E-seed skin: a carbohydrate-protein hybrid nanostructure for delayed germination and accelerated growth

The main purpose of the seed industry is to cater seeds with desired strength and viability, for which seed coating is a basic requirement. Herein, a hybrid coating of an electrosprayed protein (collagen) on electrospun nanofibers having a multidentate zinc-reinforced carbohydrate (pectin)/PVA composite (PVA/Pec/Zn/Col-NF) was developed. The zinc ensured covalent binding with the -OH in pectin/PVA in addition to the native galvanic binding between the polymers. Along with this, hydrogen bonding interactions between the -NH₂ groups of electrosprayed collagen and the -OH groups in PVA/pectin further enabled the formation of a highly stable nanostructure. Controlled electrodeposition of collagen nanoparticles on the PVA/Pec/Zn-NF led to a decreased surface roughness scale with enhanced moisture resistance. The humidity resistance of the coating and the participation of zinc as a nutrient delayed the germination by 8 days and accelerated the tomato seedling's growth by approximately two times, respectively. The presence of zinc in the coating formulation enabled oxidative stress protection by boosting the superoxide dismutase activity. Moreover, the fungal resistance of the coating enabled the seeds to germinate even in the presence of phytopathogens. Thus, the approach of using the developed PVA/Pec/Zn/Col-NF coating material to construct a tight packing without affecting viability of the seed demonstrates a pioneering seed coating technique for increasing global food security amidst climate change and global warming.