ABSTRACT
Development of a simple, fast, cost-efficient and sensitive approach for accurate protein analysis is of high significance due to its potential application in disease diagnosis and biomedicine research. Thus, we established a label-free fluorescence DNA walker for streptavidin detection based on terminal protection and dual enzyme assisted cleavage induced G-quadruplex/berberine conformation. In this paper, the swing arm probe and report probe were pre-assembled on gold nanoparticles. With the addition of a target, through the high-efficiency affinity between streptavidin and biotin in order to prevent the hydrolysis of exonuclease I, the swing arm probe which contains 8-17 DNAzyme cannot be destroyed and plays a role in the catalytic cleavage of the report probe, and the liberating fragment of the report probe which contains a specific sequence (5'-(TTAGGG)4) of G-quadruplex units can combine with berberine and shows an evident fluorescence signal enhancement. Our method, a sensitive and selective method of protein detection, achieves a 20 pM detection limit toward streptavidin. This developed DNA walker, which combines terminal protection and a dual enzyme assisted strategy, provides a prospective channel for streptavidin detection and should also be used for the design of biosensors in bio-detection and disease diagnosis.
Subject(s)
Berberine/chemistry , DNA Probes/chemistry , DNA, Catalytic/chemistry , G-Quadruplexes , Streptavidin/analysis , Biosensing Techniques/methods , Biotin/chemistry , DNA Probes/genetics , DNA, Catalytic/genetics , Exodeoxyribonucleases/chemistry , Gold/chemistry , Limit of Detection , Metal Nanoparticles/chemistry , Spectrometry, Fluorescence/methods , Streptavidin/chemistryABSTRACT
Herein, we explore a new carbon source for preparation of carbon quantum dots (CQDs) with controllable composition using a porous organic polymer (POP) derived porous carbon via a nitric acid oxidation method. The POP used for the preparation of CQDs was synthesized by mechanochemical Friedel-Crafts alkylation under solvent free conditions. Using the as-prepared CQDs, we develop a simple and effective electrochemiluminescence (ECL) detection method for dopamine (DA) using a CQD/chitosan-graphene composite modified glassy carbon electrode (GCE). Both the electrochemical and ECL behaviors were studied in detail with ammonium persulfate as a coreactant. The complementary structure and synergistic function of the composite give the ECL sensor special properties. Apart from the high stability, it also presents good repeatability and high sensitivity to DA with a wide linear range from 0.06 to 1.6 µM. And a satisfactory detection limit of 0.028 µM (S/N = 3) was achieved for the prepared sensor. Furthermore, the ECL also shows high selectivity toward DA with an excellent interference resistance ability at a high concentration ratio of 100 (C interference : C DA = 100). In addition, the ECL sensor was successfully applied for effective detection and quantitative analysis of the actual dopamine in human body fluids for disease diagnosis and pathological studies.
ABSTRACT
Selenium nanoparticles (SeNPs) have attracted increasing interest over the last decades because of their activities on redox balance in human body. However, the SeNPs tend to aggregate into large clusters, resulting in lower bioactivity, bioavailability and biocompatibility. Surface-capping agents on SeNPs play crucial roles in its stabilization and biological activity. Here, a green synthesis method for the preparation of Lycium barbarum polysaccharides capped SeNPs using green tea extracts as reductants under mild conditions, at room temperature, is reported. The structure, size, morphology and thermal behaviour were analyzed by various characterization techniques. The functionalized nanoparticles demonstrated high antioxidant activity, including DPPH and ABTS free radical scavenging. Moreover, the SeNPs significantly protected the H2O2-induced PC-12 cell death. Taken together, these results evidence the possible application of these SeNPs as antioxidants food supplement or ingredient and neuroprotective agent.
Subject(s)
Antioxidants/chemical synthesis , Antioxidants/pharmacology , Drugs, Chinese Herbal/chemical synthesis , Drugs, Chinese Herbal/pharmacology , Plant Extracts/chemistry , Selenium/chemistry , Tea/chemistry , Animals , Antioxidants/chemistry , Benzothiazoles/chemistry , Biphenyl Compounds/chemistry , Cell Death/drug effects , Chemistry Techniques, Synthetic , Drugs, Chinese Herbal/chemistry , Green Chemistry Technology , Oxidative Stress/drug effects , PC12 Cells , Picrates/chemistry , Rats , Sulfonic Acids/chemistryABSTRACT
In the title compound, [Pb2(C7H4O6S)2(C12H8N2)2(H2O)2]·CH3COOH, the seven-coordinate Pb(II) atom is chelated by two N atoms of one 1,10-phenanthroline ligand, four O atoms from three 5-sulfosalicylate dianions and one water O atom. Each dianion serves as a bridging ligand, connecting adjacent Pb(II) atoms into a centrosymmetric polymeric chain extending parallel to [001]. There are π-π inter-actions between the aromatic systems of neighbouring dianions, with plane-to-plane distances of 3.371â (2)â Å, and between phenanthroline ligands, with a centroid-to-centroid distance of 3.484â (2)â Å. O-Hâ¯O hydrogen bonding additionally stabilizes the crystal packing. The acetic acid mol-ecules are incorporated in the voids of this arrangement. They exhibit half-occupancy due to disorder around a centre of inversion.
