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    Sucrose capped gold nanoparticles as a plasmonic chemical sensor based on non-covalent interactions: Application for selective detection of vitamins B and B in brown and white rice food samples. Shrivas Kamlesh,Nirmalkar Nidhi,Thakur Santosh Singh,Deb Manas Kanti,Shinde Sandip S,Shankar Ravi Food chemistry We report simple and selective method for detection of vitamins B and B in brown and white rice samples using localized surface plasmon resonance (LSPR) of sucrose capped gold nanoparticles (AuNPs) as a chemical sensor colorimetrically. Here, detection is based on the color change of AuNPs from pink to blue followed by a red shift of LSPR absorption band in UV-vis region with the addition of vitamins B and B into the NPs solution A good linear range was observed in the range of 25-1000 ngmL with detection limit of 8 ngmL for B and 50-1000 ngmL with detection limit of 15 ngmL for vitamins B. The employment of AuNPs for detection of B and B vitamins in rice food samples showed remarkable abilities in terms of the simplicity, low cost, stability, reproducibility and sensitivity. 10.1016/j.foodchem.2018.01.002
    Fluorescence immunoassay for multiplex detection of organophosphate pesticides in agro-products based on signal amplification of gold nanoparticles and oligonucleotides. Zhang Chan,Jiang Zejun,Jin Maojun,Du Pengfei,Chen Ge,Cui Xueyan,Zhang Yudan,Qin Guoxin,Yan Feiyan,Abd El-Aty A M,Hacimüftüoğlu Ahmet,Wang Jing Food chemistry Herein, we developed a multi-analyte fluorescence immunoassay for detection of three organophosphate pesticides (triazophos, parathion, and chlorpyrifos) in various agro-products (rice, wheat, cucumber, cabbage, and apple) using fluorescently labeled oligonucleotide and gold nanoparticle (AuNP) signal amplification technology. The AuNP probes for the three analytes were constructed by simultaneously modifying the corresponding antibodies and fluorescently labeled oligonucleotides on the probe surface. Three fluorophores (6-FAM, Cy3, and Texas red) with high fluorescence intensity and little overlap of excitation/emission wavelengths were selected. The method showed satisfactory linearity for triazophos, parathion, and chlorpyrifos in the ranges of 0.01-20, 0.05-50, and 0.5-1000 μg/L, respectively. For the 3 analytes, the limits of detection (LODs) were 0.007, 0.009, and 0.087 μg/L, respectively. The average recoveries were 77.7-113.6%, with relative standard deviations (RSDs) of 7.1-17.1% in various food matrices. The proposed method offers great potential in food safety surveillance, and could be used as well as a reference for multi-residue analysis of other small-molecule contaminants. 10.1016/j.foodchem.2020.126813
    Detection of Malachite Green using a colorimetric aptasensor based on the inhibition of the peroxidase-like activity of gold nanoparticles by cetyltrimethylammonium ions. Zhao Chen,Hong Cheng-Yi,Lin Zheng-Zhong,Chen Xiao-Mei,Huang Zhi-Yong Mikrochimica acta A specific and sensitive colorimetric aptasensor is described for the determination of Malachite Green (MG). It is exploiting the inhibition of the peroxidase-like activity of gold nanoparticles (AuNPs). The AuNPs act as enzyme mimics that catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by HO to yield a dark blue solution. The catalytic activity is inhibited by hexadecyl trimethyl ammonium ion, specifically by cetyltrimethylammonium bromide (CTAB), which causes the aggregation of AuNPs. If a (negatively charged) RNA-aptamer against MG is added, it binds to the positively charged CTAB and prevents aggregation. This enhances the enzyme mimicking activity of the AuNPs and leads to the formation of a dark blue solution. However, in the presence of MG, the aptamer binds to MG, and leads to the aggregation of AuNPs again. The aggregated AuNPs possess a light blue color. A colorimetric method (best performed at 650 nm) was work out that can detect MG in a concentration range from 10 to 500 nmol L. The detection limit based on 3σ/k criterion is 1.8 nmol L. The assay is highly specific and accurate. Recoveries from spiked real samples (aquaculture water) ranged from 80% to 120%. Graphical abstract Based on the inhibition of cetyltrimethyal ammonium ion and the enhancement of RNA-aptamer, the differences of the peroxidase-like activities of AuNPs can be greatly enlarged with and without MG, by which a colorimetric aptasensor can be constructed for the detection of Malachite Green (MG). 10.1007/s00604-019-3436-3
    Sensitive, simple and rapid colorimetric detection of malachite green in water, salmon and canned tuna samples based on gold nanoparticles. Heleyel Mina,Elhami Shahla Journal of the science of food and agriculture BACKGROUND:Malachite green is used in aquaculture and fisheries as a fungicide and antiseptic and it is also used in industry as a dye. However, malachite green is carcinogenic and highly toxic for humans and animals. In this study, a spectrophotometric method was developed to detect malachite green. The method was based on the surface plasmon resonance property of gold nanoparticles and interaction between malachite green and gold nanoparticles. RESULTS:Malachite green-gold nanoparticles were rapidly aggregated in the acidic medium; as a result, a color change from red to blue was observed, which was easily detectable by the naked eye. The absorption ratio (A623/A520) of the gold nanoparticles in an optimized system exhibited a linear correlation with malachite green concentration. The method detection limit and linear range were 3 and 50-350 ng mL , respectively. The method was applied successfully to detect malachite green in different samples. CONCLUSION:The method was simple and rapid to detect malachite green. The most important advantages of the method are the possibility of malachite green determination with very good accuracy and sensitivity using a simple UV-visible spectrometer without any expensive or sophisticated instrumentation and also the versatility of real samples. © 2018 Society of Chemical Industry. 10.1002/jsfa.9387
    Voltammetric detection of carbofuran determination using screen-printed carbon electrodes modified with gold nanoparticles and graphene oxide. Jirasirichote Apapond,Punrat Eakkasit,Suea-Ngam Akkapol,Chailapakul Orawon,Chuanuwatanakul Suchada Talanta Carbofuran is a highly toxic pesticide that is heavily used in agriculture due to its high effectiveness and low cost. Improved methods that are simpler and lower cost are needed for carbofuran detection in food and agricultural samples. Herein, we describe the development of a unique electrochemical method for carbofuran-phenol, which is the main hydrolysis product of carbofuran. We have successfully developed a highly accurate and precise method in a portable size using a screen-printed carbon electrode (SPCE) that is modified with graphene oxide (GO) and gold nanoparticles (AuNPs). Consequently, the developed electrode is highly sensitive to and selective for carbofuran. Using the central composite design (CCD) approach, we optimized the method for analysis parameters including the electrode surface loadings of GO and AuNPs as well as the working solution pH. The method exhibited a wide linear range of 1-250µM for analyte detection using differential pulse voltammetry (DPV) on AuNPs/GO-SPCE under the optimized conditions. The limits of detection and quantitation were 0.22 and 0.72µM, respectively. In addition, we also report the application of the method for carbofuran determination in real cucumber and rice samples. This sensitive and selective carbofuran detection method is very promising for simple and low cost analysis in real agricultural fields. 10.1016/j.talanta.2017.07.050
    Highly sensitive visual detection of amantadine residues in poultry at the ppb level: A colorimetric immunoassay based on a Fenton reaction and gold nanoparticles aggregation. Yu Wenbo,Zhang Tingting,Ma Mingfang,Chen Chaochao,Liang Xiao,Wen Kai,Wang Zhanhui,Shen Jianzhong Analytica chimica acta Colorimetric biosensors for the on-site visual detection of veterinary drug residues are required for food control in developing countries and other resource-constrained areas, where sophisticated instruments may not be available. In this study, we developed a highly sensitive immunoassay for amantadine residues in poultry. By introducing a novel signal generation strategy into an indirect competitive immunoassay, a highly sensitive assay for amantadine residues in chicken was achieved for naked eye readout at the part per billion (ppb) level. Signal amplification was achieved in the designed immunoassay by combining conventional indirect competitive enzyme-linked immunosorbent assay, Fenton reaction-regulated oxidation of cysteine, and gold nanoparticle aggregation. Therefore, the cascade reaction remarkably enhanced the assay sensitivity and led to a pronounced color change from red to dark purple in the solution, which could be easily distinguished with the naked eye even at approximately 1 μg kg in poultry muscle. Moreover, the color change can be quantitatively assayed with a classic high-throughput plate reader for contaminated poultry samples. The limit of detection (LOD) was 0.51 nM (0.095 ng mL). The recovery rates for spiked chicken samples ranged from 78% to 84% with relative standard deviations <15%. Therefore, we propose that this immunoassay could be generally applicable for on-site detection in the field of food control. 10.1016/j.aca.2018.04.035
    Endonuclease controlled aggregation of gold nanoparticles for the ultrasensitive detection of pathogenic bacterial DNA. McVey Claire,Huang Fumin,Elliott Christopher,Cao Cuong Biosensors & bioelectronics The development of an ultrasensitive biosensor for the low-cost and on-site detection of pathogenic DNA could transform detection capabilities within food safety, environmental monitoring and clinical diagnosis. Herein, we present an innovative approach exploiting endonuclease-controlled aggregation of plasmonic gold nanoparticles (AuNPs) for label-free and ultrasensitive detection of bacterial DNA. The method utilizes RNA-functionalized AuNPs which form DNA-RNA heteroduplex structures through specific hybridization with target DNA. Once formed, the DNA-RNA heteroduplex is susceptible to RNAse H enzymatic cleavage of the RNA probe, allowing the target DNA to liberate and hybridize with another RNA probe. This continuously happens until all of the RNA probes are cleaved, leaving the nanoparticles unprotected and thus aggregated upon exposure to a high electrolytic medium. The assay is ultrasensitive, allowing the detection of target DNA at femtomolar level by simple spectroscopic analysis (40.7 fM and 2.45fM as measured by UV-vis and dynamic light scattering (DLS), respectively). The target DNA spiked food matrix (chicken meat) is also successfully detected at a concentration of 1.2pM (by UV-vis) or 18.0fM (by DLS). In addition to the ultra-high sensitivity, the total analysis time of the assay is less than 3h, thus demonstrating its practicality for food analysis. 10.1016/j.bios.2016.10.072
    Highly sensitive SERS immunosensor for the detection of amantadine in chicken based on flower-like gold nanoparticles and magnetic bead separation. Ma Mingfang,Sun Jiefang,Chen Yiqiang,Wen Kai,Wang Zhaopeng,Shen Jianzhong,Zhang Suxia,Ke Yuebin,Wang Zhanhui Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association Here we report a novel ultrasensitive surface-enhanced Raman scattering (SERS) immunosensor based on the flower-like gold nanoparticles (AuNFs) and magnetic bead separation for homogeneous detection of amantadine (AMD) in chicken just by one-step. The 5, 5'-dithiobis (2-nitrobenzoicacid) (DTNB) modified AuNFs and N-(1-adamantyl) ethylenediamine (AEDA) conjugated denatured BSA (AEDA-dBSA) was used as the SERS nanoprobe. And the capture probe was anti-AMD monoclonal antibody (mAbs)-functionalized magnetic beads (MNBs-mAbs). An immunoreaction occurred between free AMD and SERS nanoprobe for competing limited binding sites of MNBs-mAbs. This work combined inherent sensitive property of SERS with antibody-antigen highly specificity recognition for the AMD detection. The analytical results showed that the SERS-based immunosensor was sensitive, simple and reliable with a limit of detection (LOD) of 0.005 ng/mL for AMD, which were 2 orders of magnitude better than an enzyme-linked immunosorbent assay based on the same immunoreagents. Analysis of AMD-spiked chicken samples revealed that the developed immunosensor provided accepted recoveries ranging from 74.76%-89.34% with coefficient of variation less than 15.04%. This strategy represents a simple, reliable, and universal approach for detection of chemical contaminants in food samples. 10.1016/j.fct.2018.06.013
    A Colorimetric Sensor for the Visual Detection of Azodicarbonamide in Flour Based on Azodicarbonamide-Induced Anti-Aggregation of Gold Nanoparticles. Chen Zhiqiang,Chen Lian,Lin Ling,Wu Yongning,Fu FengFu ACS sensors Azodicarbonamide (ADA) in flour products can be converted into carcinogenic biurea and semicarbazide hydrochloride after baking. Thus, it is mandatory to determine ADA in flour. We herein developed a colorimetric method for the rapid and visual detection of ADA in flour based on glutathione (GSH)-induced gold nanoparticles (AuNPs) aggregation and specific reaction between ADA and GSH. The GSH can react to AuNPs via Au-SH covalent bond to form a network structure, which leads to AuNPs aggregation to produce color change, whereas ADA can specifically react with GSH to lead to the coupling of two GSH molecules, which makes GSH lose a -SH group and thus decreases the aggregation degree of AuNPs induced by GSH. This provided a platform for field-portable colorimetric detection of ADA. The colorimetric sensor can be used to detect as little as 0.33 μM (38.3 ppb) of ADA by naked eye observation and 0.23 μM (26.7 ppb) of ADA by spectrophotometry within 2 h. The method was successfully used to detect ADA in flour with a recovery of 91-104% and a relative standard deviation (RSD) < 6%. The visual detection limit of sensor is lower than the ADA limitation in flour (45 mg/kg), which makes the sensor a potential approach for the instrument-free visual and on-site detection of ADA in flour. 10.1021/acssensors.8b00705
    Lateral Flow Immunoassay Based on Polydopamine-Coated Gold Nanoparticles for the Sensitive Detection of Zearalenone in Maize. Xu Shaolan,Zhang Ganggang,Fang Bolong,Xiong Qirong,Duan Hongwei,Lai Weihua ACS applied materials & interfaces In this work, polydopamine-coated gold nanoparticles (Au@PDAs) were synthesized by the oxidative self-polymerization of dopamine (DA) on the surface of AuNPs and applied for the first time as a signal-amplification label in lateral flow immunoassays (LFIAs) for the sensitive detection of zearalenone (ZEN) in maize. The PDA layer functioned as a linker between AuNPs and anti-ZEN monoclonal antibody (mAb) to form a probe (Au@PDA-mAb). Compared with AuNPs, Au@PDA had excellent color intensity, colloidal stability, and mAb coupling efficiency. The limit of detection of the Au@PDA-based LFIA (Au@PDA-LFIA) was 7.4 pg/mL, which was 10-fold lower than that of the traditional AuNP-based LFIA (AuNP-LFIA) (76.1 pg/mL). The recoveries of Au@PDA-LFIA were 93.80-111.82%, with the coefficient of variation of 1.08-9.04%. In addition, the reliability of Au@PDA-LFIA was further confirmed by the high-performance liquid chromatography method. Overall, our study showed that PDA coating can chemically modify the surface of AuNPs through a simple method and can thus significantly improve the detection sensitivity of LFIA. 10.1021/acsami.9b08789
    Ultrasensitive electrochemical immuno-sensing platform based on gold nanoparticles triggering chlorpyrifos detection in fruits and vegetables. Talan Anita,Mishra Annu,Eremin Sergei A,Narang Jagriti,Kumar Ashok,Gandhi Sonu Biosensors & bioelectronics Chlorpyrifos (chl) is an organophosphate pesticide extensively used in agriculture and highly toxic for human health. Fluorine doped tin-oxide (FTO) based electrochemical nanosensor was developed for chlorpyrifos detection with gold nanoparticles (AuNPs) and anti-chlorpyrifos antibodies (chl-Ab). AuNPs provides high electrical conductivity and specific resistivity, thus increases the sensitivity of immunoassay. High electrical conductivity of AuNPs reveals that it promotes the redox reaction for better cyclic voltammetry. Based on the intrinsic conductive properties of FTO-AuNPs complex, chl-Ab was immobilized onto AuNPs surface. Under optimized conditions, the proposed FTO based nanosensor exhibited high sensitivity and stable response for the detection of chlorpyrifos, ranging from 1fM to 1µM with limit of detection (LOD) up to 10fM. The FTO-AuNPs sensor was successfully employed for the detection of chlorpyrifos in standard as well in real samples up to 10nM for apple and cabbage, 50nM for pomegranate. The proposed FTO-AuNPs nanosensor can be used as a quantitative tool for rapid, on-site detection of chlorpyrifos traces in real samples when miniaturized due to its excellent stability, sensitivity, and simplicity. 10.1016/j.bios.2018.01.013
    Post-assay growth of gold nanoparticles as a tool for highly sensitive lateral flow immunoassay. Application to the detection of potato virus X. Panferov Vasily G,Safenkova Irina V,Zherdev Anatoly V,Dzantiev Boris B Mikrochimica acta This article demonstrates a new kind of a highly sensitive lateral flow immunoassay (LFIA). It is based on the enlargement of the size of gold nanoparticles (GNPs) directly on the test strip after a conventional LFIA. Particle size enlargement is accomplished through the catalytic reduction of HAuCl in the presence of HO and through the accumulation of additional gold on the surface of the GNPs. To attain maximal enhancement of the coloration of the zone in the test strip and to achieve a minimal background, the concentration of precursors, the pH value, and the incubation time were optimized. GNPs on the test strip are enlarged from 20 to 350 nm after a 1-min treatment at room temperature. The economically important and widespread phytopathogen potato virus X (PVX) was used as the target analyte. The use of the GNP enlargement method results in a 240-fold reduction in the limit of the detection of PVX, which can be as low as 17 pg·mL. The total duration of the assay, including virus extraction from the potato leaves, lateral flow, and the enhancement process, is only 12 min. The diagnostic efficiency of the technique was confirmed by its application to the analysis of potato leave samples. No false positives or false negatives were found. The technique does not depend on specific features of the target analyte, and it is conceivably applicable to numerous GNP-based LFIAs for important analytes. Graphical abstract An enlargement solution (containing HAuCl and HO) was dripped on the strip after common lateral flow immunoassay. Gold nanoparticles on the strip (20 nm) catalyze gold reduction and the formation of larger particles (up to 350 nm), resulting in a 240-fold lower detection limit within 1 min. 10.1007/s00604-018-3052-7
    An ultra-sensitive aptasensor based on carbon nanohorns/gold nanoparticles composites for impedimetric detection of carbendazim at picogram levels. Zhu Chengxi,Liu Dong,Chen Zhi,Li Libo,You Tianyan Journal of colloid and interface science We reported a carbon nanohorns/gold nanoparticles composites-based impedimetric aptasensor for carbendazim (CBZ) detection in lettuce and orange juice at picogram levels. The increased electron-transfer resistance, resulting from the formation of CBZ-aptamer complex, was recorded by electrochemical impedance spectroscopy as the aptasensor response for CBZ. Under the optimal conditions, the proposed aptasensor displayed a linear response for CBZ ranging from 1 to 1000 pg mL with a detection limit of 0.5 pg mL. Noteworthy, the as-developed aptasensor displayed the lowest detection limit for CBZ among the previously reported methods. Common pesticides (atrazine, thiamethoxam, etc.) with 100-fold concentration did not interfere the CBZ detection. For CBZ detection in lettuce and orange juice, satisfactory recoveries were obtained with standard addition method. Statistics demonstrated that no significant differences were found between the data provided by standard HPLC-MS reference method and developed aptasensing method in term of accuracy and precision. We believe that the proposed aptasensor possesses a potential application for CBZ monitoring in agricultural product and food. 10.1016/j.jcis.2019.03.035
    Microwave method synthesis of magnetic ionic liquid/gold nanoparticles as ultrasensitive SERS substrates for trace clopidol detection. Li Hongmei,Yue Xiaxia,Gao Ningning,Tang Jun,Lv Xiaoyi,Hou Junwei Analytical and bioanalytical chemistry Clopidol is one of the most widely used anti-coccidiosis drugs. Its residues in poultry products and the environment pose a serious threat to human health. In this work, microwave-assisted synthesis of magnetic ionic liquid/gold nanoparticles (MIL-Au NPs) as the SERS substrates were first designed for sensitive and reliable determination of clopidol residue in egg samples. The experiment shows that MIL(1-methyl-3-hexyl imidazole ferric tetrachloride ([Cmim]FeCl)) and microwave play a key role in the dispersion and morphology of Au NPs. Under the optimal conditions, the as-prepared MIL-Au NPs were applied to the SERS detection of clopidol in methanol and egg solution and its detection limits can be as low as to 0.5 μg/kg (equal to 0.5 ppb) in both solutions. The standard curves with regression coefficients of 0.9298 and 0.93496 were constructed in the linear range of 100-1000 ppb and 0.5-50 ppb for clopidol in egg solutions. Moreover, satisfactory recoveries (97.5-103.2%) were obtained for egg samples. The developed SERS method provides a way for quantitation of clopidol and can be applied for the convenient, reliable, and highly sensitive detection of antibiotic residues in food and environment, which has great potential in food safety and biological monitoring. Graphical abstract. 10.1007/s00216-020-02588-7
    Visual detection of kanamycin with DNA-functionalized gold nanoparticles probe in aptamer-based strip biosensor. Ou Ying,Jin Xin,Liu Jing,Tian Yaping,Zhou Nandi Analytical biochemistry Kanamycin has been widely used to treat human and animal diseases. The excessive use of kanamycin causes its accumulation in animal-derived foods, and eventually threats human health. In the present study, we develop a lateral flow strip biosensor for fast and sensitive detection of kanamycin. The strip biosensor combines the easy separation of magnetic microspheres (MMS) with target-mediated chain displacement of single-stranded DNA and the capture of the visible DNA-functionalized gold nanoparticles (AuNPs) probe. The presence of kanamycin can competitively bind to the aptamer and release cDNA to the supernatant. The concentration of free cDNA, which is the direct target of the strip, is proportional to the concentration of kanamycin. The capture of DNA-functionalized AuNPs on the test zone of the strip through cDNA-induced hybridization provides a visual detection signal. The assay can be completed within 20 min. The visual detection limit by naked eyes of the strip is 50 nM. A linear detection range of 5-500 nM is derived for quantitative determination, with the detection limit of 4.96 nM (S/N = 3). This lateral flow strip biosensor can quickly and sensitively detect kanamycin in different food samples, which holds great application potential in medicine and daily life. 10.1016/j.ab.2019.113432
    Dual-functionalized gold nanoparticles probe based bio-barcode immuno-PCR for the detection of glyphosate. Guan Naiyu,Li Yansong,Yang Hualin,Hu Pan,Lu Shiying,Ren Honglin,Liu Zengshan,Soo Park Ki,Zhou Yu Food chemistry Glyphosate (GLYP) was the most widely used broad-spectrum herbicide in the world. Herein, a gold nanoparticle (AuNP) probe dual-functionalized with anti-GLYP antibody and double-stranded oligonucleotides was synthesized. An AuNP-based bio-barcode immuno-PCR (AuNP-BB-iPCR) based on the probe was developed for sensitive detection of GLYP in food samples without high-cost and time-consuming experiments. GLYP detection was accomplished with a linear range from 61.1 pg g to 31.3 ng g and a detection limit of 4.5 pg g which was 7 orders of magnitude lower than that of conventional ELISA (70 μg g) developed using the same antibody. The recoveries of GLYP from soybean, cole and maize samples were 99.8%, 102.6% and 103.7%, respectively, and all relative standard deviation values were below 12.9%. The assay time (including food samples preparation) of AuNP-BB-iPCR was 4 h. The proposed AuNP-BB-iPCR exhibits potential for sensitive detection of GLYP in foodstuffs and environment. 10.1016/j.foodchem.2020.128133
    Simple synthesis of a clew-like tungsten carbide nanocomposite decorated with gold nanoparticles for the ultrasensitive detection of tert-butylhydroquinone. Ezhil Vilian A T,Umapathi Reddicherla,Hwang Seung-Kyu,Lee Min Ji,Huh Yun Suk,Han Young-Kyu Food chemistry The excessive use of food additives in manufactured food products negatively affects their quality and potentially impacts human health. In the present study, a composite consisting of gold nanoparticles decorated on tungsten carbide (AuNP-WC) was successfully fabricated using a facile and cost-effective ultrasonication technique. Compared to a bare glassy carbon electrode (GCE), AuNP-GCE, and WC-GCE, the AuNP-WC-GCE demonstrated excellent sensing performance for tert-butylhydroquinone (TBHQ) when used as an electrocatalyst in 0.05 M phosphate buffer solution (PBS), with a low working potential and a high peak current. In particular, the composite was able to detect the oxidation of TBHQ within a linear concentration range of 5 to 75 nM, with an extremely low detection limit of 0.20 nM. The practicability of the sensor was also assessed in the analysis of TBHQ in real samples of soybean oil, blended oil, and red wine, with satisfactory recovery rates obtained. 10.1016/j.foodchem.2020.128936
    Fluorescence and colorimetric dual-mode sensor for visual detection of malathion in cabbage based on carbon quantum dots and gold nanoparticles. Liang Nini,Hu Xuetao,Li Wenting,Mwakosya Anjelina W,Guo Ziang,Xu Yiwei,Huang Xiaowei,Li Zhihua,Zhang Xinai,Zou Xiaobo,Shi Jiyong Food chemistry A dual-mode fluorescence/colorimetric sensor based on carbon quantum dots (CQDs) and gold nanoparticles (GNPs) was developed for visual detection of malathion in cabbage. The CQDs-GNPs nanocomposite exhibited emission wavelength at 527 nm and absorption wavelength at 524 nm. The fluorescence intensity increased and absorption decreased with addition of malathion. Fluorescence and colorimetric calibration curves were established based on fluorescence intensity (R = 0.9914) and absorbance (R = 0.9608) in the range of 1 × 10-1 × 10 M, respectively. Furthermore, fluorescence and colorimetric standard arrays were prepared for visual detection of malathion according to the change of fluorescence brightness and color. Finally, the approximate concentrations of malathion in cabbage samples were estimated by the standard arrays and naked eyes. The calibration curves were used for accurate detection in cabbage samples with recoveries of 89.9%-103.4% (fluorescence) and 88.7%-107.6% (colorimetric). The established sensor for visual malathion detection in cabbage was accurate with strong application potential, especially for rapid screening. 10.1016/j.foodchem.2020.128494
    Visible on-site detection of Ara h 1 by the switchable-linker-mediated precipitation of gold nanoparticles. Kim Eunghee,Hahn Jungwoo,Ban Choongjin,Jo Youngje,Han Hyebin,Lim Seokwon,Choi Young Jin Food chemistry Biosensors have been widely applied in tests for allergens, but on-site detection remains a challenge. Herein, we proposed a detection procedure for peanut Ara h 1 as a representative allergen, which was extracted from a cookie, thereby minimising the need for any complex pretreatment that was difficult to perform, and enabling the visual detection of the target without the use of analytical equipment. The extraction procedure was performed in less than 30 min using a syringe and filter (0.45 μm). The detection method for Ara h 1 was based on the aggregation of switchable linkers (SL) and gold nanoparticles (AuNP), and the presence of 0.19 mg peanut protein per 30 g of cookie could be confirmed within 30 min based on the AuNP/SL concentration ratio by the precipitation. This proposed procedure could be successfully applied to the detection of a wide range of food allergens. 10.1016/j.foodchem.2021.129354
    Dual-target electrochemical aptasensor based on co-reduced molybdenum disulfide and Au NPs (rMoS-Au) for multiplex detection of mycotoxins. Han Zheng,Tang Zhanmin,Jiang Keqiu,Huang Qingwen,Meng Jiajia,Nie Dongxia,Zhao Zhihui Biosensors & bioelectronics Multiple mycotoxin contamination has posed health risks in the area of food safety. In this study, co-reduced molybdenum disulfide and gold nanoparticles (rMoS-Au) were designed and used for the first time as an efficient platform endowing electrochemical electrodes with superior electron transfer rates, large surface areas and strong abilities to firmly couple with large amounts of different aptamers. After further modification with thionine (Thi) and 6-(Ferrocenyl) hexanethiol (FC6S), a platform enabling sensitive, selective and simultaneous determination of two important mycotoxins, zearalenone (ZEN) and fumonisin B1 (FB1), was achieved. The established aptasensor showed excellent linear relationships (R > 0.99) when ZEN and FB1 concentrations were in the range of 1 × 10-10 ng mL and 1 × 10-1 × 10 ng mL, respectively. High sensitivity of ZEN and FB1 with a limit of detection as low as 5 × 10 ng mL was obtained with excellent selectivity and stability. The effectiveness of the aptasensor was verified in real maize samples, and satisfactory recoveries were attained. The established platform could be easily expanded to other aptamer-based multiplex screening protocols in biochemical research and clinical diagnosis. 10.1016/j.bios.2019.111894