Improved Catalytic Activity of Spherical Nucleic Acid Enzymes by Hybridization Chain Reaction and Its Application for Sensitive Analysis of Aflatoxin B1.

Conventional spherical nucleic acid enzymes (SNAzymes), made with gold nanoparticle (AuNPs) cores and DNA shells, are widely applied in bioanalysis owing to their excellent physicochemical properties. Albeit important, the crowded catalytic units (such as G-quadruplex, G4) on the limited AuNPs surface inevitably influence their catalytic activities. Herin, a hybridization chain reaction (HCR) is employed as a means to expand the quantity and spaces of G4 enzymes for their catalytic ability enhancement. Through systematic investigations, we found that when an incomplete G4 sequence was linked at the sticky ends of the hairpins with split modes (3:1 and 2:2), this would significantly decrease the HCR hybridization capability due to increased steric hindrance. In contrast, the HCR hybridization capability was remarkably enhanced after the complete G4 sequence was directly modified at the non-sticky end of the hairpins, ascribed to the steric hindrance avoided. Accordingly, the improved SNAzymes using HCR were applied for the determination of AFB1 in food samples as a proof-of-concept, which exhibited outstanding performance (detection limit, 0.08 ng/mL). Importantly, our strategy provided a new insight for the catalytic activity improvement in SNAzymes using G4 as a signaling molecule.

Effects of two polybrominated diphenyl ethers (BDE-47, BDE-209) on the swimming behavior, population growth and reproduction of the rotifer Brachionus plicatilis.

Polybrominated diphenyl ethers (PBDEs) are new kinds of persistent organic pollutants (POPs) and their potential threats to the equilibrium and sustainability of marine ecosystems have raised worldwide concerns. Here, two kinds of PBDEs, tetra-BDE (BDE-47) and deca-BDE (BDE-209) were applied, and their toxic effects on the swimming behavior, population growth and reproduction of Brachionus plicatilis were investigated. The results showed that: (1) The actual concentrations of BDE-47 and -209 in the seawater phase measured by GC-MS (Gas Chromatography-Mass Spectrometer) were much lower than their nominal concentrations. (2) In accordance with the 24-hr acute tests, BDE-209 did not show any obvious swimming inhibition to rotifers, but a good correlation did exist between the swimming inhibition rate and BDE-47 concentration suggesting that BDE-47 is more toxic than BDE-209. (3) Both BDE-47 and -209 had a significant influence on the population growth and reproduction parameters of B. plicatilis including the population growth rate, the ratio of ovigerous females/non-ovigerous females (OF/NOF), the ratio of mictic females/amictic females (MF/AF), resting egg production and the mictic rate, which indicate that these parameters in B. plicatilis population were suitable for monitoring and assessing PBDEs. Our results suggest that BDE-47 and -209 are not acute lethal toxicants and may pose a low risk to marine rotifers at environmental concentrations for short-term exposure. They also accumulate differently into rotifers. Further research data are needed to understand the mechanisms responsible for the effects caused by PBDEs and to assess their risks accurately.

Levels and distribution of hexabromocyclododecane (HBCD) in environmental samples near manufacturing facilities in Laizhou Bay area, East China.

A total of 55 samples including soil, sediment, plants (cypress, reed and seepweed) and aquatic species were collected at locations around hexabromocyclododecane (HBCD) manufacturing facilities in Laizhou Bay area, East China. HBCD was determined at concentrations ranging between 0.88 and 6901 ng g(-1) dry weight (dw), 2.93-1029 ng g(-1) dw, 8.88-160241 ng g(-1) dw, and 7.09-815 ng g(-1) lipid weight (lw), respectively. Significant negative correlations (r(2) = 0.54, p = 0.006) were observed between HBCD concentrations in soils and the distance from the manufacturing facility, and the concentrations became constant when the distance was >4 km. The calculation results on the bioaccumulation factors (BAFs) suggested that HBCD may be accumulated in plants. Tissue-specific bioaccumulation of HBCD diastereoisomers was found in aquatic species. For example, in crabs the highest concentrations of HBCD (815 ng g(-1) lw for female and 446 ng g(-1) lw for male) were observed in the gill. Besides the gill, α-HBCD was more preferentially accumulated in the spermary and ovary, while ß- and γ-HBCD were more accumulated in the muscle. A similar distribution was also observed in roe and muscle of goby fish.

Polybrominated diphenyl ethers and organochlorine pesticides in sewage sludge of wastewater treatment plants in China.

The concentrations of chemicals in sewage sludge from wastewater treatment plants (WWTPs) may relate to their levels of use and environmental pollution in the region. In this work, sludge samples were collected from 31 WWTPs in 26 cities in China and analyzed for polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs). The concentrations of SigmaPBDE (sum of congeners 17, 28, 47, 66, 71, 85, 99, 100, 138, 153, 154, and 183) ranged from 6.2 to 57ng/g (dw). The concentration of decabromodiphenyl ether (BDE-209) ranged from below limit of detection (LOD) to 1109ng/g (dw) (with a median of 27ng/g (dw)), and averaged 55% (median 69%) of the total PBDEs. These levels are about 10-100 times lower than those found in Europe and North America. PBDE levels in sludge were not found to depend on the location and capacity of the WWTPs. Concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethane (DDTs) and its major degradation products, and hexachlorobenzene (HCB) ranged from below detection limit to 167ng/g (dw), 11 to 1065ng/g (dw), and 7.5 to 319ng/g (dw), respectively. The major DDT degradation products were p,p'-DDE and p,p'-DDD. The major hexachlorocyclohexane (HCH) isomer in sludge is beta-HCH, reflecting its higher affinity to solids and resistance to degradation than other isomers.

[Acupoint plaster therapy with midnight-noon ebb-flow hour-prescription method for senile osteoporosis:a randomized controlled trial].

OBJECTIVE: To compare the clinical efficacy differences between acupoint plaster therapy with midnight-noon ebb-flow hour-prescription method and traditional acupoint plaster therapy for senile osteoporosis (SOP). METHODS: With randomized controlled blind design, 76 SOP patients with deficiency of liver and kidney syndrome were randomly divided into an observation group and a control group, 38 cases in each one. Based on oral administration of caltrate D, the patients in the observation group were treated with acupoint plaster therapy with midnight-noon ebb-flow hour-prescription method at Yingu (KI 10), Taixi (KI 3), Dazhong (KI 4), Fuliu (KI 7) and Zhiyin (BL 67), while the patients in the control group were treated with traditional acupoint plaster therapy. Each plaster therapy lasted for 6 h, once a day; there was an interval of 2 d after consecutive 5-day treatment; 4 weeks were taken as one course, and totally 2 courses were given. Visual analogue scale (VAS) and Oswestry Disability Index (ODI) were used to evaluate the pain and dysfunction before intervention, after 4 weeks and 8 weeks intervention. Osteoporosis symptom rating sale and quality of life questionnaire of the European foundation for Osteoporosis (QUALEFFO-41) were adopted to evaluate the TCM syndrome and quality of life before and after 8-week intervention. RESULTS: All the outcomes were significantly improved after treatment in the two groups (P<0.01,P<0.05); after 4 weeks and 8 weeks of treatment, the VAS and ODI in the observation group were lower than those in the control group (all P<0.05). Repeated ANOVA indicated the VAS and ODI were significant in group effect, time effect and interaction effect (all P<0.01). Further comparison showed that VAS and ODI at later time points were lower than those in the early time points (all P<0.01). After the treatment, the scores of TCM syndrome and QUALEFFO-41 in the observation group were lower than those in the control group (all P<0.05). The effective rate was 85.7% (30/35) in the observation group, which was superior to the effective rate in the control group[74.3%(26/35), P<0.05]. CONCLUSIONS: The acupoint plaster therapy with midnight-noon ebb-flow hour-prescription method is superior to traditional acupoint plaster therapy in improving pain, dysfunction, TCM syndrome and quality of life in SOP patients; in addition, its clinical efficacy is significant.

Progress of solid-phase microextraction coatings and coating techniques.

Solid-phase microextraction (SPME) has been popular as an environmentally friendly sample pretreatment technique to extract a very wide range of analytes. This is partly owing to the development of SPME coatings. One of the key factors affecting the extraction performances, such as the sensitivity, selectivity, and reproducibility, is the properties of the coatings on SPME fibers. This paper classifies the materials used as SPME coatings and introduces some common preparation techniques of SPME coating in detail, such as sol-gel technique, electrochemical polymerization technique, particle direct pasting technique, restricted access matrix SPME technique, and molecularly imprinted SPME technique.