Nanocarrier-Mediated RNAi: Breaking the dsRNA Delivery Bottleneck in Crop Protection

RNA interference (RNAi) offers a sequence-specific and sustainable strategy for crop protection, yet inefficient double-stranded RNA (dsRNA) delivery remains a major bottleneck for agricultural applications. Rapid environmental degradation, restricted penetration across biological barriers, and poor intracellular availability collectively constrain gene silencing outcomes. Nanocarriers can improve dsRNA stability, biological barrier penetration, cellular uptake, and intracellular release, but rational design principles for agricultural RNAi delivery are still lacking. This review systematically summarizes inorganic, organic, hybrid, and bioderived nanocarriers and establishes a barrier-guided design framework linking specific delivery obstacles with tailored physicochemical properties. Structure-activity relationships governing dsRNA protection, transport, uptake, and release are critically analyzed, together with key challenges associated with biological variability, scalability, biosafety, regulatory pathways, and field translation. Finally, we outline future directions for moving from laboratory proof-of-concept to field-deployable RNAi delivery systems, supporting the development of sustainable crop protection.