Turning waste into wealth: nitrogen-doped carbon quantum dots derived from fruits wastes for sensing.

Hydrothermal treatment of m-phenylenediamine and grape seed powder has been adopted to synthesize nitrogen-doped carbon quantum dots (N-CQDs). The prepared N-CQDs possessed outstanding optical properties and high quantum yield. Based on the combined effect of static quenching effect and inner filter effect of permanganate (MnO4 - ) to N-CQDs and the redox reaction that occurred between MnO4 - and l-ascorbic acid (l-AA), an 'off-on' fluorescence strategy with N-CQDs has been proposed for the detection of MnO4 - and l-AA. The proposed fluorescent probe was fast, sensitive and selective to MnO4 - and l-AA under mild conditions. In addition, the satisfactory results of the proposed strategy for the detection of MnO4 - and l-AA in real samples indicated its practicability.

Redox-modulated colorimetric detection of ascorbic acid and alkaline phosphatase activity with gold nanoparticles.

Gold nanoparticles (AuNPs) exhibit characteristic absorption peaks in the ultraviolet visible region due to their special surface plasmon resonance effect. This characteristic absorption peak would change with the relative colour varying from wine red to orange-yellow upon sequential addition of ascorbic acid (AA) into the mixture of AuNPs and Ag(I). Similar observations also could be found when the hydrolysis product of sodium l-ascorbyl-2-phosphate with alkaline phosphatase (ALP) was used as an alternative to AA. Results of structure characterization confirmed that the phenomena were due to the reduction of Ag(I) to Ag(0) on the surface of AuNPs and the formation of core-shell AuNPs@Ag. Therefore, a colorimetric assay for rapid visual detection of AA and ALP based on redox-modulated silver deposition on AuNPs has been proposed. Under the optimal experimental conditions, the absorbance variation ΔA522 nm /A370 nm of AuNPs was proportional to the concentration of AA (5-60 µmol/L) and ALP (3-18 U/L) with the corresponding detection limit of 2.44 µmol/L for AA and 0.52 U/L for ALP. The assay showed excellent selectivity towards AA and ALP. Moreover, the assay has been applied to detect AA and ALP activity in real samples with satisfying results.

Thermolysis Synthesis of MoS2 Microrods for Noble Metal-Free Catalytic Reduction of 4-Nitrophenol.

MoS2 microrods constructed by ultrathin nanosheets have been synthesized, for the first time, by thermal decomposition of intermediate (NH4)2MoS4 crystals, which could not only provide the single-source for both the molybdenum and sulfur atoms, but also served as the self-sacrificed template. The well-defined microstructure was characterized by XRD, SEM, TEM, XPS, BET, respectively. The results indicated that MoS2 microrods with uniform morphology were assembled by defective ultrathin nanosheets. Moreover, these MoS2 microrods exhibit superior catalytic activity with the apparent rate constant (κapp) of 0.161 min-1 for the reduction of 4-nitrophenol (4-NP) by NaBH4. Encouragingly, the MoS2 microrods still show evident activity for the reduction of 4-NP after five cycle tests, which has significant importance for the application in the reduction of 4-NP to p-aminophenol (4-AP). Also, this method can be extended to construct other kinds of metal dichalcogenides (TMDs).

Analysis of insecticide resistance-related genes of the Carmine spider mite Tetranychus cinnabarinus based on a de novo assembled transcriptome.

The carmine spider mite (CSM), Tetranychus cinnabarinus, is an important pest mite in agriculture, because it can develop insecticide resistance easily. To gain valuable gene information and molecular basis for the future insecticide resistance study of CSM, the first transcriptome analysis of CSM was conducted. A total of 45,016 contigs and 25,519 unigenes were generated from the de novo transcriptome assembly, and 15,167 unigenes were annotated via BLAST querying against current databases, including nr, SwissProt, the Clusters of Orthologous Groups (COGs), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO). Aligning the transcript to Tetranychus urticae genome, the 19255 (75.45%) of the transcripts had significant (e-value <10-5) matches to T. urticae DNA genome, 19111 sequences matched to T. urticae proteome with an average protein length coverage of 42.55%. Core Eukaryotic Genes Mapping Approach (CEGMA) analysis identified 435 core eukaryotic genes (CEGs) in the CSM dataset corresponding to 95% coverage. Ten gene categories that relate to insecticide resistance in arthropod were generated from CSM transcriptome, including 53 P450-, 22 GSTs-, 23 CarEs-, 1 AChE-, 7 GluCls-, 9 nAChRs-, 8 GABA receptor-, 1 sodium channel-, 6 ATPase- and 12 Cyt b genes. We developed significant molecular resources for T. cinnabarinus putatively involved in insecticide resistance. The transcriptome assembly analysis will significantly facilitate our study on the mechanism of adapting environmental stress (including insecticide) in CSM at the molecular level, and will be very important for developing new control strategies against this pest mite.