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Li R.,CAS Beijing National Laboratory for Molecular | Li R.,Key Laboratory of Molecular Nanostructure and Nanotechnology | Jiang Q.,CAS Beijing National Laboratory for Molecular | Jiang Q.,Key Laboratory of Analytical Chemistry for Living Biosystems | And 15 more authors.
Analyst | Year: 2014

Direct selective determination of free heme in the cerebral system is of great significance due to the crucial roles of free heme in physiological and pathological processes. In this work, a G-quadruplex DNAzymes-induced highly sensitive and selective colorimetric sensing of free heme in rat brain is established. Initially, the conformation of an 18-base G-rich DNA sequence, PS2.M (5′-GTGGGTAGGGCGGGTTGG-3′), in the presence of K+, changes from a random coil to a "parallel" G-quadruplex structure, which can bind free heme in the cerebral system with high affinity through π-π stacking. The resulted heme/G-quadruplex complex exhibits high peroxidase-like activity, which can be used to catalyze the oxidation of colorless ABTS2- to green ABTS- by H2O 2. The concentration of heme can be evaluated by the naked eye and determined by UV-vis spectroscopy. The signal output showed a linear relationship for heme within the concentration range from 1 to 120 nM with a detection limit of 0.637 nM. The assay demonstrated here was highly selective and free from the interference of physiologically important species such as dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), ascorbate acid (AA), cysteine, uric acid (UA), glucose and lactate in the cerebral system. The basal dialysate level of free heme in the microdialysate from the striatum of adult male Sprague-Dawley rats was determined to be 32.8 ± 19.5 nM (n = 3). The analytic protocol possesses many advantages, including theoretical simplicity, low-cost technical and instrumental demands, and responsible detection of heme in rat brain microdialysate. © 2014 the Partner Organisations.

Wang H.Y.,Shanxi Datong University | Li J.J.,Dongzhimen Hospital Affiliated | Cao X.N.,Beijing Sport University | Xu J.Y.,Key Laboratory of Analytical Chemistry for Living Biosystems | And 2 more authors.
Chinese Chemical Letters | Year: 2012

A surface plasmon resonance (SPR) method was presented to discriminate hemodialyzed T-lymphocytes from the normal based on antibody-cell recognition. By dynamic reaction with fixed anti-human CD4 antibody, SPR could offer significant signals to distinguish hemodialyzed patients from the healthy controls within 200 s after the cell injection in respect of either rising speed or maximum binding capacity (p < 0.01). The ratio method is also used to exclude the non-specific adsorption. The percentage of hemodialyzed patients' CD4+ T cells against the healthy control is 69 ± 18%. The most attractive of the present method is its ability to detect the intact and label-free lymphocytes, and further to detect the subpopulations, or proteins secreted by the desired lymphocytes subset. © 2012 Yi Chen. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

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