Chinese Journal of Analytical Chemistry最新文献

Tao-He-Cheng-Qi granule (THCQ) was derived from Tao-He-Cheng-Qi Decoction, which has been proved to be one of the effective traditional Chinese medicines (TCMs) applied in the treatment of Intracerebral Hemorrhage (ICH). The objective of this investigation was to study the quality control of THCQ and explore its potential mechanism in treating ICH. According to the results, 20 batches of THCQ had similar chromatographic fingerprints. The similarities of chromatograms of the 20 batches were 0.937–0.998 and 15 major chromatographic peaks were identified as the common peaks for the quality control of THCQ. Subsequently, four analytical methods were successfully established to determine 7 index components of THCQ, respectively, which then were applied in 20 batches of THCQ to determine the content of these index components. Besides, animal experiments were conducted to explore the mechanism of THCQ in the treatment of ICH. After a three-day treatment, behavioral changes and brain histopathological evaluations of SD rats showed that THCQ dose-dependently improved the symptoms of rats with ICH. The results of immunohistochemical evaluations showed that THCQ reduced the expressions of TNF-α and IL-1β. The results of protein expressions detected by ELISA revealed that THCQ dose-dependently reduced Notch1 level and increased the expression of VEGFR. Collectively, the mechanisms of THCQ for treating ICH might be closely relevant to the downregulation of Notch and NF-κB and the upregulation of VEGFR. These findings provided insight for studies in investigating the quality control and further clinical application of THCQ.

An outstanding fluorescent probe for adenosine 5′-triphosphate (ATP) in the millimolar range will shed deep light on the physiological role of ATP. Many fluorescentprobes based on rhodamine spirolactam derivatives have been developed for this purpose and claimed to detect millimolar ATP excellently, where ATP or adenosine 5′-triphosphate disodium salt (ATP-2Na) is employed to examine their response to ATP. However, in this work, it was found that both millimolar ATP and ATP-2Na could significantly decrease the pH of the common buffer solution even for several units. Considering the dependence of the rhodamine spirolactam fluorescence on pH, a series of rhodamine spirolactam-based probes was synthesized to investigate their fluorescence response to pH and ATP-2Na. The results demonstrated that the fluorescence response of the probes to millimolar ATP-2Na indeed resulted from both ATP-2Na itself and the pH decrease induced by ATP-2Na. Furthermore, it was evidenced that acidic pH was crucial for the probes to produce fluorescence response to millimolar ATP-2Na itself, and the rhodamine spirolactam-based probes would show poor sensitivity to millimolar ATP-2Na at near-natural pH. Accordingly, the previous conclusion that the rhodamine spirolactam-based probes could detect millimolar ATP excellently was almost erroneous, and might mislead the design and practice of intracellular ATP probe in the future. This work notes that attention should be paid to the physiochemical properties of the analyte and the environmental changes produced by the target analyte.

A dualmode tetracycline (TC) assay was developed based on a colloidally stable mixture of TC-specific aptamer stabilized AuNPs (Apt-stabilized AuNPs) and graphite carbon nitride nanosheets (g-C₃N₄) for sensitive detection of TC. The presence of TC in the solution could be identified based on the colorimetric and fluorescent signals. This dual-mode assay requires no salt during TC detection and has high sensitivity, allowing detection limits (LOD) of TC to 1.0 × 10⁻¹⁶ M with a wide dynamic detection range (six orders of magnitude, from 5.0 × 10⁻¹⁶ to 5.0 × 10⁻¹¹ M), and exhibits good selectivity for TC over other metal cations, antibiotics, amino acids, and proteins. The mechanism of this dual-mode assay for TC detection was investigated in detail. Moreover, the amount of TC in actual samples (spiked drinking water and milk) was successfully monitored. The findings provide valuable guidance in developing an advanced platform for detecting TC and other antibiotics.

In this study, nanozyme is used for monitoring the dose of ultraviolet (UV) in sunlight for the first time. We find that nitrogen-doped carbon dots (N-doped C-dots) can effectively catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) under different UV region including UVA, UVB, and UVC. In comparison, the N-doped C-dots fail to show the catalytic activity under visible light. The finding is applied for distinguishing UV light and visible light through the color change of TMB. More importantly, the photo-oxidation TMB catalyzed by N-doped C-dots can work well in a near neutral pH, which is beneficial for its application in wearable device due to the reducing of acid corrosion. Finally, a wearable bracelet is fabricated by integrating N-doped C-dots and TMB into hydrogels. The bracelet is used for monitoring the UV exposure in sunlight. The color change of TMB in the bracelet can be clearly observed by naked eyes or quantified by a smartphone. The bracelet is also used for distinguishing different weather condition such as sunny/cloudy or different place such as indoor/outdoor during a sunny day. This study provides the first example of nanozyme in wearable UV sensor and will stimulate the applications of nanozyme in wearable device.

In this work, a novel ratiometric electrochemical aptasensor was designed for prostate specific antigen (PSA) detection based on toehold-mediated strand displacement reaction (TMSDR). For PSA detection, PSA could bind with the aptamer sequence in hairpin probe 1 (HP1), and HP1/PSA complex was obtained. Then, in the presence of S3 DNA, HP1/PSA could trigger two TMSDR processes by hybridizing with Fc-S2/S1 double-stranded DNA, which would generate a large amount of Fc-S2 and recycle HP1/PSA. This enabled the hybridization of Fc-S2 with methylene blue labeled thiolated hairpin probe 2 (MB-HP2) immobilized on the electrode surface, causing MB molecules away from the electrode and Fc close to the electrode. Thus, with the increasing PSA concentrations, the current of MB (I_MB) decreased and the current of Fc (I_Fc) increased. The ratio of I_Fc/I_MB was shown to be linear with the logarithm of PSA concentration from 1 pg mL⁻¹ to 100 ng mL⁻¹, with a detection limit of 0.28 pg mL⁻¹. In addition, the aptasensor had good specificity, reproducibility, repeatability, and stability for PSA detection, and was successfully applied to spiked diluted human serum samples.

There is an urgent need to develop multifunctional cost-effective nanomaterials and nanocomposites that can be used in numerous applications while showing high efficiency and cheaper implementation compared to conventional techniques and/or materials. In this work, zinc/iron layered double hydroxide (LDH) and polyaniline (PANI) were synthesized as a model LDH/conductive polymer nanocomposite, which is a promising family of cheap multifunctional materials. This electrochemical properties of this nanocomposite was investigated for detection of heavy metal (HM) ions in water streams, using lead as a model HM . In the present work, zinc/iron LDH and PANI was assigned as carbon paste electrode modifier. The composite was fully characterized using various characterization techniques including X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform InfraRed (FTIR). The electrochemical redox reactions of lead (II) ions at the modified electrode interface were investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), Accordingly, a linear relation of Pb²⁺ ions was achieved in the concentration range 1–80 µM with limit of detection (LOD) was 167.8 nM and limit of quantification (LOQ) was 559.4 nM. Furthermore, the cost of using such material for lead removal using a typical adsorption study was compared to using conventional inductively coupled plasma (ICP) or atomic absorption spectrometry (AAS) equipment for tracking HM removal during the adsorption process. Cost analysis revealed that the final overall cost of the modified carbon paste electrode is estimated as 1.25 USD. This cost represents less than 0.1% of the total cost required to conduct the same adsorption study using a typical ICP or AAS equipment. This composite can pave the road towards portable measurements for onsite detection of wastewater pollutants using cheap disposable-electrodes as compared to massive expensive off site equipment such as ICP and AAS.

Poly-ether ketone (PEEK) was modified to sulfonated poly-ether ketone (sPEEK) by sulfonation process with a degree of sulfonation 49.5%. Carbon nanotubes were acid-treated with sulfuric acid and nitric acid solution (3:1, v/v) for functionalization. sPEEK and sPEEK/c-CNT membranes were prepared by solvent casting method using dimethyl sulfoxide (DMSO) as solvent. The experimental part was conducted as per design of experiment employing response surface methodology consisting three factors, namely (A) c-CNT (wt.%), (B) mixing temperature (°C), and (C) sPEEK concentration (mg/mL). The ion exchange capacity was found to increase with c-CNT (wt.%). Fourier-transform infrared spectroscopy confirms the sulfonation of PEEK. X-Ray diffraction investigates the influence of the sulfonation in the crystal structure of the sPEEK and sPEEK/c-CNT. Scanning electron microscopy images show that c-CNTs are dispersed well in the sPEEK matrix. The results showed slightly increasing water uptake and swelling ratio of the composites membranes. The analysis of variance (ANOVA) revealed that c-CNT (wt.%) is highly affecting the responses. Proton conductivity of sPEEK specimen is about 23.9 mS/cm, which is significantly increased to 57.0 mS/cm for sPEEK/0.12 c-CNT (wt.%) membrane suggesting its application for fuel cell.

A smart glucose detection system based on organic electrochemical transistor and near field communication module was built to detect sweat sample. The system mainly consists of three parts: glucose sensor, electrochemical detection module and application. The basic three electrodes (gate, source and drain) were prepared by screen printing technology on the polyethylene terephthalate sheets selected as the substrate material. The gate electrode was multilayer modified with gold membrane, Prussian blue and glucose oxidase, and the channel between the source and drain was covered with a poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) film. The potential drop caused by the redox reaction of glucose on the gate electrode changed the response of source-drain current signal. The electrochemical detection module with near field communication function was customized to realize the functions of signal detection, amplification and data transmission. Conjunct with smart Android devices analyzed and processed the data stream from near field communication to display glucose test results. The high sensitivity attributed to the amplification function of the field effect device and high selectivity to the enzyme sensor realize the detection of glucose in simulated sweat, which paves the way to relevant glucose detection in diabetics without the need for invasive finger-stick blood sampling.

Micro-electro-mechanical system (MEMS) based mass spectrometry, MEMS mass spectrometry, emerges a new technique branch of miniature mass spectrometry. One of the main challenges hindering the development of MEMS mass spectrometry is the poor compatibility between the complex electrode structure of traditional ion optics and MEMS processes. This paper proposed a planar quadrupole mass filter utilizing a highly simplified stacked-layer structure and film electrodes, which is easy to fabricate with high precision by MEMS surface micromachining. The ion trajectory simulation model of the MEMS mass spectrometry chip involving all necessary ion optics was elaborated for investigating the preliminary performance of the planar quadrupole mass filter. By optimizing the crucial parameters such as the frequency of radio frequency voltage, the ratio of direct current voltage and radio frequency voltage, pre-pole length, main-pole length, and injection kinetic energy, the preliminary simulation result of planar quadrupole mass filter achieved a 1–2 Da peak width (at 50% of peak height) and 20–80% ion transmission efficiency. Importantly, the planar quadrupole mass filter demonstrated a maximum working pressure of 0.1 Pa (using air as the buffer gas), 100 times higher than that of conventional quadrupole mass filters, while maintaining a 0.7–1.8 Da peak width and ∼5% ion transmission efficiency. Additionally, to modify the theoretical formulas for the non-ideal quadrupolar field of planar quadrupole mass filter, a novel approach based on stability diagrams obtained by simulation was also introduced. The pretty good linearity (R²=1) between ion masses in the range of 10 to 100 Da and the corresponding radio frequency voltages was verified through the simulated mass spectra. Notably, the proportional coefficient of ion mass and radio frequency voltage exhibited a minimal 4% deviation between the simulated value (4.7132 V_0P/Da) and the calculated value (4.9036 V_0P/Da) through the modified formula. In conclusion, the preliminary simulation results demonstrated that the planar quadrupole mass filter possessed moderate performance, high-pressure tolerance, and excellent theoretical consistency, which proved it a promising technology of MEMS mass spectrometry. It can find applications in the fields of gas detection, including the rapid response to hazardous gas emissions and in situ detection of dissolved gases in the deep sea.

Panax ginseng flowers (PGF), a constituent of ginseng, possess medicinal value and are widely recognized as a functional food. Therefore, ensuring meticulous control of PGF quality has become increasingly significant. One effective method for assessing product quality is to analyze the volatile organic compounds (VOCs) present in PGF, which act as indicative markers. In this study, VOCs in PGF were analyzed using gas chromatography-mass spectrometry (GC-MS), employing four extraction methods: steam distillation (SD), supercritical fluid extraction (SFE), headspace solid-phase microextraction (HS-SPME), and static headspace sampling (SHS). The results revealed 103 annotated components using the area normalization approach, highlighting the major differences among the four extraction methods. The main sesquiterpenoid components of PGF, 1,6,10-dodecatriene, 7,11-dimethyl-3-methylene-, and (E)- were the only common components. The SD, SFE, HS-SPME, and SHS methods identified 67, 20, 38, and 18 components, respectively. These components accounted for 89.67%, 61.84%, 82.6%, and 50.3%, respectively, of the total volatile oil effluent peak areas. Additionally, each method extracted 11, 9, 8, and 8 components, with proportions exceeding 1% in the PGF extracts. Terpenoids were identified as the main VOCs in PGF, with the SD method showing the highest sesquiterpene content. Both HS-SPME and SHS methods contained sesquiterpenoids, which accounted for 61.471% and 22.708% of the total relative amount, respectively. Furthermore, the extraction capacity of the HS-SPME method is approximately three times higher than that of the SHS method. The volatile oil extract of PGF consists of main components such as alkanes, esters, sesquiterpenes, and steroids, with compound contents exceeding 1%. Our findings provide a theoretical foundation for the rational development of PGF resources.