Boosting peroxidase-like activity of Fe/Mn-N-C dual-single-atom nanozyme for colorimetric assay of total antioxidant capacity

Bingsong Yan, Yuanjie Zhang,Yizhong Lu, Zongming Liu, Jinkai Li

Total antioxidant capacity (TAC) quantification is pivotal for biomedical diagnostics and food quality control. Herein, we developed a smartphone-integrated colorimetric platform leveraging a Fe-Mn dual-single-atom nanozyme (Fe/Mn-N-C) with enhanced peroxidase-like activity. Density functional theory calculations revealed that the unique diatomic synergy reduced the energy barrier during the catalytic process, thus endowing Fe/Mn-N-C with superior peroxidase-like activity. The inhibition mechanism of different types of antioxidants on the color reaction was investigated. The system quantified AA via antioxidant-induced suppression of oxTMB formation and applied successfully to the TAC detection of several fruit juices and commercial beverages. This work provided a new perspective for designing advanced single-atom nanozyme and developed a low-cost and easy-to operate TAC detection strategy with good sensitivity and specificity.

https://www.sciencedirect.com/science/article/pii/S2772571525000506

Argonaute-Coupled Rolling Circle Amplification Enables the Rapid and Sensitive Detection of 8-Oxoguanine-Modified miRNA

Shuze Peng, Jinghan Liu, Wenqi Ge, Ran Tu, Jiaying Hu, Haoyang Wu, Bo Cao, Xiang Yu, Tianbao Yao, Xingyu Ye, Yan Feng, Qian Liu

8-Oxoguanine (o8G), a prominent oxidative RNA modification linked to aging, cancer, and cardiovascular pathologies, presents significant detection challenges due to its structural lability and sequence-dependent mutagenic effects. Current methodologies struggle to achieve rapid and sensitive identification of o8G-modified microRNAs (miRNAs), particularly in user-friendly operations. To address this limitation, an argonaute-integrated detection (AID) system was developed that synergizes the sequence-specific cleavage activity of mesophilic Argonaute (Ago) with rolling circle amplification (RCA) for the o8G-modified target selective amplification and quantification. Our strategy exploits the unique property of Ago to stall cleavage within o8G-modified miRNAs, enabling the selective cleavage of unmodified RNAs while preserving o8G-modified miRNA for subsequent RCA-mediated signal amplification. The AID platform achieved picomolar sensitivity with a single-nucleotide resolution. The isothermal reaction of this workflow permitted integration into a field-deployable device capable of the visual readout by the naked eye or smartphone, demonstrating a detection limit of pM for o8G-modified RNAs within hours. This portable system combines molecular specificity with operational simplicity, offering potential for clinical diagnostics through the rapid detection of oxidative RNA biomarkers without the need of expensive equipment, while also providing a versatile tool for mechanistic studies of epigenetic regulation in related diseases.

https://pubs.acs.org/doi/10.1021/acssensors.5c02475

Chain-Rigidity-Governed Mechanical Stiffening of Polymer Ultrathin Films

Zhao Zhang, Jiahao Li, Shuhui Yan, Yafei Wang, Xiqi Wu, Xinshuai Peng, XinAn Chen, YinBo Zhu, HengAn Wu, Guorui Wang, Zhong Zhang

Increasing the miniaturization of functional materials and devices demands polymer films with thicknesses approaching molecular length scales. Under such extreme confinement, polymer mechanics deviate sharply from bulk behavior. Of particular importance is understanding the microscopic origin of such size effects to build design principles at the molecular level. Here, we uncover the microscopic basis of mechanical stiffening in ultrathin polymer films by integrating temperature-controlled atomic force microscopy-based deflection testing, single-molecule force spectroscopy, and molecular dynamics simulations. We demonstrate that confinement alters chain-level deformation pathways, shifting load transfer from weak intermolecular cohesion to direct intrachain stretching as the thickness decreases. Comparative studies of polycarbonate and poly(methyl methacrylate) films further confirm that chain rigidity─rather than chain alignment or entanglement density─dominates the extent of reinforcement. We unify these findings in a sliding–stretching competition mechanism, which reconciles discrepancies across diverse experimental techniques. This framework establishes molecular-level design rules for creating mechanically robust polymer nanofilms and layered architectures with tailored performance for next-generation flexible electronics and protective coatings.

https://pubs.acs.org/doi/10.1021/acs.macromol.5c02437

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静远嘲风-南京（MY Scimage） 成立于2007年，嘲风取自中国传统文化中龙生九子，子子不同的传说，嘲风为守护屋脊之瑞兽，喜登高望远；静远取自成语“宁静致远”，登高莫忘初心，远观而不可务远。

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