Boosting Conductive Bioplastic Applications with SpyCatcher–SpyTag Technology and Cellulose Scaffolds

Bioplastics offer eco-friendly alternatives to conventional plastics. This study aimed to expand the application scope of bioplastics by developing a functional material with enhanced conductivity. We recombined the SpyCatcher-SpyTag system from <i>Streptococcus pyogenes</i> with leghemoglobin from <i>Glycine max</i> to generate SpyCatcher-GmLegC₂-SpyTag, SpyCatcher-GmLegC₂-SpyCatcher, and SpyTag-GmLegC₂-SpyTag proteins, which assembled into a conductive polymer. This polymer exhibited electrical conductivity 2.5 times higher than free hemin in aqueous solution when mixed with hemin. For improved stability, SpyCatcher-GmLegC₂ was fused with a carbohydrate-binding module from <i>Clostridium cellulovorans</i> and integrated into bacterial cellulose scaffolds. The resulting composite showed a 141-fold increase in conductivity compared to free hemin and exhibited uniform, stable performance. This eco-friendly conductive bioplastic demonstrates strong potential for applications in wearable sensors, electronic devices, and sustainable conductive materials.