A novel colorimetric biosensor based on non-aggregated Au@Ag core–shell nanoparticles for methamphetamine and cocaine detection

We report a novel colorimetric biosensor based on non-aggregation Au@Ag core-shell nanoparticles to detect methamphetamine and cocaine. The biosensor consisted of a reporter probe (RP) that is a specific single-stranded DNA (ssDNA) sequence coated on Au@Ag nanoparticles, a capture probe (CP) conjugated with magnetic beads, and an illicit drug-binding DNA aptamer (Apt). Au@Ag nanoparticles were synthesized by seed growth and characterized by scanning electron microscope (SEM), high-resolution transmission electron microscopy (HR-TEM), and UV–vis spectra. Methamphetamine (METH) was used as an example to evaluate the feasibility of the biosensor and to optimize the detection conditions. We demonstrated that this sensing platform was able to detect as low as 0.1 nM (14.9 ng L−1) METH with a negligible interference from other common illicit drugs. Various concentrations of METH were spiked into urines, and the biosensor yielded recoveries more than 83.1%. In addition, the biosensor also showed a high sensitivity to detect cocaine. These results demonstrated that our colorimetric sensor holds promise to be implemented as a visual sensing platform to detect multiple illicit drugs in biological samples and environmental matrices

Quartz sand surface morphology of granitic tafoni at Laoshan, China

43-48In this study, a SEM method was used to analyze the surface morphology of the quartz sand granitic tafoni at Laoshan, for the purpose of exploring the weathering process of this tafoni. Present study showed that granitic tafoni at Laoshan, the quartz sand roundness was dominated by angular and sub-angular morphologies. Massive Hydrodynamic features had been developed on the quartz sand surfaces, as well as wind and chemistry forms, which were more developed. It was determined that granitic tafoni at Laoshan, the quartz sand had suffered long-term rainy and windy mechanical erosion, as well as chemical dissolution from residual pit water. These findings differed from the earlier views that the tafone was formed by the glacial melt water

G-quadruplex–hemin DNAzyme molecular beacon probe for the detection of methamphetamine

In this work, a simple, cost-effective, and label-free biosensor was constructed for methamphetamine (METH) detection. The biosensor consists of a G-quadruplex–hemin DNAzyme molecular beacon (DNAzyme MB), a METH aptamer, and a colorimetric substrate. The DNAzyme MB loses peroxidase activity when it hybridizes with the METH aptamer. In the presence of METH, DNAzyme MB dissociates from the inactive hybrid due to preferable hybridization of METH with the aptamer. This process recovers the activity of DNAzyme MB, which catalyzes a reaction with the colorimetric substrate to yield measurable signals. Under optimized conditions, a detection limit as low as 0.5 nM (74.6 ng L−1) was achieved. Common illicit drugs were found to have little interference on detection of METH. Recoveries of METH spiked in urines of addicts were greater than 85%. Good agreement was observed between METH concentrations in urines determined by the sensor and by liquid chromatography-tandem mass spectrometer. These results indicate that the G-quadruplex–hemin DNAzyme MB probe holds promise to detect METH not only in biological samples, but also in environmental matrices

A novel biosensor based on Au@Ag core-shell nanoparticles for sensitive detection of methylamphetamine with surface enhanced Raman scattering

We describe a novel biosensing strategy for sensitive detection of methylamphetamine (MAMP) based on surface enhanced Raman scattering (SERS) by the mediation of spacing between 4-mercaptobenzoic acid (4-MBA) labeled Au@Ag core-shell nanoparticles (Au@Ag). To achieve a favorable SERS substrate, Au@Ag shell-core nanoparticle was synthesized with seeds growth method and well characterized by SEM, TEM and UV-vis spectrometer. The uniform Au@Ag shows an excellent dispersion ability for SERS detection. Under the optimized conditions, the novel biosensor shows a good logarithm linear correlation with the concentration of MAMP ranging from 0.5 ppb to 40 ppb (R = 0.986), with a limit of detection at 0.16 ppb of MAMP (3σ). Furthermore, our biosensors hold an excellent selectivity, demonstrated by the negligible interference from the detection of other illicit drugs and metabolites. The concentrations determined with our biosensor from spiked MAMP in human urine sample fell within the same range with the results from mass spectrometry. This indicates that our sensor has a clear potential for the rapid detection of illicit drug in real samples

Rapid duplexed detection of illicit drugs in wastewater using gold nanoparticle conjugated aptamer sensors

The abuse of illicit drug addiction is a worldwide public health and social problem. In this paper, we reported on a simple and rapid colorimetric biosensor for duplexed detection of methamphetamine (METH) and cocaine in a single assay. Gold nanoparticles (AuNPs) and Au@Ag NPs were synthesized and functionalized with DNA reporter probes (RPs) for METH and cocaine, respectively. The magnetic beads (MBs) were conjugated with two capture probes (CPs) respective to METH and cocaine. The respective RPs and CPs were designed to hybridize with each illicit drug-binding DNA aptamers through DNA-DNA hybridization, forming a sandwich structure. This MBs-based sandwich structure could be removed with an external magnetic field. However, due to the higher affinity of DNA aptamers with illicit drugs, the sandwich structure was disassembled when illicit drugs are introduced into the solution, leading to the colour changes of the supernatant. Utilizing a non-negative matrix factorization (NMF) algorithm to process the data, we demonstrated the ability of our biosensor for the simultaneous quantification of two illicit drugs. Under the optimal condition, our sensors were able to detect both METH and cocaine at the nM level with a wide dynamic range. This sensing platform provides a huge potential on drug consumption evaluation at the community level for wastewater-based epidemiology

The effect of ultralow-dose antibiotics exposure on soil nitrate and N2O flux

Exposure to sub-inhibitory concentrations of antibiotics has been shown to alter the metabolic activity of micro-organisms, but the impact on soil denitrification and N2O production has rarely been reported. In this study, incubation and column transport experiments were conducted on soils exposed to as many as four antibiotics in the ng·kg−1 range (several orders of magnitude below typical exposure rates) to evaluate the impact of ultralow dose exposure on net nitrate losses and soil N2O flux over time. Under anaerobic incubation conditions, three antibiotics produced statistically significant dose response curves in which denitrification was stimulated at some doses and inhibited at others. Sulfamethoxazole in particular had a stimulatory effect at ultralow doses, an effect also evidenced by a near 17% increase in nitrate removal during column transport. Narasin also showed evidence of stimulating denitrification in anaerobic soils within 3 days of exposure, which is concurrent to a statistically significant increase in N2O flux measured over moist soils exposed to similar doses. The observation that even ultralow levels of residual antibiotics may significantly alter the biogeochemical cycle of nitrogen in soil raises a number of concerns pertaining to agriculture, management of nitrogen pollution, and climate change, and warrants additional investigations

Paper-based nanosensors to evaluate community-wide illicit drug use for wastewater-based epidemiology

Wastewater-based epidemiology (WBE) is a powerful technique for monitoring illicit drugs of abuse in the community. Here, we report on a surface-enhanced Raman scattering/spectroscopy (SERS) sensor for the sensitive and selective detection of methamphetamine based on the assembly of noble metal core-shell nanoparticles on a bespoke glassy nanofibrous electrospun paper matrix. The hierarchical structure of the fibrous paper, modified with the synthesized Au@Ag core-shell nanoparticles (Au@Ag) possessing good SERS efficiency, enables us to evaluate the community-wide prevalence of methamphetamine in wastewater treatment plants around Beijing. We show that when normalized for the daily flow of the wastewater treatment plants, higher mass loads of drugs are found in sewage influent from urban areas, implying greater local methamphetamine usage than that in less populated areas. These user-friendly and disposable paper devices demonstrate the applicability of rapid on-site illicit drug detection, illustrating the application to wastewater-based epidemiology, which has the potential to inform government agencies regarding societal interventions

Microbial behavior and influencing factors in the anaerobic digestion of distiller: a comprehensive review

Anaerobic digestion technology is regarded as the most ideal technology for the treatment of a distiller in terms of environmental protection, resource utilization, and cost. However, there are some limitations to this process, the most prominent of which is microbial activity. The purpose of this paper is to provide a critical review of the microorganisms involved in the anaerobic digestion process of a distiller, with emphasis on the archaea community. The effects of operating parameters on microbial activity and process, such as pH, temperature, TAN, etc., are discussed. By understanding the activity of microorganisms, the anaerobic treatment technology of a distiller can be more mature. Aiming at the problem that anaerobic treatment of a distiller alone is not effective, the synergistic effect of different substrates is briefly discussed. In addition, the recent literature on the use of microorganisms to purify a distiller was collected in order to better purify the distiller and reduce harm. In the future, more studies are needed to elucidate the interactions between microorganisms and establish the mechanisms of microbial interactions in different environments

Nanomaterial-based aptamer sensors for arsenic detection

Arsenic (As) is a highly toxic contaminant in the environment and a serious carcinogen for the human being. The toxicity of arsenic significantly threatens environmental and human health. The effective removing technology for arsenic remains challenging, and one of the reasons is due to the lack of powerful detection method in the complex environmental matrix. There is thus an urgent need to develop novel analytical methods for arsenic, preferably with the potential for the field-testing. To combat arsenic pollution and maintain a healthy environment and eco-system, many advanced analytical methods have been developed for arsenic detection in various samples. Among these strategies, biosensors hold great promise for rapid detection of arsenic, in particular, nanomaterials-based aptamer sensors have attracted significant attention due to their simplicity, high sensitivity and rapidness. In this paper, we reviewed the recent development and promising applications of aptamer sensors (aptasensors) based-on nanomaterial for arsenic detection, in particular with emphasis on the works using optical and electrochemical technologies. We also discussed the recent novel technology in aptasensors development for arsenic detection, including nucleic acid amplification for signal enhancement and device integration for the portability of arsenic sensors. We are hoping this review could inspire further researches in developing novel nanotechnologies based aptasensors for possible on-site detection of arsenic

Metabolomics of Clinical Poisoning by Aconitum Alkaloids Using Derivatization LC-MS

The root of Aconitum kusnezoffii (Caowu in Chinese, CW) is not only commonly used as a traditional Chinese medicine (TCM), but also served as a tonic in China. Due to its high toxicity, clinical poisoning cases induced by CW have frequently been reported. However, the mechanism is still unclear. In this study, Aconitum alkaloids and altered endogenous metabolites in CW poisoning patients were investigated to elucidate the possible intoxication mechanism. Eighteen alkaloids, including 6 toxic diester diterpenoid alkaloids (DDAs), were determined from the sera of patients. At the same time, 5-(diisopropylamino)amylamine (DIAAA) derivatization-ultrahigh performance liquid chromatography- quadrupole-time of flight mass spectrometry (UHPLC-Q-TOF/MS) approach was applied in the metabolomics analysis to find much more carboxyl-containing metabolites (CCMs), which are the essential components for life and critical to elucidate the mechanism of toxicity. As a result, 32 altered metabolites after poisoning were identified. Among them, hydroxyeicosatetraenoic acids (HETEs) and some dicarboxylic acids were first found to be related to Aconitum alkaloids toxicity. Finally, biological pathway analysis indicated that the significantly changed metabolites were primarily involved in amino acid metabolism, TCA cycle, fatty acid metabolism, pyruvate metabolism, arachidonic acid metabolism, sphingolipid metabolism and so on. These results can not only provide more information on the mechanism of CW intoxication but also help the clinical diagnosis of CW poisoning