Fluorescence-based immunoassay for human chorionic gonadotropin based on polyfluorene-coated silica nanoparticles and polyaniline-coated Fe3O4 nanoparticles

We report on an ultrasensitive fluorescence immunoassay for human chorionic gonadotrophin antigen (hCG). It is based on the use of silica nanoparticles coated with a copolymer (prepared from a fluorene, a phenylenediamine, and divinylbenzene; PF@SiO₂) that acts as a fluorescent label for the secondary monoclonal antibody to β-hCG antigen. In parallel, Fe₃O₄ nanoparticles were coated with polyaniline, and these magnetic particles (Fe₃O₄@PANI) served as a solid support for the primary monoclonal antibody to β-hCG antigen. The PF@SiO₂ exhibited strong fluorescence and good dispersibility in water. A fluorescence sandwich immunoassay was developed that enables hCG concentrations to be determined in the 0.01–100 ng·mL^?1 concentration range, with a detection limit of 3 pg·mL^?1.

A glassy carbon electrode modified with poly(eriochrome black T) for sensitive determination of adenine and guanine

A thin film of poly(eriochrome black T) was deposited on the surface of glassy carbon electrode by cyclic voltammetry, and this system is shown to enable the sensitive determination of adenine (A) and guanine (G). Scanning electron microscopy, Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy were carried out to characterize the film which exhibits excellent electrocatalytic activity toward the oxidation of A and G in 0.1 M phosphate buffer solution (pH 4.0). Square wave voltammetry reveals an oxidation peak at 1084 mV whose current is linearly related to the concentration of A in the range from 0.05 to 1.00 μM. The oxidation peak for G occurs at 788 mV, and its current is linearly related to the concentration of G in the range from 0.025 to 1.00 μM. The detection limits are 0.017 μM for A and 0.008 μM for G (at S/N?=?3), respectively. The modified electrode displays good reproducibility and selectivity for the determination of A and G. The sensor was applied to quantify A and G in fish sperm DNA with satisfactory results.

Gold-nanoparticle on the surface of L-cysteine modified gold electrode and its application

A sensor based on gold nanoparticle on the surface of L-cysteine modified gold electrode is prepared. Electrochemical behavior of dopamine hydrochloride is investigated. The linear relation between peak current of dopamine hydrochloride and scan speed in the range of 10 to 1000 mV s^?1 indicates that a diffusion-adsorption controls the process. The linearity range is 1.05 × 10^?5–7.38 × 10^?4 M with detection limit of 1.05 × 10^?6 M. The recoveries were in the range from 99.8 to 101.5% with relative standard deviations of 1.3 ～ 2.3% (n = 6). The modified electrode under ambient conditions over a period of 2 weeks has an excellent repeatability and reproducibility.     

Microbial desulfurization of waste latex rubber with Alicyclobacillus sp.

A microbe with desulfurizing capability, Alicyclobacillus sp., was selected to recycle waste latex rubber (WLR). The growth characteristics of the microorganism and the technical conditions in the co-culture desulfurization process were studied. The desulfurization effect of Alicyclobacillus sp. on the WLR was characterized, and the mechanism for the microbial desulfurization of WLR was tentatively explored. The results showed that adding 5% (w/v) WLR into medium had little effect on the growth of Alicyclobacillus sp. The surfactant polysorbate 80 (Tween 80) had a toxic effect on Alicyclobacillus sp., but the growth of the microbe was vigorous if the proper technique was used: the mixing of WLR with Tween 80, followed by the addition of the mixture into the culture media. With the increase of desulfurization time, the swelling value of desulfurizated waste latex rubber (DWLR) increased, but the crosslink density decreased. After co-culture desulfurization for 8–10 days, a DWLR with good desulfurization effect was obtained. The mechanical properties of natural rubber (NR)/DWLR composite improved significantly over those of NR/WLR composite. XPS and FTIR results revealed that Alicyclobacillus sp. could break the crosslinked sulfur bonds and oxidize them to sulfones groups. The increase of O element content on the surface of DWLR was confirmed by water contact angle measurements. The relationship between the crosslink density and sol fraction of DWLR with different desulfurization times agreed with the Horikx equation, an indication that the microorganisms could break the crosslinked sulfur bonds on the surface of WLR, but leaving the main chains intact.     

分子模拟在二氧化碳转化研究中的应用

本文介绍了国内外近年来运用分子模拟技术辅助CO2转化研究的部分工作,主要包括CO2分子在金属原子、团簇、金属表面上的吸附活化以及CO2催化转化的反应路径分析等。分子模拟作为一种有效的分子水平认识工具将在CO2的俘获、封存、利用和储存(CCUS)研究领域中发挥着越来越重要的作用。     

Zethrene and Dibenzozethrene: Masked Biradical Molecules?

The syntheses, structures, and physical properties of dibenzozethrenes were explored. The results thus obtained were compared with those for zethrenes. Dibenzozethrenes were synthesized by the nickel‐catalyzed cyclodimerization of 9‐ethynyl‐1‐iodoanthracenes. The substituents in zethrene and dibenzozethrene twisted their backbones, and remarkably influenced their properties. Unlike closed‐shell disubstituted derivatives, the parent zethrene and dibenzozethrene are singlet open‐shell biradicals, which were studied by variable‐temperature ¹H NMR, ESR, SQUID and computational methods. Since substituents were observed to affect significantly the biradical properties, the relevant mechanisms were analyzed. The nonlinear optical performance of each of these compounds depends on its π‐conjugation and biradical properties. Dibenzozethrenes have larger two‐photon absorption cross‐sections than zethrenes, as most strongly evidenced by the parent dibenzothrene [σ_max=4323 GM at 530 nm].     

Self-calibration method for cerium-doped lanthanum bromide scintillator detector in the 0.1–2.0 MeV energy range

In recent years, the cerium-doped lanthanum bromide, LaBr₃ (Ce = 5 %) detector is increasingly playing an important role in radiation measurements because of its higher energy resolution (~3 % at 662 keV), faster luminescence decay time (~35 ns) and higher detection efficiency compared to 7.65 cm × 7.65 cm NaI(Tl) detector. Intrinsic spectra between 1,800 and 3,000 keV derived from internal radioactivity within LaBr₃(Ce) scintillators have been investigated in some literatures, and these results are confirmed by the experiments in this work. In this paper, a new method for LaBr₃(Ce) detector energy calibration from 100 to 2,000 keV is proposed using the intrinsic spectra (self-calibration) instead of the standard gamma sources. Proof-of-concept experiment results show that self-calibration can guarantee energy accuracy of better than 0.815 % and can be applied outside the laboratory. The stability and applicability of this method are also investigated systematically.