Junfeng Zhai

Carbon nanoparticle for highly sensitive and selective fluorescent detection of mercury(II) ion in aqueous solution.

In this article, carbon nanoparticles (CNPs) were used as a novel fluorescent sensing platform for highly sensitive and selective Hg(2+) detection. To the best of our knowledge, this is the first example of CNPs obtained from candle soot used in this type of sensor. The general concept used in this approach is based on that adsorption of the fluorescently labeled single-stranded DNA (ssDNA) probe by CNP via π-π stacking interactions between DNA bases and CNP leads to substantial dye fluorescence quenching; however, in the presence of Hg(2+), T-Hg(2+)-T induced hairpin structure does not adsorb on CNP and thus retains the dye fluorescence. A detection limit as low as 10nM was achieved. The present CNP-based biosensor for Hg(2+) detection exhibits remarkable specificity against other possible metal ions. Furthermore, superior selectivity performance was observed when Hg(2+) detection was carried out in the presence of a large amount of other interference ions. Finally, in order to evaluate its potential practical application, Hg(2+) detection was conducted with the use of lake water other than pure buffer and it is believed that it holds great promise for real sample analysis upon further development.

Preparation of photoluminescent carbon nitride dots from CCl4 and 1,2-ethylenediamine: a heat-treatment-based strategy

In this communication, we report on our recent finding that photoluminescent carbon nitride dots (CNDs) can be prepared by a simple heat-treatment-based strategy for the first time. It suggests the CNDs thus obtained exhibit strong fluorescence. The formation of such CNDs can be attributed to the polymerization of CCl4 and 1,2-ethylenediamine under reflux, microwave, or solvothermal heating.

Sensitive and selective detection of silver(I) ion in aqueous solution using carbon nanoparticles as a cheap, effective fluorescent sensing platform.

In this Letter, we demonstrate the first use of carbon nanoparticles (CNPs) obtained from carbon soot by lighting a candle as a cheap, effective fluorescent sensing platform for Ag(+) detection with a detection limit as low as 500 pM and high selectivity. We further demonstrate its practical application to detect Ag(+) in a real sample.

Ordered magnetic core-manganese oxide shell nanostructures and their application in water treatment

In this paper, we have reported a facile method for the synthesis of ordered magnetic core–manganese oxide shell nanostructures. The process included two steps. First, manganese ferrite nanoparticles were obtained through a solvothermal method. Then, the manganese ferrite nanoparticles were mixed directly with KMnO4 solution without any additional modified procedures of the magnetic cores. It has been found that Mn element in the core can react with KMnO4 to form manganese oxide which acts as a seed for the in-situgrowth of manganese oxide shells. This is significant for the controllable fabrication of symmetrical ordered manganese oxide shell structures. The shell thickness can be easily controlled through the reaction time. Transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction and energy-dispersive X-ray spectroscopy have been employed to characterize the products at different reaction time. The magnetic materials can be used as absorbents in wastewater treatment and exhibit a strong capability to remove organic pollutants. Furthermore, the materials are superparamagnetic and exhibit relative high saturation magnetization at room temperature, which makes the separation procedure more convenient in wastewater treatment.

Acid-driven, microwave-assisted production of photoluminescent carbon nitride dots from N,N-dimethylformamide

In this communication, we report on acid-driven, microwave-assisted production of fluorescent carbon nitride dots (CNDs) on a large scale by microwave irradiation of N,N-dimethylformamide (DMF) solution in the presence of acids including chlorosulfonic acid (CSA), H2SO4, HCl, or HNO3. It suggests these CNDs are well water-soluble and exhibit strong fluorescence.

One-Step Synthesis of Folic Acid Protected Gold Nanoparticles and Their Receptor-Mediated Intracellular Uptake

We report here a facile method to obtain folic acid (FA)-protected gold nanoparticles (Au NPs) by heating an aqueous solution of HAuCl(4)/FA in which FA acts as both the reducing and stabilizing agent. The successful formation of FA-protected Au NPs is demonstrated by UV/Vis spectroscopy, transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The intracellular uptake of these nanoparticles is facilitated by HeLa cells overexpressing the folate reporter, which itself is significantly inhibited by free FA in a competitive assay as quantified by inductively coupled plasma mass spectroscopy (ICP-MS). This simple one-step approach affords a new perspective for creating functional nanomaterials, and the resulting biocompatible, functional Au NPs may find some prospective applications in various biomedical fields.

A membraneless biofuel cell powered by ethanol and alcoholic beverage

In this study, we reported on the construction of a stable single-chamber ethanol/O(2) biofuel cell harvesting energy from the ethanol and alcoholic beverage. We prepared a composite film which consisted of partially sulfonated (3-mercaptopropyl)-trimethoxysilane sol-gel (PSSG) and chitosan (CHI). The combination of ion-exchange capacity sol-gel and biopolymer chitosan not only provided the attached sites for mediator MDB and AuNPs to facilitate the electron transfer along the substrate reaction, but also gave the suitable microenvironment to retain the enzyme activity in long term. The ethanol bioanode was constructed with the film coimmobilized dehydrogenase (ADH), Meldolas blue (MDB) and gold nanoparticles (AuNPs). The MDB/AuNPs/PSSG-CHI-ADH composite modified electrode showed prominent electrocatalytic activity towards the oxidation of ethanol. The oxygen biocathode consisted of laccase and AuNPs immobilized on the PSSG-CHI composite membrane. The AuNPs/PSSG-CHI-laccase modified electrode catalyzed four-electron reduction of O(2) to water, without any mediator. The assembled single-chamber biofuel cell exhibited good stability and power output towards ethanol. The open-circuit voltage of this biofuel cell was 860 mV. The maximum power density of the biofuel cell was 1.56 mWcm(-2) at 550 mV. Most interestingly, this biofuel cell showed the similar performance when the alcoholic beverage acted as the fuel. When this biofuel cell ran with wine as the fuel, the maximum power output density was 3.21 mAcm(-2) and the maximum power density was 1.78 mWcm(-2) at 680 mV of the cell voltage. Our system exhibited stable and high power output in the multi-component substrate condition. This cell has great potential for the development and practical application of bioethanol fuel cell.

A Facile and Controllable Strategy to Synthesize Au−Ag Alloy Nanoparticles within Polyelectrolyte Multilayer Nanoreactors upon Thermal Reduction

A new synthesis strategy has been developed for the preparation of bimetallic gold-silver (Au-Ag) alloy nanoparticles by the virtue of polyelectrolyte multilayer (PEM) nanoreactors. By controlling the assembly conditions, gold and silver ions can be effectively loaded onto the PEM composed of polyethylenimine (PEI) and poly(acrylic acid) (PAA) simultaneously. Upon further thermal treatment, Au-Ag alloy nanoparticles with sizes of ca. 3.8 nm formed in the PEM, which were characterized in detail by UV-vis absorption spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX) analysis. Appearance of a single plasmon band in the visible region and lack of apparent core-shell structures in the TEM images confirm the formation of homogeneous Au-Ag alloy nanoparticles. In addition, the surface plasmon absorption band of the Au-Ag alloy nanoparticles shows linear blue-shift with increasing Ag content, which also supported the formation of alloy nanoparticles. Several key parameters of the present strategy have been investigated, which showed that pH of both the assembly solution and gold salt solution and the choice of polymers for constructing PEM, as well as the reduction approach, all played an important role in successfully synthesizing bimetallic Au-Ag nanoparticles. The formation mechanism of alloy nanoparticles has also been discussed based on the spectral evolution during the thermal reduction.

One-pot synthesis of monodispersed ZnS nanospheres with high antibacterial activity

A facile one-pot method to prepare water-soluble, uniform-sized ZnS nanospheres (NSs) is reported. In the reaction, gradually decomposed thioacetamide (TAA) was used as the sulfur precursor, and cationic surfactant didodecyldimethylammonium bromide (DDAB) embedded with ferrocene (Fc) as the ligands for anions. The synthesized ZnS NSs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Wonderfully, the obtained ZnS NSs exhibited high performance in prohibiting the growth of Escherichia coli strain MG1655 (E. coli) and negligible mammalian cell toxicity, and these important features make it a promising antimicrobial agent for controlling implant-related infections.

Nano-C60 as a novel, effective fluorescent sensing platform for mercury(II) ion detection at critical sensitivity and selectivity

The present communication demonstrates the use of water-soluble nano-C(60) as a novel, effective fluorescent sensing platform for Hg(2+) detection for the first time. This sensing system achieves a detection limit as low as 500 pM and exhibits excellent selectivity.