Publications by authors named "Zhenli Sun"

14 Publications

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Surface-enhanced Raman scattering for mixing state characterization of individual fine particles during a haze episode in Beijing, China.

J Environ Sci (China) 2021 Jun 22;104:216-224. Epub 2020 Dec 22.

MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China; Guangdong Provincial Key Laboratory of Petrochemcial Pollution Processes and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China.

The nondestructive characterization of the mixing state of individual fine particles using the traditional single particle analysis technique remains a challenge. In this study, fine particles were collected during haze events under different pollution levels from September 5 to 11 2017 in Beijing, China. A nondestructive surface-enhanced Raman scattering (SERS) technique was employed to investigate the morphology, chemical composition, and mixing state of the multiple components in the individual fine particles. Optical image and SERS spectral analysis results show that soot existing in the form of opaque material was predominant during clear periods (PM ≤ 75 µg/m). During polluted periods (PM > 75 µg/m), opaque particles mixed with transparent particles (nitrates and sulfates) were generally observed. Direct classical least squares analysis further identified the relative abundances of the three major components of the single particles: soot (69.18%), nitrates (28.71%), and sulfates (2.11%). A negative correlation was observed between the abundance of soot and the mass concentration of PM. Furthermore, mapping analysis revealed that on hazy days, PM existed as a core-shell structure with soot surrounded by nitrates and sulfates. This mixing state analysis method for individual PM particles provides information regarding chemical composition and haze formation mechanisms, and has the potential to facilitate the formulation of haze prevention and control policies.
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http://dx.doi.org/10.1016/j.jes.2020.12.008DOI Listing
June 2021

Hairpin-Structured Magnetic SERS Sensor for Tetracycline Resistance Gene Detection.

Anal Chem 2020 12 20;92(24):16229-16235. Epub 2020 Nov 20.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

Antibiotic resistance genes (ARGs) have become emerging environmental contaminants, and the effective on-site detection of ARGs is urgently needed. Herein, we constructed a hairpin-structured magnetic sensor for the analysis of a widespread ARG, , using surface-enhanced Raman scattering (SERS). The SERS sensor was assembled by immobilizing core-satellite structured [email protected] with single-stranded DNA in a folded hairpin structure. The SERS sensor exhibited good sensitivity and specificity for the detection of laboratory-synthesized ssDNA fragments. In addition, this SERS strategy is the first of its kind to be employed for monitoring environmental samples in the field, with a limit of detection reaching as low as 25 copies μL. Univariate and multivariate linear regression equations verify the practicability of the SERS sensor for quantitative determination, showing the prospect for an amplification-free alternative platform for sensitive and reliable on-site detection of ARGs in the environment.
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http://dx.doi.org/10.1021/acs.analchem.0c04085DOI Listing
December 2020

Calcium Ions Turn on the Fluorescence of Oxytetracycline for Sensitive and Selective Detection.

J Fluoresc 2020 May 6;30(3):463-470. Epub 2020 Mar 6.

MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, People's Republic of China.

Herein, we report an interesting finding about the new application of oxytetracycline (OTC), as a fluorescent probe for the detection of calcium ion (Ca), which proved that it can offer an expeditious, highly sensitive, and selective detection method for Ca. Upon the addition of Ca, the fluorescence of OTC could be significantly enhanced with rapid response and high sensitivity, and achieved a good limit of detection as low as 125 nM in aqueous solution. The complex formed via Ca coordinating to the hydroxyl group of OTC contributes to the fluorescence enhancement, which has been proved by several characterization methods including UV-vis analysis, binding constant determination, and fluorescence titration. The method avoided complexity for EDTA measurement of Ca in running water as proposed previously. Taking advantage of good availability, stability and operability, the OTC was further successfully applied to the detection of Ca in a real environment. Graphical Abstract.
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http://dx.doi.org/10.1007/s10895-020-02512-3DOI Listing
May 2020

Bombyx mori bidensovirus infection alters the intestinal microflora of fifth instar silkworm (Bombyx mori) larvae.

J Invertebr Pathol 2019 05 11;163:48-63. Epub 2019 Mar 11.

School of Biology and Basic Medical Science, Soochow University, Suzhou 215123, China; National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123, China; Agricultural Biotechnology Research Institute, Agricultural Biotechnology and Ecological Research Institute, Soochow University, Suzhou 215123, China. Electronic address:

Bacterial diseases can occur as a result of disruption of the intestinal microbial population in the silkworm, Bombyx mori, and are often induced by bidensovirus (BmBDV) infection. We investigated the effects of BmBDV infection on intestinal microbes and immune gene responses in fifth instar silkworm larvae. Midgut contents were collected from BmBDV-infected and uninfected silkworms at 48, 96, and 144 h post-infection (hpi) and the intestinal flora were analyzed using 16S rRNA gene Illumina MiSeq sequencing technology. The abundance of intestinal bacteria differed between BmBDV-infected and uninfected silkworms. There were no significant differences in bacterial diversity at 48 and 96 hpi, but bacterial diversity in infected larvae was lower at 144 hpi compared with that of uninfected larvae. At the phylum level, the ratio of Proteobacteria was higher in infected larvae than in uninfected larvae at 48 and 96 hpi, but was lower after 144 hpi, while the ratio of Firmicutes had increased relative to uninfected silkworms. At the genus level, the ratio of Enterococcus increased gradually in infected silkworms, however, proportion of bacteria genera Incertae sedis were increased at 96 hpi, and the proportion of Lactococcus had decreased at 96 hpi. Principal component analysis showed that the proportion of Enterococcus species present was negatively correlated with most dominant genera. Increases in the abundances of the genera Anderseniella, Simplicispira, Enterococcus and, genera Incertae sedis, were associated with BmBDV infection. Quantitative reverse transcription-polymerase chain reaction indicated that expression levels of genes associated with immune deficiency (IMD), Toll, and JAK/STAT pathways were higher at 144 hpi with BmBDV infection. Enterococcus abundance was higher and was positively correlated with the expression level of spatzle-1, peptidoglycan recognition protein LE, and peptidoglycan recognition protein LB genes, suggesting that an increase in the abundance of Enterococcus leads to activation of the Toll and IMD immune pathways.
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http://dx.doi.org/10.1016/j.jip.2019.03.004DOI Listing
May 2019

Physicochemical analysis of individual atmospheric fine particles based on effective surface-enhanced Raman spectroscopy.

J Environ Sci (China) 2019 Jan 19;75:388-395. Epub 2018 Jun 19.

State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.

Fine particles associated with haze pollution threaten the health of more than 400 million people in China. It is therefore of great importance to thoroughly investigate and understand their composition. To determine the physicochemical properties in atmospheric fine particles at the micrometer level, we described a sensitive and feasible surface-enhanced Raman scattering (SERS) method using Ag foil as a substrate. This novel method enhanced the Raman signal intensities up to 10,000 a.u. for ν(NO) in fine particles. The SERS effect of Ag foil was further studied experimentally and theoretically and found to have an enhancement factor of the order of ~10. Size-fractionated real particle samples with aerodynamic diameters of 0.4-2.5 μm were successfully collected on a heavy haze day, allowing ready observation of morphology and identification of chemical components, such as soot, nitrates, and sulfates. These results suggest that the Ag-foil-based SERS technique can be effectively used to determine the microscopic characteristics of individual fine particles, which will help to understand haze formation mechanisms and formulate governance policies.
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http://dx.doi.org/10.1016/j.jes.2018.06.006DOI Listing
January 2019

Sulfate-nitrate-ammonium as double salts in PM: Direct observations and implications for haze events.

Sci Total Environ 2019 Jan 3;647:204-209. Epub 2018 Aug 3.

State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.

Obtaining detailed information on sulfate-nitrate-ammonium (SNA) is fundamentally important to explain the formation of haze in China, since it is a dominant component of fine particulate matter (PM) and plays a critical role in the deterioration of air quality. Several single-particle analysis methods have been applied to study and explain SNA formation; however, determining its mixture state remains a challenge. This study describes a direct observation of the SNA components in atmospheric particles on a single-particle scale, and details the first use of a non-destructive surface-enhanced Raman scattering (SERS) technique for SNA analysis. We studied PM collected at a site on the premises of Tsinghua University in Beijing, China, during a winter haze episode (12.15.2016-12.23.2016). The on-line data show that the SNA component accounted for 9.4% to 68.2% of the total mass of PM, becoming dominant on heavy haze days, and the sulfate concentration increased with the nitrate concentration (R = 0.72). Furthermore, the off-line SERS and scanning electron microscopy-energy dispersive X ray analysis (SEM-EDS) results for the single particles collected also indicated that SNA increase with increasing haze pollution. The existing state of the SNA component on each haze day was observed directly in a non-destructive manner mainly in the form of double salts such as 3(NHNO)·(NH)SO and 2(NHNO)·(NH)SO. A Raman mapping experiment further confirmed that the SNA was internally mixed. Our data also show that SNA can evaporate under high-vacuum scanning electron microscopy conditions, suggesting that SERS is an effective method to directly observe SNA without sample loss and may represent a promising single-particle technique to supplement traditional electron microscopy methods. This work will provide evidence for the SNA formation, particularly during haze events.
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http://dx.doi.org/10.1016/j.scitotenv.2018.07.107DOI Listing
January 2019

Improvement of a combination of TMPA (or IMERG) and ground-based precipitation and application to a typical region of the East China Plain.

Sci Total Environ 2018 Nov 7;640-641:1165-1175. Epub 2018 Jun 7.

Institute of Water Problems, Hohai University, Nanjing 210098, China; College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China.

Hydrological model and water resource assessment performance are highly dependent on the quality of the precipitation input, which can be improved by means of the optimal interpolation method for the merged precipitation. However, the traditional first-guess field of satellite precipitation often increases the merging error on account of its inherent bias. Some authors have suggested the need of generating a more accurate first-guess field for the merged precipitation, but the research in this improvement is rarely reported. Therefore, an improved merging method is proposed in this paper in which the precipitation from rain gauges is added to the first-guess field when combining the precipitation estimates of Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA) 3B42 with rain gauges in a typical region of the East China Plain, China. Furthermore, the influence of the gauge station densities on the merged accuracy of the precipitation is investigated based on the traditional and improved methods. The results show that the improved merging method has effectively reduced the influence of the uncertainty caused by the error of the first-guess field owing to the consideration of the spatial distribution of TMPA precipitation and the precision of the gauge precipitation. Compared with results of traditional interpolation methods using only gauge data, the precipitation-merging method in this study can obtain better performance results only when the observation density is lower than 6.0 × 10 km per gauge under average conditions of many years. The higher the observation density, the more notably the accuracy increases. In addition, the greater the precipitation, the more homogeneous the spatial and temporal distribution of the precipitation and the better the improved effect of the merging method. The Integrated Multi-satellitE Retrievals for the Global Precipitation Measurement (GPM) mission (IMERG) data is also used to validate the conclusions here.
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http://dx.doi.org/10.1016/j.scitotenv.2018.05.272DOI Listing
November 2018

Effects of transient high temperature treatment on the intestinal flora of the silkworm Bombyx mori.

Sci Rep 2017 06 13;7(1):3349. Epub 2017 Jun 13.

School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China.

The silkworm Bombyx mori is a poikilotherm and is therefore sensitive to various climatic conditions. The influence of temperature on the intestinal flora and the relationship between the intestinal flora and gene expression in the silkworm remain unknown. In the present study, changes of the intestinal flora at 48, 96 and 144 h following transient high temperature treatment (THTT) of 37 °C for 8 h were investigated. According to principal component analysis, the abundances of Enterococcus and Staphylococcus showed a negative correlation with other dominant genera. After THTT, the gene expression levels of spatzle-1 and dicer-2 were increased and decreased, respectively, which suggested that the Toll and RNAi pathways were activated and suppressed, respectively. The species-gene expression matrix confirmed that the spatzle-1 and dicer-2 gene expression levels were negatively and positively correlated, respectively, with the abundance of Enterococcus and Staphylococcus in the control. The abundance of Variovorax post-THTT was positively correlated with the spatzle-1 gene expression level, whereas the community richness of Enterococcus was negatively correlated with the spatzle-1 gene expression level and positively correlated with the dicer-2. The results of the present investigation provide new evidence for understanding the relationships among THTT, intestinal flora and host gene expression.
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http://dx.doi.org/10.1038/s41598-017-03565-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5469737PMC
June 2017

Typical winter haze pollution in Zibo, an industrial city in China: Characteristics, secondary formation, and regional contribution.

Environ Pollut 2017 Oct 10;229:339-349. Epub 2017 Jun 10.

School of Resources and Environmental Engineering, Shandong University of Technology, Zibo 255049, Shandong Province, China.

Heavy haze pollution occurs frequently in northern China, most critically in the Beijing-Tianjin-Hebei area (BTH). Zibo, an industrial city located in Shandong province, is often listed as one of the top ten most polluted cities in China, particularly in winter. However, no studies of haze in Zibo have been conducted, which limits the understanding of the source and formation of haze pollution in this area, as well as mutual effects with the BTH area. We carried out online and continuous integrated field observation of particulate matter in winter, from 11 to 25 January 2015. SO, NO, and NH (SIA) and organics were the main constituents of PM, contributing 59.4% and 33.6%, respectively. With the increasing severity of pollution, the contribution of SIA increased while that of organics decreased. Meteorological conditions play an important role in haze formation; high relative humidity (RH) and low wind speed increased both the accumulation of pollutants and the secondary transition from gas precursors (gas-particle phase partitioning). Since RH and the presence of O can indicate heterogeneous and photochemistry processes, respectively, we carried out correlation analysis and linear regression to identify their relative importance to the three main secondary species (sulfate, nitrate, and secondary organic carbon (SOC)). We found that the impact of RH is in the order of SO > NO > SOC, while the impact of O is reversed, in the order of SOC > NO > SO, indicating different effect of these factors on the secondary formation of main species in winter. Cluster analysis of backward trajectories showed that, during the observation period, six directional sources of air masses were identified, and more than 90% came from highly industrialized areas, indicating that regional transport from industrialized areas aggravates the haze pollution in Zibo. Inter-regional joint prevention and control is necessary to prevent further deterioration of the air quality.
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http://dx.doi.org/10.1016/j.envpol.2017.05.081DOI Listing
October 2017

Characteristics of the secondary water-soluble ions in a typical autumn haze in Beijing.

Environ Pollut 2017 Aug 3;227:296-305. Epub 2017 May 3.

College of Resources and Environmental Sciences, China Agricultural University, Beijing 100094, China.

Four haze episodes (EPs) were observed in October 2014 in Beijing, China. For better understanding of the characteristics and the formation mechanisms of PM (particulate matter with an aerodynamic diameter ≤ 2.5 μm), especially secondary water-soluble inorganic species in these haze events, hourly concentrations of PM, sulfate, nitrate, and ammonium (SNA) were measured in this study. Concentrations of gaseous pollutants and meteorological parameters were also measured. The average concentration of PM was 106.6 ± 83.5 μg m, which accounted for around 53% of PM (particulate matter with an aerodynamic diameter ≤ 10 μm) mass. Nitrogen dioxide (NO) concentration was much higher than that of sulfur dioxide (SO) since October is a non-heating month. SNA is the most abundant secondary water-soluble inorganic species and contributed to 33% of PM mass concentration. Sulfur oxidation ratio (SOR) was much higher than nitrogen oxidation ratio (NOR). NOR and SOR increased with elevated PM levels and heterogeneous processes seemed to be the most plausible explanation of this increase. Relative humidity (RH), which is of great influence on aerosol liquid water content (ALWC), played a considerable role in the formation of secondary inorganic aerosols, accelerated the secondary transformation of gaseous precursors, and further aggravated haze pollution. The positive feedback loop associated with high aerosol levels and low planetary boundary layer (PBL) height led to the evolution and exacerbation of heavy haze pollution. Fire maps and 48-h air mass backward trajectories supported the significant impact of biomass burning activities and regional transport on haze formation over Beijing in October 2014.
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http://dx.doi.org/10.1016/j.envpol.2017.04.076DOI Listing
August 2017

Au nanoparticles grafted on Fe3O4 as effective SERS substrates for label-free detection of the 16 EPA priority polycyclic aromatic hydrocarbons.

Anal Chim Acta 2016 Apr 12;915:81-9. Epub 2016 Feb 12.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address:

Several methods and materials have been explored for the sensitive and practicable detection of polycyclic aromatic hydrocarbons (PAHs). However, it is still a challenge to develop simple and cost-effective sensing techniques for PAHs. Herein we report the synthesis and construction of [email protected] SERS substrate. This magnetic substrate was composed by Fe3O4 microspheres and Au NPs. The size, morphology, and surface composition of [email protected] were characterized by multiple complimentary techniques including scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray powder diffraction. The spatial distributions of electro-magnetic field enhancement around [email protected] was calculated using finite difference time domain (FDTD) simulations. As a result of its remarkable sensitivity, the [email protected] SERS assay has been applied to detect the 16 EPA priority PAHs. The LODs achieved by our method (100-5 nM, 16.6-1.01 μg L(-1)) make it promising for the rapid screening of highly contaminated cases. As a proof-of-concept study, the substrate was applied in SERS sensing of PAHs in river matrix. The 16 PAHs could be differentiated based upon their characteristic SERS peaks. Most importantly, the detection was successfully conducted using a portable Raman spectrometer, which could be used for on-site monitoring of PAHs.
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http://dx.doi.org/10.1016/j.aca.2016.02.009DOI Listing
April 2016

Recent progress in detection of mercury using surface enhanced Raman spectroscopy--A review.

J Environ Sci (China) 2016 Jan 28;39:134-143. Epub 2015 Dec 28.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address:

Concerns over exposure to mercury have motivated the exploration of cost-effective, rapid, and reliable method for monitoring Hg(2+) in the environment. Recently, surface-enhanced Raman scattering (SERS) has become a promising alternative method for Hg(2+) analysis. SERS is a spectroscopic technique which combines modern laser spectroscopy with the optical properties of nano-sized noble metal structures, resulting in substantially increased Raman signals. When Hg(2+) is in a close contact with metallic nanostructures, the SERS effect provides unique structural information together with ultrasensitive detection limits. This review introduces the principles and contemporary approaches of SERS-based Hg(2+) detection. In addition, the perspective and challenges are briefly discussed.
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http://dx.doi.org/10.1016/j.jes.2015.11.009DOI Listing
January 2016

Multifunctional [email protected] Satellite Structured SERS Probe for Charge Selective Detection of Food Dyes.

ACS Appl Mater Interfaces 2016 Feb 26;8(5):3056-62. Epub 2016 Jan 26.

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China.

Nanofabrication of multifunctional surface-enhanced Raman scattering (SERS) substrates is strongly desirable but currently remains a challenge. The motivation of this study was to design such a substrate, a versatile core-satellite [email protected] (FA) hetero-nanostructure, and demonstrate its use for charge-selective detection of food dye molecules as an exemplary application. Our experimental results and three-dimensional finite difference time domain (FDTD) simulation suggest that tuning the Au nanoparticle (NP) gap to sub-10 nm, which could be readily accomplished, substantially enhanced the Raman signals. Further layer-by-layer deposition of a charged polyelectrolyte on this magnetic SERS substrate induced active adsorption and selective detection of food dye molecules of opposite charge on the substrates. Molecular dynamics (MD) simulations suggest that the selective SERS enhancement could be attributed to the high affinity and close contact (within a 20 Å range) between the substrate and molecules. Density function theory (DFT) calculations confirm the charge transfer from food dye molecules to Au NPs via the polyelectrolytes. This multifunctional SERS platform provides easy separation and selective detection of charged molecules from complex chemical mixtures.
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http://dx.doi.org/10.1021/acsami.5b10230DOI Listing
February 2016

Effects of BmCPV Infection on Silkworm Bombyx mori Intestinal Bacteria.

PLoS One 2016 8;11(1):e0146313. Epub 2016 Jan 8.

School of Biology & Basic Medical Science, Soochow University, Suzhou, 215123, China.

The gut microbiota has a crucial role in the growth, development and environmental adaptation in the host insect. The objective of our work was to investigate the microbiota of the healthy silkworm Bombyx mori gut and changes after the infection of B. mori cypovirus (BmCPV). Intestinal contents of the infected and healthy larvae of B. mori of fifth instar were collected at 24, 72 and 144 h post infection with BmCPV. The gut bacteria were analyzed by pyrosequencing of the 16S rRNA gene. 147(135) and 113(103) genera were found in the gut content of the healthy control female (male) larvae and BmCPV-infected female (male) larvae, respectively. In general, the microbial communities in the gut content of healthy larvae were dominated by Enterococcus, Delftia, Pelomonas, Ralstonia and Staphylococcus, however the abundance change of each genus was depended on the developmental stage and gender. Microbial diversity reached minimum at 144 h of fifth instar larvae. The abundance of Enterococcus in the females was substantially lower and the abundance of Delftia, Aurantimonas and Staphylococcus was substantially higher compared to the males. Bacterial diversity in the intestinal contents decreased after post infection with BmCPV, whereas the abundance of both Enterococcus and Staphylococcus which belongs to Gram-positive were increased. Therefore, our findings suggested that observed changes in relative abundance was related to the immune response of silkworm to BmCPV infection. Relevance analysis of plenty of the predominant genera showed the abundance of the Enterococcus genus was in negative correlation with the abundance of the most predominant genera. These results provided insight into the relationship between the gut microbiota and development of the BmCPV-infected silkworm.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0146313PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4706323PMC
July 2016