Aptamer-based DNA-catalyzed amplification strategy for sensitive fluorescence resonance energy transfer detection of Acinetobacter baumannii

Biosensor development for diabetes diagnosis: Determining relevant miRNA using a newly developed N-annulated perylene fluorescent dye

MicroRNAs (miRNAs) have emerged as essential biomarkers for disease diagnosis, and several techniques are available to determine type 2 diabetes (T2D) relevant miRNAs. However, detecting circulating miRNAs can be challenging due to their small size, low abundance, and high sequence similarity, often requiring sensitive detection approaches combined with additional amplification processes. Laser-induced fluorescence (LIF) is a classic analytical method suitable for sensitively detecting trace amounts of nucleotide acid. Duplex-specific nuclease (DSN)-mediated amplification recently gained attention due to its catalytic activity based on target recycling, demonstrating a promising approach for miRNA amplification. This work developed a novel N-annulated perylene fluorescent dye to create a biosensor to analyze the miRNA (miR-223) relevant to T2D. The amine-reactive fluorescent dye assists the amidation reaction for nucleotide labeling, giving the oligonucleotide probe a high fluorescence quantum yield and sufficient water solubility. By combining the locked nucleic acid (LNA) modified oligonucleotide fluorescent probe to enhance the stability of LNA/RNA hybrids, thereby improving the DSN-mediated target miR-223 recycling for signal amplification, the proposed biosensor can highly selectively determine miR-223 with a limit of detection (LOD, S/N = 3) of 9.5 pM. When applied to real-world samples, the biosensor demonstrated its potential to distinguish between T2D patients and healthy controls.

Advances in signal amplification strategies applied in pathogenic bacteria apta-sensing analysis-A review

Pathogenic bacteria are primarily kinds of food hazards that provoke serious harm to human health via contaminated or spoiled food. Given that pathogenic bacteria continue to reproduce and expand once they contaminate food, pathogenic bacteria of high concentration triggers more serious losses and detriments. Hence, it is essential to detect low-dose pollution at an early stage with high sensitivity. Aptamers, also known as "chemical antibodies", are oligonucleotide sequences that have attracted much attention owing to their merits of non-toxicity, small size, variable structure as well as easy modification of functional group. Aptamer-based bioanalysis has occupied a critical position in the field of rapid detection of pathogenic bacteria. This is attributed to the unique advantage of using aptamers as recognition elements in signal amplification strategies. The signal amplification strategy is an effective means to improve the detection sensitivity. Some diverse signal amplification strategies emphasize the synthesis and assembly of nanomaterials with signal amplification capabilities, while others introduce various nucleic acid amplification techniques into the detection system. This review focuses on a variety of signal amplification strategies employed in aptamer-based detection approaches to pathogenic bacteria. Meanwhile, we provided a detailed introduction to the design principles and characteristics of signal amplification strategies, as well as the improvement of sensor sensitivity. Ultimately, the existing issues and development trends of applying signal amplification strategies in apta-sensing analysis of pathogenic bacteria are critically proposed and prospected. Overall, this review discusses from a new perspective and is expected to contribute to the further development of this field.

Programmable electrochemical biosensing platform based on catalytic hairpin assembly and entropy-driven catalytic cascade amplification circuit

Herein, powerful DNA strand displacement reaction and sensitive electrochemical analysis method were ingeniously integrated to develop a programmable biosensing platform. Using DNA as the detection model, a cascade amplification system based on catalytic hairpin assembly and entropy-driven catalytic was constructed, and the reaction rate and signal amplification effect were significantly improved. The product of the cascade amplification circuit could undergo strand displacement reaction with the signal probe on the electrode surface to obtain sensitive electrochemical signal changes and realize highly sensitive detection of the target. In addition, without redesigning the DNA sequences in the cascade amplification circuit, the by-product strand typically wasted in traditional entropy-driven catalytic reactions can be fully utilized to construct a single-signal output biosensing system and even a dual-signal output ratiometric biosensing platform, improving the detection repeatability and reliability of the system, and expanding the application of DNA strand displacement reaction in electrochemical biosensing. Furthermore, benefiting from the design flexibility of the DNA molecules, the constructed biosensing platform realized the sensitive detection of aptamer substrate (kanamycin as an example) and certain metal ion (mercury as an example) by simply recoding the corresponding recognition sequence, demonstrating the good versatility of the biosensing platform.