The cell-free biosensor is a tool designed to detect trace substances based on a cell-free system, which solves the problems of the traditional cell-based biosensor including having no ability to detect toxic substances, long response time, being controlled by living cells, and inconvenient operation. In recent years, cell-free biosensors have attracted extensive attention for their wide detection range, fast response speed, high sensitivity and portability. In this paper, the construction and characteristics of different types of cell-free sensors are reviewed. In addition, their applications in the detection of metal ions, pesticide residues and veterinary drug residues are introduced, and future prospects also are discussed.

A gold@platinum (Au@Pt) nanozyme-based test strip for the convenient and sensitive detection of hydrogen peroxide residues in foods was developed using Whatman No.1 filter paper as the carrier, Au@Pt nanozyme as the catalyst, 3,3’,5,5’-tetramethylbenzidine as the color developer, and acetic acid-sodium acetate solution at pH 4.6 as the buffer system. The optimized test strip soaking time was 10 s. The test paper could detect hydrogen peroxide in samples within 3 min with a minimum detection limit of 0.34 mg/kg and a good linearity (R² = 0.9931). The test paper is easy to make, highly accurate, stable and simple to operate, and can be used in the real-time on-site detection of food products in various distribution channels.

Gluten-induced celiac disease (CD) is a serious autoimmune disorder whose symptoms in most gluten-sensitive populations can only be relieved by strict lifelong adherence to a gluten-free diet (GFD). Sensors for immediate, on-site and quick detection of the gluten content in foods can effectively ensure the quality of life of gluten-sensitive people. In this article, gluten sensitivity and the pathogenesis of CD are introduced, and the recognition principle of gluten detection biosensors is elaborated. Finally, the application scenarios of biosensors with three different types of signal output: colorimetry, fluorescence and electrochemistry for the rapid detection of gluten in foods are summarized in order to provide a basis for research on sensors for the rapid detection of gluten in foods.