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Dopamine-functionalized upconversion nanoparticles as fluorescent sensors for organophosphorus pesticide analysis
摘要： Organophosphorus pesticide (OP) residues in agricultural products, herbal medicines and environment have attracted increasing concerns because they cause high healthy risk. Herein, a tyrosinase-mediated photoinduced electron transfer system was constructed for OPs analysis by using dopamine-functionalized upconversion nanoparticles (UCNPs) as fluorescent (FL) sensors. Dopamine quinone was produced by tyrosinase-mediated oxidation of dopamine on the surface of UCNPs, which acted as electron accepter to quench the FL emission of UCNPs. The FL quenching was inhibited by OP since it inhibited the activity of tyrosinase. Chlorpyrifos was used as a model analyte to investigate the feasibility of the FL sensor for the analysis of OPs. Under the optimal conditions, chlorpyrifos can be analysed in a wide range of 1.0 ? 1000 ng mL?1, with a detection limit of 0.38 ng mL?1 (3σ). Some other groups pesticides, including organonitrogen pesticide, organochlorine pesticide and chloronicotinyl insecticide all showed negligible interference. The proposed sensor was successfully used to analyse chlorpyrifos spiked in Balloonflower and Angelica with acceptable recovery values of 95.4–120.0%, demonstrating its application potential for real samples. It exhibits some advantages like low cost, high sensitivity and free of autofluorescent interference and photobleaching.
关键词： Tyrosinase,Photoinduced electron transfer,Fluorescent sensor,Organophosphorus pesticide,Upconversion nanoparticles,Chlorpyrifos
更新于2025-11-14 17:15:25
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Simultaneous photoreduction and Raman spectroscopy of red blood cells to investigate the effects of organophosphate exposure
摘要： Simultaneous photoreduction and Raman spectroscopy with 532 nm laser has been used to study the effects of organophosphate (chlorpyrifos) exposure on human red blood cells. Since in red blood cells, auto-oxidation causes oxidative stress, which, in turn, is balanced by the cellular detoxicants, any possible negative effect of chlorpyrifos on this balance should results in an increased level of damaged (permanently oxygenated) hemoglobin. Therefore, when 532 nm laser, at a suitable power, was applied to photoreduce the cells, only common oxygenated form of hemoglobin got photoreduced leaving the permanently oxygenated hemoglobin detectable in the Raman spectra simultaneously excited by the same laser. Using the technique effects of chlorpyrifos to build up oxidative stress on red blood cells could be detected at concentrations as low as 10 ppb from a comparison of relative strengths of different Raman bands. Experiments performed using simultaneously exposing the cells, along with chlorpyrifos, to H2O2 (oxidative agent) and/or 3-Aminotriazole (inhibitor of anti-oxidant catalase), suggested role of chlorpyrifos to suppress the cellular anti-oxidant mechanism. Since the high level of damaged hemoglobin produced by the action of chlorpyrifos (at concentrations > 100 ppm) is expected to cause membrane damage, atomic force microscopy was used to identify such damages.
关键词： atomic force microscopy,Photoreduction,optical trap,Raman spectroscopy,red blood cells,chlorpyrifos
更新于2025-09-19 17:15:36
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All-Dielectric Terahertz Plasmonic Metamaterial Absorbers and High-Sensitivity Sensing
摘要： Two types of plasmonic metamaterial absorbers (PMAs) formed from patterned all-dielectric resonators are designed and demonstrated experimentally in the terahertz (THz) range. Both PMAs use a simple grating design on highly N-doped silicon. The first shows broadband absorption with near-perfect peak absorbance at 1.45 THz and a bandwidth of 1.05 THz for 90% absorbance, while the second is a dual-band absorber. Experiments show that the second absorber has two distinct absorption peaks at 0.96 and 1.92 THz with absorption rates of 99.7 and 99.9%, respectively. A fundamental cavity mode coupled to coaxial surface plasmon polaritons is responsible for the characteristics of both PMAs. Additionally, the optically tunable responses of these all-dielectric absorbers demonstrate that the absorption behavior can be modified. The quality factor (Q) values of the dual-band resonances are 4.6 and 7.8 times larger than those of the broadband PMAs, respectively, which leads to a better sensing performance. As an example, the two proposed PMAs act as high-sensitivity sensors and demonstrate considerable potential for chlorpyrifos detection. These results show that these PMAs can be used as sensors that can detect the presence of trace pesticides in adsorption analyses, among other practical applications.
关键词： broadband absorption,all-dielectric resonators,plasmonic metamaterial absorbers,chlorpyrifos detection,dual-band absorber,terahertz,high-sensitivity sensors
更新于2025-09-12 10:27:22
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Ecotoxicity response of chlorpyrifos in Aedes aegypti larvae and Lactuca sativa seeds after UV/H2O2 and UVC oxidation
摘要： Chlorpyrifos (CP) is an organophosphate pesticide widely used in agriculture known to cause neurological and immunological effects in addition to interfering in the reproduction and development of organisms. In this study, CP degradation by UV/H2O2 process and UVC radiation was investigated, and the ecotoxicity and phytotoxicity was evaluated using bioassays of Aedes aegypti larvae and Lactuca sativa seeds. CP degradation was monitored by HPLC-DAD, and kinetic parameters were calculated for all processes evaluated. Results demonstrated that both processes are efficient, showing a reduction of over 97% of initial CP after 20 and 60 min of UV/H2O2 and UVC radiation, respectively. However, samples treated by UV/H2O2 process demonstrated increase of toxicity, leading to larvae mortality (> 90% of organisms) and inhibition effects in seed root growth. The relationship between increased toxicity and the CP byproducts formed was not confirmed due to its low concentration. However, the direct influence of acetonitrile solvent, specifically their toxic byproducts, was observed. This study provides insights into parent compound abatement using oxidative treatment and the changes in toxicity due to the transformation of CP byproducts and complex mixtures (acetonitrile as solvent and hydrogen peroxide).
关键词： Liquid chromatography,Chlorpyrifos,Bioassays,Phytotoxicity,Larvae mortality,Advanced oxidation processes
更新于2025-09-10 09:29:36