Journal of Nanomaterials
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2015
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IF 1.644
Song Yang,Tian Zeng,Yaling Li,Jun Liu,Qian Chen,Ji Zhou,Yong Ye,Bin Tang
The fast detection and removal of organic dyes from contaminated water has become an urgent environmental issue due to their high toxicity, chemical stability, and low biodegradability. In this paper, we have developed graphene oxide decorated Fe3O4@SiO2 (Fe3O4@SiO2-GO) as a novel adsorbent aiming at the rapid adsorption and trace analysis of organic dyes followed by surface enhanced Raman scattering (SERS). The structure and morphology of the nanocomposites were characterized by transmission electron microscopy (TEM), Fourier infrared spectrometry (FT-IR), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The obtained nanocomposites were used to adsorb methylene blue (MB) in aqueous solution based on π-π stacking interaction and electrostatic attraction between MB and GO, and the adsorption behaviors of MB were investigated. Moreover, the obtained nanocomposites with adsorbed dyes were separated from the solution and loaded with silver nanoparticles for SERS detection. These nanocomposites showed superior SERS sensitivity and the lowest detectable concentration was 1.0 × 10−7 M.
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APPLIED SURFACE SCIENCE
·
2015
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IF 2.711
Rong Wang,Yi Xu,Chunyan Wang,Huazhou Zhao,Renjie Wang,Xin Liao,Li Chen,Gang Chen
A novel composite structure of reduced graphene oxide (rGO)–Ag nanoparticles (Ag NPs) nanocomposite, which was integrated on the indium tin oxide (ITO) glass by a facile and rapid two-step chronoamperometry electrodeposition route, was proposed and developed in this paper. SERS-activity of the rGO/Ag NPs nanocomposite was mainly affected by the structure and size of the fabricated rGO/Ag NPs nanocomposite. In the experiments, the operational conditions of electrodeposition process were studied in details. The electrodeposited time was the important controllable factor, which decided the particle size and surface coverage of the deposited Ag NPs on ITO glass. Under the optimized conditions, the detection limit for rhodamine6G (R6G) was as low as 10 −11 M and the Raman enhancement factor was as large as 5.9 × 10 8 , which was 24 times higher than that for the ITO–Ag NPs substrate. Apart from this higher enhancement effect, it was also illustrated that extremely good uniformity and reproducibility with low standard deviation could be obtained by the prepared ITO-rGO/Ag NPs nanocomposite for SRES detection.
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Journal of Physical Chemistry C
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2014
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IF 4.835
Sujie Chang,Shigang Ruan,Erlong Wu,Weixin Huang
Oxide-on-metal particles with exposed interfaces exhibit wealthy structures and functions, but their facile synthesis remains as a challenge. Herein we report a facile O2-assisted hydrothermal method to synthesize CeO2-on-Ag particles with different CeO2 thicknesses. In this novel approach Ag particles catalyze the O2 + H2O reaction to form surface hydroxyls that induce the preferential nucleation of Ce(OH)3 on the surfaces of Ag particles, eventually forming CeO2 adlayers on Ag particles. CeO2-on-Ag particles exhibit the CeO2 thickness-dependent SERS effect in which their best SERS effect is 2 orders stronger than that of Ag particles. They also exhibit CeO2 thickness-dependent catalytic performance in CO oxidation in which the best one is as active as traditional CeO2-supported Ag catalyst. These results open up new opportunities to synthesize oxide-on-metal particles and explore their functions by tuning the oxide adlayer thickness.
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JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
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2014
·Vol. 90
·期 4
·678-685
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IF 2.494
Xiaolian Jing,Dengpo Huang,Huimei Chen,Tareque Odoom-Wubah,Daohua Sun,Jiale Huang,Qingbiao Li
BACKGROUND The synthesis and application of novel Au nanostructures are of increasing importance in modern nanotechnology. RESULTS Closely packed and chemically difficult-to-synthesize Au nanohorns (AuNHs) were synthesized in the presence of Escherichia coli cells (ECCs) and hexadecyltrimethylammonium chloride (CTAC) by a microorganism-mediated, CTAC-directed (MCD) approach. A proper ECC dosage, ascorbic acid (AA) and CTAC concentrations were essential for the growth of the AuNHs. In the formation mechanism of the AuNHs the ECCs surface acted as a platform for preferential nucleation and initial anisotropic growth of Au nanocrystals. As a result, some of the adjacent nanoparticles over the cell surface connected together via linear fusion to form dendritic nanostructures. Meanwhile, secondary nucleation in the solution gave rise to smaller nanoparticles that were consumed later on via Ostwald ripening during the formation of the AuNHs. Eventually, the two-dimensional film-like nanostructures between adjacent cells easily connected to form well-defined AuNHs with three-dimensional nanostructures. Interestingly, the AuNH/ECC composites can be used directly as sensitive surface-enhanced Raman spectroscopy (SERS) substrates for effective detection of 4-mercaptobenzoic acid (MBA). CONCLUSION The MCD strategy was an effective approach to novel AuNHs and AuNH/microorganism nanocomposites as SERS substrate. © 2014 Society of Chemical Industry
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APPLIED SURFACE SCIENCE
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2015
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IF 2.711
Guihong Ding,Shi Xie,Ying Liu,Li Wang,Fugang Xu
Hybrid of graphene or graphene oxide (GO) with gold or silver nanoparticles (AgNPs) as substrate for SERS detection often brings large background and low signal to noise ratio, which leads to poor sensitivity. In this study, it is proposed that the silver loading amount on GO and dosage of GO-Ag composite have significant influence on its SERS activity (SERS signal intensity and signal to noise ratio). The adsorption ability and SERS activity of GO-Ag composite for several dye molecules were investigated in detail. It was found increasing the dosage of GO-Ag or AgNPs loading on GO always enhances its absorption to dye molecules, while in both cases the SERS signal first increase and then decrease. The reason for this fluctuation of SERS signal was investigated and discussed, which indicate high silver loading amount leads to enhanced background response, while high composite dosage could decrease the signal of target molecule. Finally, an optimized GO-Ag substrate providing strong SERS signal and high signal to noise ratio was used for the detection of several dye molecules by SERS with the lowest detectable concentration down to 1 μM. Our results indicated that great caution should be paid on the silver loading amount and dosage of GO-Au/Ag when using GO-Au/Ag as SERS substrate for molecule sensing or comparing different results reported in reference.
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ACS Applied Materials & Interfaces
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2013
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IF 5.008
Yong Liu,Peiyi Wu
Gold nanoparticles (Au NPs) are very attractive candidate nanoparticles in biological assay because of their high chemical stabilities, high homogeneities, good biocompatibilities, and low toxicities. However, molecular beacon assays via encapsulating the combined fluorescence or surface-enhanced Raman scattering (SERS) signals of reporters and Au NPs in nanobarcodes particles usually suffer from fluorescence quenching or weak Raman enhancement when Au NPs are employed (especially with size smaller than 15 nm). Herein, we present a new design of simultaneously realizing metal-enhanced fluorescence and coenhanced surface-enhanced Raman scattering by facilely embedding Ag nanoparticle into the shell of two kinds of Au nanoaggregate (5 and 10 nm), meanwhile, fluorophore is located between the silver core and gold nanoparticle layers and the distance among them is adjusted by SiO2 spacer (Ag@first SiO2 spacer@FiTC+SiO2@second SiO2 spacer@Au nanoaggregate). In this architecture, Ag nanoparticle not only is utilized as an efficient fluorescence enhancer to overcome the common fluorescence quenching around Au nanoaggregates but also behaves like a mirror. Thus, incident light that passes through the SERS-active Au nanoaggregate and the intervening dielectric layer of SiO2 could be reflected multiply from the surface of Ag nanoparticle and coupled with the light at the nanogap between the Au nanoaggregates to further amplify Raman intensity. This results in enhancement factors for fluorescence and SERS ∼1.6-fold and more than 300-fold higher than the control samples without silver core under identical experimental conditions, respectively. Moreover, fluorophore and SERS reporters are assembled onto different layers of the concentric hybrid microsphere, resulting in a feasible fabrication protocol when a large number of agents need to be involved into the dual-mode nanobarcodes. A proof-of-concept chip-based DNA sandwich hybridization assay using genetically modified organisms as a model system has been investigated based on the concentric hybrid microsphere. The high specificity and sensitivity of the assays suggest that the new architecture has a potential for various bioanalytical applications and provides opportunities for other similar metal nanoparticles to realize coenhancement effect.
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SENSORS AND ACTUATORS B-CHEMICAL
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2016
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IF 4.758
Ning Dong,Yongjun Hu,Kang Yang,Jianzhi Liu
Herein, we developed a novel nanosenor to detect trace amount of melamine (M) in the milk using aptamer-modified surface-enhanced Raman scattering (SERS) nanosensor and oligonucleotide chip. The SERS nanosensor was prepared by attaching Raman tag and ploy-thymine (T) aptamer to the gold nanoparticles, respectively. SERS nanosensor can be absorbed to the oligonucleotide chip with a high specificity where a “T–M–T” structure via multi-hydrogen-bond could be formed between the melamine molecule and the thymine molecule. In the measurement, the Raman signal intensities obtained from the chip increase when the concentrations of melamine in solutions increase. The proposed method allows us to detect melamine with a limit of 1.0 ppt (1.0 pg mL −1 ), which is fall far below the strictest safety limit. Compared with the previous methods, the sensitivity of this sensor shows about 100-fold improvement. The advantages of the present sensor are its low detection cost and the simplified sample pretreatment. Furthermore, the reliable and enough accurate results have been obtained by the using of the proposed nanosensor in the assay of trace melamine in real milk sample.
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BIOSENSORS & BIOELECTRONICS
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2016
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IF 7.476
Kang Yang,Yongjun Hu,Ning Dong
The accurate and sensitive detection of chloramphenicol (CAP) is particularly imperative to public health and safety. Here, we present a novel sensor for residual CAP detection based on competitive surface-enhanced Raman scattering (SERS) immunoassay and magnetic separation. In this nanosensor , functionalized Au nanoparticles (AuNPs) were labeled with the Raman reporter molecule (e.g. 4,4′-dipyridyl). With the addition of free CAP, a competitive immune reaction was initiated between free CAP and above AuNPs for conjugating with CAP antibody-modified magnetic nanoparticles (MNPs). Instead of the solid substrate, the antibody conjugated-magnetic beads were used as supporting materials and separation tools in the present sensor. With the aid of a magnet, the mixture was removed from the supernatant for concentration effects. This caused obvious change of SERS signal intensity obtained from supernatant. The SERS signals were collected from the supernatant directly, which made the SERS measurements more stable, repeatable and reliable. The proposed SERS-based magnetic immunosensor allows us to detect CAP in a fast, selective and sensitive (1.0 pg/mL) manner over a wide concentration range ( 1–1×10 4 pg/mL). In addition, these results demonstrate that this immunosensor holds great potential for the detection of antibiotics in real aquatic environment, which is crucial to our life.
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OPTIK
·
2017
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IF 0.835
Guochao Shi,Yanying Zhu,Mingli Wang,Lin Shen,Yuee Chen,Yuhong Wang,Xiaona Xu,Ruifeng Li,Wanli Ma
Two different types of Au nanoparticles (Au)/cicada wing (CW) arrays were synthesized by chemical reduction impregnation method and magnetron sputtering technique, respectively. And three-dimensional (3D) Au/CW-c (prepared by chemical reduction impregnation method) arrays and Au/CW-m (prepared by DC magnetron sputtering system) substrate were used as active substrates for SERS . The morphologies and Raman signals of the synthesized Au/CW-c and Au/CW-m substrates were characterized by field emission scanning electron microscopy (FE-SEM) and Raman system. Characterizations of the synthesized Au/CW-c and Au/CW-m substrates exhibited outstanding SERS properties. By comparing the enhanced Raman signal of Rhodamine 6G (R6G), it was found that the Au/CW-m substrate was more sensitive than Au/CW-c substrate. The results showed that the limit of detection (LOD) for R6G was as low as 10 −8 M for the Au/CW-m substrate. The enhancement factors (EF) were calculated to be 5.09 × 10 4 for the Au/CW-c substrate and 1.12 × 10 6 for the Au/CW-m substrate. This phenomenon is due to the fact that the high-dense SERS “hot spots” where the collective resonance of the absorbed electrons enhances contribute to the high SERS enhancement of Au/CW-m substrate. What we have found provides a promising approach to the rapid and sensitive detection of trace of organic pollutants.
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TALANTA
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2017
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IF 4.162
Libin Yang,Yongliang Chen,Yu Shen,Ming Yang,Xiuling Li,Xiaoxia Han,Xin Jiang,Bing Zhao
Bisphenol A (BPA) is a highly toxic chemical, and its residue in milk product is threatening people's health due to its possible leaching from the packagings and cans with BPA coating. In this work, halides modified Au nanoparticles (NPs) as the modification substrates were first designed for rapid and sensitive determination of BPA residue in real milk by SERS method with the assistance of aggregation agents (Zn 2+ ). It can be concluded that Au NPs modification substrate with assistance of the aggregation agent can remarkably improve the detection sensitivity of BPA residue, which can significantly enhance the SERS signal of BPA and achieve the trace-level detection of BPA residue. Under the optimal conditions, the limit of detection of BPA residue can be as low as to 4.3 × 10 −9 mol/L (equal to 0.98 × 10 −3 mg/kg), which is much less than the standard of European Union (0.6 mg/kg). And, there is a good linear relationship (R 2 = 0.990) between the intensity of SERS signal and the logarithm of BPA concentration in the range of 1.0 × 10 −8 –1.0 × 10 −3 mol/L. By this method, the recovery of BPA residue ranges from 89.5% to 100.2% with relative standard deviation between 4.6% and 2.7%. The proposed SERS method proves to be reliable, highly sensitive and possesses good reproducibility, which is very promising for sensitive detection of bisphenols residue in foodstuff.
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Analytical Methods
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2017
·Vol. 9
·期 11
·1816-1824
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IF 1.9
Lanlan Xiao,Min Zhang,Zhen Liu,Weiwei Bian,Xiaoli Zhang,Jinhua Zhan
The migration of solid samples from the interior to the surface of materials has raised serious concerns due to the increasing environmental health hazards in recent years. The convenient in situ detection of polycyclic aromatic hydrocarbons (PAHs) is especially needed. Surface-enhanced Raman spectroscopy (SERS) has emerged as an effective tool for spectroscopic detection and gives unique spectroscopic fingerprints of analytes. In this study, a hydrophobic 1-propanethiol-modified Ag nanowire membrane (PTH-Ag NMs) coupled with a portable Raman spectrometer was developed for the flexible on-site swabbing extraction and detection of typical PAHs. The swabbing process using an extracting agent was similar to the contact between a baby's mouth and toys. The SERS substrate suggested high uniformity, stability, and reusability. The curve of the normalized SERS intensity against the fluoranthene concentration displayed a good linear relationship (R2 = 0.98). The detection levels of fluoranthene, anthracene and pyrene reached 40.45, 35.65, and 45.45 ng cm−2, respectively. In addition, the simulated detection of these three PAHs on children's toys was demonstrated. The prepared hydrophobic PTH-Ag NMs have potential applications in the field of the inspection of toys by a simultaneous processing with simple pretreatment and a short total analysis time.
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Analytical Methods
·
2017
·Vol. 9
·期 17
·2517-2522
·
IF 1.9
Chenmeng Zhang,Xiu Liang,Tingting You,Nan Yang,Yukun Gao,Penggang Yin
An ultrasensitive “turn off” Surface Enhanced Raman Spectroscopy (SERS) sensor was developed for the detection of heparin based on the anti-aggregation of 4-mercaptobenzoic acid stabilized gold nanoparticles. In this paper, protamine, a small protein molecule with positive charges, could induce the aggregation of 4-MBA functionalized gold nanoparticles via surface electrostatic interaction. However, in the presence of heparin, the aggregation of 4-MBA functionalized gold nanoparticles decreased due to the fact that heparin has a strong affinity toward protamine, further causing the loss of the Raman enhanced effect. The normalized SERS intensity of the Raman reporter was proportional to the concentration of added heparin and a good linear detection range was obtained from 0.05 to 20 ng mL−1 (R2 = 0.999) with a calculated detection limit of 0.03 ng mL−1. Moreover, the developed highly selective method is also successfully demonstrated in fetal bovine serum. Our method is specific, simple and cheap, which could be applied to other further research studies of heparin.
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