Application of multi-metallic nanoparticles in agriculture: The more, the better?

Over the years, nanotechnology has emerged as an innovative and sustainable alternative to traditional agricultural practices. There have been a plethora of reports on the application of nanoparticles as nano fertilizers, nano pesticides, nano fungicides, nano herbicides, and nano biosensors for various agronomic troubleshooting. Nutrient-based nano-fertilizers have however been in the limelight because of the advantages they possess over conventional agro-chemicals. While most of the research to date has been directed towards the use of a single nutrient in the form of mono-metallic nanoparticles (MNPs), recently the focus has shifted towards the use of multi-metallic nanoparticles (MMNPs). Owing to the synergy offered by integrating more than one nutrient, multi-metallic nanoparticles appear to have a better and broader range of efficacy compared to their mono-metallic counterparts. The application of such multi-metallic nanoparticles in bio-medical, and microbial research has been well-documented but their application in agriculture is yet emerging. Therefore, in this review, we attempt to put forth the recent progress associated with the implementation of MMNPs in promoting plant growth and offering environmental stress resistance alongside bringing out the major research gaps and limitations that require immediate attention. The review also highlights the importance and associated risks with the use of such nanoparticles that might be insightful to drive the future research direction.