Design, Fabrication, and Applications of SERS Substrates for Food Safety Detection: Review.

Sustainable and safe food is an important issue worldwide, and it depends on cost-effective analysis tools with good sensitivity and reality. However, traditional standard chemical methods of food safety detection, such as high-performance liquid chromatography (HPLC), gas chromatography (GC), and tandem mass spectrometry (MS), have the disadvantages of high cost and long testing time. Those disadvantages have prevented people from obtaining sufficient risk information to confirm the safety of their products. In addition, food safety testing, such as the bioassay method, often results in false positives or false negatives due to little rigor preprocessing of samples. So far, food safety analysis currently relies on the enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), HPLC, GC, UV-visible spectrophotometry, and MS, all of which require significant time to train qualified food safety testing laboratory operators. These factors have hindered the development of rapid food safety monitoring systems, especially in remote areas or areas with a relative lack of testing resources. Surface-enhanced Raman spectroscopy (SERS) has emerged as one of the tools of choice for food safety testing that can overcome these dilemmas over the past decades. SERS offers advantages over chromatographic mass spectrometry analysis due to its portability, non-destructive nature, and lower cost implications. However, as it currently stands, Raman spectroscopy is a supplemental tool in chemical analysis, reinforcing and enhancing the completeness and coverage of the food safety analysis system. SERS combines portability with non-destructive and cheaper detection costs to gain an advantage over chromatographic mass spectrometry analysis. SERS has encountered many challenges in moving toward regulatory applications in food safety, such as quantitative accuracy, poor reproducibility, and instability of large molecule detection. As a result, the reality of SERS, as a screening tool for regulatory announcements worldwide, is still uncommon. In this review article, we have compiled the current designs and fabrications of SERS substrates for food safety detection to unify all the requirements and the opportunities to overcome these challenges. This review is expected to improve the interest in the sensing field of SERS and facilitate the SERS applications in food safety detection in the future.

QuEChERS sample pre-processing with UPLC-MS/MS: A method for detecting 19 quinolone-based veterinary drugs in goat's milk.

We develop and validate a method for the rapid determination and identification of 19 quinolones in goat's milk by combining the QuEChERS technique with ultra-performance liquid chromatography-tandem mass spectrometry. Plackett-Burman and Central Composite Design methods were used to select the parameters that best promote the extraction efficiency, which led to extraction with acetonitrile/5% formic acid, followed by phase separation with sodium citrate, disodium hydrogen citrate, Na2SO4, and NaCl as optimal. The supernatant was then extracted and cleaned by dispersive solid-phase extraction using C18 and Na2SO4 aided by low-temperature clean-up. The method was validated, with limits of quantification (LOQs) of 5 ppb, specificities of 1/5 LOQ, linearities (R2) > 0.9853, recoveries of 73.4-114.2%, repeatabilities < 15.0%, and intermediate precisions < 13.6%. The developed method was suitable for the routine analysis of quinolone residues in goat's milk and was used to test 10 goat milk samples produced in Taiwan.

Novel strategy for food safety risk management and communication: Risk identification for benzoic acid residues in pickled vegetables.

Benzoic acid (BA) is widely used as an antimicrobial preservative to prolong the shelf-life of pickled vegetables. A method for rapidly determining the BA content in forty pickled vegetable samples was developed by coupling ultrasonic extraction with surface-enhanced Raman scattering (SERS) and an adaptive iteratively reweighted penalized least-squares (AirPLS) algorithm. The results obtained with this method were compared and correlated with those from high-performance liquid chromatography measurements. Amplification of the Raman scattering via the SERS effect was induced by gold nanoparticles (AuNPs) when BA was irradiated with a 785 nm laser. The AirPLS algorithm was used to reduce the background interference signal, which was also amplified. The amplified Raman scattering effect of BA in the pickled vegetables displayed a positive and significant correlation with the HPLC concentration of BA, with high reproducibility. For HPLC determination of the concentration of BA in the range of 0-820 ppm, the BA monomer's intensity of the 944-1,005 cm-1 and 1,366-1,373 cm-1 peaks, and BA dimer's intensity of the 1,025 cm-1 and 1,465-1,482 cm-1 peaks in the SERS spectrum were respectively converted to the Z-ratio BA monomer and Z-ratio BA dimer standard scores by Z-Score conversion. The sum's (Z-ratio BA monomer + Z-ratio BA dimer) sensitivity was 100%, and specificity was 90.9% by receiver operating characteristic curve. This study found that a Raman spectroscopy-based monitoring method can be one of the fastest screening inspection options that can complete an analysis within a short period of time and produce reliable results. This approach is particularly cost-effective, which makes it suitable for the initial screening of raw materials and provides an effective management strategy easy to communicate with food safety officials.

Estrogenic effects in the influents and effluents of the drinking water treatment plants.

Estrogen-like endocrine disrupting compounds (EEDC) such as bisphenol A, nonylphenol, and phthalic acid esters are toxic compounds that may occur in both raw- and drinking water. The aim of this study was to combine chemical- and bioassay to evaluate the risk of EEDCs in the drinking water treatment plants (DWTPs). Fifty-six samples were collected from seven DWTPs located in northern-, central-, and southern Taiwan from 2011 to 2012 and subjected to chemical analyses and two bioassay methods for total estrogenic activity (E-Screen and T47D-KBluc assay). Among of the considered EEDCs, only dibutyl phthalate (DBP) and di (2-ethylhexyl) phthalate (DEHP) were detected in both drinking and raw water samples. DBP levels in drinking water ranged from

An AhR-Luciferase Adenovirus Infection System for Rapid Screening of Dioxins in Soils.

Our goal was to develop a fast-screening method for measuring dioxin levels in soils. The adenovirus (Ad)-dioxin-responsive (DR) bioassay system (AdEasy-6XDRE-TATA-Luc) combined with a fast-cleanup system was examined under conventional conditions (i.e., with incubation at 37°C) and three alternative conditions [incubation at 37°C with addition of phorbol-12-myristate-13-acetate (PMA), incubation at 33°C, and incubation at 33°C with addition of PMA]. The best conditions for carrying out the Ad-DR bioassay was 33°C and no addition of PMA. The background level of soil dioxins determined by the chemical assay [6.49 ng I-TEQ/kg dry weight (dw)] was well correlated (Pearson's r = 0.873, p < 0.001) with that by the Ad-DR bioassay [expressed in ng bioanalytical equivalents (BEQ) 81.1 ng BEQ/kg dw] (n = 17). When surveyed in contaminated soil samples (n = 114) from industrial areas by the Ad-DR bioassay, dioxin levels were 117, 102, 98.5, and 112 ng BEQ/kg dw, respectively, in northern, central, southern, and eastern Taiwan.

Combination of a fast cleanup procedure and a DR-CALUX® bioassay for dioxin surveillance in Taiwanese soils.

Our goal was to determine dioxin levels in 800 soil samples collected from Taiwan. An in vitro DR-CALUX® assay was carried out with the help of an automated Soxhlet system and fast cleanup column. The mean dioxin level of 800 soil samples was 36.0 pg-bioanalytical equivalents (BEQs)/g dry weight (d.w.). Soil dioxin-BEQs were higher in northern Taiwan (61.8 pg-BEQ/g d.w.) than in central, southern, and eastern Taiwan (22.2, 24.9, and 7.80 pg-BEQ/g d.w., respectively). Analysis of multiple linear regression models identified four major predictors of dioxin-BEQs including soil sampling location (ß = 0.097, p < 0.001), land use (ß = 0.065, p < 0.001), soil brightness (ß = 0.170, p < 0.001), and soil moisture (ß = 0.051, p = 0.020), with adjusted R2 = 0.947 (p < 0.001) (n = 662). An univariate logistic regression analysis with the cut-off point of 33.4 pg-BEQ/g d.w. showed significant odds ratios (ORs) for soil sampling location (OR = 2.43, p < 0.001), land use (OR = 1.47, p < 0.001), and soil brightness (OR = 2.83, p = 0.009). In conclusion, four variables, including soil sampling location, land use, soil brightness, and soil moisture, may be related to soil-dioxin contamination. Soil samples collected in northern Taiwan, and especially in Bade City, soils near industrial areas, and soils with darker color may contain higher dioxin-BEQ levels.

Atmospheric concentrations of persistent organic pollutants over the Pacific Ocean near southern Taiwan and the northern Philippines.

This study investigates the atmospheric occurrence of persistent organic pollutants (POPs) over the Pacific Ocean near southern Taiwan and the northern Philippines. We determined sixty-six compounds, including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (DLPCBs), polybrominated diphenyl ethers (PBDEs), as well as polychlorinated diphenyl ethers (PCDEs), polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), and polybrominated biphenyls (PBBs), in air samples simultaneously collected from the offshore oceanic atmosphere (n=6) and over a rural area (n=2). We calculated the atmospheric World Health Organization 2005 toxic equivalency levels (WHO2005-TEQ), for the total dioxin-like POPs, including PCDD/Fs, DLPCBs, and PBDD/Fs, being 0.00612 pg WHO2005-TEQ/m(3) and 0.0138 pg WHO2005-TEQ/m(3) over the ocean and land, respectively. We found unexpected lower averaged atmospheric PBDE concentrations in the rural area (15.9 pg/m(3)) than over the ocean (31.1 pg/m(3)) due to higher levels of the BDE209 congener, although the difference was not statistically significant. We have compared and reported our field results with previously published datasets over the global oceans, which suggest PCBs and PBDEs are the dominant chemical contaminants in the global oceanic atmosphere among these halogenated POPs (e.g. PCBs and Σdi-hepta PBDEs could be found in the range of 0.09-48.7 and 8.07-94.0 pg/m(3), respectively, including our dataset). However, there are still very few investigations on the global atmospheric levels of PBDD/Fs, PCDEs and PBBs and our data sums to these earlier studies. Finally, we point out that the halogenated POPs originated from Taiwan or the continental East Asia which could easily reach remote ocean sites via atmospheric transport.

Use of a highly sensitive recombinant hepatoma cell method to determine dioxin concentrations in samples of fish and crab from a hotspot area.

A new and easy fast-screening test (the Ad-DR (adenoviral vector-dioxin response) bioassay) for dioxins in biological samples from highly dioxin-contaminated areas was developed. The aryl-hydrocarbon-receptor (AhR) reporter system was utilized to transport a dioxin-responsive-element (DRE) via an adenovirus vector into rat hepatoma (H4IIE) cells before each experiment; these DRE-H4IIE cells were utilized in the Ad-DR bioassay. Biological extracts were simultaneously analyzed by the Ad-DR bioassay and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). A good correlation was found between the results of the HRGC/HRMS assay and those of the Ad-DR bioassay (R(2) = 0.920, p < 0.001). The bio-analytical equivalent (BEQ) value found in fish or crab caught in the abandoned pentachlorophenol plant (AP) was extremely high compared with the BEQ in fish or crab caught in two rivers nearby this abandoned plant. Dioxins were more heavily bioaccumulated in fish viscera than in fish muscles or in the whole fish. Two-way analysis of variance tests identified the significant effects of fish collection site, fish or crab tissue sample and the interaction between them on dioxin levels in the tissues of these aquatic animals. In conclusion, the Ad-DR bioassay is a useful tool to determine dioxin levels in samples of fish and crab. Compared with fish tissues, where a sample is taken (in the PCP plant or nearby rivers) is the most important factor to determine bioaccumulation of dioxins in fish.

An improved AhR reporter gene assay for analyzing dioxins in soil, sediment and fish.

Our goal was to develop a fast-screening bioassay to determine dioxin levels in the environmental and biological samples from dioxin-contaminated areas. Our original dioxin-responsive-element (DRE)-driven luciferase bioassay (using Huh7-DRE-Luc cells) was modified by reducing the incubation temperature of the cell culture from 37 to 35°C and by adding phorbol-12-myristate-13-acetate, and the modified bioassay was used to examine samples from soil, sediment, and fish. The results of this bioassay were shown to be significantly related to those of the high-resolution gas chromatography/high-resolution mass spectrometry assay of dioxins. The correlative equation was: log (PCDD/Fs I-TEQs) = 1.19 × log (BEQs) - 1.15 with R(2) = 0.95 (p < 0.001).

Fast cleanup system combined with a dioxin-responsive element-driven luciferase bioassay for analysis of polychlorinated dibenzo-p-dioxins/furans in sediments and soils.

A green technique was designed for assessing toxic equivalence (TEQ) levels of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) in sediments and soil from dioxin-contaminated areas. This technique combines a fast cleanup system with a dioxin-responsive-element (DRE)-driven luciferase bioassay. Samples from sediment (n = 10) and soil (n = 11) were analyzed with the technique; levels of PCDD/Fs ranged from 75.1 to 2,670 ng DRE-driven luciferase activity (DL)-TEQ/kg dry weight (d.w.). Significant correlations were found between DL-TEQs (by the bioassay) and PCDD/F WHO-TEQs (by HRGC/HRMS). DL-TEQs is significantly correlated with WHO-TEQs of 2,3,7,8-TCDD and 1,2,3,7,8-PeCDD using a multiple stepwise linear regression model (adjusted R(2) = 0.962, p < 0.001).

Breast-milk levels of polybrominated diphenyl ether flame retardants in relation to women's age and pre-pregnant body mass index.

The aim of the present study was to determine associations between the occurrence of PBDEs in breast milk of women and their demographic parameters. Participants were randomly recruited from the general population in southern Taiwan. Thirty two breast milk samples were collected and subsequently 30 congeners of PBDEs were analyzed using a high resolution gas chromatograph with a high resolution mass spectrometer. The mean and median of SigmaPBDEs were 3.54 and 3.31 ng/g lipid, respectively. SigmaPBDE levels in breast milk were not significantly correlated with age and pre-pregnant BMI of Taiwanese mothers. We did find, however, that the higher hexaBDE level was significantly related to older age (>29 years). Higher levels of SigmaPBDEs and higher brominated PBDEs, such as nonaBDEs and decaBDE, had slightly but not significantly negative correlations with lower pre-pregnant BMI (< or =21 kg/m(2)). There were no significant differences in PBDE levels among parity and ethnic groups. SigmaPBDE levels in Taiwanese breast milk were lower than those reported from the United States or Canada. SigmaPBDE levels of the present study (2007-2008) are significantly lower than those found in our previous report (2000-2001). Although our results were limited by the sampling size, preliminary results suggest the exploratory relations to show positive associations of PBDE homologues (e.g. triBDEs and hexaBDEs) with maternal age. PBDEs pattern of breast milk may have changed after pentaBDEs were stopped to use in Taiwan.

The inhibition effect of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin-induced aryl hydrocarbon receptor activation in human hepatoma cells with the treatment of cadmium chloride.

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), considered as endocrine disruptors, tend to accumulate in fatty tissues. Dioxin-responsive element chemical activated luciferase gene expression assay (DRE-luciferase assay) has been recognized as a semi-quantitative method for screening dioxins for its fast and low-cost as compared with HRGC/HRMS. However, some problems with the bioassay, including specificity, detection variation resulted from different cleanup strategies, and uncertainty of false-negative or false-positive results, remain to be overcome. Cadmium is a prevalent environmental contaminant around the world. This study was aimed to examine the effects of cadmium on the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced activation of aryl hydrocarbon receptor (AhR)-mediated gene expression in human hepatoma cells (Huh7-DRE-Luc cells and Huh7 cells). Ethoxyresorufin-O-deethylase (EROD) and DRE-luciferase assay were employed to determine the enzyme activity of cytochrome P450 1A1 (CYP1A1) and activation of AhR, respectively. The results showed that Cd(2+) levels significantly inhibited the induction of TCDD-induced CYP1A1 and DRE luciferase activation in hepatoma cells. The 50% inhibited concentrations (IC(50)) of CdCl(2) were 0.414 microM (95% confidence interval (C.I.): 0.230-0.602 microM) in Huh7-DRE-Luc cells and 23.2 microM (95% C.I.: 21.7-25.4 microM) in Huh7 cells. Accordingly, prevention of interference with non-dioxin-like compounds in a DRE-luciferase assay is of great importance in an extensive cleanup procedure.

Emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans from a heavy oil-fueled power plant in northern Taiwan.

We measured the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from the flue gas and the ambient atmosphere of a power plant fueled by heavy oil in northern Taiwan. The mean emission concentration and I-TEQ concentration of total PCDD/Fs were 0.292 ng/Nm(3) and 0.016 ng I-TEQ/Nm(3), respectively. All PCDD/F emission concentrations in the flue gas were supposed to meet the Environmental Protection Administration Executive Yuan, R.O.C. standard (1.0 ng I-TEQ/Nm(3) from 2008). Furthermore, the mean I-TEQ concentration in the ambient atmosphere was 0.011 pg I-TEQ/Nm(3), which was much lower than the environmental quality standards for dioxins in Japan (0.6 pg TEQ/Nm(3)). Also, the PCDD/F emission factor was 0.188 ng I-TEQ/L fuel, which was comparable to the data issued in US EPA [EPA, Locating and estimating air emissions from sources of dioxins and furans, Office of Air Quality Planning and Standards, Research Triangle Park, NC, DCN No. 95-298130-54-01, 1997] (0.2 ng I-TEQ/L of fuel). Also, the result of the correlations of PCDD/Fs and operational parameters illustrated that the positively significant correlation (r=0.502, p=0.048) was found only between PCDD/Fs (I-TEQ) and the flue gas emission temperature (125-157 degrees C). However, PCDD-TEQ/PCDF-TEQ ratios were statistically significantly associated with the decreased flue gas flow (r=-0.659, p=0.006), moisture (r=-0.612, p=0.012) and flue gas temperature (r=-0.503, p=0.047). For proper environmental management of dioxins, it is necessary to establish a complete emission inventory of PCDD/Fs, and, in particular, the government should pay more attention to power plants to address the information shortage.