Atomic Fluorescence Spectrometer Research Articles

On-site monitoring of dissolved Sb species in natural waters by an automatic system using flow injection coupled with hydride generation atomic fluorescence spectrometer

Antimony (Sb) is a toxic and potentially carcinogenic element in the environment. The toxicity of Sb(III) is ten times that of Sb(V). Therefore, on-site monitoring technique for dissolved Sb species is crucial for the study of Sb environmental processes. In this study, an automated, portable, and cost-effective system was developed for field simultaneous analysis of Sb(III) and Sb(III + V) in natural waters. The system comprised a portable atomic fluorescence spectrometer equipped with a built-in electrochemical H2 generator to reduce the consumption of acid/borohydride solution and make the atomizer more stable for on-site analysis. Flow injection technique was also used to achieve on-line pretreatment of water samples, including filtration, acidification, pre-reduction, and hydride generation procedures. Under the optimal conditions, the limits of detection (3σ, n = 11) of the developed method were 0.015 μg/L and the linear ranges were 0.05–5.0 μg/L for both Sb(III) and Sb(III + V). The relative standard deviations (n = 11) of the spiked samples of Sb(V) were 3.2% (0.05 μg/L), 3.3% (0.2 μg/L), and 1.7% (0.5 μg/L), respectively. The spiked recoveries of lake water, treated wastewater, and seawater ranged from 97.0% to 108.5%. The novel system of flow injection coupled with hydride generation atomic fluorescence spectrometer (FI-HG-AFS) was applied to carry out an 18-h fixed-point monitoring at a secondary settling tank of a wastewater treatment facility in Xiamen University, and a 6-h real-time underway analysis in the surface seawater of Dongshan Bay, China, proving that the system was capable of long-term monitoring in the field.

Simultaneous Measurement of Trace Levels of Hg, As, Sb, and Bi in Coastal Seawater with a Multichannel Chemical Vapor Generation Atomic Fluorescence Spectrometer.

Trace levels of Hg, As, Sb, and Bi in coastal seawater have been simultaneously detected by a laboratory-built multichannel chemical vapor generation coupled to an atomic fluorescence spectrometer. The system was configured with a built-in electrochemical H2 generator as the fuel supplier to replace chemical H2 produced by the oxidation of potassium borohydride under acidic conditions in traditional instruments. The electrochemical H2 generator not only isolated the atomization process from the chemical vapor injection process but also improved the stability of atomization, excitation, and fluorescence emission in the hydrogen flame, making it easier to optimize conditions for CVG while introducing evaporating multielement vapors. Calibrations were obtained using a mixed standard solution of Hg(II), As(III), Sb(III), and Bi(III). The addition of KBr to a 3% (v/v) HCl solution was selected as the preservative to ensure the stability of 0.10 μg/L Hg(II) in a multielement standard solution for at least 15 days while also preserving μg/L levels of As(III), Sb(III), and Bi(III) stable. The method detection limits (LOD, 3σ) were 0.001, 0.015, 0.010, and 0.005 μg/L for Hg, As, Sb, and Bi, respectively. The relative standard deviations (RSD, n = 7) of the standard spiked seawater samples were 3.2% (0.020 μg/L Hg), 1.2% (0.50 μg/L As), 1.0% (0.50 μg/L Sb), and 3.5% (0.050 μg/L Bi), respectively. The recoveries of seawater samples spiked with different salinities were in the range of 84.5%(Sb)-114%(Hg). The system has been successfully applied to the simultaneous analysis of the four elements in the seawater samples collected from Xiamen Bay, Southeast China.

Shipboard determination of arsenite and total dissolved inorganic arsenic in estuarine and coastal waters with an automated on-site-applicable atomic fluorescence spectrometer

The speciation of trace level arsenic (As) in estuarine and coastal waters is crucial for both biogeochemical and toxicological studies of this toxic metalloid. However, the accurate and on-site determination of As in complex seawater matrices is challenging because of the low concentration of As, the easy conversion of arsenite (As(III)) to arsenate (As(V)), and the considerable effect of salinity on the determination of As via conventional methods. In this study, a custom-made shipboard atomic fluorescence spectrometer (AFS) is reported for the on-site speciation of inorganic As in estuarine and coastal waters. After comprehensive optimization of the instrumental and chemical parameters, the method demonstrated high sensitivity (limits of detection: 0.02 μg L−1), good linearity (R2 > 0.999 for all calibration curves up to 8 μg L−1), high precision (relative standard deviations (RSDs) of less than 2% at 1 μg L−1 over a year-long evaluation), and excellent performance for sample analysis for different matrices with varying salinities (recoveries: 96.3%–105.3%). The portable and field-applicable AFS was successfully applied to the on-site and shipboard simultaneous determination of As(III) and total dissolved inorganic arsenic (TDIAs) in the coastal waters of Shandong, Jiangsu, Zhejiang, Fujian, and Guangdong province of China, demonstrating its robustness and applicability in harsh conditions.

Spatial Distribution Characteristics and Source Analysis of Heavy Metals in Urban River Surface Sediments from the Lanzhou Reach of the Yellow River

In order to investigate the contamination characteristics and potential sources of heavy metals from the urban river surface sediments in the Yellow River Basin, we selected the Lanzhou reach of the Yellow River as the object of investigation. A total of 46 surface sediment samples were collected along the Lanzhou reach of the Yellow River, and the contents of eight heavy metals, Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb, were determined by using inductively coupled plasma mass spectrometry and an atomic fluorescence spectrometer. Contamination indexes including single factor pollution index (Pi) and geo-accumulation index (Igeo), together with the sediment pollution index (SPI), were used to assess heavy metal pollution characteristics and ecological risk levels in the urban river surface sediments of the Lanzhou reach of the Yellow River. Pearson's correlation analysis (CA), positive matrix factorization (PMF), and principal component analysis/absolute principal component score (PCA/APCS) were jointly employed to quantitatively analyze pollution sources of heavy metals. The results showed that the mean concentrations of the majority of heavy metals exceeded their corresponding background values of Gansu Province and Lanzhou City with the exception of As, and the spatial distribution of high concentrations of heavy metals was mainly concentrated in the corner of the river. Based on the single factor pollution and geo-accumulation indexes of the eight heavy metals, in the Lanzhou reach of the Yellow River, Cr was the dominant pollution element in the urban river surface sediments, followed by Cd and Ni. Additionally, the SPI values for the eight heavy metals in the surface sediments ranged from 0.48 to 8.56, presenting natural to low ecological risk level. Furthermore, source apportionment revealed that a mixture source of industrial and agricultural activities (77.6%) was the largest contributor of Cr, Ni, Zn, As, Cd, and Pb in the urban river surface sediments, followed by natural sources (11.4%) and a mixed source of industrial and traffic activities (11%).

Comparison of bismuth atomic lamps for a non-dispersive atomic fluorescence spectrometry

The performance of two types of radiation sources – an electrodeless discharge lamp (EDL) and a boosted discharge hollow cathode lamp (Superlamp) – for atomic fluorescence spectrometry (AFS) was studied and compared using bismuth as a model analyte at 222.8 and 223.1 nm fluorescence lines. Hydride generation was used for analyte introduction to a miniature diffusion flame where the generated bismuthane was atomized. An in-house assembled non-dispersive atomic fluorescence spectrometer was adjusted so that either of the sources could be employed. The optimization of the radiation sources at chosen 40 Hz modulation rate included a duty cycle and applied currents (primary and boost), in addition to proper focusing on the flame atomizer. With optimum operation parameters the sensitivity achieved with the EDL was around an order of magnitude higher than that with the Superlamp, in agreement with the higher radiation intensity measured by an optical power meter and resulting limits of detection of 1.5 pg and 11 pg, for the EDL and the Superlamp, respectively.

Rapid detection of ultratrace urinary arsenic by direct sampling microplasma vaporization based on silicon nitride

At present, immediate monitoring urinary arsenic is still a challenge for treating arsenic poisoning patients. Thus, a fast, reliable and accurate analytical approach is indispensable to monitor ultratrace arsenic in urine sample for health warning. In this work, a silicon nitride (SN) rod was first integrally utilized as a sample carrier for ≤50 μL urinary aliquot, an electric heater for removing water and ashing sample as well as a high voltage electrode for dielectric barrier discharge vaporization (DBDV). The direct analytical method of arsenic in urine without sample digestion was thus developed using atomic fluorescence spectrometer (AFS) as a model detector. After 4 V electrically heating the SN rod for 60 s, urine sample was dehydrated and ashed outside; then, DBD was exerted under 0.8 A with 0.8 L/min H2 + Ar (1:9, v:v) for 20 s to vaporize arsenic analyte from the SN rod. After optimization, 0.014 μg/L arsenic detection limit (LOD) was reached with favorable analytical precision (RSD <5%) and accuracy (91–110% recoveries) for real sample analysis. As a result, the whole analysis process only consumes <3 min to exclude complicated sample preparation; furthermore, the designed DBDV system only occupies 25 W and <2 kg, which renders a miniature sampling component to hyphenate with a miniature detector to detect arsenic. Thus, this direct sampling DBDV method extremely fulfills the fast, sensitive and precise detection of ultratrace arsenic in urine sample.

Novel Platinum-Nickel Composite Trap for Simultaneous and Direct Determination of Mercury and Cadmium in Soil and Its Mechanism Study.

In this work, following a metal-ceramic heater (MCH) as an electrothermal vaporizer (ETV), a novel composite Pt/Ni trap based on platinizing the foamed nickel was first fabricated to trap Hg and Cd simultaneously. So, a solid sampling Hg-Cd analyzer was developed to simultaneously detect trace Hg and Cd in soil samples, mainly consisting of an MCH, a composite Pt/Ni trap, and an atomic fluorescence spectrometer (AFS). This small-size MCH-ETV system only consumes 100 W for the complete vaporization of Hg and Cd in soil matrices. The Pt/Ni trap fulfills the complete trapping of Hg and Cd following the solid sampling MCH-ETV system and then fast releases them by heating. It was proved that trapped and released Hg and Cd by the Pt/Ni trap are atomic species using X-ray photoelectron spectroscopy (XPS) and other approaches; specially, the effective cotrapping of Hg and Cd might be due to forming alloys of Hg + Pt and Cd + Ni on the Pt/Ni trap. Under the optimized conditions, the method detection limits (LODs) of Hg and Cd reached 0.4 μg/kg and 0.04 μg/kg for a 20 mg sample size, the relative standard deviations (RSDs) were within 12% and 8% for soil samples, respectively, and the recoveries ranged from 96% to 105%, indicating favorable analytical sensitivity, precision, and accuracy. The whole analysis time can be controlled within 5 min without the soil digestion process. The proposed Hg-Cd analyzer is thus suitable for rapid detection of Hg and Cd in soil samples with advantages such as simplicity, green, and safety. Further, the proposed solid sampling ETV-composite trap method has a promising application potential in the field and rapid detection for multielements.

A county-level spatial epidemiological study of hair selenium and Keshan disease.

No spatial analysis of hair selenium and Keshan disease (KD) on a nationwide county-level has been performed. Selenium deficiency is a recognized environmental risk factor for KD. Hair selenium is one of the recognized biomarkers of selenium nutrition. This study aimed to perform a geographically precise and visualized assessment of the achievement of KD prevention and control at the level of selenium nutrition in terms of etiology. A spatial ecological study was conducted. The hair selenium content of the residents was assayed using an atomic fluorescence spectrometer. The spatial analysis was performed using ArcGIS. The median of the hair selenium levels of the 3,028 participants in the 1,174 counties was 0.38 mg/kg, and the content of inhabitants in KD endemic counties was significantly lower than that in KD non-endemic counties (0.34 vs. 0.39 mg/kg, z = -10.03, P < 0.0001). The proportion of Se-deficient and Se-marginal counties in KD endemic counties was significantly higher than that in KD non-endemic counties (59.4 vs. 29.0%, z = -7.45, P < 0.0001). The global autocorrelation analysis was not statistically significant (Moran's I = 0.0005, P = 0.68). Local autocorrelation analysis identified 174 low-low clusters of hair selenium levels, 83 (47.7%) of which are KD endemic counties located in KD endemic provinces of Henan, Gansu, Shaanxi, Inner Mongolia, Jilin, and Heilongjiang. The hair selenium featured a positive correlation with per capita GDP (r s = 0.20, P < 0.0001). The median of the hair selenium levels of inhabitants living in KD endemic counties was significantly lower than that in KD non-endemic counties. All the 83 KD endemic counties with low-low clusters of hair selenium levels should be prioritized in KD precision prevention and control. These findings are geographically precise and visualized evidence of the assessment of the effectiveness of KD prevention and control at the level of selenium nutrition in terms of etiology.

Hair Selenium of Residents in Keshan Disease Endemic and Non-endemic Regions in China.

Few nationwide investigations on hair selenium (Se) and Keshan disease (KD) have been conducted. KD is closely associated with Se deficiency. Hair Se is an important biomarker for selenium nutrition. This research aimed to provide evidence for assessment of KD prevention, control, and elimination at the molecular level from the etiological perspective of selenium nutrition. The hair Se of the residents living in the KD endemic and non-endemic areas were determined through atomic fluorescence spectrometer. The median of the hair Se levels of the inhabitants living in KD endemic counties was significantly lower than that in KD non-endemic counties (0.34 vs 0.39 mg/kg, U = -10.03, P < 0.0001). The proportion of Se-deficient or Se-marginal residents in KD endemic counties was significantly higher than that in KD non-endemic counties (56.9% vs 36.6%, U = -9.57, P < 0.0001). The medians of the hair Se levels in KD endemic provinces of Shannxi, Heilongjiang, and Gansu were the lowest (0.35mg/kg), and in the category of Se-marginal status. The hair Se level featured a positive Spearman correlation with per capita disposable income (rs = 0.20, P < 0.0001). In conclusion, the median of the hair Se contents of residents living in KD endemic counties was significantly lower than that in KD non-endemic counties. The hair Se contents of nearly 57% of inhabitants living in KD endemic regions were in Se-deficient or Se-marginal status. The KD endemic provinces of Shannxi, Heilongjiang, and Gansu should be given high priority in KD prevention and control.

Morphological characterization, hazardous metal contamination, source identification, and health risk assessment of the fine road dust from Dachang mining area, China.

Dachang mining area in China is known as "paradise for mineralogists" due to its most reserves of Sn, Sb, Pb, and Zn non-ferrous metal resources; thus, its evaluation for heavy metal assessment and consequent health risk is unavoidable. Sixty road dust samples were collected from study area to explore pollution level, ecological, and health risks from heavy metals and were analyzed by an inductively coupled plasma optical emission spectrometer and atomic fluorescence spectrometer. The results showed that average concentration of all the heavy metals in road dust in both mining and residential areas were remarkable higher than its corresponding background values, the former being more severe, except for Cr and Co. The morphological investigation showed that most of the particles were much less than 100μm illustrating fine part of the road dust samples. Based on integrated pollution indices, Cd, Sb, As, Zn, and Pb were extremely contaminated and exceeded hundred times of the maximum risk value. The health risk assessment revealed substantially higher carcinogenic and non-carcinogenic risks to children and adult. Highest non-carcinogenic risk resulted from arsenic in mining and residential area with HQing of 644.56 and 267.94 respectively (standard HQ ≥ 1) while carcinogenic risk to children (1.94E + 00) which greatly exceeded from the threshold value of (1.0E-4). Sb, Cd, and Pb also posed carcinogenic and non-carcinogenic risk in road dust which is caused by excessive mining activities and heavy vehicle movement in the study area.

Dissolved Potentially Toxic Elements (PTEs) in Relation to Depuration Plant Outflows in Adriatic Coastal Waters: A Two Year Monitoring Survey

The Adriatic Sea is vulnerable to pollution due to its low bathymetry, intense industrial activity, and tourism. In this context, a good depuration plant activity could play a key role for the maintenance of a good environmental quality. In the framework of the AdSWiM project, “Managed use of treated urban wastewater for the quality of the Adriatic Sea”, a study on dissolved potentially toxic element (PTE) levels was carried out to assess the impact of treated urban wastewaters on the quality of the bathing waters in the Adriatic Sea during the 2019 and 2020 summer period. In the present study, three areas along the Italian–Croatian coastline (Gulf of Trieste, Zadar, and Split) were identified for the monitoring of five depuration plant (DP) outflows. Water samples were collected after the treatment inside the DPs, and coastal seawater was sampled in the proximity of the discharging pipelines. Dissolved Hg, Cd, and As levels were determined with an atomic fluorescence spectrometer. Results did not show statistically significant differences between treated wastewater and seawater samples (Hg 10 ± 6 and 10 ± 4, Cd 14 ± 6 and 21 ± 8, As 610 ± 176 and 687 ± 140 ng L−1, respectively), while the geographical area and the seasonality affected the PTE concentration. Furthermore, the levels detected were lower than the European and national limits, indicating a good environmental status of the northern Adriatic Sea waters. The determination of further parameters (nutrients, microbiological indicators) must be investigated to identify possible synergistic effects. However, our results demonstrate the efficiency of DPs investigated, underlining the importance of the wastewater treatment for the protection of the Adriatic Sea.

Shipboard Determination of Arsenite and Total Dissolved Inorganic Arsenic in Estuarine and Coastal Waters with an Automated On-Site-Applicable Atomic Fluorescence Spectrometer

Shipboard Determination of Arsenite and Total Dissolved Inorganic Arsenic in Estuarine and Coastal Waters with an Automated On-Site-Applicable Atomic Fluorescence Spectrometer

The ultrathin palladium nanosheets for sensitive and visual Hg2+ detection in the food chain

The detection of mercury, one of the ten most dangerous chemicals, is significant to provide helpful information for assessing mercury toxicity and health risks. However, it is a challenge to explore simple, sensitive, accurate, and cheap Hg2+ detection methods. Noble metal nanomaterials are used for Hg2+ detection by the colorimetric method widely. Still, the pure noble metal materials’ detection limit of Hg2+ is high, and sensitivity enhancement usually requires further complex modification. Here, we use a facile one-step route to synthesize ultra-thin two-dimensional palladium nanosheets (PdNS), which have high selectivity and sensitivity for Hg2+ detection by colorimetric method with a low detection limit (0.55 ppb). The detection of Hg2+ by PdNS involves multiple mechanisms, including the formation of amalgam and PdO to improve the peroxidase-mimic activity of PdNS and PdNS motor function to increase its collision probability with the detection reactant. The PdNS can be used to detect Hg2+ in various actual samples. The detection results are highly consistent with the data obtained by the atomic fluorescence spectrometer (AFS). Then, we developed a Hg2+ detection kit, which can realize simple, sensitive, and accurate Hg2+ detection by naked eye or cellphone at a meager cost (0.3 dollars each sample).

A software system for dispersive atomic fluorescence spectrometry based on UV digital micromirror device.

A dispersive atomic fluorescence spectrometer based on a UV digital micromirror device (UV-DMD-AFS) has been proposed by our team for attenuating spectral and scattering interferences. Software is nontrivial for the automation of component control and sample analysis in the new instrument. In this work, the software was developed using the C# programming language together with multi-threading and combined with the SQLite database, which consists of component control and data acquisition, database, wavelength initialization, and real-time interference reduction module. To realize the accurate analysis of the trace heavy metal concentration, the spectral interference was avoided by measuring the non-interference wavelength, and the scattering interference was eliminated by the real-time proportional coefficient method. The microsecond rotation speed of the DMD is the key to achieving real-time reduction. The concentration of arsenic in Water Quality (GSB 07-3171-2014) was detected to validate the practicability of the software with the concentration deviation of 0.02 ng/mL.

Comparison of Uncertainty Evaluation for the Determination of Mercury Content in Dictyophora by Automatic Mercury Analyzer and Atomic Fluorescence Spectrometer

The content of mercury in Dictyophora was determined by automatic mercury analyzer and atomic fluorescence spectrometer. The main sources of uncertainty were analyzed and the main uncertainty components were calculated by establishing mathematical model, and the synthetic uncertainty and extended uncertainty were obtained, and the uncertainties results were compared. Results showed that, the expanded uncertainties of these two methods were 0.006 and 0.002 mg/kg (k=2), when the determination results of mercury were 0.050 mg/kg.This study might provide a guideline for uncertainty evaluation for determining mercury in edible fungus by automatic mercury analyzer and atomic fluorescence spectrometry.

Health risk assessment and bioaccumulation of heavy metals in Procambarus clarkii from six provinces of China.

Contamination with heavy metals in wild red swamp crayfish (Procambarus clarkii) from 7 different geographical areas in six provinces of China (Hubei, Hunan, Jiangxi, Anhui, Jiangsu, and Shandong) was evaluated. Concentrations of chromium (Cr), arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg) in the abdominal muscle, gonad, and hepatopancreas were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic fluorescence spectrometer (AFS). Except for the Cd content in the hepatopancreas, the contents of selected heavy metals in three different tissues were significantly lower than the proposed limits provided by United States Environmental Protection Agency (USEPA). The maximum accumulations of Cd and Pb were in the hepatopancreas, while the maximum accumulation of As was in the gonad, and the maximum accumulations of Hg and Cr were in the abdominal muscle. The highest contents of Cr, Hg, and Pb were all detected in Dongting Lake, Hunan, which was consistent with the trend of the metal pollution index (MPI). Risk value of the target hazard quotient (THQ) was below 1.0, suggesting that the intake of selected heavy metals through crayfish consumption would not pose a significant health risk to consumers.

The Interactions Between Antibiotic Resistance Genes and Heavy Metal Pollution Under Co-Selective Pressure Influenced the Bio-Enzyme Activity.

The spread of antibiotic resistance genes (ARGs) has brought potential risks to public health. However, the interactions between heavy metals and ARGs, as well as their potential effect on bio-enzyme activity under the pressure of co-selectivity in soil still remain poorly understood. In this work, the distribution characteristics and the co-selective relationship of 28 ARGs and eight heavy metals in soil in a dairy farm were visualized via the geographic information system (GIS) technique. Eight kinds of heavy metals were detected by an atomic fluorescence spectrometer and atomic absorption spectrophotometer, which were further evaluated via the single factor pollution index value. The GIS analysis showed that arsenic (As) was the key element responsible for soil pollution, which was found to be positively related to soil depths. The top three comprehensive scores of ARGs ranked the orders of sul2 > tetX > blaTEM, indicating the high potential of risk caused by these genes in the soil environment. In addition, the functional predications performed with the 16 SrDNA sequencing data based on the KEGG database indicated that the sulfonamides in soil involved multiple pathways, especially the metabolism, transport and catabolism, and membrane transport processes. This suggested that most bio-enzymes were found to be expressed in low activities in different pathways. Significant correlations were observed between the heavy metals and ARGs (p < 0.05), particularly between the ARGs and As, Cu, Ni, Pb, and Zn (p < 0.01). This study offers deep insights into the potential interactions between heavy metals and ARGs in soil and provides guidance for the fabrication of enzyme-based smart materials for soil remediation in dairy farms.

Mercury contamination at Vembanad Lake and near-shore regions in the southwest coast of India

Mercury (Hg) contamination in aquatic systems is a universal concern because of its persistence, bioaccumulation, toxicity, and trans-boundary nature. The current study focuses on monitoring the fate and transport of Hg in aquatic matrices such as water, interstitial water, sediment and fish in a tropical coastal ecosystem. The cold vapour atomic fluorescence spectrometer was used for the Hg analysis. The study assessed the fractionation of Hg and its methylation potential in sediments. The high Hg concentration in fish tissues showed the ineffectiveness of biogeochemical control over the methyl Hg mobility and bioavailability through the food web. Research results indicate that the accumulation potential of Hg subsequently increases along the food chain. The conducive physico-chemical environment at the sediment–water interface supports chemical transformations/transport of Hg from one matrix to the next. The fate of Hg in the lake has also been discussed based on the data generated.

Silver nanoparticles protect against arsenic induced genotoxicity via attenuating arsenic bioaccumulation and elevating antioxidation in mammalian cells

Arsenic (As) and its compounds have been classified as Group I carcinogenic agents by the International Agency for Research on Cancer (IARC); however, there is few specific and efficient antidotes used for As detoxification. The present study aimed to investigate the protective effects of silver nanoparticles (AgNPs) at non-toxic concentrations on As(Ⅲ) induced genotoxicity and the underlying mechanism. Our data showed that AgNPs pretreatment significantly inhibited the generation of phosphorylated histone H2AX (γ-H2AX, marker of nuclear DNA double strand breaks) and the mutation frequencies induced by As(Ⅲ) exposure. Atomic fluorescence spectrometer (AFS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis revealed that the intracellular accumulation of As(Ⅲ) in human-hamster hybrid AL cells was declined by AgNPs via suppressing the expression of specific As(Ⅲ)-binding protein (Gal-1). Moreover, the activities of antioxidant enzymes were greatly up-regulated by AgNPs, which eventually inhibited the generation of reactive oxygen species (ROS) induced by As(Ⅲ) and the downstream stress-activated protein kinases/c-Jun amino-terminal kinases (SAPK/JNK) signaling pathway. These results provided clear evidence that AgNPs dramatically suppressed the genotoxic response of As(Ⅲ) in mammalian cells via decreasing As(Ⅲ) bioaccumulation and elevating intracellular antioxidation, which might provide a new clue for AgNPs applications in As(Ⅲ) detoxification.

Antibacterial mechanism for inactivation of E. Coli by AgNPs@polydoamine/titania nanotubes via speciation analysis of silver ions and silver nanoparticles by cation exchange reaction

In this method, silver nanoparticles (AgNPs) were anchored on titania nanotubes (TNT) surface by chelation of polydopamine (PD) to generate an AgNPs@polydopamine/titania nanotubes (TPAS). To reveal the antibacterial mechanism of TPAS, a speciation analysis of silver ion (Ag+) and AgNPs was developed based on cation exchange reaction (CER). Owing to only the Ag+ can exchange the Cd2+ in the CdTe quantum dots (QDs), the speciation of Ag+ and AgNPs was realized via detecting the Cd2+ for the indirect but ultrasensitive detection of Ag+ by hydride generation (HG)-atomic fluorescence spectrometer (AFS). The limit of detections (LODs) of Ag+ and AgNPs were 0.0001 ng mL−1. Relative standard deviations (n = 7) are better than 2.2% at a concentration of 0.02 ng mL−1 Ag+. Due to this strategy, the trace AgNPs and Ag+ in antibacterial assay were accurately detected. The results show AgNPs anchored on TPAS predominantly contributed to bactericidal action by contact-killing. Ag+, released from TPAS, synergistically increased the antibacterial activity by release-killing. The proposed method has been successfully utilized for inactivation of E. Coli to explore the antibacterial mechanisms of AgNPs.