Ultrasound-assisted microwave carbonization of neem biomass for fluorescent carbon dots in integrated crop growth and pest management

The fall armyworm (Spodoptera frugiperda) poses a serious threat to global maize production, underscoring the urgent need for sustainable alternatives to synthetic agrochemicals. In order to create a multipurpose nano-agrochemical platform for combined crop protection and growth improvement, neem-derived fluorescent carbon dots (NCDs) with abundant surface functional groups were synthesized and evaluated for their multifunctional agricultural applications. Due to their consistent shape, graphitic characteristics, and abundance of surface functional groups, the resultant NCDs had improved bioactivity and high water stability. Strong insecticidal and feeding deterrent effects against S. frugiperda larvae were demonstrated by the synthesized NCDs, coupled with noteworthy antioxidant, antibacterial, and antifungal properties against important maize phytopathogens. Furthermore, studies on seed priming and foliar spray in both pot and field settings showed significant increases in maize production, biomass buildup, chlorophyll content, and germination while also lowering damage from pests. At moderate treatment doses, optimal physiological performance was indicated by a concentration-dependent response. Overall, this work demonstrates that ultrasonically produced neem carbon dots are a scalable, environmentally benign, and multipurpose nanoplatform that can simultaneously increase crop productivity and inhibit pests and diseases. The results lend credence to their possible use in precision-based and sustainable maize farming systems.