Tellurium (Te) is a rare element of great value, but it exists mainly in the toxic form of tellurite (TeIV) in water. Effective approaches that are able to reduce the toxicity and recover Te from contaminated water are highly needed. Here, we developed a simple but effective way to reduce toxic TeIV to widely applicable elemental Te0. With the combination of ultraviolet (UV) and biacetyl (BD), the oxidation state of Te could be feasibly changed from IV to 0 or VI. The consumption of dissolved oxygen (DO) was a key factor in the redox conversion of TeIV. Under UV irradiation, BD was first cleaved to acetyl radicals, which could then combine with water molecules to form more reductive diol radicals or combine with DO to form strongly oxidative peroxide radicals. Even without deoxygenation, the UV/BD system could rapidly change from being oxidative to being reductive because of the fast depletion of DO. Owing to the high quantum yield of the acetyl radical, the reduction efficiency of the UV/BD system was about 1 order of magnitude higher than that of UV/sulfite and was more efficient than the commonly used biological methods. This work provides a proof of concept for the reduction of tellurite, which could have relevant implications for water treatment and resource recovery applications.
Ce Shi,Li Jia,Yangyang Chen,Tariq Aziz,Ashwag Shami,Fahad Al-Asmari,Fakhria A. Al-Joufi,Haiying Cui,Lin Lin
Listeria monocytogenes ( L. monocytogenes ) biofilm adhered to food or food contacting surfaces causes food cross-contamination and poses a threat to food safety. Diacetyl, a natural compound produced by lactic acid bacteria, showed efficient anti- L. monocytogenes activity, while its anti-biofilm effects have not been explored yet. Herein, the inhibitory and eradicative effects of diacetyl on L. monocytogenes biofilm were determined, and its potential application on cantaloupe preservation was also assessed. Results showed the minimum biofilm inhibitory and eradication concentration of diacetyl against L. monocytogenes biofilm was 2 and 4 mg/mL, respectively. It was observed that diacetyl could effectively inhibit the biofilm formation through decreasing bacterial metabolism, hydrophobicity, initial bacterial auto-aggregation, as well as cell swimming and swarming ability. Moreover, diacetyl could also down-regulate the expression of the genes relevant to biofilm formation, such as agr A , agr C , sigB, and prfA . Besides, the existing mature L. monocytogenes biofilm could be completely eradicated by diacetyl through disrupting biofilm structural integrity and destroying the extracellular polymeric substances including protein, polysaccharides, and extracellular DNA. Furthermore, diacetyl treatment could eradicate L. monocytogenes biofilm on cantaloupe peels, which achieved a 3.08 Log CFU/cm 2 reduction in bacterial colonization while maintained acceptable color stability, delayed the chlorophyll degradation, and thereby extending the shelf life. These findings demonstrated the dual-functionality of diacetyl against L. monocytogenes biofilms, and suggested its promising application to control and prevent L. monocytogenes biofilms contamination on fresh food produce.
In this work, a dumbbell-shaped bi-acetylferrocene ethylenediamine complex, (AFc) 2 -en (AFc = acetylferrocene, en = ethylenediamine) was synthesized and its interaction with double-stranded DNA (dsDNA) was comprehensively studied by electrochemical methods on a gold electrode. The experimental results reveal that the highly electroactive (AFc) 2 -en complex can interact with dsDNA via a specific bis-groove binding mode. The binding constant and binding site size between the two species were determined to be 3.7 × 10 5 L mol −1 and 4.2, respectively. The surface-based studies further show that (AFc) 2 -en presents the stronger electrochemical response on dsDNA modified electrode than on the single-stranded DNA (ssDNA) modified electrode, suggesting that the complex can well distinguish dsDNA from ssDNA. Based on this characteristic, the bi-acetylferrocene complex was utilized as an electrochemical hybridization indicator in a DNA biosensor for the detection of oligonucleotides from CaMV35S promoter gene. The specificity experiments indicate that the biosensor can well discriminate the complementary sequence from the base-mismatched and the non-complementary sequences. The complementary target sequence can be quantified over a wide range from 1.0 × 10 −14 mol L −1 to 1.0 × 10 −6 mol L −1 with a detection limit of 2.0 × 10 −15 mol L −1 .
危险品化学品经营许可证（带存储）