 and their hydrogen-bond interaction with d-tartaric acid on the chiral MOF. Furthermore, the k-values can also be used to estimate the change of chiral AAs in complex samples. Consequently, this chiral MOF-controlled CCL reaction is applied to differentiate enantiomer AAs involved in the quality monitoring of dairy products and auxiliary diagnosis, which provides a new approach for chiral studies and their potential applications.

Size-resolved counting of circulating tumor cells on pinched flow-based microfluidic cytometry.

Precise cell detecting and counting is meaningful in circulating tumor cells (CTCs) analysis. In this work, a simple cyclic olefin copolymer (COC) microflow cytometer device was developed for size-resolved CTCs counting. The proposed device is constructed by a counting channel and a pinched injection unit having three channels. Through injection flow rate control, microspheres/cells can be focused into the centerline of the counting channel. Polystyrene microspheres of 3, 9, 15, and 20 µm were used for the microspheres focusing characterization. After coupling to laser-induced fluorescence detection technique, the proposed device was used for polystyrene microspheres counting and sizing. A count accuracy up to 97.6% was obtained for microspheres. Moreover, the proposed microflow cytometer was applied to CTCs detecting and counting. To mimic blood sample containing CTCs and CTCs mixture with different subtypes, an MDA-MB-231 (human breast cell line) spiked red blood cells sample and a mixture of MDA-MB-231 and MCF-7 (human breast cell line) sample were prepared, respectively, and then analyzed by the developed pinched flow-based microfluidic cytometry. The simple fabricated and easy operating COC microflow cytometer exhibits the potential in the point-of-care clinical application.

The association between creatinine to body weight ratio and the risk of progression to diabetes from pre-diabetes: a 5-year cohort study in Chinese adults.

OBJECTIVE: Evidence on the association between the creatinine to body weight (Cre/BW) ratio and the risk of pre-diabetes to diabetes development remains limited. Our study aimed to examine the association between the Cre/BW ratio and incident diabetes in pre-diabetic patients. METHODS: This retrospective cohort study included 24,506 pre-diabetic participants who underwent health checks from 2010 to 2016 in China. We used the Cox proportional-hazards regression model to explore the relationship between baseline Cre/BW ratio and diabetes risk in pre-diabetes patients. Using a Cox proportional hazards regression with cubic spline function and smooth curve fitting (cubical spline smoothing), we were able to determine the non-linear relationship between them. We also carried out a number of subgroup and sensitivity analyses. RESULTS: The age range of the participants included in this study was 20-99 years, with a majority of 16,232 individuals (66.24%) being men. The mean baseline Cre/BW ratio was 1.06 (SD 0.22) umol/L/kg. 2512 (10.25%) participants received a diabetes final diagnosis over a median follow-up period of 2.89 years. After adjusting for covariates, the Cre/BW ratio had a negative association with incident diabetes in participants with pre-diabetes, per umol/L/kg increase in Cre/BM ratio was accompanied by a 55.5% decrease in diabetes risk (HR = 0.445, 95%CI 0.361 to 0.548). The Cre/BW ratio and risk of diabetes had a non-linear connection, with 1.072 umol/L/kg serving as the ratio's inflection point. The HR were 0.294 (95%CI:0.208-0.414) and 0.712 (95%CI:0.492-1.029), respectively, on the left and right sides of the inflection point. The sensitivity analysis demonstrated the robustness of these results. Subgroup analyses indicated that the Cre/BW ratio was strongly associated with the risk of diabetes among participants who were younger than 50 years, as well as among those with diastolic blood pressure (DBP) < 90 mmHg and triglyceride (TG) < 1.7 mmol/L. In contrast, among participants 50 years of age or older, those with DBP ≥ 90 mmHg, and those with TG ≥ 1.7 mmol/L, the relationship between the Cre/BW ratio and the risk of diabetes was attenuated. CONCLUSION: This study demonstrates a negative, non-linear relationship between the Cre/BW ratio and the risk of diabetes among the Chinese population with pre-diabetes. From a therapeutic standpoint, it is clinically meaningful to maintain the Cre/BW ratio levels above the inflection point of 1.072 umol/L/kg.

Enhancing doctor-patient relationships in community health care institutions: the Patient Oriented Four Habits Model (POFHM) trial-a stepped wedge cluster randomized trial protocol.

BACKGROUND: The poor relationship between doctors and patients is a long-standing, global problem. However, current interventions tend to focus on the training of physicians, while patient-targeted interventions still need to be improved. Considering that patients play a significant role in outpatient consultations, we developed a protocol to assess the effectiveness of the Patient Oriented Four Habits Model (POFHM) in improving doctor-patient relationships. METHODS: A cross-sectional incomplete stepped-wedge cluster randomized trial design will be conducted in 8 primary healthcare institutions (PHCs). Following phase I of "usual care" as control measures for each PHC, either a patient- or doctor-only intervention will be implemented in phase II. In phase III, both patients and doctors will be involved in the intervention. This study will be conducted simultaneously in Nanling County and West Lake District. The primary outcomes will be evaluated after patients complete their visit: (1) patient literacy, (2) sense of control and (3) quality of doctor-patient communication. Finally, a mixed-effects model and subgroup analysis will be used to evaluate the effectiveness of the interventions. DISCUSSION: Fostering good consultation habits for the patient is a potentially effective strategy to improve the quality of doctor-patient communication. This study evaluates the implementation process and develops a rigorous quality control manual using a theoretical domain framework under the collective culture of China. The results of this trial will provide substantial evidence of the effectiveness of patient-oriented interventions. The POFHM can benefit the PHCs and provide a reference for countries and regions where medical resources are scarce and collectivist cultures dominate. TRIAL REGISTRATION: AsPredicted #107,282 on Sep 18, 2022; https://aspredicted.org/QST_MHW.

An integrated plastic microchip for enhancing electrophoretic separation using tunable pressure-driven backflows.

Microfluidic CE (MCE) is an effective solution for rapid and sensitive determination of multiple analytes. Herein, a dynamic coated cyclic olefin copolymer microchip was developed having an on-chip micropump for fluid velocity adjusting in electrophoretic separations. This micropump was fabricated by constructing a polyacrylamide gel membrane at one channel terminal. Once applying electric field across the membrane, a pressure-driven flow generated automatically to balance the electroosmotic flow (EOF) mismatch at the channel-membrane interface. The influence of gel precursor concentration and operating voltages on the fluid velocity was carefully evaluated. Moreover, the highly integration of injection, separation, and pumping units of the MCE system minimized the dead volume and provides satisfied column efficiency. Experiments showed that by adjusting of pumping voltage reduced the fluid velocity by a factor of 6, resulting six- and threefold resolving power enhancements of rhodamine dye mixture and amino acid mixture, respectively. Furthermore, the developed MCE method was applied for rhodamines and amino acids quantitation in food and cosmetics, with standard addition recoveries of 87.3-106.9% and 89.9-117.4%, respectively. These results were also confirmed by standard HPLC method, revealing the application potential in fast and onsite analysis of complex samples.

Enhanced capillary zone electrophoresis in cyclic olefin copolymer microchannels using the combination of dynamic and static coatings for rapid analysis of carnosine and niacinamide in cosmetics.

Cosmetics that have medicinal effects, including anti-inflammatory and antioxidant, have become a daily care routine consumption. The peptide additives, such as carnosine and nicotinamide, were frequently used to realize these medicinal effects. To accomplish rapid and effective quantitation of carnosine and niacinamide in cosmetics, capillary zone electrophoresis was executed in cyclic olefin copolymer microchips having both dynamic and static coatings. The static coating of cyclic olefin copolymer microchannel was constructed from bovine serum albumin adsorption, immobilization, and active site closure, while the dynamic coating was formed by adding surfactant into running buffer of capillary zone electrophoresis. The static coating can improve the hydrophilicity of cyclic olefin copolymer surface and avoid nonspecific peptide adsorption. The dynamic coating of sodium dodecyl sulfate in running buffer proved to be useful in flow velocity adjustment and the column efficiency enhancement in the capillary zone electrophoresis separation channel of the cyclic olefin copolymer microchip device. A separation resolution up to 4.24 on the mixture of carnosine and nicotinamide was obtained. Moreover, an analysis method was established and applied to simultaneous carnosine and nicotinamide determination in a liquid whitening essence and a solid antiglycation pill, and the results were verified by comparison with high-performance liquid chromatography methods, indicating its potential in complex sample analysis.

Aldehyde spiropyran fluorescent probe for rapid determination of hydrazine in environmental water.

Hydrazine often receives publicity because it has a wide range of applications but high toxicity at the same time. Here, we invented a novel aldehyde spiropyran fluorescent probe (SP-CHO) for fluorescence determination of hydrazine. The probe was synthesized through a hydrolysis reaction and a condensation reaction. It exhibits a specific response to hydrazine. The influence factors and anti-interference ability of SP-CHO identifying hydrazine were studied. HRMS, 1 H NMR, and density functional theory (DFT) calculations were used to reveal the recognition mechanism. Results showed that SP-CHO can be used for fluorescence determination of hydrazine with high selectivity and sensitivity. An SP-CHO-based fluorescence method was established for quantitation of hydrazine. The detection limit was 1.26 µmol/l, and the linear range was 5-100 µmol/l. The determination of hydrazine in water samples can be completed within 10 min, which shows good application prospects in real-time detection and process monitoring.

Microfluidic Magnetic Analyte Delivery Technique for Separation, Enrichment, and Fluorescence Detection of Ultratrace Biomarkers.

A microfluidic magnetic analyte delivery (µMAD) technique was developed to realize sample preparation and ultrasensitive biomarker detection. A simply designed microfluidic device was employed to carry out this technique, including a poly(dimethylsiloxane)-glass hybrid microchip having four straight rectangular channels and a permanent magnet. In the µMAD process, functionalized magnetic beads (MBs) were used to recognize and isolate analytes from a complex sample matrix, deliver analytes into tiny microchannels, and preconcentrate analytes in the magnetic trapping/detection region for in situ fluorescence detection. In the feasibility study and sensitivity optimization, horseradish peroxidase-labeled MBs were used, and critical parameters for the signal amplification performance of µMAD were carefully evaluated. At optimized conditions, a sensitivity improvement of at least 2 orders of magnitude was achieved. As a proof of concept, µMAD was combined with the enzyme-linked immunosorbent assay (ELISA), while carcinoembryonic antigen (CEA), prostate-specific antigen (PSA), and interleukin 6 (IL-6) were selected as model biomarkers. The limits of detection (LODs) of µMAD-ELISA were as low as 0.29 pg/mL for CEA, 0.047 pg/mL for PSA, and 0.021 pg/mL for IL-6, which corresponded to an over 200-fold reduction compared to their commercial ELISA results. Meanwhile, µMAD-ELISA revealed high selectivity and reproducibility. In clinical sample analysis, good accuracy was acquired for human serum analysis relative to commercial ELISA kits, and satisfied recoveries of 85.1-102% with RSDs of 1.7-9.8% for IL-6 and 84.7-113% with RSDs of 3.2-8.3% for interferon-γ were obtained. This ultrasensitive and easy operation technique provides a valuable approach for trace-level biomarker detection for practical applications.

Multifunctional MgO/HKUST-1 Composite for Capture, Catalysis, and Cyclic Cataluminescence Detection of Esters All-In-One to Rapidly Identify Scented Products.

The integration of metallic oxide and metal-organic frameworks has attracted considerable attention as obtained composite materials because they show synergistic effects in applications of catalysis and sensing. Herein, we developed the hybrid MgO and HKUST-1 for efficient capture, catalysis, and cyclic cataluminescence (CCTL) detection of esters all-in-one to rapidly identify scented products. The multifunctional MgO/HKUST-1 composite with high CCTL activity was synthesized and characterized. The multifunctional MgO/HKUST-1 composite acts as an enrichment material for ester capture and serves as a catalyst, assisting the analyte to trigger multistage signals. The multistage signals of ester-containing scented products also satisfy the exponential decay equation with a certain τ-value. The τ-values obtained by the CCTL system were applied to identify the brands of essential oils. The working temperature served as the sensor element to obtain various τ-values. The τ-values constituted a digital code to label the different brands of cigarettes with the same aroma type. The multistage signals could be used to distinguish the origin regions of essential oils and tobacco. This work combines the CCTL strategy with the sample pretreatment, opening up a new direction to develop CCL and providing a new platform to rapidly identify ester-containing scented products.

Maternal folic acid supplementation mediates the associations between maternal socioeconomic status and congenital heart diseases in offspring.

Low maternal socioeconomic status (SES) is considered as a risk factor of congenital heart diseases (CHDs) in offspring. However, the pathways underpinning the SES-CHDs associations are unclear. We assessed if first trimester maternal folic acid supplementation (FAS) is a mediator of the SES-CHDs associations. This case-control study included 8379 CHD cases and 6918 CHD-free controls from 40 participating centers in Guangdong, Southern China, 2004-2016. All fetuses were screened for CHDs using ultrasound and cases were confirmed by echocardiogram. We collected SES and FAS information during face-to-face interview by obstetricians using a structured questionnaire. Low SES was defined as education attainment <12 years, household individual income <3000 Chinese Yuan/person/month or unemployment. FAS referred to at least 0.4 mg of daily folic acid intake over 5 days/week continuously. We used causal mediation analysis to estimate the direct, indirect and proportion mediated by FAS on the SES-CHDs associations adjusted for confounders. Both low maternal income and education were significantly associated with increased risks of CHDs and lower prevalence of FAS. Low maternal FAS prevalence mediated 10% [95%CI:5%,13%] and 3% [95%CI:1%,5%] of the maternal low income-CHDs and the maternal low education-CHDs associations, respectively. In addition, FAS mediated the highest proportion of the associations between income and multiple critical CHDs [46.9%, 95%CI:24.7%,77%] and conotruncal defects [31.5%, 95%CI:17.1%,52.0%], respectively. Maternal FAS partially mediated the SES-CHDs associations, especially among the most critical and common CHDs. Promoting FAS in low SES women of childbearing age may be a feasible intervention to help prevent CHDs.

Serum albumin predicts hyperuricemia in patients with idiopathic membranous nephropathy.

AIM: The aim of the study was to examine the cross-sectional association between serum albumin and hyperuricemia (HU). MATERIALS AND METHODS: HU was defined as uric acid ≥ 420 umol/L for the male population and ≥ 357 umol/Lfor the female population. We reviewed the files of 216 consecutive patients with idiopathic membranous nephropathy treated at our hospital between 2010 and 2019. The correlation of serum albumin with hyperuricemia and the association between serum uric acid levels and the clinical of Idiopathic membranous nephropathy were assessed by statistical analysis. A multivariable logistic analysis model was applied to test the association after adjusting for a number of potential confounding factors. RESULTS: Triglyceride and serum albumin were higher in the group with hyperuricemia than in the group without hyperuricemia (p = 0.020, p < 0.001, respectively). As serum albumin rose to 1 g/L, the probability for hyperuricemia increased to 17% (adjusted II OR = 1.17, 95% CI (1.02, 1.35), p = 0.0294). A unit increase in serum albumin was associated with an increase of 6.64 g/L in uric acid (adjusted II ß = 6.64, p = 0.0135). Using tertile 1 (T1) for reference, the tertile 3 (T3) group was positively associated with both hyperuricemia (adjusted II OR = 44.21, 95% CI (12.76, 75.67), p = 0.0064) and uric acid (adjusted II ß = 98.64, p = 0.0116). The interaction test showed significant interactions between serum albumin and the body mass index (BMI) when hyperuricemia or uric acid were used to determine the outcomes. The participants with a BMI ≥ 25 kg/m2 had a higher OR between serum albumin and hyperuricemia and had a higher ß between serum albumin and uric acid than those with a BMI ≥ 25 kg/m2 (for hyperuricemia: OR = 1.01 vs. 1.18, p for interaction = 0.0056; for uric acid: ß = 0.96 vs. 6.23, p for interaction = 0.0154). The area under the ROC curve (AUC) was 0.7615 in the participants with a BMI ≥ 25 kg/m2. The sensitivity and specificity of this point were 47.37% and 95.83%, respectively. CONCLUSION: Our study showed that serum albumin was positively associated with hyperuricemia and uric acid, especially in obese subjects.

Measuring Public Reaction to Violence Against Doctors in China: Interrupted Time Series Analysis of Media Reports.

BACKGROUND: Violence against doctors in China is a serious problem that has attracted attention from both domestic and international media. OBJECTIVE: This study investigates readers' responses to media reports on violence against doctors to identify attitudes toward perpetrators and physicians and examine if such trends are influenced by national policies. METHODS: We searched 17 Chinese violence against doctors reports in international media sources from 2011 to 2020. We then tracked back the original reports and web crawled the 19,220 comments in China. To ascertain the possible turning point of public opinion, we searched violence against doctors-related policies from Tsinghua University ipolicy database from 2011 to 2020, and found 19 policies enacted by the Chinese central government aimed at alleviating the intense patient-physician relationship. We then conducted a series of interrupted time series analyses to examine the influence of these policies on public sentiment toward violence against doctors over time. RESULTS: The interrupted time series analysis (ITSA) showed that the change in public sentiment toward violence against doctors reports was temporally associated with government interventions. The declarations of 10 of the public policies were followed by increases in the proportion of online public opinion in support of doctors (average slope changes of 0.010, P<.05). A decline in the proportion of online public opinion that blamed doctors (average level change of -0.784, P<.05) followed the declaration of 3 policies. CONCLUSIONS: The government's administrative interventions effectively shaped public opinion but only temporarily. Continued public policy interventions are needed to sustain the reduction of hostility toward medical doctors.

A "Polymer Template" Strategy for Carbonized Polymer Dots with Controllable Properties.

Limited avenues are available for property control of carbonized polymer dots (PDs) owing to the unsatisfactory understanding of PDs" formation. Herein, a de novo "polymer template" strategy is presented for PDs with customizable functional surface groups (FSG), size, and underlying fluorescence, with a detailed mechanism. The strategy relies on novel di-active site polymers (DASPs) prepared from alkenyl azides via [3+2] cycloaddition and guanidino hydrolysis. Benefiting from these specific reactions, the DASPs were convenient for mass production and stable for storage, and could be transformed to PDs upon addition of nucleophilic agents through nucleophilic addition and substitution at 70 °C. By regulating the types of alkenyl azides, nucleophilic agents, and reaction conditions, the as-prepare PDs could be tailored with controlled types of core, FSG, and particle size, as well as fluorescence properties of quantum yield from 8.2-55.6 %, and emission maximum from 380-500 nm. These specialties make this "polymer template" strategy a promising start for building PDs-based sensor platforms. Moreover, the strategy could further our understanding towards PDs' formation, and open up a new way to customize PDs for specific needs in the fields of analysis, catalysis, images, etc.

Recent advances in sample preparation techniques in China.

Sample preparation is the procedure before instrumental analysis and significant to its effectiveness and efficiency. However, this procedure is usually time-consuming, labor intensive, and prone to error. In the last decade, the development of sample preparation techniques has received increasing attention, especially in complex sample application. To pretreat samples faster and more effectively, advanced materials, instrumentation, and methods have been combined with typical techniques, including extraction, membrane separation, and chemical conversion techniques. Researchers in China focused on the development of simple, efficient sample preparation methods with selective enrichment and rapid separation capabilities for target analysis in complicated sample matrix and contribute almost a half of the publications in this specific field. In this review, a panorama of sample preparation techniques in China has been composed from more than 140 references, and we highlight some promising methods developed during recent years and introduce different separation materials with respect to these methods.

A microchip device to enhance free flow electrophoresis using controllable pinched sample injections.

Micro free flow electrophoresis (µFFE) is a valuable technique capable of high throughput rapid microscale electrophoretic separation along with mild operating conditions. However, the stream flow separation nature of free flow electrophoresis affects its separation performance with additional stream broadening due to sample stream deflection. To reduce stream broadening and enhance separation performance of µFFE, we presented a simple microfluidic device that enables injection bandwidth control. A pinched injection was formed in the reported µFFE system using operating buffer at sample flow rate ratio (r) setting. Initial bandwidth at the entrance of separation chamber can be shrunk from 800 to 30 µm when r increased from 1 to 256. Stream broadening at the exit of separation chamber can be reduced by about 96% when r increased from 4 to 128, according to both theoretical and experimental results. Moreover, the separation resolution for a dye mixture was enhanced by a factor of 4 when r increased from 16 to 128, which corresponded to an 80% reduction in sample initial bandwidth. Furthermore, a similar enhancement on amino acids separation was obtained by using injection control in the reported µFFE device and readily integrated into online/offline sample preparation and/or downstream analysis procedures.

An online field-assisted micro-solid-phase extraction device coupled with high-performance liquid chromatography for the direct analysis of solid samples.

Herein, a total online device based on field-assisted extraction (FAE), micro-solid-phase extraction (µ-SPE), and high-performance liquid chromatography (HPLC) was designed. Solid samples were pretreated with ultrasound-microwave synergic effects, and then the extract was cleaned up online with a monolithic column, followed by HPLC analysis. The cross-actions between ultrasound and microwave along with other extraction parameters were studied systematically. The efficiency of this online method was verified in the determination of polycyclic aromatic hydrocarbons (PAHs) in foods and tetracycline antibiotics (TCAs) in cosmetic samples. The detection limits of nine PAHs including fluorene, phenanthrene, anthracene, fluoranthene, benzo[k]fluoranthene, benz[a]anthracene, benzo[b]fluoranthene, pyrene, and benzo[a]pyrene were all within 0.075-0.30 µg/kg, as well as four TCAs including oxytetracycline, tetracycline, chlortetracycline, and doxycycline were within 0.02-0.06 µg/kg. Six PAHs were found in roast potatoes and baked fish and the recoveries were in the range of 71.5-119.7% with RSDs of 0.2-10.9% (n = 3). The recoveries for TCAs in cosmetic samples were in the range of 75.3-118.0% with RSDs lower than 8.2% (n = 3). Compared with those offline methods, this total online FAE-µ-SPE-HPLC method not only simplifies the operation process, but also increases the precision and accuracy. Beyond trace analytes analysis in solid and semi-solid matrixes, application of this total online analysis method can also be extended to investigate field-assisted extraction mechanisms. Graphical abstract.