Inorganic layered materials with the open structure of low dimension and good biological compatibility and stability are considered as one of the most promising materials for immobilizing biomolecules, which can not only adjust the spacing of layers according to guest molecular size to prevent leakage of guest molecule, but also reduce the effects of surrounding elements on immobilized molecules significantly. Moreover, they can promote electron transfer between enzyme and the electrode. Therefore, the inorganic layered materials have great application potential in electrochemical sensors. This paper reviews the ways of immobilizing guest molecules of inorganic layered materials and the applications and development prospects of the different types of inorganic layered materials including cationic, anionic and nonionic inorganic layered materials in electrochemical sensor.

Fluorescent technology is widely used in many fields due to its high sensitivity. However, the direct quantification of one target analyte in complex system is still difficult to be achieved when using the traditional fluorescent method without any pretreatment separation procedure. This is due to the fact that serious overlapping of fluorescence spectra often occurs, mainly originating from natural interferences in complex sample backgrounds, or the interferents with similar structures to a target analyte, particularly in the simultaneous analysis of multi-components samples. The rapid development of modern analytical instruments and three-way data collection techniques has led to a resurgence of interest in the development of chemomet-rics-based analytical strategies, which might light a new avenue to simple experimentation using“mathematical separation” as a replacement or enhancement of“physical or chemical separation” of uncalibrated background or interferents. These methods can offer a highly attractive property, called“second-order advantage”, which allows for the direct and rapid determination of a single target component or simultaneous determination of multiple target components in complex samples, even in the presence of uncalibrated interferences. The property has been a hotspot in the current chemometric domain, and was successfully employed for many applications, such as pharmaceuticals, biological, food, environmental analysis and so on.

A novel method was proposed for the quantification of nitrite ion in aqueous samples by the combination of an advanced quantitative fluorescence model with ratiometric fluorescence indicator 2 , 3-diaminonaphthalene . The proposed method was tentatively applied to direct quantitative determination of nitrite ion in turbid environmental water samples containing both scatterers and absorbers; and its performance was thoroughly investigated and evaluated. Experimental results showed that the proposed method could realize accurate quantitative determination of nitrite ion in environmental water samples with recovery rates in the range of 90. 8%-103. 0%, which were comparable to the corresponding values of HPLC-DAD experiments. The limit of detection and limit of quantification of the proposed method were estimated to be 1 . 9 and 5. 8 nmo/L, respectively.

Based on the competition reaction of target protein, aptamer probe, padlock probe and complementary sequence, a highly sensitive fluorescent aptasensor was developed in this study in combination with rolling circle amplification. In the absence of target protein, the ligation-rolling circle amplification reaction was repressed because the complementary sequence hybridized with aptamer probe to form double-stranded duplex. While in the presence of target protein, the target molecules bound specifically with aptamer probe, inducing displacement of the complementary sequence and hybridization with padlock probe. The padlock probe was circularized with the assistance of E. coli DNA ligase, and the rolling circle amplification process could be accomplished by Phi 29 DNA polymerase. The amplification product contained thousands of repeated sequences which could hybridize with the loop of molecular beacon ( the detection probes) , resulting in a significant fluorescence signal. The effects of length of complementary DNA ( CDNA ) sequence and concentration of padlock probe were investigated. Under the optimized experimental conditions, the model target protein thrombin could be highly sensitively detected by the proposed aptasensing system in a linear range of 0 . 067-32 . 4 nmol/L with a detection limit of 0 . 03 nmol/L ( approximately 90 amol target molecules). Moreover, the presented sensing method was universal for other target analysis by skillfully design of the sequence of aptamer probe and related oligonucleotides.

Whennearinfraredspectroscopyisappliedtoon-linemonitoringandcontroloftobaccoflavors,the variation in temperature can severely deteriorate the predictive performance of near infrared spectroscopic calibration models and results in a significant increases of the root mean square error value for the main constituents in syrup samples from 2. 4% to 29. 0%. In this paper, near infrared spectroscopy has been incorporated with an advanced calibration transfer method-loading space standardization to effectively eliminate the deteriorate effects of temperature variation on quantitative results and finally realize the fast and accurate on-line quantitative monitoring and control of tobacco flavors. The root mean square error value for the main constituents in syrup samples is successfully retained at a satisfying low level of 3 . 8%. The results of this paper will provide technical support for the preparation, preservation and use of tobacco flavors, and realize on-line process quality control of cigarettes.

A novel and highly sensitive voltammetric enzyme-linked immunosensor was developed based on tyramine) oxidation deposition. It was shown that gold nano-particles(colloid Au) could be used as a platform to immobilize antibodies by adsorption. By a sandwich immunossary format with goat-anti-human IgG labled Horseradish peroxidase(HRP) as the second antibody and catalytic amplification by biotin-tyramine, the immunosensor′s) catalytic ability to hydrogen peroxide increased nearly 20 times), the sensor exhibitd a linear response to human IgG in the concentration range from 1.5 μg/L-22 mg/L, and the detection limit was 0.1 μg/L), the regression equation could be expressed as Δi_p(μA) =2.8859c(mg/L)+17.152 with a correlation) coefficient of 0.9872. The immunosensor can be used to quantitatively determine hIgG in the sample) of human serum).

A novel simple,sensitive fluorescence immunosensing method based on aptamer-plasmid complex amplification was developed. This method utilized the specific recognition between antibody and antigen as well as aptamer-plasmid complex and the intercalation of fluorescence dye SYBR Green Ⅰ in the groove of duplex plasmid DNA in detection of Platelet-Derived Growth Factor BB (PDGF-BB). The immunoassay was performed in the microtiter wells in which rabbit anti PDGF-BB antibody was immobilized. The PDGF BB analyte was captured by the primary antibody and then sandwiched by the aptamer-plasmid DNA complex. The introduction of fluorescence dye SYBR Green Ⅰ allows for the detection of the sandwiched immunocomplex of antibody/anigen/aptamer-plasmid complex. Under the optimized conditions of salt concentration,ratio of aptamer to PUC19,and SYBR Green Ⅰ concentration,the proposed method offers a linear detection range from 0.2 μg/L to 200 μg/L with a detection limit of 0.1μg/L.

The effectiveness of traditional Chinese medicine (TCM) against various diseases urges more low cost,speed and sensitive analytical methods for investigating the phamacology of TCM and providing a theoretical basis for clinical use.The potential of second-order calibration method was validated for the quantification of two effective ingredients of Schisandra chinensis in human plasma using spectrofluorimetry.The results obtained in the present study demonstrate the advantages of this strategy for multi-target determination in complex matrices.Although the spectra of the analytes are similar and a large number of interferences also exist,second-order calibration method could predict the accurate concentrations together with reasonable resolution of spectral profiles for analytes of interest owing to its ‘second-order advantage'.Moreover,the method presented in this work allows one to simply experimental procedure as well as reduces the use of harmful chemical solvents.

Objective:To investigate the association between solid fuel use for heating, smoking, and respiratory diseases.Methods:This study is based on the Qingdao project of the China Kadoorie Biobank. After screening, 26 165 individuals were included in the study. We employed Cox proportional hazards regression models, stratified by risk age (in 5-year intervals) and sex while adjusting for confounding variables such as occupation and physical activity level to analyze the association between solid fuel use for heating, smoking, and increased risk of respiratory diseases.Results:Among the 26 165 participants, the average age of those using solid fuel for heating was (52.57±10.31) years, with females constituting 58.04% and former/current smokers accounting for 65.38%. The results indicated that both the solid fuel group and the former/current smoking group had a higher risk of respiratory diseases, with hazard ratios ( HR) (95% CI) of 1.21 (1.04-1.41) and 1.41 (1.16-1.71), respectively. For the duration of solid fuel use, the HR (95% CI) for 20 years or more, it was 1.27 (1.07-1.51). The multiplicative interaction term between solid fuel use and smoking was statistically significant. Conclusions:The use of solid fuel for heating and smoking significantly increases the risk of respiratory diseases, and there may be a multiplicative interaction between solid fuel use and smoking.

Objective:To analyze the association between waist circumference (WC) and ischemic stroke (IS).Methods:The data for the present study were from the prospective cohort study of China Kadoorie Biobank in Qingdao. Using baseline information and IS events of the participants, the Cox proportional hazard regression model and restricted cubic spline (RCS) were used to analyze the association between WC and IS.Results:A total of 33 355 participants were included in the study, with 302 008.88 person-years of follow-up. A total of 1 093 new cases of IS were observed. Multivariate Cox proportional hazard regression model analysis showed that compared to the respondents with normal WC (male <85.0 cm, female <80.0 cm), respondents with excessive WC (male ≥85.0 cm, female ≥80.0 cm) had a 78% higher risk of IS incidence [hazard ratio( HR)=1.78, 95% CI: 1.51-2.10], and the risk increased by 72% ( HR=1.72, 95% CI: 1.40-2.12) and 83% ( HR=1.83, 95% CI: 1.40-2.39) in men and women. According to the RCS, the increase in WC and the risk of IS showed an "S" trend of nonlinear dose-response relationship. Conclusions:The risk of IS would increase with the WC. Keeping a normal WC is important for preventing IS.