Electronic biopolymers: From molecular engineering to functional devices

•The performance of biopolymers can be modified via molecular engineering.•Modified biopolymers are promising for advanced functional electronics.•Biopolymers are featured in low-cost, eco-friendly and large-scale fabrication.•Future challenges and developments of electronic biopolymers are proposed. Biopolymers with excellent biocompatibility, biodegradability, and multiple active sites have been widely used in biomedical fields. Currently, the unique electronic properties of biopolymers have been continuously exploited for designing wearable, implantable and biodegradable electronics. In the view of molecular engineering including molecular design and assembly and structural modification, this review provides a comprehensive overview of advanced biopolymers related to energy, sensors, displays and bionic devices, and indicates the important roles of structural modification on tuning device performance. In addition, representative printing technologies are discussed to highlight their features in low-cost, eco-friendly and scalable-up fabrication of biopolymer electronics. Furthermore, the current challenges and future opportunities are prospected to point out how electronic biopolymers will be modified or developed for next-generation flexible and wearable bioelectronics.