The growing concern over heavy metal contamination in environmental and industrial settings has intensified the need for sensitive, selective, and cost-effective detection technologies. Electrochemical sensors, due to their high sensitivity, rapid response, and portability, have emerged as promising tools for detecting heavy metals. Recent years have seen significant progress in utilizing biopolymer-based materials to enhance the performance of these sensors. Biopolymers, derived from renewable raw materials, have garnered considerable interest in both science and industry. These biopolymer-based composites are increasingly recognized as superior alternatives to conventional non-biodegradable materials because of their ability to degrade through environmental exposure. This review provides a comprehensive overview of recent advancements in biopolymer-based electrochemical sensors for heavy metal detection. It discusses various types of biopolymers and bio-sourced polymers, their extraction methods, and chemical properties. Additionally, it highlights the state of the art in applying biopolymers to electrochemical sensor development for heavy metal detection, synthesizing recent advances and offering insights into design principles, fabrication strategies, and analytical performance. This review underscores the potential of biopolymer-based sensors as cost-effective, eco-friendly, and efficient tools for addressing the pressing issue of heavy metal contamination in water and discusses their advantages and limitations. It also outlines future research directions to further enhance the performance and applicability of these sensors.

Boron-doped diamond electrode surfaces were modified by a polyphenol—polyvinyl chloride membrane. The polyphenols were extracted from the skin of acorns, the fruit of the oak tree. The polymer film was applied on the boron-doped diamond electrode surface by solvent evaporation. The resulting polyphenol–polyvinyl chloride–boron-doped diamond electrode was used as a sensor for cadmium, lead, and nickel. The synergy between the chemically modified surfaces and electrochemical performances of the boron-doped diamond microcell electrode was examined by differential pulse anodic stripping voltammetry at nanomolar concentrations of the three metal ions. The modified electrode provided a stable, sensitive, and selective response to cadmium, lead(II), and nickel(II) ions. The resulting detection limits were 0.0221, 0.25, and 0.00424 nmole L⁻¹, respectively.