MicroRNAs (MiRNAs) are valuable biomarkers for the diagnosis and prognosis of diseases. The development of reliable assays is an urgent pursuit. We herein fabricate a novel electrochemical sensing strategy based on the conformation transitions of DNA nanostructures and click chemistry. Duplex-specific nuclease (DSN)-catalyzed reaction is first used for the disintegration of the DNA triangular pyramid frustum (DNA TPF). A DNA triangle is formed, which in turn assists strain-promoted alkyne-azide cycloaddition (SPAAC) to localize single-stranded DNA probes (P1). After SPAAC ligation, multiple DNA hairpins are spontaneously folded, and the labeled electrochemical species are dragged near the electrode interface. By recording and analyzing the responses, a highly sensitive electrochemical biosensor is established, which exhibits high sensitivity and reproducibility. Clinical applications have been verified with good stability. This sensing strategy relies on the integration of DNA nanostructures and click chemistry, which may inspire further designs for the development of DNA nanotechnology and applications in clinical chemistry.
To compare the pharmacokinetics of levornidazole and ornidazole in healthy Chinese subjects after a single intravenous injection, and to determine whether the chiral inversion of levornidazole occurs in vivo.The study was a randomized, open-label, two-period crossover, single-dose design. A total of 12 subjects were enrolled in this study. Subjects received an intravenous injection of either levornidazole sodium chloride injection (200 mL: 0.5 g) or ornidazole sodium chloride injection (200 mL: 0.5 g) once per period. The plasma concentrations of levornidazole, ornidazole, and their metabolites were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Phenix WinNolin software (version 6.4) was used to calculate the pharmacokinetic parameters of levornidazole, ornidazole, and their metabolites.Dexornidazole was not detected in the plasma or urine. After a single intravenous injection of levornidazole or ornidazole, there was no significant difference in Cmax between the two drugs (p < 0.05). The AUC0-∞ and AUC0-t of levornidazole were slightly lower than those of ornidazole. Metabolites M1 and M4 were detected in the plasma of both drugs, and their pharmacokinetic parameters were similar. Metabolites M1, M2, and M4 were present in urine. The average cumulative urinary excretion rates of levornidazole and its metabolites M1 and M4 were: during 0 - 24 hours (8.14 ± 0.80%, 0.560 ± 0.072%, and 1.42 ± 0.19%) and 0 - 60 hours (10.5 ± 1.0%, 0.960 ± 0.084%, and 2.52 ± 0.20%), the average cumulative urinary excretion rates of ornidazole and its metabolites M1 and M4 were: 0 - 24 hours (8.64 ± 0.98%, 0.486 ± 0.074%, and 1.46 ± 0.21%), 0 - 60 hours (11.8 ± 1.0%, 0.888 ± 0.070%, and 2.76 ± 0.20%). The incidence of adverse reactions was similar between the two drugs.No chiral inversion of levornidazole occurred in vivo after intravenous administration of levornidazole. The pharmacokinetic parameters and cumulative excretion rates of levornidazole and ornidazole were similar. The safety results were basically consistent between the two drugs.
Poly(ethylene oxide) (PEO) adsorption behavior on kaolinite surfaces in aqueous solution was investigated through experiments, the density functional theory (DFT), and molecular dynamics (MD) simulations. The experimental results showed that as the PEO concentration increased, the adsorption capacity first increased then slightly decreased and the turbidity change was opposite. The adsorption isotherm on the kaolinite surface was more suitable for the Langmuir model and valid for single-layer adsorption. The results of simulations showed that the PEO chains extended along the two basal surfaces of kaolinite or were partly adsorbed, forming loops and tails that caused most of the particles to flocculate, contributing to the turbidity lowering. When the number of PEO chains was excessive, their self- and inter-aggregation occured with some PEO far from the surface, and the turbidity increased. On the kaolinite (001) surface, the hydrogen bonds between the PEO ether O and the hydroxyl groups constituted the main interaction mechanism. However, the hydrophobic force of the (CH2–CH2)–moiety of PEO might have dominated its adsorption on the (00 ) surface. The hydrogen bonds were stronger than the hydrophobic interactions.
An SPE cartridge based on an ampholine-functionalized hybrid organic-inorganic silica sorbent has been adopted for the analysis of aromatic amines including 4-aminobiphenyl, benzidine, 2-naphthylamine, p-chloroaniline, 2,4,5-trimethylaniline, and 3,3'-dichlorobenzidine. Crucial variables governing the extraction efficiency of the material such as the pH of sample, sample loading volume, solvent used for elution, and elution volume have been thoroughly optimized. The adsorption capacities for the six aromatic amines ranged from 0.17 to 1.82 μg/mg. The recoveries of aromatic amines spiked in textile samples ranged from 78.9 to 103.0%, with RSDs of 1.1-11.9% (n = 3). Moreover, the extraction efficiency of the ampholine-functionalized hybrid organic-inorganic silica sorbent was at least comparable with that of Oasis WCX.
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