An electrochemical aptasensor for the milk allergen ß-lactoglobulin detection based on a target-induced nicking site reconstruction strategy.

Food allergy is an immune system reaction to a particular food, milk being the most common one. ß-Lactoglobulin (ß-Lg) is the main ingredient of milk protein and the main cause of infant milk allergy. On such an occasion, the determination of ß-Lg is very important and the electrochemical sensors are a good alternative for this purpose since they are sensitive, selective and inexpensive. In this work, an electrochemical aptasensor was fabricated for the quantitative detection of ß-Lg in hypoallergenic formula (HF) milk. A tri-functional hairpin (HP) was designed, which was composed of an aptamer sequence, a nicking site and a DNA sequence (T1). In the absence of ß-Lg, the aptamer part hybridized with T1 to form a stable stem-loop structure. However, in the presence of ß-Lg, the capture of the aptamer sequence towards ß-Lg caused the reconstruction of HP and thus the nicking sites were exposed. Then, the nicking enzyme was activated and T1 could be released, which bound with the end of the hairpin 1-methylene blue (HP1-MB)/HP2-MB conjugation on the Au nanoparticle (AuNP) modified electrode surface. Thus, the insulating property of the electrode was enhanced and the current response of MB decreased, which built the quantitative basis for ß-Lg detection. In this way, the proposed aptasensor exhibited a wide linear range of 0.01-100 ng mL-1 and a low detection limit of 5.7 pg mL-1. This aptasensor also displayed high selectivity, reproducibility and stability, and became a promising platform for ß-Lg detection in real food samples.

Effect of assembling errors on the diffraction efficiency for multilayer diffractive optical elements.

Based on the expression function of diffraction efficiency, and the phase delay function of diffractive optical elements (DOEs), the diffraction efficiency for multilayer diffractive optical elements (MLDOEs) is described with tilt and decenter assembling errors. A mathematical model of the relationship between diffraction efficiency and assembling errors of MLDOEs is proposed to analyze the effect of assembling errors on the diffraction efficiency of MLDOEs. The analyzed results from the mathematical model provide a range of values for the effect of assembling errors on the diffraction efficiency of MLDOEs. Assembling errors are important parameters for hybrid diffractive refractive optical systems, including MLDOEs, and so the proposed model will be useful for guiding the design and fabrication of such optical systems.

Cognitive behavioral therapy may rehabilitate abnormally functional communication pattern among the triple-network in major depressive disorder: A follow-up study.

BACKGROUND: Cognitive behavioral therapy (CBT) is an established treatment for Major Depressive Disorder (MDD). MDD is characterized by imbalanced communication patterns among three networks: the central executive network (CEN), the default mode network (DMN) and the salience network (SN). The effect of CBT in restoring communications among these networks in MDD is unknown. METHODS: Thirty-three patients with MDD and 27 healthy controls (HC) participated in the study. Patients were treated with CBT. Resting-state functional magnetic resonance imaging (rs-fMRI) data were obtained in patients at three stages (T0: before treatment; T1: after 6 weeks CBT; T2: after 28 weeks CBT) and in HC (only T0). Both independent component analysis (ICA) and granger causality analysis (GCA) were used to explore dynamic causal communication patterns among the three networks (CEN, DMN, SN) over a course of CBT treatment. RESULTS: In the HC group, the SN had an inhibitory causal effect on CEN; the CEN and DMN had an excitatory causal effect on the SN. The SN had an inhibitory causal effect on the CEN and the DMN; only the DMN had an excitatory causal effect on the SN in the MDD patients at the T0 stage. As the CBT treatment went on for MDD patients, the CEN restored excitatory causal effect on the SN, and the SN lost inhibitory effect on the DMN. This result mimicked the one found in the HC group. Four regions, left ventromedial prefrontal cortex (lvmPFC), posterior cingulate gyrus (PCC), right inferior parietal lobule (rIPL) and right insula, were implicated in mediating network communications. LIMITATIONS: The findings should be considered preliminary given the small sample sizes, and assessed only one stage in HC subjects. CONCLUSION: CBT may enhance the regulatory function of the SN, and rehabilitate the imbalanced brain network communication mode in the MDD. PCC, lvmPFC and rIPL may all be potential targets of CBT.

A novel electrochemical immunosensor for hepatitis B surface antigen based on Fe3O4 nanoflowers and heterogeneous chain reaction signal amplification strategy.

Herein, a novel sandwich-type electrochemical immunosensor was fabricated based on Fe3O4 nanoflowers (Fe3O4 NFs) and heterogeneous chain reaction (HCR) signal amplification strategy for the sensitive detection of hepatitis B surface antigen (HBsAg). The aldehyde-functionalized Fe3O4 NFs are used as a supporting matrix to immobilize the hepatitis B surface antibody 1 (HBsAb1). The biotin-modified single-strand DNA (biotin-S0) was connected onto the biotin-HBsAb2 via linkage of streptavidin (SA), followed by addition of methylene blue (MB) modified single strand DNA1 (MB-S1) and DNA2 (MB-S2) for HCR signal amplification. The designed immunosensor exhibited a detection linear range of 0.5 pg mL-1-0.25 ng mL-1 and a low detection limit of 0.16 pg mL-1, with excellent stability, selectivity and reproducibility. Furthermore, HBsAg is detected in the serum samples with a stable and fast response, indicating that the proposed immunosensor has a promising potential application in clinical analysis.

Cu-based metal-organic framework HKUST-1 as effective catalyst for highly sensitive determination of ascorbic acid.

In this work, a Cu-based nanosheet metal-organic framework (MOF), HKUST-1, was synthesised using a solvent method at room temperature. Its morphology, structure and composition were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, nitrogen adsorption and desorption isotherms, energy dispersive X-ray spectroscopy (EDS) and elemental analysis (EA). This material was then loaded onto the surface of an indium tin oxide (ITO) electrode to catalyse the electrochemical oxidation of ascorbic acid (AA). An equal-electron-equal-proton reaction was deduced from the pH investigation, and a diffusion-controlled process was reinforced by the dynamics study. Under optimal conditions, the oxidation peak current at +0.02 V displayed a linear relationship with the concentration of AA within the ranges of 0.01-25 and 25-265 mM, respectively. The limit of detection (LOD) was 3 µM at S/N of 3. The superb response could be ascribed to the porous nanosheet structure of HKUST-1, which enhanced both the effective surface area and the electron transfer ability significantly. Moreover, the novel AA sensor demonstrated good reproducibility, favourable stability and high sensitivity towards glucose, uric acid (UA), dopamine (DA) and several amino acids. It was also successfully applied to the real sample testing of various AA-containing tablets.