The demand for real-time monitoring of human health is of great significance with the revolutionary development of science and technology. Lactate is a major analyte in bioprocess engineering, sports medicine and clinical care unit, and it is also a reliable biomarker referring to tumor generation, metastasis and recurrence. Thus, it is very important to develop portable biosensors with good performance for monitoring the lactate content in body fluids for healthcare and cancer treatment.
Living materials are a new type of biohybrid material consisting of living elements (bacteria, mammalian cells, fungi and algae, etc.) and artificial functional materials. Benefiting from the combination of their respective advantages, living materials are well used for biosensing, biosynthesis, and biomedical diagnosis. Conjugated polymers (CPs) are characterized by a delocalized electronic structure that allows electron transfer along the backbone. By further modification of the CP backbone using water-soluble side chains, a series of novel water-soluble conjugated polymers (WSCPs) were designed and synthesized with excellent water-solubility, photoelectric property and biocompatibility. WSCPs are expected to be good artificial functional materials for constructing living materials and bioelectronic devices.
A research team led by Prof. WANG Shu and Prof. BAI Haotian from the Institute of Chemistry, Chinese Academy of Sciences (ICCAS) recently constructed a living material with cationic polythiophene (PMNT) and Shewanella oneidensis MR-1. The PMNT could contribute to the biofilm formation and optimize bioelectronic process inside S. oneidensis MR-1, thus, the constructed living materials could accelerate the oxidization process from lactate and enhance the outward electron transfer rate. The living material is then employed to fabricate a flexible bioelectronic device for lactate detection in physiological fluids (sweat, urine and plasma) and tumor cell through further functional module integration and engineering technology processing. All the collected electrical signals by the flexible bioelectronic device could be further wirelessly transferred to a portable smartphone for reading and analyzing.
This work provides a new strategy that integrated the biological activity of living cells and the optoelectronic properties of CPs for preparing living materials. The flexible and wearable electronic devices based on the new living materials will have good potential applications for personal health monitoring in the future.
The study was published in Science Advances (DOI: 10.1126/sciadv.abo1458) . 

Schematic diagram of PMNT-based living material and bioelectronic device for monitoring
lactate in physiological fluids (sweat, urine, and plasma) and counting tumor cells
(Image by WANG Zenghao)

Contact: 
Prof. WANG Shu
Prof. BAI Haotian
Institute of Chemistry, Chinese Academy of Sciences
Email: wangshu@iccas.ac.cn
Email: baihaotian@iccas.ac.cn