Designing Triangular Silver Nanoplates with GSH/GSSG Surface Mixed States as Novel Nanoparticle-based Redox Mediators for Electrochemical Biosensing

Engineering Entropy-Driven Nanomachine-Mediated Morphological Evolution of Anisotropic Silver Triangular Nanoplates for Colorimetric and Photothermal Biosensing

A DNA/RNA biosensor capable of single nucleotide variation (SNV) resolution is highly desirable for drug design and disease diagnosis. To meet the point-of-care demand, rapid, cost-effective, and accurate SNV detection is of great significance but still suffers from a challenge. In this work, a unique nonenzymatic dual-modal (multicolorimetric and photothermal) visualization DNA biosensor is first proposed for SNV identification on the basis of an entropy-driven nanomachine with double output DNAs and coordination etching of anisotropic silver triangular nanoplates (Ag TNPs). When the target initiates the DNA nanomachine, the liberated multiple output DNAs can be utilized as a bridge to produce a superparamagnetic sandwich complex. The incoming poly-C DNA can coordinate and etch highly active Ag+ ions at the tips of Ag TNPs, causing a shift in the plasmon peak of Ag TNPs from 808 to 613 nm. The more target DNAs are introduced, the more output DNAs are released and thus the more Ag+ ions are etched. The noticeable color changes of anisotropic Ag TNPs can be differentiated by "naked eye" and accurate temperature reading. The programmable DNA nanotechnology and magnetic extraction grant the high specificity. Also, the SNV detection results can be self-verified by the two-signal readouts. Moreover, the dual-modal biosensor has the advantages of portability, cost-effectiveness, and simplicity. Particularly, the exclusive entropy-driven amplifier liberates double output DNAs to bridge more poly-C DNAs, enabling the dual-modal visualization DNA biosensor with improved sensitivity.

Ablation of Gap Junction Protein Improves the Efficiency of Nanozyme-Mediated Catalytic/Starvation/Mild-Temperature Photothermal Therapy

Reactive oxygen species (ROS)-mediated tumor catalytic therapy is typically hindered by gap junction proteins that form cell-to-cell channels to remove cytotoxic ROS, thereby protecting tumor cells from oxidative damage. In this work, a multifunctional nanozyme, FePGOGA, is designed and prepared by Fe(III)-mediated oxidative polymerization (FeP), followed by glucose oxidase (GOx) and GAP19 peptides co-loading through electrostatic and π-π interactions. The FePGOGA nanozyme exhibits excellent cascade peroxidase- and glutathione-oxidase-like activities that efficiently catalyze hydrogen peroxide conversion to hydroxyl radicals and convert reduced glutathione to oxidized glutathione disulfide. The loaded GOx starves the tumors and aggravates tumor oxidative stress through glucose decomposition, while GAP19 peptides block the hemichannels by inducing degradation of Cx43, thus increasing the accumulation of intracellular ROS, and decreasing the transport of intracellular glucose. Furthermore, the ROS reacts with primary amines of heat shock proteins to destroy their structure and function, enabling tumor photothermal therapy at the widely sought-after mild temperature (mildPTT, ≤45 °C). In vivo experiments demonstrate the significant antitumor effectof FePGOGA on cal27 xenograft tumors under near-infrared light irradiation. This study demonstrates the successful ablation of gap junction proteins to overcome resistance to ROS-mediated therapy, providing a regulator to suppress tumor self-preservation during tumor starvation, catalytic therapy, and mildPTT.

Nanoassemblies Based on a Cationic Perylene Diimide Derivative and Sodium Dodecyl Sulfate: A Simple Fluorescent Platform for Efficient Analysis of Aflatoxin B1

Aflatoxin B₁ (AFB₁) is a kind of potently carcinogenic fungal metabolite in food threatening human health, and it is crucial and challenging to develop advanced nonimmune approaches for AFB₁ determination. Addressing this challenge, we successfully constructed a nanoassembly (PdE-PDI/SDS) by noncovalently coupling a cationic perylene diimide derivative (PdE-PDI) and sodium dodecyl sulfate (SDS), exhibiting high-density charges and a specific surface area for rapid sensing of AFB₁. The large electronic conjugate structure and rigid plane of PdE-PDI enable it to form more stable σ-π, π-π coordination, and hydrogen bonds with AFB₁. Additionally, the introduction of SDS significantly amplifies noncovalent interactions and enhances the quenching efficiency of PdE-PDI toward AFB₁. The proposed PdE-PDI/SDS exhibited excellent specificity to AFB₁ and showed dosage-sensitive detection with detection limit as low as 0.74 ng mL^-1. Finally, the PdE-PDI/SDS was successfully applied in cereal samples with good recoveries from 94.61 to 109.92%. To our knowledge, this is the first time a fluorescent strategy from the point of self-assembly for AFB₁ determination is reported, which holds great promise for wide applications of perylene diimide derivative in food safety.

Array-based sensing and discrimination of segmented Baijiu using organic molecules-regulated PEI@Ag NPs@Ln as fluorescent probes

Quickly discriminating different segmented Baijiu can directly control its grade and indirectly affect the quality of the finished Baijiu. A fluorescence sensor array was constructed based on PEI-terminated silver nanoparticles and lanthanide metal ions (PEI@Ag NPs@Ln). Ag NPs were stably dispersed in the PEI-woven network, initially accompanied by excellent fluorescence signals. Organic molecules disrupted the PEI structure and dragged the Ag NPs out. The free Ag NPs sintered or aggregated with the diffusion, resulting in fluorescence quenching. The three lanthanide ions speed up the process, allowing different organic molecules to exhibit more distinct signals. Thus, this sensor was used to map 11 organic molecules' fingerprints and to discriminate segmented Baijiu. The whole process takes only 2 min. With the assistance of pattern recognition, segmented Baijiu from three cellars were successfully discriminated. Fast, effective and simple are highlights, which opens up its practical application potential in the detection field.

Heterojunction MnO2-nanosheet-decorated Ag nanowires with enhanced oxidase-like activity for the sensitive dual-mode detection of glutathione

The biocatalytic design of nanomaterials with enzyme-like activity is considered a reliable and promising toolkit for the generation of diagnostic agents in complex biological microenvironments. However, the preparation of nanomaterials while maintaining a high catalytic activity in tumor cells (pH 6.0-6.5) poses a prominent challenge. Herein, we constructed a biomimetic enzyme-trigged dual-mode system with colorimetry at 652 nm and photothermal biosensors to detect glutathione based on hollow MnO₂-nanosheet-decorated Ag nanowires (Ag@MnO₂) as an oxidase-like nanozyme. As expected, Ag@MnO₂ catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the absence of H₂O₂, leading to a blue-colored oxidized TMB (oxTMB) that displayed oxidase-like activity in pH 6.0. Interestingly, the portable dual-mode colorimetry and photothermal method for GSH was developed based on the redox reaction between GSH and oxTMB. This detection method exhibited a wide linear range of 0.1-55 μM for GSH with a low detection limit of 0.08 μM. This work highlights a new insight into nanotechnology by taking advantage of biomimetic design in biological analysis.