Jun Ai

Green-fluorescent carbon quantum dots (CQDs) were hydrothermally synthesized from the Mongolian medicine Harigabri, exhibiting uniform size (∼2.5 nm) and strong emission at 521 nm under 468 nm excitation. Based on the fluorescence resonance energy transfer (FRET) between the CQDs (donors) and AgNPs (acceptors), an aptamer-functionalized biosensor (Apt-CQDs/AgNPs) was constructed for selective Escherichia coli detection. Target recognition by the aptamer inhibited FRET and restored fluorescence. The sensor showed a linear response from 9 × 102 to 9 × 107 CFU/mL with a detection limit of 5 CFU/mL. This work highlights Harigabri-derived CQDs as promising nanomaterials for rapid pathogen detection and demonstrates the potential of traditional medicinal resources in biosensing applications.

G-Quadruplex (G4) aptamers have emerged as versatile functional nucleic acid architectures for biosensing because of their unique conformational plasticity, programmable topologies, and intrinsic signal-regulation capabilities. Unlike conventional recognition elements that mainly function as passive binding scaffolds, G4 aptamers can actively regulate signal generation and transduction through topology-dependent structural dynamics. Increasing evidence indicates that biosensing performance is closely governed by conformational energetics, folding kinetics, loop organization, ion coordination, and nano-interfacial coupling. This review summarizes recent advances in structure-guided G4 aptamer biosensing from the perspective of “structural empowerment”, where conformational architectures directly determine sensing behavior and analytical output. We first discuss the structural fundamentals of G4 aptamers, including topology diversity, thermodynamic stability, folding pathways, and environmental responsiveness, emphasizing their influence on molecular recognition and signal accessibility. We then analyze the mechanistic relationship between G4 conformational transitions and multiple signal transduction modes, including fluorescence, electrochemical, colorimetric, surface-enhanced Raman scattering, photoelectrochemical, and catalytic sensing systems. Particular attention is given to the integration of G4 architectures with CRISPR platforms, nanozymes, DNA amplification circuits, metal–organic frameworks, and nanointerfacial engineering strategies. Importantly, this review establishes a structure–performance framework correlating G4 topological features and kinetic behaviors with analytical outcomes. Current limitations, including structural polymorphism, ionic dependence, reproducibility issues, and limited quantitative predictability, are critically discussed. Finally, future opportunities in adaptive biosensing, intelligent molecular interfaces, and AI-assisted structural design are highlighted. This review establishes a quantitative structure–performance framework by correlating G4 structural descriptors, conformational energetics, kinetic parameters, and analytical outputs, providing a basis for predictive design of G4-based sensing systems.

This work presents a G-quadruplex heme chloride DNA peroxidase biosensing system. To address the instability and strong background signal issues in visual H₂O₂ detection, a G-quadruplex was prepared by using four trimeric DNA strands, and hemin was attached via covalent binding. The covalent binding significantly improved the color rendering effect and reduced the background signal. Four types of single-stranded DNA were compared for catalytic activity, with (GGGA)3 showing the best performance. The system was successfully applied to detect H₂O₂ in human serum, reaching a minimum detection concentration at the nanomolar level. This study provides valuable data for selecting single-stranded DNA in G-quadruplex preparation and holds potential for visual H₂O₂ detection in biomedicine and various industrial fields.

Aptamer-based electrochemical biosensors (AEBs) have emerged as a highly promising platform for disease diagnostics, offering high specificity, sensitivity, and real-time detection capabilities.

Hydrogen, as a clean and renewable energy source, offers a solution to the global energy crisis and environmental challenges. Among the many methods of hydrogen production, electrolysis of water is an efficient and sustainable hydrogen production technology. However, at the anode of electrolyzed water, the slow kinetics of oxygen evolution reaction and high energy consumption limit the development of electrocatalytic water decomposition. In order to meet this challenge, researchers have explored and developed better‐performing electrocatalysts and alternative oxidation reactions. This paper reviews the latest progress of coupled electrocatalytic hydrogen production strategies, such as oxidation of small molecules to produce value‐added products, oxidation of urea and hydrazine as sacrificial agents to assist hydrogen evolution, and upgrading, recycling, and degradation of waste. The catalytic mechanism of nickel‐based catalysts is mainly discussed. Finally, the development of energy‐saving electrolysis of water for hydrogen production is prospected.