Engineering algal nanocellulose-reinforced PVA bioplastics for material-enabled seed coating processes

Algal nanocellulose (ANC) derived from Desmodesmus abundans offers a sustainable reinforcement material for biodegradable polymer systems. However, the use of microalgae-derived nanocellulose in polyvinyl alcohol (PVA) bioplastic films for agricultural seed coating applications remains largely unexplored. In this work, ANC was extracted through controlled acid hydrolysis, yielding 21.6% cellulose from algal biomass and exhibiting characteristic cellulose functional groups confirmed by FTIR, while crystallinity (82.77%) was determined using XRD. ANC-PVA composite films were fabricated using glycerol as a plasticizer and characterized for mechanical, structural, and thermal properties. RSM revealed that PVA had the strongest positive effect on tensile strength, while excessive ANC or glycerol reduced performance due to agglomeration and over-plasticization. The optimized formulation (PVA 1.5 g, ANC 0.3 g, glycerol 0.1 g), predicted through RSM, achieved a tensile strength of 5.02 MPa while maintaining balanced flexibility, whereas individual composite films exhibited higher tensile strength values under specific ANC loadings during mechanical testing. Application of the optimized film as a seed coating significantly enhanced germination performance; coated seeds exhibited 36% higher root length, 22% higher shoot length, and significant improvements from day 3 onward. These results establish ANC-PVA bioplastic films as an effective biodegradable seed-coating material with strong potential for sustainable agricultural applications.