Recent global warming has resulted in shifting of weather patterns and led to intensification of natural disasters and upsurges in pests and diseases. As a result, global food systems are under pressure and need adjustments to meet the change—often by pesticides. Unfortunately, such agrochemicals are harmful for humans and the environment, and consequently need to be monitored. Traditional detection methods currently used are time consuming in terms of sample preparation, are high cost, and devices are typically not portable. Recently, Surface Enhanced Raman Scattering (SERS) has emerged as an attractive candidate for rapid, high sensitivity and high selectivity detection of contaminants relevant to the food industry and environmental monitoring. In this review, the principles of SERS as well as recent SERS substrate fabrication methods are first discussed. Following this, their development and applications for agrifood safety is reviewed, with focus on detection of dye molecules, melamine in food products, and the detection of different classes of pesticides such as organophosphate and neonicotinoids.

In this research, a selective, cost-efficient, highly sensitive Ag nanostructure Surface Enhanced Raman Spectroscopy (SERS) sensor was developed as a methodological approach to rapidly detect a targeted-ss-DNA (stx2) in STEC (Shiga toxin-producing Escherichia coli). The Ag nanostructure-based SERS substrate was functionalized by two type of thiols: thiol-ss-DNA for bonding targeted-ss-DNA and 6-Mercapto-1-hexanol (HS(CH2)6OH) for blocking the Ag nanostructure surface. Methylene Blue (MB) was used as a Raman marker to quantify targeted-ss-DNA, as well as a model molecule to characterize the electrodeposited Ag nanostructure SERS substrate. Ag nanostructure SERS substrates showed good sensitivity and repeatability towards MB detection, with a LOD = 0.3158 μM, RSD = 12.48% (at 45 different random points). More importantly, the Ag nanostructure/ss-DNA SERS substrate showed good selectivity towards STEC O157 stx2 targeted DNA, as well as good linearity and sensitivity towards its detection in a buffer solution. A limit of detection of 0.4900 aM in a wide linear range from 1 aM to 100 pM was demonstrated. The SERS sensors were able to identify target DNA ( stx2) in an STEC strain and the study showed proof of principle that SERS substrate has potential as a cost effective, highly selective, highly sensitive DNA and bacteria sensor without the aid of DNA amplification. With further development and validation, this methodological approach has the potential for use in the point-of-use detection for instance on a farm or in the food industry.