Design and experiment of high-field asymmetric waveform ion mobility spectrometry chip based on an integrated temperature control printed circuit board structure.

RATIONALE: During the detection of volatile organic compounds (VOC) using high-field asymmetric waveform ion mobility spectrometry (FAIMS), the ambient temperature significantly impacts the accuracy of planar FAIMS. To mitigate the influence of ambient temperature on detection accuracy and enhance resolution, a FAIMS system based on the inner impedance characteristics of a printed circuit board (PCB) was designed for temperature control. METHODS: This study, conducted under standard atmospheric pressure, aimed to assess the signal stability of a planar FAIMS instrument with and without temperature control, and the effect of temperature change on the detection ability of acetone, ethanol, and their mixture was studied using PCB self-heating. RESULTS: Experimental results demonstrated that the base noise in FAIMS with temperature control was 0.2 pA, whereas that in FAIMS without temperature control was 1.8 pA. Notably, with increasing temperature, the detection ability of FAIMS changes accordingly. The optimal relative detection ability of acetone was observed when the electrode plate was heated to 45°C under an electric field of 15 kV/cm. CONCLUSIONS: This study provides a novel approach to improve the resolving power of FAIMS systems and their signal-to-noise ratio. The utilization of a PCB-based temperature control proved effective in stabilizing FAIMS signal characteristics and optimizing detection capabilities, particularly for VOCs such as acetone. These findings have significant implications for improving the accuracy and resolving power of FAIMS systems in VOC detection applications.

A detection system for serum cholesterol based on the fluorescence color detection of beta-cyclodextrin-capped gold nanoclusters.

Cholesterol is one of the major markers for cardiovascular diseases. Herein, a portable cholesterol measurement system based on fluorescence color detection was constructed by combining the high sensitivity of fluorescence analysis with the ease of color sensing to determine low levels of serum cholesterol. Cyclodextrin capping gold nanoclusters with blue-green emission were used as fluorescent probes because cholesterol exposure induced fluorescence enhancement of the probe due to the host-guest inclusion interaction between cholesterol and the cavity of cyclodextrin. The integrated sensing system consisted of modules including a microprocessor, a power supply, an LED light with a constant current source, an RGB color sensor, a display, and a darkroom. All the modules except the display screen were placed in a 3D printing darkroom to avoid interference from ambient light. An RGB color sensor TCS230 was applied to capture the RGB signals of the fluorescent color of the probe solution before and after cholesterol addition. Then the obtained RGB signals were converted into the signals in Hue, Saturation, and Value (HSV) color space with a central control chip STM32F407. The Hue value of the fluorescent color of the solution can discriminate the concentration change of cholesterol. Experimental results demonstrate that the system responds linearly to cholesterol in the concentration range of 20.00 âˆ¼ 150.00 µmol·L-1 with a detection limit of 16.07 µmol·L-1 (3σ, n = 3). The detection of the system has good consistency and accuracy compared with the standard instrument, showing potential for the detection of low levels of serum cholesterol.

Mechanism of the Change in the Intestinal Microbiota of C-Strain Spodoptera frugiperda (Lepidoptera: Noctuidae) after an Interspecific Transference between Rice and Corn.

Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae) was first found in 2019 in Yunnan, China, and it was characterized as a corn strain; it was also found on rice strains there, and it damages rice in China, but little is known about the effect of host plant transfer on the intestinal microbiota and the activities of detoxification enzymes in the C-strain (corn strain) S. frugiperda. The intestinal microbiota and the protective enzyme activity of S. frugiperda that were transferred from rice plants were assessed, and the fourth generation of insects transferred from corn were studied; the gene types of S. frugiperda that were transferred from rice plants were tested using mitochondrial Tpi gene sequences. The results showed that the intestinal microbiota in the C-strain S. frugiperda were changed after the host transference, and the diversity and richness of the intestinal bacterial communities of the S. frugiperda feeding on rice were significantly reduced after the transfer of the host from corn. The predominant species of intestinal bacteria of the S. frugiperda on rice transferred from corn were Enterococcus and Enterobacter, with relative abundances of 28.7% and 66.68%; the predominant species of intestinal bacteria of the S. frugiperda that were transferred from rice and feeding on corn were Enterococcus (22.35%) and Erysipelatoclostridium (73.92%); and the predominant species of intestinal bacteria of S. frugiperda feeding on corn was Enterococcus, with a relative abundance of 61.26%. The CAT (catalase) activity of the S. frugiperda transferred from corn onto rice from corn was reduced, the POD (peroxidase) activity was significantly increased after the transfer from corn, and no significant variations were found for the SOD (superoxide dismutase), CarE (carboxylesterase), and GST (glutathione S-transferase) activities of S. frugiperda after the host plant transfer. The results showed that after feeding on rice, the activities of CAT and POD in the in S. frugiperda body changed in order to resist plant secondary metabolites from corn or rice, but there was no significant change in the detoxification enzymes in the body. In summary, switching the host plant between corn and rice induced variations in the intestinal microbiota in C-strain S. frugiperda owing to the strain difference between the C-strain and the R-strain (rice strain), and this was consistent with the results of the activities of detoxification enzymes. The results indicat that changes in intestinal microbiota and physiological enzymes may be important reasons for the adaptive capacity of C-strain S. frugiperda to rice.

Fluorescence turn-on detection of human serum albumin based on the assembly of gold nanoclusters and bromocresol green.

As the most abundant protein in plasma, human serum albumin plays a vital role in physiological processes, such as maintaining blood osmotic pressure and carrying small-molecule ligands. Since the content of albumin in the human serum can reflect the status of liver and renal function, albumin quantitation is significant in clinical diagnosis. In this work, fluorescence turn-on detection of human serum albumin (HSA) had been performed based on the assembly of gold nanoclusters and bromocresol green. Gold nanoclusters (AuNCs) capped by reduced glutathione (GSH) were assembled with bromocresol green (BCG), and the assembly was used as a fluorescent probe for HSA. After BCG assembling, the fluorescence of gold nanoclusters was nearly quenched. In acidic solution, HSA can selectively bind to BCG on the assembly and recover the fluorescence of the solution. Based on this turn-on fluorescence, ratiometric HSA quantification was realized. Under optimal conditions, HSA detection by the probe possessed a good linear relationship in the range of 0.40-22.50 mg·mL-1, and the detection limit was 0.27 ± 0.04 mg·mL-1 (3σ, n = 3). Common coexisting components in serum and blood proteins did not interfere with the detection of HSA. This method has the advantages of easy manipulation and high sensitivity, and the fluorescent response is insensitive to reaction time.

Non-Enzymatically Colorimetric Bilirubin Sensing Based on the Catalytic Structure Disruption of Gold Nanocages.

As an essential indicator of liver function, bilirubin is of great significance for clinical diagnosis. A non-enzymatic sensor has been established for sensitive bilirubin detection based on the bilirubin oxidation catalyzed by unlabeled gold nanocages (GNCs). GNCs with dual-localized surface plasmon resonance (LSPR) peaks were prepared by a one-pot method. One peak around 500 nm was ascribed to gold nanoparticles (AuNPs), and the other located in the near-infrared region was the typical peak of GNCs. The catalytic oxidation of bilirubin by GNCs was accompanied by the disruption of cage structure, releasing free AuNPs from the nanocage. This transformation changed the dual peak intensities in opposite trend, and made it possible to realize the colorimetric sensing of bilirubin in a ratiometric mode. The absorbance ratios showed good linearity to bilirubin concentrations in the range of 0.20~3.60 µmol/L with a detection limit of 39.35 nM (3σ, n = 3). The sensor exhibited excellent selectivity for bilirubin over other coexisting substances. Bilirubin in real human serum samples was detected with recoveries ranging from 94.5 to 102.6%. The method for bilirubin assay is simple, sensitive and without complex biolabeling.

Precise Control of Glioma Cell Apoptosis Induced by Micro-Plasma-Activated Water (µ-PAW).

To verify the existence of plasma with the potential to kill tumor cells, this paper designed a novel helium (He) micro-plasma jet array device and detected the concentration of typical long-lived reactive oxygen and nitrogen species (RONS) with oxidative activity generated by it. The paper described a new He micro-plasma jet array device consisting of nine flexible quartz capillaries with an inner diameter of 75 µm arranged in a 3 × 3 array. Sterilized ultrapure water (up water) was first treated with the He micro-plasma jet array device to activate it to form enriched RONS micro-plasma-activated water (µ-PAW), and then µ-PAW was added to the cell culture medium (with cells) to observe the proliferation of human glioma cells. The concentration of long-lived RONS, such as nitrate (NO3-), was detected according to Beer-Lambert's law in combination with UV spectrophotometry as well as a color development method. The MTT Cell Proliferation and Cytotoxicity Assay Kit combined with the Hoechst Staining Kit were used to assess the proliferation status of the cells. The results showed that the range of RONS concentration variation could be controlled in the order of micromoles (µmol), while plasma-induced tumor cell death is apoptosis that does not affect the surrounding environment.

[Occupational health risk assessment of pneumoconiosis caused by dust exposure at 18 quarries in a given area of Hubei Province].

OBJECTIVE: To explore the occupational health risk level of pneumoconiosis caused by dust exposure in a given area of Hubei province. METHODS: From April 2021 to October 2021, 18 quarries were randomly selected in the areas where quarries were concentrated in Hubei Province to conduct on-site hygiene investigation and detection. A total of 384 workers were employed in the above quarries, and 293 workers were exposed to dust. The International Mining and Metals Commission's risk rating table method and occupational hazard risk index method were used to analyze the occupational health risk level from total and respirable dust views, respectively. Meanwhile, the square weighted Kappa test was performed to analyze the consistency between two risk assessment method. RESULTS: The median dust exposure rate of workers in the above18 enterprises was 73.22%, small, underground mining, and barite quarries had relatively higher dust exposure rates(all median were 100.00%). The medians of daily dust exposure time, personal protective equipment wearing rate, free silica content of dust, 8-hour time weighted average exposure concentration of total dust and respirable dust in each assessment indicator were 6-8 hours, 0%-24.00%, 1.69%-35.30%, 0.56-3.70 mg/m~3, and 0.33-1.20 mg/m~3, respectively. Occupational health risk assessment result showed the overall occupational health risk levels of quarries, as well as different production scales and mining method, were all low. Among different positions, wind driller and tunneling worker had high and medium occupational health risk, respectively, and the rest of the positions had low or very low risk. International Council on Mining and Mentals(ICMM) risk rating table method and the INDEX method consistency analyses showed that these two risk assessment method had strong consistency in terms of total dust(Kappa value was 0.65(95%CI 0.57-0.73)), and general consistency in term of respirable dust(Kappa value was 0.51(95%CI 0.39-0.62)). CONCLUSION: The overall occupational health risk level of pneumoconiosis caused by dust exposure in quarries was low, but risk levels were higher for wind driller and tunneling worker.

[Design and implementation of ratiometric fluorescence detection system for serum bilirubin].

The current quantitative methods of bilirubin have disadvantages such as high cost and low sensitivity. Due to the negative correlation between the level of serum bilirubin and the risk of cardiovascular diseases, a fluorescent ratiometric film sensor was developed aiming at bilirubin detection at low level concentration. Blue-emitting and red-emitting gold nanoclusters were assembled into the same film using layer-by-layer self-assembly technology. Detection of bilirubin was achieved based on the intensity ratio of the two nanoclusters. Bilirubin exposure causes fluorescent quenching of the film. The fluorescence intensity ratio of the two cluster probes had quantitative relationship versus bilirubin concentration. Based on this film sensor, a portable fluorescence detection system was designed for the ratiometric sensing of bilirubin. The hardware of the system was mainly composed of main control chip STM32F407, TSL237 and TSL238T optical frequency sensor. A light-avoiding dark room and detection light path were designed through three-dimensional printing to reduce the interference from ambient light and improve detection accuracy. Experimental results showed that the proposed detection system had strong anti-interference, good stability and accuracy. The linear coefficient of bilirubin detected by this system was 0.987. The system presented good results in reproducible experiments and possessed a good linear relationship with the data obtained by standard spectrofluorometer. The portable system is expected to detect serum bilirubin at low levels.

Fluorescent sensing of free bilirubin at nanomolar level using a Langmuir-Blodgett film of glucuronic acid-functionalized gold nanoclusters.

Serum bilirubin is an important indicator to assess liver function and diagnose various types of liver diseases. The level of serum bilirubin is also negatively correlated with the risk of cardiovascular disease and cancer. We had fabricated a fluorescent film sensor aiming at free bilirubin detection at the nanomolar level. Gold nanoclusters capped by human serum albumin (HSA-AuNCs) were utilized as a fluorescent platform for bilirubin biorecognition. HSA-AuNCs were functionalized with glucuronic acid to increase the binding sites for bilirubin. An ultrathin film of glucuronic acid-functionalized gold nanoclusters was obtained by the Langmuir-Blodgett (LB) technique. When exposed to bilirubin, the interaction between free bilirubin and the functionalized AuNCs resulted in fluorescent quenching of the film. Good linearity could be achieved for the quenching efficiency versus the logarithm of free bilirubin concentration over a concentration range of 1.00 nM~5.00 µM. The limit of detection (LOD) was calculated to be (2.70 ± 0.14) × 10-1 nM (S/N = 3). The film sensor presents a good anti-interference capability towards common substances coexisting with bilirubin in serum. Satisfactory results achieved in the tests of real serum samples indicate that the LB film sensor can be used for bilirubin determination in nanomolar concentration.

Identification of Specific Substances in the FAIMS Spectra of Complex Mixtures Using Deep Learning.

High-field asymmetric ion mobility spectrometry (FAIMS) spectra of single chemicals are easy to interpret but identifying specific chemicals within complex mixtures is difficult. This paper demonstrates that the FAIMS system can detect specific chemicals in complex mixtures. A homemade FAIMS system is used to analyze pure ethanol, ethyl acetate, acetone, 4-methyl-2-pentanone, butanone, and their mixtures in order to create datasets. An EfficientNetV2 discriminant model was constructed, and a blind test set was used to verify whether the deep-learning model is capable of the required task. The results show that the pre-trained EfficientNetV2 model completed convergence at a learning rate of 0.1 as well as 200 iterations. Specific substances in complex mixtures can be effectively identified using the trained model and the homemade FAIMS system. Accuracies of 100%, 96.7%, and 86.7% are obtained for ethanol, ethyl acetate, and acetone in the blind test set, which are much higher than conventional methods. The deep learning network provides higher accuracy than traditional FAIMS spectral analysis methods. This simplifies the FAIMS spectral analysis process and contributes to further development of FAIMS systems.

Simultaneously improving the resolving power and sensitivity for planar high-field asymmetric waveform ion mobility spectrometry using a mixed gas inlet mode at two ends.

RATIONALE: Resolution and sensitivity are two key parameters for describing the performance of high-field asymmetric waveform ion mobility spectrometry (FAIMS). An increase in the resolving power of FAIMS has been realized by adding helium to nitrogen in planar FAIMS, but it comes at the expense of sensitivity. METHODS: Here, a new hollow needle-to-ring discharge device integrated on a PCB substrate is used as the ion source for FAIMS. Helium flows from the hollow part of the hollow needle to improve the ionization effect. Nitrogen carries the sample into the ionization chamber and is mixed with helium as the carrier gas. RESULTS: Under a nitrogen flow rate of 1 L min-1 , 1.5 L min-1 , 2 L min-1 , and 2.5 L min-1 , adding helium at different flow rates (0.2 L min-1 , 0.3 L min-1 , 0.5 L min-1 , and 1 L min-1 ) can simultaneously improve the separation ability and sensitivity. Helium and nitrogen with flow rates of 0.2, 0.3, 0.5, and 1 L min-1 were added to nitrogen (2 L min-1 ). The separation ability and sensitivity of the mixed gases doped with helium are better than those of nitrogen. The larger the RF voltage amplitude is, the more obvious the improvement in the separation ability when helium is added. However, helium doping has the opposite effect on the sensitivity. CONCLUSIONS: This study provides a new idea and technical means for the application of helium and nitrogen gas mixtures in planar FAIMS. This method can greatly improve the performance of FAIMS.

Helium-assisted enhanced discharge in a hollow needle for high-field asymmetric ion mobility spectrometry (FAIMS).

A carrier gas mixture of nitrogen and helium has been employed to improve the resolving power at the expense of sensitivity for planar high-field asymmetric ion mobility spectrometry (FAIMS) in previous work. In this paper, a new hollow needle-to-ring ion source was developed, where the helium and nitrogen enter from the hollow needle and ring, respectively. It was found that the signal strengths of acetone, ethanol, and ethyl acetate increased by 8.5, 2.0, and 3.3 times for helium ratios of 20%, 20%, and 10%, respectively. At the same time, the absolute value of compensation voltage and the number of ion peaks increases. It shows that adding an appropriate helium ratio to nitrogen simultaneously improved the sensitivity and resolving power of planar FAIMS, which is reported for the first time.

A ratiometric bilirubin sensor based on a fluorescent gold nanocluster film with dual emissions.

Bilirubin originates from hemoglobin metabolism and is an important biomarker for liver function. A ratiometric film sensor based on gold nanoclusters (AuNCs) was fabricated for highly sensitive determination of free bilirubin (fBR). Using bovine serum albumin (BSA) as a template, AuNCs that can emit blue and red fluorescence were prepared by the hydrothermal method at different pH values. Two kinds of AuNCs were incorporated into a single film by the layer-by-layer assembly (LBL) technique. The obtained thin-film showed dual fluorescence peaks excited at 372 nm, corresponding to the blue (443 nm) and red (622 nm) emissions of AuNCs respectively. When fBR interacted with the film, both fluorescence peaks were quenched at different degrees. A ratiometric method for fBR detection was established based on the fluorescence intensity ratio of the two emissions. The linear calibration curve for fBR lay in the concentration range of 0.01-2.00 µmol L-1 with a detection limit of 8.90 ± 0.34 nmol L-1 (S/N = 3). The film sensor showed a quick and sensitive response to fBR and could detect fBR in real samples with satisfactory results.

A Gold Nanoclusters Film Supported on Polydopamine for Fluorescent Sensing of Free Bilirubin.

Serum bilirubin is an important biomarker for the diagnosis of various types of liver diseases and blood disorders. A polydopamine/gold nanoclusters composite film was fabricated for the fluorescent sensing of free bilirubin. Bovine serum albumin (BSA)-stabilized gold nanoclusters (AuNCs) were used as probes for biorecognition. The polydopamine film was utilized as an adhesion layer for immobilization of AuNCs. When the composite film was exposed to free bilirubin, due to the complex that was formed between BSA and free bilirubin, the fluorescence intensity of the composite film was gradually weakened as the bilirubin concentration increased. The fluorescence quenching ratio (F0/F) was linearly proportional to free bilirubin over the concentration range of 0.8~50 µmol/L with a limit of detection of 0.61 ± 0.12 µmol/L (S/N = 3). The response was quick, the film was recyclable, and common ingredients in human serum did not interfere with the detection of free bilirubin.

Interaction Study of Ferrocene Derivatives and Heme by UV-Vis Spectroscopy.

The interaction between ferrocene derivatives, such as Fc(COOH)2(λmax=286 nm), Fc(OBt)2(λmax=305 nm), Fc(Cys)(λmax=289 nm) and heme(λmax=386 nm) were studied by UV-Vis spectroscopy, respectively. The results show that, when the concentration of heme is fixed, the absorbance of heme increases with the increase of Fc(COOH)2 and Fc(Cys) concentration, the absorbance of heme almost keep the same when Fc(OBt)2 concentration increases; when the concentration of ferrocene derivatives are fixed, the absorbance of Fc(COOH)2 and Fc(Cys) also increases with the increase of heme concentration, the absorbance of Fc(OBt)2 almost keep the same when heme concentration increase. It is demonstrated that the hydrogen bonding interactions happen between Fc(COOH)2, Fc(Cys) and heme, none of Fc(OBt)2, the formation of hydrogen bonding lead to the growth of molecular chain, the bigger molecule can absorb more energy and increase the absorbance. Meanwhile, the stability of molecule is affected by the formation of hydrogen bonding, when the reaction time increases from 0.5 h to 18 h and 48 h, the absorbance at λmax=384 nm change from 2.64 to 2.53 and 2.51 with fixed concentration of Fc(COOH)2, the absorbance at λmax=384 nm change from 1.76 to 1.72 and 1.68 with fixed concentration of heme, the absorbance at λmax=397 nm change from 2.74 to 2.63 and 2.55 with fixed concentration of Fc(Cys), and the absorbance at λmax=397 nm change from 1.82 to 1.58 and 1.49 with fixed concentration of heme, respectively.

Aminopyrene functionalized mesoporous silica for the selective determination of resorcinol.

Aminopyrene was convalently anchored onto the surface of mesoporous MCM-41 silica by post-grafting. This organic-inorganic hybrid has been applied as sensing material to phenols determination. Experimental results reveal that the functionalized material presents good sensitivity and selectivity towards resorcinol and can be used for resorcinol determination in water at pH 6.0. The fluorescence intensity of aminopyrene functionalized mesoporous silica decreases proportionally to the logarithm of resorcinol concentration in water. The linear range for resorcinol detection lies in 4.79-163muM with a detection limit of 2.86muM (S/N=3).