A low-background fluorescent aptasensor for acetamiprid detection based on DNA three-way junction-formed G-quadruplexes and graphene oxide

Advancements in nanomaterial-based aptasensors for the detection of emerging organic pollutants in environmental and biological samples

The combination of nanomaterials (NMs) and aptamers into aptasensors enables highly specific and sensitive detection of diverse pollutants. The great potential of aptasensors is recognized for the detection of diverse emerging organic pollutants (EOPs) in different environmental and biological matrices. In addition to high sensitivity and selectivity, NM-based aptasensors have many other advantages such as portability, miniaturization, facile use, and affordability. This work showcases the recent advances achieved in the design and fabrication of NM-based aptasensors for monitoring EOPs (e.g., hormones, phenolic contaminants, pesticides, and pharmaceuticals). On the basis of their sensing mechanisms, the covered aptasensing systems are classified as electrochemical, colorimetric, PEC, fluorescence, SERS, and ECL. Special attention has been paid to the fabrication processes, analytical achievements, and sensing mechanisms of NM-based aptasensors. Further, the practical utility of aptasensing approaches has also been assessed based on their basic performance metrics (e.g., detection limits, sensing ranges, and response times).

Recent Developments in the Applications of GO/rGO-Based Biosensing Platforms for Pesticide Detection

Pesticides are often used in different applications, including agriculture, forestry, aquaculture, food industry, etc., for the purpose of controlling insect pests and weeds. The indiscriminate usage of pesticides poses a massive threat to food, environmental, and human health safety. Hence, the fabrication of a sensitive and reliable sensor for the detection of pesticide residues in agro products and environmental samples is a critical subject to be considered. Recently, the graphene family including graphene oxide (GO) and reduced graphene oxide (rGO) have been frequently employed in the construction of sensors owing to their biocompatibility, high surface-area-to-volume ratio, and excellent physiochemical, optical, and electrical properties. The integration of biorecognition molecules with GO/rGO nanomaterials offers a promising detection strategy with outstanding repeatability, signal intensity, and low background noise. This review focuses on the latest developments (2018 to 2022) in the different types of GO/rGO-based biosensors, such as surface plasmon resonance (SPR), fluorescence resonance energy transfer (FRET), and electrochemical-based techniques, among other, for pesticide analysis. The critical discussions on the advantages, limitations, and sensing mechanisms of emerging GO/rGO-based biosensors are also highlighted. Additionally, we explore the existing hurdles in GO/rGO-based biosensors, such as handling difficult biological samples, reducing the total cost, and so on. This review also outlines the research gaps and viewpoints for future innovations in GO/rGO-based biosensors for pesticide determination mainly in areas with insufficient resources.

G-quadruplex based biosensors for the detection of food contaminants

G-quadruplex (G4) is a very interesting DNA structure, commonly associated with cancer and its treatment. With flexible binding ability, G4 has been extended as a significant component in biosensors. On account of its simple operation, high sensitivity and low cost, G4-based biosensors have attracted considerable interest for the detection of food contaminants. In this review, research published in recent 5 years is collated from a principle perspective, that is target recognition and signal transduction. Contaminants with G4 binding capacity are illustrated, emerging G4-based biosensors including colorimetric, electrochemical and fluorescent sensors are also elaborated. The current review indicates that G4 has provided an efficient and effective solution for the rapid detection of food contaminants. A distinctive feature of G4 as recognition unit is the simple composition, but the selectivity is still unsatisfactory. As signal reporter, G4/hemin DNAzyme has not only achieved amplified signals, but also enabled visualized detection, which offers great potential for on-site measurement. With improved selectivity and visualized signal, the combination of aptamer and G4 seems to be an ideal strategy. This promising combination should be developed for the real-time monitor of multiple contaminants in food matrix.