Biopolymer-mediated metallic nanomaterials: recent advancements, current challenges and future outlooks

Metallic biopolymer-based nanomaterials have emerged as a sustainable and versatile class of hybrid nanostructures, offering environmentally benign alternatives to conventionally synthesized nanomaterials. This review provides a comprehensive and critical assessment of recent advances in metallic and metal oxide nanomaterials engineered using natural biopolymers, including polysaccharides, proteins and nucleic acid derivatives. Particular emphasis is placed on the fundamental interactions between biopolymers and metal ions or atoms, where coordination through polar functional groups governs nucleation dynamics, particle growth, morphology, crystallinity, surface chemistry and colloidal stability. The review systematically discusses the fabrication of diverse biopolymer-metal architectures, including biopolymer-mediated nanoparticles, biopolymer@MOFs, nanogels and nanotubular systems, together with widely employed synthetic approaches such as in situ polymerization, template-assisted assembly, melt intercalation and solution-phase methodologies. Structure-property relationships are critically correlated with functional performance across a broad spectrum of applications, including antimicrobial platforms, food packaging, catalysis, environmental remediation, sensing, biomedicine, drug delivery and energy-related technologies. Emerging strategies involving hierarchical nanoarchitectures, bioinorganic hybrid interfaces and stimuli-responsive biopolymer matrices are further highlighted as promising avenues for next-generation multifunctional materials. Finally, the review critically addresses the major challenges associated with scalability, reproducibility, mechanistic understanding and long-term stability, while outlining future perspectives for translating biopolymer-based metallic nanomaterials from laboratory-scale innovation to practical and industrial applications.