Handheld Platform for Sensitive Rosiglitazone Detection: Immunosensor Based on a Time-Based Readout Device

Abstract

The detection of rosiglitazone (RSG) in food is of great importance since the excessive intake of RSG could cause adverse effects on the human body. Although liquid chromatography–mass spectrometry and gas chromatography–mass spectrometry are the preliminary methods for the detection of hazardous materials in food, they are not suitable for point-of-care or on-site detection. Herein, a time-based readout (TBR) device with an application software (APP) controlled by a smart phone was developed for the sensitive and selective immunoassay of RSG. The homemade TBR device was based on a two-electrode system, where the immune molecule-modified glassy carbon electrode was used as the bioanode, and Prussian blue-modified FTO was used as the cathode. By using Au-modified octahedral Cu2O with high catalytic activity as mimetic peroxidase, an insulating layer was generated on the cathode by catalyzing 4-chloro-1-naphthol (4-CN) into benzo-4-chlorohexadienone (B4Q). The time to reach a fixed potential varied indirectly with the concentrations of RSG and was recognized by the APP, while the electrochromic property on the cathode was also correspondingly changed. Under optimum conditions, both the square root of the time and the chroma value of the electrochromism exhibited linear responses for the detection of RSG ranging from 5 × 10–10 to 5 × 10–7 g/L, while the limits of detection were 8.2 × 10–11 and 1.3 × 10–10 g/L, respectively. With easy operation and portability, this TBR device showed a promising application for point-of-care monitoring of hazardous materials in food or the environment.

Engineered DNAzyme Enables Homogeneous Detection of Cereulide via Polychromic Fluorescence Modality

“…The peroxidase activities of mixed-type hybrid structures depended on the ratio of the CD peak at 260 nm to that at 290 nm. 33 The peak intensities of G4 (+) DNAzyme at 264 and 290 nm were higher and lower, respectively, than those of G4 (0) DNAzyme (Figure 4A), which resulted in that the ratio of parallel to antiparallel structures of G4 (+) DNAzyme (3.48) was higher than the G4 (0) DNAzyme (2.18); thereby, the peroxidase activities of G4 (+) DNAzyme were stronger than G4 (0) DNAzyme. Furthermore, the impact of cereulide on the thermal stability of G4 DNAzyme was also assessed.…”

Efficient Nanozyme-Triggered Pressure Sensor for Point-of-Care Immunoassay: Visual Sensing and Time Readout Device

“…Thanks to the explosion of advanced biomaterials and manufacture technologies, innovative biosensors are developed with high sensitivity and portable instruments for food safety-related biomarkers. For example, many simple readout techniques such as timing, temperature, distance, weight, and pressure have been introduced in combination with immunoassays to identify different targets. Pressure is widely used as a classical physical principle to measure the process of chemical and biochemical reactions, since the small amount of gas produced by gas-producing reactions in a sealed device can significantly increase the pressure, which is conducive to improving the detection sensitivity and shortening the detection time .…”

DNA Nanomachine-Driven Heterogeneous Quadratic Amplification for Sensitive and Programmable miRNA Profiling

“…To address the limitations of HOQAC, the higher-order nucleic acid structures, such as track structures, spherical nucleic acids, and DNA nanomachines, were used as highentropy phase interfaces for constructing versatile heterogeneous quadratic amplification circuits (HEQACs). 13,14 Through the deliberate design of the nucleic acid structure, a series of biological functions, including signal exchange, amplification, and transduction, can be conferred upon the heterogeneous interface, thereby realizing the biomimetic property. In addition, the establishment of a localized high osmotic pressure difference facilitates rapid and directed movement of signal molecules, ultimately accelerating the efficient signal multiplication at the biomimetic heterogeneous interface.…”