Porous materials nanohybridized with metal nanoparticles as substrates for enhancing SERS detection in food safety applications

Food safety is directly relevant to human health and has drawn the intense attention of the public. Surface-enhanced Raman scattering (SERS), as a rapid and facile technology, has been widely employed for food safety detection. SERS substrates, as an important part of this technology, greatly influence SERS performance. Currently, porous materials (PSM) nanohybridized with metal nanoparticles (MNPs) (PSM/MNPs) for serving SERS substrates have attracted great interest due to their excellent merits in the improvement of SERS sensitivity, specificity and stability, posing a great potential for rapid and in-situ detection for food contaminants in complex food matrixes. In this review, the types and synthesis methods of PSM available for the fabrication of SERS substrates, which include porous carbon (PC), porous silicon/silica (PS/PSiO2), metal-organic frameworks (MOFs), high polymer, semiconductor, cellulose and other porous materials are introduced and their nanohybridization methods with MNPs are discussed. In addition, recent applications of PSM/MNPs for enhancing SERS detection in food safety areas such as pesticide and veterinary drug residues, illegal additives, foodborne bacteria, mycotoxin, spoilage markers and heavy metals are also presented, and future challenges and potential solutions are finally detailed in the current review. Compared to non-porous materials, porous materials with high porosity and large surface specific area prevent MNPs from aggregation and increase the adsorption of the target analyte, leading to the improvement in stability and sensitivity of SERS substrates. Moreover, adjustable pore sizes in these substrates enable the selective absorption of specific molecules, blocking interference of big molecules. On the other hand, multiple scattering from the porous structure enhances SERS intensity, leading to high sensitivity for analytes. Recent applications in detecting various food hazards show the promising prospect of PSM/MNPs for sustainable, environmentally friendly and large-scale detection for ensuring food safety.