Yurong Tang

Carbon Nitride Quantum Dots: A Novel Chemiluminescence System for Selective Detection of Free Chlorine in Water

A facile one-step microwave-assisted approach for the preparation of strong fluorescent carbon nitride quantum dots (g-CNQDs) by using guanidine hydrochloride and EDTA as the precursors was developed. Strong chemiluminescence (CL) emission was observed when NaClO was injected into the prepared g-CNQDs, and a novel CL system for direct detection of free chlorine was established. Free residual chlorine in water was sensitively detected with a detection limit of 0.01 μM and had a very wide detection range of 0.02 to 10 μM. On the basis of CL spectral, UV-visible absorption spectral, and electron spin resonance (ESR) spectral studies, as well as investigations on the effects of various free radical scavengers, a possible CL mechanism was proposed. It was suggested that the radiative recombination of oxidant-injected holes and electrons in the g-CNQDs accounted for the CL emission. Meanwhile, (1)O2 on the surface of g-CNQDs, generated from some reactive oxygen species in the g-CNQDs-NaClO system, could transfer energy to g-CNQDs and thus further enhance the CL emission. The CL system is highly sensitive and differentiable, opening a new field for the development of novel CL-emitting species, but also expanding the conventional optical utilizations of g-CNQDs.

SiO2/graphene composite for highly selective adsorption of Pb(II) ion

SiO(2)/graphene composite was prepared through a simple two-step reaction, including the preparation of SiO(2)/graphene oxide and the reduction of graphene oxide (GO). The composite was characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscope, and X-ray photoelectron spectroscopy, and what is more, the adsorption behavior of as-synthesized SiO(2)/graphene composite was investigated. It was interestingly found that the composite shows high efficiency and high selectivity toward Pb(II) ion. The maximum adsorption capacity of SiO(2)/graphene composite for Pb(II) ion was found to be 113.6 mg g(-1), which was much higher than that of bare SiO(2) nanoparticles. The results indicated that SiO(2)/graphene composite with high adsorption efficiency and fast adsorption equilibrium can be used as a practical adsorbent for Pb(II) ion.

Highly Sensitive Immunoassay Based on Immunogold−Silver Amplification and Inductively Coupled Plasma Mass Spectrometric Detection

In this work, we demonstrated a highly sensitive inductively coupled plasma mass spectrometric (ICPMS) method for the determination of human carcinoembryonic antigen (CEA), which combined the inherent high sensitivity of elemental mass spectrometric measurement with the signal amplification of catalytic silver deposition on immunogold tags. The silver amplification procedure was easy to handle and required cheap reagents, and the sensitivity was greatly enhanced to 60-fold after a 15 min silver amplification procedure. The experimental conditions, including detection of gold and silver by ICPMS, immunoassay parameters, silver amplification parameters, analytical performance, and clinical serum samples analysis, were investigated. The ICPMS Ag signal intensity depends linearly on the logarithm of the concentration of human CEA over the range of 0.07-1000 ng mL(-1) with a limit of detection (LOD, 3σ) of 0.03 ng mL(-1) (i.e., 0.15 pM). The LOD of the proposed method is around 2 orders of magnitude lower than that by the widely used enzyme-linked immunosorbent assay (ELISA) and 1 order of magnitude lower than that by clinical routine chemiluminescence immunoassay (CLIA) or time-resolved fluoroimmunoassay (TRFIA) and conventional ICPMS immunoassay. The present strategy was applied to the determination of human CEA in clinical human serum samples, and the results were in good agreement with those obtained by chemiluminescence immunoassay.

Highly sensitive resonance light scattering bioassay for heparin based on polyethyleneimine-capped Ag nanoclusters.

Ag nanoclusters (NCs) possessed distinct physical and chemical attributes that made them excellent scaffolds for the development of novel bio-analytical methodology. In the present work, a green approach for the preparation of Ag nanoclusters (NCs) was proposed on the basis of templated polyethyleneimine (PEI) assisted in-situ reductive crystallization of Ag (I), and then a sensitive resonance light scattering bioassay for the determination of heparin was established on the basis of the enhanced resonance light scattering of the PEI-capped Ag NCs during the presence of heparin. Further investigation indicated that the molecular weight of PEI, the PEI/Ag (I) ratio and the pH value of reaction conditions had great influence on the formation of Ag NCs, which was directly correlated to resonance light scattering. The bioassay allows sensitive and selective detection of heparin with a detection limit of 27.5 nM, and successfully applied for the determination of heparin in human serum samples.

Hapten Design,Modification and Preparation of Artificial Antigens

Abstract The key step to develop an immunoassay for small molecular compounds is to synthesize artificial antigens with good immunogenicity. In this paper, the design and modification of hapten (e.g. the choice of modified sites, preparation of hapten derivative, choice of linking spacer), selection of carrier, coupling of hapten derivative to carrier (including coupling method, coupling conditions, the optimal coupling rate), purification and identification of artificial antigens are reviewed in detail.

Inductively coupled plasma mass spectrometry for determination of total urinary protein with CdTe quantum dots label

In the present work, a novel methodology for sensitive quantification of human total urinary protein by using CdTe quantum dots label and inductively coupled plasma mass spectrometry (ICP-MS) was developed. It combined the intrinsically high sensitivity of elemental mass spectrometric analysis with the remarkable quantity of metallic ions from the nanoparticles label. Through the direct conjugation of CdTe quantum dots and proteins, the ICP-MS signal intensity of cadmium is proportional to the concentration of proteins. The optimization of bio-conjugation parameters was investigated and discussed in detail. The proposed method featured a low detection limit (0.008 μg mL−1 for HSA) and wide linear range response over 4 orders of magnitude. Moreover, there are very little interferences from common inorganic ions and other coexisting compounds. The developed method was successfully applied for detecting total protein in 50 human urine samples and the results were in good agreement with those reported by the hospital, which indicated a great potential for routine clinical application.

An upconversion fluorescence based turn-on probe for detecting lead(II) ions

A new fluorescent probe for detecting lead ions (Pb2+) is reported in this work. Positively charged UCPs capped with ethylene imine polymer (PEI) and negatively charged AuNPs capped with 11-mercaptoundecanoic acid (MUA) were used as fluorescent donors and acceptors, respectively. The fluorescence quenching process was initiated by the electrostatic interaction between PEI–UCPs and MUA–AuNPs. Upon the addition of Pb2+, functionalized AuNPs were aggregated by an ion-templated chelation process, causing the departure of AuNPs from UCPs. As a result, the fluorescence of the donor was restored and the recovery was found to be proportional within the range of 0.5–10 μM to the concentration of Pb2+. The detection limit was found to be 20 nM. This method was easy to operate with satisfactory selectivity and remarkable sensitivity which would be meaningful in Pb2+-related detection.

Application of NaYF4:Yb,Er Nanoparticles as Peroxidase Mimetics in Uric Acid Detection

Abstract The poly(acrylic acid) functionalized NaYF 4 :Yb,Er nanoparticles (NPs) were found to possess intrinsic peroxidase-like activity, which could catalyze oxidization of 3,3′,5,5′-tetramethylbiphenyl (TMB) by H 2 O 2 to produce a color variation. Using TMB as substrate, we systematically studied the effect of a series of conditions, such as temperature and pH, on the catalytic activity of NaYF 4 :Yb,Er NPs. When combined with uricase, the proposed colorimetric method could be successfully used for the determination of uric acid. Under the optimum conditions, the linear range of this method was from 1.0 × 10 −5 M to 2.0 × 10 −4 M with the detection limit down to 5.3 × 10 −6 M. Moreover, the developed method was applied to detect uric acid in serum samples and the results were in good agreement with those reported by the hospital.

Application of NaYF4:Yb,Er Nanoparticles as Peroxidase Mimetics in Uric Acid Detection: Application of NaYF4:Yb,Er Nanoparticles as Peroxidase Mimetics in Uric Acid Detection

聚丙烯酸修饰的NaYF4∶Yb,Er纳米粒子能够有效地催化H2O2氧化3,3＇,5,5＇-四甲基联苯胺（TMB）产生显色反应,表现出良好的过氧化物模拟酶催化活性。本研究以TMB为模型底物,研究了催化条件（温度和pH值）对催化活性的影响。同时,结合尿酸在尿酸氧化酶作用下产生H2O2的原理,建立了比色法测定血样中尿酸含量的简便方法。在最优条件下,本方法的检测范围为1.0×10＂5～2.0×10＂4mol/L,检出限为5.3×10＂6mol/L,并对实际样品进行测定,测定结果与临床结果一致。