Jialin Zhang

DNA methylation, as an important epigenetic modification, is closely related to gene expression regulation and cancer development. This study developed a new electrochemical biosensor for ultrasensitive detection of DNA methylation based on the combination of Fe/metal-organic framework (MOF)/polymer polyaniline (PANI) composite materials and catalytic hairpin assembly (CHA) cascade reaction. The Fe/MOF/PANI/S1, as the signal probe, significantly improved the conductivity and stability by doping conductive PANI into Fe/MOF. The sensor used DNAzyme to catalyze methylated DNA to trigger the CHA cascade reaction, and thus several cross-shaped CHA products were achieved. The capture probe was modified on the surface of the Au electrode to hybridize with CHA products. Thus, the binding sites were exposed to enable large amounts of Fe-MOF/PANI/S1 signal probes to bind effectively, and the electrochemical signals were generated. The sensor could produce measurable electrochemical responses in the presence of methylated DNA, with the limit of detection as low as 0.58 fM. It showed excellent specificity, repeatability (RSD = 2.23%), and stability (over 90% signal retention after 20 days). In addition, it showed high recovery in human serum samples, verifying its potential for practical applications. This will pave a new way for the rapid and sensitive detection of DNA methylation.

Recent advances in upconversion nanoparticles for biomolecule detection.

Assessing the activity of DNA methyltransferases (MTases) and screening for methyltransferase inhibitors not only allow for a deep exploration of the role of methylation regulation in disease initiation and progression but also provide an important experimental and clinical basis for the diagnosis and treatment of diseases. Herein, a new COFs functionalized electrochemical biosensor has been developed to detect DNA adenine methylation (Dam) MTase activity with high sensitivity and rapidity by taking advantage of the DNA walker and rolled circular strand displacement amplification (RC-SDA) reaction. Specifically, hairpin probe H1 was methylated by Dam MTase, followed by methylation site-specific cleavage of DpnI enzyme to generate the S5 probe. The padlock probes with two nucleic acid endonuclease sites were introduced to trigger the RC-SDA reaction under the action of the primer, releasing a large number of single-stranded S6 probes. The released probe worked synergistically with the Exo III enzyme to trigger DNA walking, which exposed the binding sites to enable the Au-COF-MB signal probes to bind effectively to the electrode surface, and the electrochemical signals were thus generated. The result showed that the designed electrochemical biosensor demonstrated excellent sensitivity and specificity in detecting the activity of Dam MTase, with the detection limit (LOD) of 6.85 × 10^-5 U/mL. This method provides support for the development of new treatment strategies for methylation related diseases.

CdS quantum dots (CdS QDs) are regarded as a promising photocatalyst due to their remarkable response to visible light and suitable placement of conduction bands and valence bands. However, the problem of photocorrosion severely restricts their application. Herein, the CdS QDs-Co₉S₈ hollow nanotube composite photocatalyst has been successfully prepared by loading Co₉S₈ nanotubes onto CdS QDs through an electrostatic self-assembly method. The experimental results show that the introduction of Co₉S₈ cocatalyst can form a stable structure with CdS QDs, and can effectively avoid the photocorrosion of CdS QDs. Compared with blank CdS QDs, the CdS QDs-Co₉S₈ composite exhibits obviously better photocatalytic hydrogen evolution performance. In particular, CdS QDs loaded with 30% Co₉S₈ (CdS QDs-30%Co₉S₈) demonstrate the best photocatalytic performance, and the H₂ production rate reaches 9642.7 μmol·g⁻¹·h⁻¹, which is 60.3 times that of the blank CdS QDs. A series of characterizations confirm that the growth of CdS QDs on Co₉S₈ nanotubes effectively facilitates the separation and migration of photogenerated carriers, thereby improving the photocatalytic hydrogen production properties of the composite. We expect that this work will facilitate the rational design of CdS-based photocatalysts, thereby enabling the development of more low-cost, high-efficiency and high-stability composites for photocatalysis.

GR and Ni₂P dual cocatalysts modified ZnIn₂S₄ nanoflower has been prepared and they can simultaneously utilize photogenerated electrons and holes to actuate the oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) integrated with H₂ evolution.