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[en] Highlights: • First principles is employed to study the structure of K2B12H12. • Predict the thermodynamic reversible hydrogen reactions in the KBH4/M(M = Li, Na, Ca)(BH4)n(n = 1,2) system. • Predict two new hydrogen storage reactions involving KBH4 for on-board hydrogen storage. - Abstract: Potassium borohydrides [KBH4] is an attractive candidate for on-board storage because it contains high densities of hydrogen by weight and volume. Using a set of recently developed theoretical first-principles methods, we predict hydrogen storage reactions in the K-M(Li, Na, Ca)-B-H system. Hydrogen release from KBH4 is predicted to proceed via intermediate K2B12H12 phase. In the present study, we predict two new hydrogen storage reactions that are some of the most attractive among the presently known ones. They are predicted to have thermodynamics for hydrogen release within the target window for on-board storage being actively considered for hydrogen storage applications
[en] Development of simple but sensitive biosensor for influenza detection is highly important in immediate and effective clinical treatment. In this study, a sensitive colorimetric immunosensor which combines the advantages of high selectivity of immunoassay and simplicity of colorimetric detection has been developed to detect influenza virus H5N1 based on enzyme-encapsulated liposome. Biotin-tagged liposome encapsulated with large amount of horseradish peroxidase (HRP) was firstly synthesized. In the presence of H5N1, H5N1 co-bound with the capture antibody and the biotinylated detection antibody to form sandwich immunocomplex. Subsequently, the HRP-encapsulated liposome was introduced to conjugate with the detection antibody through biotin-avidin-biotin linkage. Upon the addition of substrate (mixture of 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2), the liposome was directly lysed to release large amount of HRP by TMB. The released HRP catalyzed the H2O2-mediated oxidation of TMB, resulting in color change of the system, which was observed by naked eyes or UV–vis spectra. The result showed that the absorption intensity enhanced with the increase of H5N1 concentration ranging from 0.1 to 4.0 ng/mL, and the detection limit was calculated to be 0.04 ng/mL. The sensitivity of the proposed biosensor is much higher than that of conventional enzyme-linked immunosorbent assay method. The proposed immunosensor is relatively simple, low-cost, sensitive, and selective without using any sophisticated instruments, therefore it may have a promising prospect for detecting targets in clinical medicine, food safety analysis, and environmental monitoring. - Highlights: • We have proposed a simple but sensitive colorimetric immunosensor for influenza detection. • The biosensor combines the advantages of high selectivity of immunoassay and simplicity of colorimetric detection. • The sensitivity of the biosensor is much higher than that of conventional ELISA method. • Such immunosensor has been successfully demonstrated its practical application for the detection of H5N1 in human serum.
[en] Alkaline phosphatase (ALP) plays an important role in phosphate metabolism processes; deviation from its normal level may indicate different kinds of diseases, so it is highly necessary to develop some simple and sensitive methods to monitor the ALP level. In this study, a simple, high selective, and sensitive fluorescent biosensor has been proposed for ALP activity determination. The Cu(II)-dependent DNAzyme (Cu-Enzyme) are divided into two parts: Cu-Enzyme 1 and Cu-Enzyme 2, and labelled with alkyne and azido groups, respectively. The Cu-substrate (Cu-Sub) is labelled with a FAM fluorophore (6-carboxyfluorescein) at the 3′-end and an additional quencher (BHQ1) at the 5′-end. The 5′-end of Cu-Enzyme 1 is labelled with BHQ1 as well. The hybridization of the Cu-Enzyme 1 and Cu-Enzyme 2 with Cu-Sub strand results in the low background fluorescence signal because the fluorescence from FAM is quenched. The addition of ALP can hydrolyze AA-P into AA, which can reduce Cu(II) into Cu(I) and in turn catalyze the cycloaddition of Cu-Enzyme 1 and Cu-Enzyme 2 to form a modified Cu-Enzyme. Then the modified Cu-Enzyme catalyzes the cleavage of the Cu-Sub strands into two pieces. One piece containing FAM fluorophore can easily diffuse into solution and give off a strong fluorescence signal. The enhanced fluorescent intensity has a linear relationship with the ALP concentration in the range of 0.36–54.55 U L"−"1 with the detection limit of 0.14 U L"−"1 (S/N = 3). The proposed biosensor has been successfully applied to detect ALP in serum samples with satisfied results. - Highlights: • We have proposed a simple, high selective and sensitive fluorescent biosensor for ALP. • The biosensor combines the high selectivity and the click reaction and the high sensitivity of the fluorescence detection. • The biosensor has been successfully applied to detect ALP in serum samples with satisfied results.
[en] Highlights: • A simple, low-cost, and sensitive liposome-based colorimetric aptasensor has been developed to detect OTA. • The strategy combines advantages of the signal amplification of liposome and the high specificity and low cost of aptamer. • The signal amplification via HRP-encapsulated lipsomes can be achieved in one step without additional surfactant. • The proposed colorimetric aptasensor has been applied to detect OTA concentration in corn samples with satisfied result. - Abstract: A simple, low-cost, and sensitive liposome-based colorimetric aptasensor has been developed to detect ochratoxin A (OTA). Specifically, a dumbbell-shaped probe was designed, including magnetic beads (MBs), double-stranded DNA (dsDNA), and enzyme-encapsulated liposome. The dsDNA formed by the hybridization between OTA aptamer and its complementary probe. And the dsDNA was used to contact the MBs and the enzyme-encapsulated liposome. In the presence of OTA, the aptamer preferred to combine with OTA to form G-quadruplex, resulting in the release of the detection probe and the enzyme-encapsulated liposome. Each liposome contained a large amount of HRP. Thus, when the liposome was lysed by adding the mixed solution of 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2, a large number of HRP were released. HRP could catalyze the H2O2-mediated oxidation of TMB and hence resulted in the color change from colorless to blue with the OTA concentration varying, and this variation can be observed by naked eyes easily. The result showed that the absorption intensity at 652 nm enhanced with the increase of OTA concentration ranging from 0.05 to 2.0 ng mL−1, and the limit of detection was calculated to be 0.023 ng mL−1 (S/N = 3). The developed colorimetric aptasensor has been applied to detect OTA concentration in corn samples with satisfied results.
[en] Highlights: → LNA-modified oligonucleotides can pass through the plasma membrane of cultured cells even without using transfection machinery. → LNA-modified oligonucleotides passed efficiently across the cell membrane, and lipid-coating facilitated translocation from the cytoplasm to the nucleus. → LNA-oligonucleotide designed to target nuclear HBV DNA efficiently suppresses HBV replication and transcription in cultured hepatic cells. -- Abstract: Silencing target genes with small regulatory RNAs is widely used to investigate gene function and therapeutic drug development. Recently, triplex-based approaches have provided another attractive means to achieve targeted gene regulation and gene manipulation at the molecular and cellular levels. Nuclear entry of oligonucleotides and enhancement of their affinity to the DNA targets are key points of such approaches. In this study, we developed lipid-based transport of a locked-nucleic-acid (LNA)-modified oligonucleotide for hepatitis B virus (HBV) DNA interference in human hepatocytes expressing HBV genomic DNA. In these cells, the LNA-modified oligonucleotides passed efficiently across the cell membrane, and lipid-coating facilitated translocation from the cytoplasm to the nucleus. The oligonucleotide specifically targeting HBV DNA clearly interfered with HBV DNA transcription as shown by a block in pregenomic RNA (pgRNA) production. The HBV DNA-targeted oligonucleotide suppressed HBV DNA replication and HBV protein production more efficiently than small interfering RNAs directed to the pgRNA. These results demonstrate that fusion with lipid can carry LNA-modified oligonucleotides to the nucleus where they regulate gene expression. Interfering with HBV DNA transcription by LNA-modified oligonucleotides has strong potential as a new strategy for HBV inhibition.