Sustainable alternatives to petroleum-based micro/nanospheres: a systematic scoping review on biodegradable materials and applications

Adhering to PRISMA-ScR guidelines, this systematic review evaluates sustainable alternatives to petroleum-based micro/nanospheres. We classify biodegradable materials into natural, synthetic, and composite systems, analyzing their fabrication alongside diverse applications in cosmetics, biomaterials, environmental remediation, catalysis, and thermal energy storage. By addressing technical trade-offs, standardized testing, and critical research gaps, this work provides a strategic roadmap for engineering high-performance, eco-friendly microspheres to mitigate the global microplastic crisis and promote a circular bioeconomy.