Xing Li

A cost-effective sandwich electrochemiluminescence immunosensor for ultrasensitive detection of HIV-1 antibody using magnetic molecularly imprinted polymers as capture probes

In this report, a rapid and cost-effective sandwich electrochemiluminescence (ECL) immunosensor was constructed for the ultrasensitive detection of human immunodeficiency virus type 1 antibody (anti-HIV-1) using magnetic molecularly imprinted polymers (MMIPs) as capture probes by combining surface and epitope imprinting techniques and antigen conjugated with horseradish peroxidase (HRP-HIV-1) as labels. First, 3-aminobenzeneboronic acid (APBA) was used as the functional monomer and cross-linking reagent, which was polymerized on the surface of silicate-coated magnetic iron oxide nanoparticles (Fe3O4@SiO2 NPs) in the presence of human immunoglobulin G (HIgG), as the template exhibiting the same Fc region but different Fab region to anti-HIV-1 after the addition of the initiator, ammonium persulfate. This process resulted in grafting a hydrophilic molecularly imprinted polymer (MIP) film on the Fe3O4@SiO2 NPs. Thus, MMIPs, which could be reused after eluting the template, were used to recognize and enrich ultra-trace levels of anti-HIV-1. Subsequently, a novel sandwich ECL immunosensor was formed through the immunoreaction between MMIPs conjugated with varied concentrations of anti-HIV-1 and HRP-HIV-1. By the catalysis of HRP immobilized onto HRP-HIV-1 on the ECL system of Luminol-H2O2, a linear response range of the anti-HIV-1 dilution ratio (standard positive serum) was achieved from 1:20,000 to 1:50, with a detection limit of 1:60,000 (S/N=3). The developed method provides a low-cost, simple, and sensitive way for the early diagnosis of HIV infected patients.

A Rapid Colorimetric Sensor of Clenbuterol Based on Cysteamine-Modified Gold Nanoparticles

Demonstrated was a simple visual and rapid colorimetric sensor for detection of clenbuterol (CLB) based on gold nanoparticles (AuNPs) modified with cysteamine (CA) and characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-vis. The solution color from red to blue gray with increasing clenbuterol concentration resulted from the aggregation of AuNPs. The detection limit of clenbuterol is 50 nM by naked eyes. The selectivity of CA-AuNPs detection system for clenbuterol is excellent compared with other interferents in food. This sensor has been successfully applied to detect clenbuterol in real blood sample.

Electrochemiluminescence immunosensor for tumor markers based on biological barcode mode with conductive nanospheres

A novel sandwich-type electrochemiluminescence (ECL) immunosensor was developed for highly sensitive and selective determination of tumor markers based on biological barcode mode. N-(4-aminobutyl)-N-ethylisoluminol (ABEI) and the second antibody (Ab2) were simultaneously immobilized on conductive nanospheres to construct ABEI/Ab2-CNSs probes, which could form sandwich immunocomplex by Ab2 and emit ECL signals by ABEI. The gold layer coated on the surface of the conductive nanospheres could extend the outer Helmholtz plane (OHP) of the ECL immunosensor effectively. Benefited from it, all ABEI molecules immobilized on conductive nanospheres would act as biological barcode to give in-situ ECL signals without interfering with the activity of the second antibody. In such a case, the sensitivity of the ECL immunosensor would be greatly improved because an antigen molecule would correspond to ECL signals of thousands of ABEI molecules. Using prostate specific antigen (PSA) as a model tumor marker, the ECL intensity was found to increase with the logarithm of PSA concentration with a wide linear range from 0.04 to 10 fg/mL. In addition, specificity, stability, reproducibility, regeneration and application were satisfactory. Therefore, this developed ECL immunosensor has a potential for practical detection of disease-related proteins besides tumor markers in the clinical diagnostics.

Shape-controlled growth and single-crystal XRD study of submillimeter-sized single crystals of SnO

Submillimeter-sized single crystals of SnO exhibiting well-defined symmetric shapes of four-armed star and square plate were successfully synthesized through a mild surfactant-free hydrothermal reaction. Crystal structures, refined by single-crystal X-ray diffraction, and Raman scattering investigations performed on an individual SnO single crystal are reported.

Biotemplated Syntheses of Macroporous Materials for Bone Tissue Engineering Scaffolds and Experiments in Vitro and Vivo

The macroporous materials were prepared from the transformation of cuttlebone as biotemplates under hydrothermal reactions and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric/differential thermal analyses (TG-DTA), and scanning electron microscopy (SEM). Cell experimental results showed that the prepared materials as bone tissue engineering scaffolds or fillers had fine biocompatibility suitable for adhesion and proliferation of the hMSCs (human marrow mesenchymal stem cells). Histological analyses were carried out by implanting the scaffolds into a rabbit femur, where the bioresorption, degradation, and biological activity of the scaffolds were observed in the animal body. The prepared scaffolds kept the original three-dimensional frameworks with the ordered porous structures, which made for blood circulation, nutrition supply, and the cells implantation. The biotemplated syntheses could provide a new effective approach to prepare the bone tissue engineering scaffold materials.

Pd- and Ni-Pyridyl Complexes Deposited as Films for Suzuki–Miyaura and Mizoroki–Heck Cross Coupling Reactions

Abstract A pyridyl fluorene ligand, 2,7-bis(4-pyridyl)-9,9-diethylfluorene (1), has been synthesized by a simple route. The ability of the two linearly terminal pyridyl nitrogen atoms of 1 to coordinate with the Pd(II) or Ni(II) ions has enabled the use of 1 as a linking ligand in the preparation of (PdCl2/1)n, (Ni(NO3)2/1)n films, PdCl2/1 and Ni(NO3)2/1 complex. The resulting films and complexes were characterized by UV–vis spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectrometer. The application of films and complexes as catalysts for Suzuki–Miyaura and Mizoroki–Heck reactions was carried out. (PdCl2/1)n films show high catalytic activity in the reactions with the Pd loading of ppm. (Ni(NO3)2/1)n multilayers as the active catalytic moieties for these reactions were investigated with very low Ni(II)-loading.Graphical AbstractThe (Pd or Ni/1)n multilayer films were used as high active catalysts for the C-C formation with extremely low M(II)-loading in ppm level.

Synthesis, photoluminescence, catalysis and multilayer film assembly of an ethynylpyridine platinum compound

An alkynyl platinum(II) compound of [Pt(CCPy)2(dppe)] (1) was prepared by reaction of [PtCl2(dppe)] and 4-ethynylpyridine hydrochloride in the presence of base and CuI (dppe = 1,2-bis(diphenylphosphino)ethane). Single crystal X-ray diffraction analysis reveals that compound 1 crystallizes in a monoclinic system and Cc space group with a = 17.8507(7), b = 21.4219(7), c = 9.0526(5) A, β = 108.98(2)°. Thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), UV-vis spectra, photoluminescence, and catalysis properties of 1 are discussed. The multilayer films formed with ruthenium trichloride by a layer-by-layer self-assembly method were characterized by UV-vis spectra, atomic force microscopy (AFM) images and cyclic voltammograms (CV).

Amplified spontaneous emission from 2,7-bis(4-pyridyl)fluorene-doped DNA- cetyltrimethyl ammonium complex films

Abstract. The 2,7-bis(4-pyridyl)fluorene (BPF) was synthesized via a Suzuki coupling reaction. The optical spectra properties of BPF and BPF-deoxyribonucleic acid (DNA)-cetyltrimethyl ammonium (CTMA) thin films composed of BPF, DNA, and CTMA were characterized by the measurements of UV/Vis absorption spectra and fluorescence spectra. The amplified spontaneous emission (ASE) of the BPF-DNA-CTMA films was researched experimentally by pumping of a pulse laser with a wavelength of 355 nm. The results show that the absorption peak and the fluorescence peak of BPF are located at 327 and 380 nm, respectively. The emission peak of BPF corresponds to the vibronic transitions from an excited state of S1 level to the ground state of S0 level. The ASE peak of the BPF-DNA-CTMA film is located at 384 nm, and the threshold of ASE excited energy density is 3.12  mJ·cm−2.

catena-Poly[cadmium-bis-(μ-N,N-dimethyl-dithio-carbamato-κS,S':S)].

In the title compound, [Cd(C3H6NS2)2]n, the CdII atom, lying on a twofold rotation axis, is coordinated by six S atoms from four different N,N-dimethyldithiocarbamate ligands in a distorted octahedral geometry. The bridging of S atoms of the ligands leads to the formation of a one-dimensional structure along [001].

Detection of herbicide glyphosates based on an anti-aggregation mechanism by using unmodified gold nanoparticles in the presence of Pb2+

In this study, a new detection method for glyphosate (GPS) based on an anti-aggregation mechanism by using gold nanoparticles (AuNPs) is proposed. A certain amount of Pb2+ can cause the aggregation of AuNPs because of electrostatic interactions and the color of the solution changed from red to gray. However, in the presence of GPS, the above-mentioned process can be strongly hindered due to the chelation between GPS and Pb2+. Based on this anti-aggregation mechanism, the colorimetric detection method exhibits excellent sensitivity for GPS. The limit of detection (LOD) is 0.5 μM by the naked eye and 2.38 nM by UV-vis spectroscopy. The selectivity of the AuNP detection system for GPS is excellent compared with other pesticides. A good linear relationship (R2 = 0.99695) between the absorption intensity ratio and GPS concentrations indicates that our probe can be used for the quantitative assay of GPS. The detection method has been successfully used for detecting GPS in real environmental samples.