Photoresponsive DNA-Modified Magnetic Bead-Assisted Rolling Circle Amplification-Driven Visual Photothermal Sensing of Escherichia coli

Abstract

The development of facile, reliable, and accurate assays for pathogenic bacteria is critical to environmental pollution surveillance, traceability analysis, prevention, and control. Here, we proposed a rolling circle amplification (RCA) strategy-driven visual photothermal smartphone-based biosensor for achieving highly sensitive monitoring of Escherichia coli (E. coli) in environmental media. In this design, E. coli could specifically bind with its recognition aptamer for initiating the RCA process on a magnetic bead (MB). Owing to the cleaving of UV irradiation toward photoresponsive DNA on MB, the RCA products were released to further hybridize with near-infrared excited Cu x S-modified DNA probes. As a result, the photothermal signal was enhanced by RCA, while the background was decreased by UV irradiation and magnetic separation. The correspondingly generated photothermal signals were unambiguously recorded on a smartphone, allowing for an E. coli assay with a low detection limit of 1.8 CFU/mL among the broad linear range from 5.0 to 5.0 × 105 CFU/mL. Significantly, this proposed biosensor has been successfully applied to monitor the fouling levels of E. coli in spring water samples with acceptable results. This study holds great prospects by integrating a RCA-driven photothermal amplification strategy into a smartphone to develop accurate, reliable, and efficient analytical platforms against pathogenic bacteria pollutions for safeguarding environmental health.

AgAuS Quantum Dots as a Highly Efficient Near-Infrared Electrochemiluminescence Emitter for the Ultrasensitive Detection of MicroRNA

“…11,12 Therefore, the rapid and accurate detection of trace miRNA is particularly important to achieve early disease diagnosis. Over the years, nucleic acid amplification strategies (rolling circle amplification, 13 hybridization chain reaction, 14 catalytic hairpin assembly, 15 etc.) had been proposed and applied in the fabrication of biosensor for miRNA detection.…”

“…MicroRNA-222 (miRNA-222) played a critical role as a regulator of gene expression in some diseases such as liver cancer and rheumatoid arthritis, , whose expression was associated with toxic heavy metal exposure in the environment. , Therefore, the rapid and accurate detection of trace miRNA is particularly important to achieve early disease diagnosis. Over the years, nucleic acid amplification strategies (rolling circle amplification, hybridization chain reaction, catalytic hairpin assembly, etc.) had been proposed and applied in the fabrication of biosensor for miRNA detection.…”

Dual-Modal Bimetallic Nanozyme-Based Sensing Platform Combining Colorimetric and Photothermal Signal Cascade Catalytic Enhancement for Detection of Hypoxanthine to Judge Meat Freshness

“…It is known that a majority of artificial peroxidase-like nanozymes show more economical and robust catalytic activity than natural enzymes, which has exhibited great potential in developing efficient analytical techniques for food quality and safety analysis. − However, most of the peroxidase mimic-based assays usually required directly added H 2 O 2 to act as a coreactant for generating reactive oxygen species (ROS, e.g., • OH), thereby oxidizing the substrates to produce analytical signals for reporting the levels of targets. , Nevertheless, the poor stability of H 2 O 2 limits its practical application in onsite food quality and safety analysis. On this background, the self-supplying H 2 O 2 -facilitated cascade catalytic analytical system, which involves natural enzyme-assisted peroxidase-like nanozymes, has become a very promising way to improve the analytical stability of assays. , Recently, the unique light-to-heat photophysical conversion feature has exhibited great potential in developing a portable and low-cost visual sensing platform . Combining these properties, several researchers have successfully designed multienzymatic cascade systems for self-contained H 2 O 2 photothermal visualization.…”

Rapid Testing of Δ9-Tetrahydrocannabinol and Its Metabolite On-Site Using a Label-Free Ratiometric Fluorescence Assay on a Smartphone

“…Upon exposure to increasing amounts of targets, the green fluorescence gradually weakened and showed the reference red fluorescence, resulting in noticeable visualization in the fluorescence color from green to red (Scheme ). Owing to the advantages of smartphone-based sensing, − we fabricated a portable fluorescence device integrated with a color recognizer Python program for the rapid visualization of THC, which provides a promising approach for the quantitative detection of the consumption of THC on site. Moreover, this established ratiometric fluorescence sensor was successfully used in both urine and saliva samples.…”