Colorimetric based on-site sensing strategies for the rapid detection of pesticides in agricultural foods: New horizons, perspectives, and challenges

Background Food quality and safety are very important from health as well as fiscal point of view. Surface-enhanced Raman spectroscopy (SERS) techniques have unique advantages in the field of food detection , with characteristics of fast analysis speed, high detection sensitivity, and without interference from the water phase. Scope and approach In this review, recent and potential advances in the application of SERS in food safety and quality from the perspective of SERS substrate and SERS composite systems are addressed. SERS systems such as molecular labeling, immunochromatographic assay, microfluidics, molecularly imprinted polymers, colorimetry and imaging are discussed, and their main advantages and limitations are highlighted. The applications of SERS in food safety are reviewed critically, with focus on the detection of microorganisms, pesticides, metal ions and antibiotics. Furthermore, applications of SERS in food quality regarding food freshness and ingredients are discussed. Key findings and conclusions SERS technology has been widely used in food testing, but it still has shortcomings. In order to establish SERS as a routine tool for the monitoring of food safety and quality, future research should focus on minimizing technical costs, standardizing experimental protocols, developing new SERS substrates, and integrating SERS with other methods to overcome its shortcomings.

Evolving trends in SERS-based techniques for food quality and safety: A review

Recent progress in immunosensors for pesticides

Lateral flow assays (LFAs) provide some of the most attractive point-of-care instruments for broad applications with simple, rapid, user-friendly, and cost-effective characteristics. However, these technologies suffer from low sensitivity, the poor limit of detection, and just qualitative or semi-quantitative results that restrict their practical applications. Extensive research has been reported in this area involving sensitivity enhancement, multiplex analysis, the implementation for broad analytes, and development of novel electronic readers for quantitative analysis. This review presents recently reported works for the structural improvements of LFAs considering antibody immobilization, manipulation of the membrane, structural variants of LFAs, and single and dual detection mode LFAs, all these aspects focused on the visual, fluorescent, magnetic, surface-enhanced Raman scattering, electrochemical, and nanozyme-based detection.

Recent advancements in structural improvements of lateral flow assays towards point-of-care testing

This review (with 187 refs.) summarizes the progress that has been made in the design of lateral flow biosensors (LFBs) based on the use of micro- and nano-materials. Following a short introduction into the field, a first section covers features related to the design of LFBs, with subsections on strip-based, cotton thread-based and vertical flow- and syringe-based LFBs. The next chapter summarizes methods for sample pretreatment, from simple method to membrane-based methods, pretreatment by magnetic methods to device-integrated sample preparation. Advances in flow control are treated next, with subsections on cross-flow strategies, delayed and controlled release and various other strategies. Detection conditionst and mathematical modelling are briefly introduced in the following chapter. A further chapter covers methods for reliability improvement, for example by adding other validation lines or adopting different detection methods. Signal readouts are summarized next, with subsections on color-based, luminescent, smartphone-based and SERS-based methods. A concluding section summarizes the current status and addresses challenges in future perspectives. Graphical abstractRecent development and breakthrough points of lateral flow biosensors.

Lateral flow biosensors based on the use of micro- and nanomaterials: a review on recent developments

Here we describe a surface-enhanced Raman scattering (SERS)-based immunochromatographic assay (ICA) method for the dual detection of two pyrethroid pesticides cypermethrin and esfenvalerate. In the proposed ICA-SERS methods, antibody conjugated gold nanoparticles (AuNPs) were used as the SERS substrate while fluorescence tags labeled on AuNPs were used as the Raman reporters for SERS. Through the immuno-specific combination of antigen and antibody, Raman reporter labeled AuNPs were immobilized on the test line of the ICA strip and facilitated the SERS measurement. And by immobilizing two test lines designed for the detection of two pesticides, a simultaneous dual detection was accomplished. The LODs of the ICA-SERS system was 2.3 × 10−4 and 2.6 × 10-5 ng/mL for cypermethrin and esfenvalerate, respectively. The sensitivity was 3 to 4 times higher than ELISA and fluorescent-based ICA methods using the same indirect competitive immunoassay methods. For the three types of samples (tap water, river water, and milk), the recoveries ranged from 94.9% to 112%, with RSD values ranged from 1.3% to 13.5%. The research reveals that this ICA-SERS method possesses high specificity, sensitivity, and reproducibility, and can be reliably used to detect dual pesticides in real samples. An R Shiny-based application 2plex-speclysis was built and used for all the data analyses in this paper. The application was designed to incorporate all the analyses including spectral preprocessing, performance evaluation, and PCA analysis, and make the spectral analysis accessible for people without programming experience.

Jinghai Zhu

Papers

Surface-enhanced Raman spectroscopy (SERS)-based immunochromatographic assay (ICA) for the simultaneous detection of two pyrethroid pesticides