Entropy-driven dynamic self-assembled DNA dendrimers for colorimetric detection of African swine fever virus.

Herein, we subtly engineered an amplified colorimetric biosensor for the cyclic detection of African swine fever virus DNA (ASFV-DNA), which associated the branched catalytic hairpin assembly (bCHA) amplification with G-quadruplex DNAzyme activity through triplex DNA formation. Firstly, a Y-shaped hairpin trimer was constructed for the dynamic self-assembly of DNA dendrimers. Then, in the presence of ASFV-DNA, the signal strand CP was opened, exposing the toehold regions, which would trigger the CHA cascade reaction between hairpin trimers. In the CHA cascade reaction, H1, H2, and H3 opened and bound in sequence, eventually forming the structure of DNA dendrimers. Subsequently, the obtained bCHA product was specifically recognized by the GGG repeat sequences of L1 and L2, then amplified by the synergistic effect of triplex DNA and the formation of asymmetric split G-quadruplex. Benefiting from the amplification properties of bCHA and the high peroxidase-like catalytic activity of asymmetrically split G-quadruplex DNAzymes, it could achieve effective colorimetric signal output in the presence of ASFV-DNA by means of triplex DNA formation. Under the optimal experimental conditions, this biosensor exhibited excellent sensitivity with a detection limit of 1.8 pM. Further, it was applied to the content detection of simulated samples of African swine fever, and the recoveries were 98.9 ~ 103.2%. This method has the advantages of simple operation, good selectivity, and high sensitivity, which is expected to be used for highly sensitive detection of actual samples of African swine fever virus.

Boosting photocatalytic hydrogen generation of cadmium telluride colloidal quantum dots by nickel ion doping.

Splitting water into hydrogen (H2) with sunlight is an appealing approach towards alleviating the fossil fuel crisis. However, as one of the most promising light harvesters, colloidal quantum dots (QDs) generally exhibit low photocatalytic activity towards H2 evolution because of the lack of catalytic sites on their surface. Many researchers have focused on activating QDs by anchoring metal complexes on their surface, in which the photoexcited electrons may transfer from the QDs to the metal centres via the organic ligands. These bulky organic ligands usually have poor electrical conductivity and chemical instability, thereby causing high charge recombination and low durability in these QDs/metal complex catalysts. To address these issues, we herein report the doping of cadmium telluride (CdTe) QDs with nickel ions (Ni2+), achieving a remarkable H2 generation rate without the use of co-catalysts. The formation rate of H2 exceeded 27.3 mmol/g/h under visible light irradiation, which is approximately 110-fold higher than that of pristine CdTe QDs. This doping strategy provides a versatile route to reduce protons to H2 with a turnover number of 13,650 in terms of Ni and confer superior durability on the CdTe QDs.